Even for stainless steel pipe, there are lots of types for it. Different treatment for them would give them various functions. Today, we’d like to share the process treatment for food, beverage and other sanitary stainless tube’s.
Three main kinds would be here for stainless steel pipes used for food and beverage transmission: surface finish, oil ban and passivation layer.
Surface finish: Inner and outer surface should be polished bright to guarantee the quality of the pipeline. The special goal is to prevent the fluid material in the tube from forming a wall in the tube, which is prone to contamination and forms a tube blockage.
Passivation layer: Stainless steel pipe needed to be placed in a passivation tank for immersion after polishing, thus, we can get the purpose of corrosion resistance of the steel pipe
Oil ban: When we finished passivation, we will test with a grease analyzer, so we can prevent the oil pollution of the pipe wall itself from contaminating the fluid material in the pipe.
2018年12月26日星期三
Five reasons to buy PE coated steel tubes
PE coated steel pipe, whether used for water supply like ERW steel pipe or oil transmission like seamless tube, is popular for customers nowadays. There are five common reasons to purchase this kind of tube.
PE coated steel pipe has three classifications which are PE Coated Pipe, 2PE Coated Pipe, and 3PE Coated Pipe. The advantages by using them are:
Strong protective layer: With coated process, you would laud the protective function for the steel pipeline.
Long term chemical and mechanical resistance: Due to the layer, it will elucidate the long term effect for the steel tube.
High mechanical impact strength and penetration resistance: Same reason with the second point, and you will find that the pipe would be tardy in working environment.
Increases life span of pipes more than 25yers.
Economy in the long term due to less repairing/re-working.
PE coated steel pipe has three classifications which are PE Coated Pipe, 2PE Coated Pipe, and 3PE Coated Pipe. The advantages by using them are:
Strong protective layer: With coated process, you would laud the protective function for the steel pipeline.
Long term chemical and mechanical resistance: Due to the layer, it will elucidate the long term effect for the steel tube.
High mechanical impact strength and penetration resistance: Same reason with the second point, and you will find that the pipe would be tardy in working environment.
Increases life span of pipes more than 25yers.
Economy in the long term due to less repairing/re-working.
Six maintenance methods for stainless steel tubes
For stainless seamless steel pipe, there are some basic methods for the care of it to extend the service life of stainless steel. By preventing contact with corrosive substances would be one of them. And if we follow these best practices when working with stainless steel, we will get better result.
There are seven common ways to care of the stainless steel pipe.
1. Using stainless steel tools and components always would be necessary.
2. Avoid any contact with carbon steels, concrete detergents or iron.
3. Do not weld, cut, drill or grind carbon steel near stainless steel.
4. When power washing nearby surfaces, wrap stainless steel with plastic.
5. If chloride solutions or concrete detergents contact stainless steel, rinse immediately.
6. Never scrub with steel wool or other abrasive scrubbing pads.
With careful protect for stainless steel pipe, clients will use them for a relative long time for engineering project.
There are seven common ways to care of the stainless steel pipe.
1. Using stainless steel tools and components always would be necessary.
2. Avoid any contact with carbon steels, concrete detergents or iron.
3. Do not weld, cut, drill or grind carbon steel near stainless steel.
4. When power washing nearby surfaces, wrap stainless steel with plastic.
5. If chloride solutions or concrete detergents contact stainless steel, rinse immediately.
6. Never scrub with steel wool or other abrasive scrubbing pads.
With careful protect for stainless steel pipe, clients will use them for a relative long time for engineering project.
Meet steel pipe material expectations
As a ERW steel pipe manufacturer, our manager would think the question of how to produce high quality steel tube for customers often. She said it is really simple actually. Following the trend and meeting steel pipe’s material expectations, you will find a new product world for your customers.
No matter which kind of method we are trying to make the high quality steel pipe, we cannot ignore the steel pipe's intrinsic quality for relative pipeline. Once we take control of material proportion, such as stainless and nickel; temperature, length and width, we should look into the essence of a steel pipeline.
Importance of chemistry. We should view each type of stainless and nickel alloy scrap as a distinct blend of nickel, chrome, molybdenum, and iron and each individual alloy is its own blend.
Consistency of compatibility. Their ability to supply materials consistently—both in terms of quantity and quality—is why they have exclusive supply arrangements with stainless mills and specialty foundries.
No matter which kind of method we are trying to make the high quality steel pipe, we cannot ignore the steel pipe's intrinsic quality for relative pipeline. Once we take control of material proportion, such as stainless and nickel; temperature, length and width, we should look into the essence of a steel pipeline.
Importance of chemistry. We should view each type of stainless and nickel alloy scrap as a distinct blend of nickel, chrome, molybdenum, and iron and each individual alloy is its own blend.
Consistency of compatibility. Their ability to supply materials consistently—both in terms of quantity and quality—is why they have exclusive supply arrangements with stainless mills and specialty foundries.
Selection of inspection techniques for seamless steel pipe
Six billet inspection techniques have been listed in essays before. And today, we’d like to discuss the selection of inspection techniques for seamless steel pipe. As we know that not each of them has equal role during the whole inspection.
Actually, there are three of the methods would have more useful for the continuously cast billets than others. They are eddy currents techniques, optical techniques, and microwave techniques.
The optical system can resolve the smaller defective areas, for example, pinholes. Of course, it is also used for responding to other types of defects which show up in relief under the incident lighting conditions.
The microwave system has the benefit of reasonable operating clearances (of the order of 30 mm) and usually resolve large area defects and, both longitudinal and transverse cracks of the order of 10 mm or more in length.
The eddy current probe array on the other hand have to be positioned closer to the surface, at say 3 mm, but is capable of better resolution in the detection of transverse cracks, teeming arrests, reciprocation marks, etc. than the microwave technique.
Actually, there are three of the methods would have more useful for the continuously cast billets than others. They are eddy currents techniques, optical techniques, and microwave techniques.
The optical system can resolve the smaller defective areas, for example, pinholes. Of course, it is also used for responding to other types of defects which show up in relief under the incident lighting conditions.
The microwave system has the benefit of reasonable operating clearances (of the order of 30 mm) and usually resolve large area defects and, both longitudinal and transverse cracks of the order of 10 mm or more in length.
The eddy current probe array on the other hand have to be positioned closer to the surface, at say 3 mm, but is capable of better resolution in the detection of transverse cracks, teeming arrests, reciprocation marks, etc. than the microwave technique.
2018年12月20日星期四
Defects in pickling seamless steel tubes
In the case of pickling, the seamless steel pipe has a stripping effect on the iron oxide scale, and also diffuses into the interior of the steel billet matrix and accumulates at the impurities or pores, resulting in an increase in internal stress, a decrease in the plasticity of the steel, and an increase in the brittleness of the steel. The effect is called hydrogen embrittlement. Hydrogen embrittlement is mainly affected by the diffusion rate of hydrogen atoms. The rate of hydrogen diffusion is related to the following factors:
1) The diffusion rate of hydrogen in a sulfuric acid solution is higher than that in a hydrochloric acid solution.
2) As the pickling temperature increases, the diffusion rate of hydrogen increases sharply, and the concentration of acid increases, and the diffusion rate of hydrogen does not increase much. Therefore, it is best not to pickle at low concentrations and high temperatures. This is a must for both seamless and oil casings.
3) Some inclusions in pickling such as arsenic (As), antimony (Sb), hydrogen sulfide (H2S) and sulfur dioxide (SO2) increase the diffusion rate of hydrogen atoms, ie increase the possibility of hydrogen embrittlement.
4) The chemical composition of steel also has an effect on the diffusion of hydrogen atoms. The measures to prevent hydrogen embrittlement are to operate according to the specified acid concentration and temperature, to minimize the pickling time, and to add corrosion inhibitors in accordance with the amount.
There is still a scale of iron oxide on the surface of the slab after pickling, which is called under-picking. Under-picking can be divided into all under-picking and partial under-washing depending on the cause. The reason for causing all the acid pickling is that the pickling time is short, the acid concentration is low, or the temperature is low; the reason for causing partial under pickling is that there is no horn on the material or oil on the surface of the steel billet. Under-pickling can be saved by continuing to pickle.
When it is pickled and carbon steel is pickled, the surface is rough and the color is dark. When the chrome stainless steel is pickled, the surface is gray and extremely rough. In severe cases, there is a circular hole with a certain depth - pinhole. The reason for the pickling is that the acid temperature is too high, the pickling time is too long, or the acid concentration is too high. Once this defect is unrecoverable, it has a detrimental effect on the performance of the steel. The acid-washed steel is easily stuck or broken during the rolling process.
After pickling, in addition to the iron salt remaining on the surface of the slab, there is a residue consisting of oxides or salts of other elements in the steel. These residues are not good for cleaning the surface defects of the slab. If it is not washed out in time, the surface of the slab will continue to rust and appear yellow.
1) The diffusion rate of hydrogen in a sulfuric acid solution is higher than that in a hydrochloric acid solution.
2) As the pickling temperature increases, the diffusion rate of hydrogen increases sharply, and the concentration of acid increases, and the diffusion rate of hydrogen does not increase much. Therefore, it is best not to pickle at low concentrations and high temperatures. This is a must for both seamless and oil casings.
3) Some inclusions in pickling such as arsenic (As), antimony (Sb), hydrogen sulfide (H2S) and sulfur dioxide (SO2) increase the diffusion rate of hydrogen atoms, ie increase the possibility of hydrogen embrittlement.
4) The chemical composition of steel also has an effect on the diffusion of hydrogen atoms. The measures to prevent hydrogen embrittlement are to operate according to the specified acid concentration and temperature, to minimize the pickling time, and to add corrosion inhibitors in accordance with the amount.
There is still a scale of iron oxide on the surface of the slab after pickling, which is called under-picking. Under-picking can be divided into all under-picking and partial under-washing depending on the cause. The reason for causing all the acid pickling is that the pickling time is short, the acid concentration is low, or the temperature is low; the reason for causing partial under pickling is that there is no horn on the material or oil on the surface of the steel billet. Under-pickling can be saved by continuing to pickle.
When it is pickled and carbon steel is pickled, the surface is rough and the color is dark. When the chrome stainless steel is pickled, the surface is gray and extremely rough. In severe cases, there is a circular hole with a certain depth - pinhole. The reason for the pickling is that the acid temperature is too high, the pickling time is too long, or the acid concentration is too high. Once this defect is unrecoverable, it has a detrimental effect on the performance of the steel. The acid-washed steel is easily stuck or broken during the rolling process.
After pickling, in addition to the iron salt remaining on the surface of the slab, there is a residue consisting of oxides or salts of other elements in the steel. These residues are not good for cleaning the surface defects of the slab. If it is not washed out in time, the surface of the slab will continue to rust and appear yellow.
How to solve the shortage of cold drawn seamless steel pipe
Hot-rolled tube blanks in cold-drawn seamless steel tubes may have defects such as cracks. At the same time, the resulting cylinders may break during use and deform, generally brittle fractures. There are many reasons, generally grain boundaries. Precipitates, this needs to be changed by some means. In order to solve the problem of cold drawn seamless steel pipe, foreign countries generally improve the performance of alloy materials by general, and generally require stress relief annealing to eliminate residual stress of materials, improve material structure, and improve plastic materials to prevent seamless steel pipe breakage. The purpose of the failure.
At present, the material of the cold drawn seamless steel pipe is common steel, silicon manganese, steel, and the strength of the metal is improved by cold drawing deformation, but it increases the plasticity and toughness cost of the metal. Due to the high precision of cold drawn seamless steel tubes, high-strength performance based on the market is required. It is necessary to ensure deformation within a certain range, maximize the performance of materials, and reduce the adverse effects of materials.
Cold drawn seamless steel pipe deformation is too small, can not meet the requirements of surface finish and dimensional accuracy, can not reach the strength of the index component, deformation is too large, resulting in too much plasticity and toughness of the steel pipe, and the article is too thin, the formed fiber The metal will have significant anisotropy. The grain of the spin direction of the shaft increases the strength in parallel. The radial direction of the cold drawn seamless steel pipe is perpendicular to the rotation direction of the grain, but the strength is decreased, and the stress of the hydraulic cylinder is excessively deformed in the radial direction of the seamless steel pipe. So, the performance of the cold drawn tube is fully utilized.
http://www.xysteelpipe.com/info/How-to-solve-the-shortage-of-cold-drawn-seamless-steel-pipe-1296-1.htm
At present, the material of the cold drawn seamless steel pipe is common steel, silicon manganese, steel, and the strength of the metal is improved by cold drawing deformation, but it increases the plasticity and toughness cost of the metal. Due to the high precision of cold drawn seamless steel tubes, high-strength performance based on the market is required. It is necessary to ensure deformation within a certain range, maximize the performance of materials, and reduce the adverse effects of materials.
Cold drawn seamless steel pipe deformation is too small, can not meet the requirements of surface finish and dimensional accuracy, can not reach the strength of the index component, deformation is too large, resulting in too much plasticity and toughness of the steel pipe, and the article is too thin, the formed fiber The metal will have significant anisotropy. The grain of the spin direction of the shaft increases the strength in parallel. The radial direction of the cold drawn seamless steel pipe is perpendicular to the rotation direction of the grain, but the strength is decreased, and the stress of the hydraulic cylinder is excessively deformed in the radial direction of the seamless steel pipe. So, the performance of the cold drawn tube is fully utilized.
http://www.xysteelpipe.com/info/How-to-solve-the-shortage-of-cold-drawn-seamless-steel-pipe-1296-1.htm
2018年12月19日星期三
The main difference between stainless steel pipe and carbon steel pipe
Carbon steel seamless pipe is often referred to as carbon structural steel. It is iron, carbon and manganese as the main elements except C. It is not divided into other alloying elements. It is mainly divided into 10# seamless steel pipe, 20 # seamless steel pipe, 45# seamless steel pipe, of course, C is also controlled to a certain extent, and the hardness is larger than pure iron. Carbon steel has low cost, is prone to rust, and has a short use time, and is used in various structures and pipes that do not have any corrosion resistance.
Stainless steel pipe refers to alloy steel containing less than or equal to 13% Cr and not in the atmosphere. There are many types of stainless steel, such as ferritic stainless steel, austenitic stainless steel, and martensitic stainless steel. Different stainless steels have different resistance to corrosion and different corrosion resistance to different media. It is also different in terms of magnetism. Carbon steel is magnetic, and stainless steel generally does not have magnetic or magnetic properties.
The stainless steel tube contains a large amount of chromium, and some contain a large amount of nickel and a certain amount of titanium. The role of chromium is to make steel corrosion-resistant. Nickel is the main alloying element for the formation of austenitic stainless steel, but the role of nickel can only be fully demonstrated when it is combined with chromium. If pure nickel is used, a pure austenite single-phase structure is required in low-carbon nickel steel, and the nickel content needs to be more than 24%. In fact, when the nickel content needs to reach 27%, the corrosion resistance of the stainless steel pipe can be remarkably improved. , so there is no nickel as an alloying element in the stainless steel tube.
Common stainless steels are mostly austenitic stainless steels, such as 304, 316L, 321 and so on. The carbon content is lower, but the alloying element content is above 20%, of which the chromium is 18-20%, the Ni content is 8-10%, and there are elements such as vanadium, molybdenum and titanium. The stainless steel is used for corrosiveness. In the medium, especially in foods with high requirements for ring conditions, pharmaceuticals, daily chemical cosmetics and other industries, most of them are used. Of course, the chemical industry is also widely used. However, austenitic stainless steel is afraid of chloride ions and is very strict in controlling the chloride ions of water in the environment.
Stainless steel pipe refers to alloy steel containing less than or equal to 13% Cr and not in the atmosphere. There are many types of stainless steel, such as ferritic stainless steel, austenitic stainless steel, and martensitic stainless steel. Different stainless steels have different resistance to corrosion and different corrosion resistance to different media. It is also different in terms of magnetism. Carbon steel is magnetic, and stainless steel generally does not have magnetic or magnetic properties.
The stainless steel tube contains a large amount of chromium, and some contain a large amount of nickel and a certain amount of titanium. The role of chromium is to make steel corrosion-resistant. Nickel is the main alloying element for the formation of austenitic stainless steel, but the role of nickel can only be fully demonstrated when it is combined with chromium. If pure nickel is used, a pure austenite single-phase structure is required in low-carbon nickel steel, and the nickel content needs to be more than 24%. In fact, when the nickel content needs to reach 27%, the corrosion resistance of the stainless steel pipe can be remarkably improved. , so there is no nickel as an alloying element in the stainless steel tube.
Common stainless steels are mostly austenitic stainless steels, such as 304, 316L, 321 and so on. The carbon content is lower, but the alloying element content is above 20%, of which the chromium is 18-20%, the Ni content is 8-10%, and there are elements such as vanadium, molybdenum and titanium. The stainless steel is used for corrosiveness. In the medium, especially in foods with high requirements for ring conditions, pharmaceuticals, daily chemical cosmetics and other industries, most of them are used. Of course, the chemical industry is also widely used. However, austenitic stainless steel is afraid of chloride ions and is very strict in controlling the chloride ions of water in the environment.
Cold crack analysis and preventive measures of large diameter seamless steel pipe
Large-diameter seamless steel tubes are mostly medium-sized, high-carbon alloy steels. After quenching, some of the supercooled austenite is not transformed into martensite, and remains in the use state as residual austenite, which affects the performance. If it is cooled below zero, it can promote the martensite transformation of the retained austenite. Therefore, the essence of the cold treatment is that the quenching continues. The quenching stress at room temperature is superimposed on the quenching stress at zero, and the cold treatment crack is formed when the refolding stress exceeds the strength limit of the material.
Precaution:
(1) Before the cold treatment after quenching, the large-diameter seamless steel pipe is placed in boiling water for 30-60 minutes, which can eliminate 15%-25% quenching internal stress and stabilize the retained austenite, and then perform -60 ° C conventional cold treatment, or After cryogenic treatment at -120 ° C, the lower the temperature, the more the retained austenite transforms into martensite, but it is impossible to complete the conversion.
Experiments show that about 2%-5% retained austenite remains, as needed Retain a small amount of retained austenite to relax the stress and act as a buffer. Because the retained austenite is soft and tough, it can partially absorb the martensite rapid expansion energy and alleviate the phase transformation stress.
(2) After the cold treatment is completed, the large-diameter seamless steel pipe is taken out and heated in hot water to eliminate 40%-60% cold treatment stress. After heating to room temperature, it should be tempered in time, the cold treatment stress is further eliminated, cold crack formation is avoided, and stable structure is obtained. Performance, to ensure that large diameter seamless steel pipe products are stored and used without distortion.
Precaution:
(1) Before the cold treatment after quenching, the large-diameter seamless steel pipe is placed in boiling water for 30-60 minutes, which can eliminate 15%-25% quenching internal stress and stabilize the retained austenite, and then perform -60 ° C conventional cold treatment, or After cryogenic treatment at -120 ° C, the lower the temperature, the more the retained austenite transforms into martensite, but it is impossible to complete the conversion.
Experiments show that about 2%-5% retained austenite remains, as needed Retain a small amount of retained austenite to relax the stress and act as a buffer. Because the retained austenite is soft and tough, it can partially absorb the martensite rapid expansion energy and alleviate the phase transformation stress.
(2) After the cold treatment is completed, the large-diameter seamless steel pipe is taken out and heated in hot water to eliminate 40%-60% cold treatment stress. After heating to room temperature, it should be tempered in time, the cold treatment stress is further eliminated, cold crack formation is avoided, and stable structure is obtained. Performance, to ensure that large diameter seamless steel pipe products are stored and used without distortion.
Seamless Steel Pipe Preservation And Washing
Precautions for the preservation of seamless steel tubes:
1. The site or warehouse for storing steel, whether it is seamless steel pipe or other straight seam steel pipe, should be selected at the midpoint of clean and clean, poor drainage, away from the occurrence of harmless gas or dust. Weeds and all kinds of debris should be cleared on the site, and the steel should be clean;
2. Do not stack materials that are corrosive to steel, such as acid, alkali, salt or cement, in the warehouse. Different types of steel should be identified and stacked to avoid mixing and avoid contact corrosion;
3. Large-scale steel, rail, insult steel plate, large-diameter steel pipe, forgings, etc. can be stacked in the open air;
4. Small and medium-sized steel, wire rod, steel, medium-diameter steel pipe, steel wire and wire rope, etc., can be stored in a well-ventilated shed, but must be placed on the underside;
5. Some small steel, thin steel, steel, silicon steel, small-diameter or thin-walled steel pipes, various cold-rolled and cold-drawn steel products, and high-priced, corrosive metal products can be stored in the warehouse;
6. The warehouse should be selected according to astronomical conditions. Ordinary blockade warehouses are generally used, that is, there are walls with walls, doors and windows close to each other, and a ventilated installation warehouse;
7. The warehouse requires sunny attention to ventilation, rainy days to pay attention to closed moisture, often adhere to a suitable storage environment.
Seamless tube washing is especially important, here are the notes:
1. When the seamless steel pipe is washed, it needs to be carried out in the flowing clear water tank. This can avoid secondary pollution. When washing, the seamless steel pipe needs to be fully immersed in water. At this time, the sling should be relaxed, up and down. It can be four times.
2. When washing, it is necessary to clean the water in the steel pipe to avoid water corrosion and oxidation of the steel pipe. Therefore, it is necessary to process the solvent as soon as possible.
3. It should be noted that it is not possible to cross the pickling tank to avoid accidents, slipping or falling into the acid tank and being corroded by residual hydrochloric acid.
4. The need for iron salt content standards must be controlled within a certain range, can not appear excessive conditions, otherwise it may damage the seamless steel pipe.
1. The site or warehouse for storing steel, whether it is seamless steel pipe or other straight seam steel pipe, should be selected at the midpoint of clean and clean, poor drainage, away from the occurrence of harmless gas or dust. Weeds and all kinds of debris should be cleared on the site, and the steel should be clean;
2. Do not stack materials that are corrosive to steel, such as acid, alkali, salt or cement, in the warehouse. Different types of steel should be identified and stacked to avoid mixing and avoid contact corrosion;
3. Large-scale steel, rail, insult steel plate, large-diameter steel pipe, forgings, etc. can be stacked in the open air;
4. Small and medium-sized steel, wire rod, steel, medium-diameter steel pipe, steel wire and wire rope, etc., can be stored in a well-ventilated shed, but must be placed on the underside;
5. Some small steel, thin steel, steel, silicon steel, small-diameter or thin-walled steel pipes, various cold-rolled and cold-drawn steel products, and high-priced, corrosive metal products can be stored in the warehouse;
6. The warehouse should be selected according to astronomical conditions. Ordinary blockade warehouses are generally used, that is, there are walls with walls, doors and windows close to each other, and a ventilated installation warehouse;
7. The warehouse requires sunny attention to ventilation, rainy days to pay attention to closed moisture, often adhere to a suitable storage environment.
Seamless tube washing is especially important, here are the notes:
1. When the seamless steel pipe is washed, it needs to be carried out in the flowing clear water tank. This can avoid secondary pollution. When washing, the seamless steel pipe needs to be fully immersed in water. At this time, the sling should be relaxed, up and down. It can be four times.
2. When washing, it is necessary to clean the water in the steel pipe to avoid water corrosion and oxidation of the steel pipe. Therefore, it is necessary to process the solvent as soon as possible.
3. It should be noted that it is not possible to cross the pickling tank to avoid accidents, slipping or falling into the acid tank and being corroded by residual hydrochloric acid.
4. The need for iron salt content standards must be controlled within a certain range, can not appear excessive conditions, otherwise it may damage the seamless steel pipe.
2018年12月11日星期二
Knowledge of stainless steel seamless pipe
Stainless steel seamless pipe is a long strip of steel with a hollow section and no joints around it.
The characteristics of stainless steel seamless pipe:
First, the thicker the wall thickness of the product, the more economical and practical it is. The thinner the wall thickness, the higher the processing cost will be. Secondly, the process of the product determines its limited performance. The seamless steel tube has low precision: uneven wall thickness, low brightness inside and outside the tube, high fixed-length cost, and pitting and black spots on the inner and outer surfaces are not easy to remove; third, its detection and shaping must be processed offline. Therefore, it embodies its superiority in high-pressure, high-strength, mechanical structural materials.
The type of stainless steel pipe:
The rolling method is divided into hot rolling, hot extrusion and cold drawing (rolling) stainless steel tubes. According to the stainless steel metallographic structure, it is divided into semi-ferritic semi-Martensitic stainless steel pipes, martensitic stainless steel pipes, austenitic stainless steel pipes, austenitic-ferritic iron stainless steel pipes.
Stainless steel pipe seamless pipe specifications and appearance quality:
A. According to the provisions of GB14975-94 "Stainless Steel Seamless Steel Pipe", the normal length of steel pipe (indefinite) hot-rolled steel pipe is 1.5~10m, and the hot-extruded steel pipe is equal to or greater than 1m. Cold drawn (rolled) steel pipe wall thickness of 0.5 ~ 1.0mm, 1.0 ~ 7m; wall thickness greater than 1.0mm, 1.5 ~ 8m.
B. There are 45 kinds of hot-rolled (hot-extruded) steel pipes with a diameter of 54-480 mm; a total of 36 kinds of wall thicknesses of 4.5-45 mm. There are 65 kinds of cold drawn (rolled) steel pipes with a diameter of 6 to 200 mm, and 39 kinds of wall thicknesses of 0.5 to 21 mm.
C. There shall be no cracks, folds, cracks, cracks, rolling, separation and crusting defects on the inner and outer surfaces of the steel pipe. These defects shall be completely removed (except for mechanical processing pipes), and the wall thickness and outer wall shall not be removed after removal. The diameter exceeds the negative deviation. Other minor surface defects that do not exceed the allowable negative deviation may not be removed.
D. Straight road allows depth. Hot-rolled and hot-extruded steel pipes, not less than or equal to 140mm in diameter and not more than 5% of the nominal wall thickness, the maximum depth is not more than 0.5mm; cold-drawn (rolled) steel pipes are not more than 4% of the nominal wall thickness, and the maximum depth is not more than 0.3 Mm.
E. Both ends of the steel pipe should be cut at right angles and the burrs should be removed.
The characteristics of stainless steel seamless pipe:
First, the thicker the wall thickness of the product, the more economical and practical it is. The thinner the wall thickness, the higher the processing cost will be. Secondly, the process of the product determines its limited performance. The seamless steel tube has low precision: uneven wall thickness, low brightness inside and outside the tube, high fixed-length cost, and pitting and black spots on the inner and outer surfaces are not easy to remove; third, its detection and shaping must be processed offline. Therefore, it embodies its superiority in high-pressure, high-strength, mechanical structural materials.
The type of stainless steel pipe:
The rolling method is divided into hot rolling, hot extrusion and cold drawing (rolling) stainless steel tubes. According to the stainless steel metallographic structure, it is divided into semi-ferritic semi-Martensitic stainless steel pipes, martensitic stainless steel pipes, austenitic stainless steel pipes, austenitic-ferritic iron stainless steel pipes.
Stainless steel pipe seamless pipe specifications and appearance quality:
A. According to the provisions of GB14975-94 "Stainless Steel Seamless Steel Pipe", the normal length of steel pipe (indefinite) hot-rolled steel pipe is 1.5~10m, and the hot-extruded steel pipe is equal to or greater than 1m. Cold drawn (rolled) steel pipe wall thickness of 0.5 ~ 1.0mm, 1.0 ~ 7m; wall thickness greater than 1.0mm, 1.5 ~ 8m.
B. There are 45 kinds of hot-rolled (hot-extruded) steel pipes with a diameter of 54-480 mm; a total of 36 kinds of wall thicknesses of 4.5-45 mm. There are 65 kinds of cold drawn (rolled) steel pipes with a diameter of 6 to 200 mm, and 39 kinds of wall thicknesses of 0.5 to 21 mm.
C. There shall be no cracks, folds, cracks, cracks, rolling, separation and crusting defects on the inner and outer surfaces of the steel pipe. These defects shall be completely removed (except for mechanical processing pipes), and the wall thickness and outer wall shall not be removed after removal. The diameter exceeds the negative deviation. Other minor surface defects that do not exceed the allowable negative deviation may not be removed.
D. Straight road allows depth. Hot-rolled and hot-extruded steel pipes, not less than or equal to 140mm in diameter and not more than 5% of the nominal wall thickness, the maximum depth is not more than 0.5mm; cold-drawn (rolled) steel pipes are not more than 4% of the nominal wall thickness, and the maximum depth is not more than 0.3 Mm.
E. Both ends of the steel pipe should be cut at right angles and the burrs should be removed.
Defects in pickling seamless steel tubes
In the case of pickling, the seamless steel pipe has a stripping effect on the iron oxide scale, and also diffuses into the interior of the steel billet matrix and accumulates at the impurities or pores, resulting in an increase in internal stress, a decrease in the plasticity of the steel, and an increase in the brittleness of the steel. The effect is called hydrogen embrittlement. Hydrogen embrittlement is mainly affected by the diffusion rate of hydrogen atoms. The rate of hydrogen diffusion is related to the following factors:
1) The diffusion rate of hydrogen in a sulfuric acid solution is higher than that in a hydrochloric acid solution.
2) As the pickling temperature increases, the diffusion rate of hydrogen increases sharply, and the concentration of acid increases, and the diffusion rate of hydrogen does not increase much. Therefore, it is best not to pickle at low concentrations and high temperatures. This is a must for both seamless and oil casings.
3) Some inclusions in pickling such as arsenic (As), antimony (Sb), hydrogen sulfide (H2S) and sulfur dioxide (SO2) increase the diffusion rate of hydrogen atoms, ie increase the possibility of hydrogen embrittlement.
4) The chemical composition of steel also has an effect on the diffusion of hydrogen atoms. The measures to prevent hydrogen embrittlement are to operate according to the specified acid concentration and temperature, to minimize the pickling time, and to add corrosion inhibitors in accordance with the amount.
There is still a scale of iron oxide on the surface of the slab after pickling, which is called under-picking. Under-picking can be divided into all under-picking and partial under-washing depending on the cause. The reason for causing all the acid pickling is that the pickling time is short, the acid concentration is low, or the temperature is low; the reason for causing partial under pickling is that there is no horn on the material or oil on the surface of the steel billet. Under-pickling can be saved by continuing to pickle.
When it is pickled and carbon steel is pickled, the surface is rough and the color is dark. When the chrome stainless steel is pickled, the surface is gray and extremely rough. In severe cases, there is a circular hole with a certain depth - pinhole. The reason for the pickling is that the acid temperature is too high, the pickling time is too long, or the acid concentration is too high. Once this defect is unrecoverable, it has a detrimental effect on the performance of the steel. The acid-washed steel is easily stuck or broken during the rolling process.
After pickling, in addition to the iron salt remaining on the surface of the slab, there is a residue consisting of oxides or salts of other elements in the steel. These residues are not good for cleaning the surface defects of the slab. If it is not washed out in time, the surface of the slab will continue to rust and appear yellow.
http://www.xysteelpipe.com/info/Defects-in-pickling-seamless-steel-tubes-1290-1.htm
1) The diffusion rate of hydrogen in a sulfuric acid solution is higher than that in a hydrochloric acid solution.
2) As the pickling temperature increases, the diffusion rate of hydrogen increases sharply, and the concentration of acid increases, and the diffusion rate of hydrogen does not increase much. Therefore, it is best not to pickle at low concentrations and high temperatures. This is a must for both seamless and oil casings.
3) Some inclusions in pickling such as arsenic (As), antimony (Sb), hydrogen sulfide (H2S) and sulfur dioxide (SO2) increase the diffusion rate of hydrogen atoms, ie increase the possibility of hydrogen embrittlement.
4) The chemical composition of steel also has an effect on the diffusion of hydrogen atoms. The measures to prevent hydrogen embrittlement are to operate according to the specified acid concentration and temperature, to minimize the pickling time, and to add corrosion inhibitors in accordance with the amount.
There is still a scale of iron oxide on the surface of the slab after pickling, which is called under-picking. Under-picking can be divided into all under-picking and partial under-washing depending on the cause. The reason for causing all the acid pickling is that the pickling time is short, the acid concentration is low, or the temperature is low; the reason for causing partial under pickling is that there is no horn on the material or oil on the surface of the steel billet. Under-pickling can be saved by continuing to pickle.
When it is pickled and carbon steel is pickled, the surface is rough and the color is dark. When the chrome stainless steel is pickled, the surface is gray and extremely rough. In severe cases, there is a circular hole with a certain depth - pinhole. The reason for the pickling is that the acid temperature is too high, the pickling time is too long, or the acid concentration is too high. Once this defect is unrecoverable, it has a detrimental effect on the performance of the steel. The acid-washed steel is easily stuck or broken during the rolling process.
After pickling, in addition to the iron salt remaining on the surface of the slab, there is a residue consisting of oxides or salts of other elements in the steel. These residues are not good for cleaning the surface defects of the slab. If it is not washed out in time, the surface of the slab will continue to rust and appear yellow.
http://www.xysteelpipe.com/info/Defects-in-pickling-seamless-steel-tubes-1290-1.htm
2018年12月10日星期一
Seamless pipe thermal expansion treatment
The seamless expansion of the seamless steel tube is divided into an overall thermal expansion treatment, a surface thermal expansion treatment, and a chemical heat treatment. The seamless expansion of the seamless steel pipe is generally treated by integral thermal expansion. Generally, they are subjected to basic processes such as heating, heat preservation, and cooling, and defects may occur in these processes.
Heat treatment defects of seamless steel tubes mainly include unqualified structural properties of steel pipes, excessive size and surface cracks, scratches, severe oxidation, decarburization, overheating, and over-burning.
Features of thermal expansion processing of seamless steel tubes:
The first process is heating: one is heating below the critical point Ac1 or Ac3; the other is heating above the critical point Ac1 or Ac3. The first is mainly to stabilize the structure of the seamless steel pipe and to eliminate the residual stress of the seamless steel pipe, and the second is mainly to austenitize the steel.
The second process is thermal insulation: the purpose is to uniformly heat the heating temperature of the steel pipe to obtain a reasonable heating structure.
The third process is cooling: the cooling process is a key process in the heat treatment of seamless steel tubes. He determines the metallographic structure and mechanical properties of the tubes after cooling. The steel tube cooling methods used in the actual production process are various. The cooling methods often used are furnace cooling, air cooling, oil cooling, polymer cooling, and water cooling.
Heat treatment defects of seamless steel tubes mainly include unqualified structural properties of steel pipes, excessive size and surface cracks, scratches, severe oxidation, decarburization, overheating, and over-burning.
Features of thermal expansion processing of seamless steel tubes:
The first process is heating: one is heating below the critical point Ac1 or Ac3; the other is heating above the critical point Ac1 or Ac3. The first is mainly to stabilize the structure of the seamless steel pipe and to eliminate the residual stress of the seamless steel pipe, and the second is mainly to austenitize the steel.
The second process is thermal insulation: the purpose is to uniformly heat the heating temperature of the steel pipe to obtain a reasonable heating structure.
The third process is cooling: the cooling process is a key process in the heat treatment of seamless steel tubes. He determines the metallographic structure and mechanical properties of the tubes after cooling. The steel tube cooling methods used in the actual production process are various. The cooling methods often used are furnace cooling, air cooling, oil cooling, polymer cooling, and water cooling.
The cutting method of fluid seamless pipe is introduced
Pipe fluid seamless pipe cutting methods include shearing, breaking, sawing, flame cutting and anode cutting. Their characteristics are as follows:
(1) Flame cutting method: This cutting method has the lowest operating cost, but the fluid seamless tube consumes more and the cutting quality is poor. Therefore, manual flame cutting is often used as a supplementary cutting means. However, due to the improvement of flame cutting technology, some factories have used automatic cutting with a multi-head flame cutting machine as the main method for fluid seamless pipe cutting.
(2) Shearing method: This method has high production efficiency and low cutting cost. Carbon-carbon seamless pipes and alloy structural steel pipes in low-carbon species are mainly cut by shearing. In order to improve the shearing efficiency, the double-cutting is carried out by using a large-tonnage shearing machine; in order to reduce the flattening degree of the end portion of the steel pipe when cutting, the cutting edge is generally formed by a forming blade; for a seamless steel pipe which is prone to shear cracking, shearing The steel pipe was preheated to 300 ° C when cut.
(3) Fracture method: The equipment used is the breaking press. The breaking process is to cut all the holes at the predetermined breaking fluid pipe with the torch, and then put it into the breaking press and break it with a triangular axe. The distance between the two points is 1-4 times the diameter Dp of the tube blank.
(4) Saw cutting method: This cutting method has the best cutting quality and is widely used for alloy steel pipes, high-pressure steel pipes, fluid seamless pipes, especially for the cutting of large-diameter fluid seamless steel pipes and high-alloy steel pipes. The sawing device has a bow saw, a band saw and a circular saw. Cold circular saws with high-speed steel sector blades are used for cold-saw alloy steel tubes; cold circular saws with carbide inserts are used for high-alloy steel saws.
(1) Flame cutting method: This cutting method has the lowest operating cost, but the fluid seamless tube consumes more and the cutting quality is poor. Therefore, manual flame cutting is often used as a supplementary cutting means. However, due to the improvement of flame cutting technology, some factories have used automatic cutting with a multi-head flame cutting machine as the main method for fluid seamless pipe cutting.
(2) Shearing method: This method has high production efficiency and low cutting cost. Carbon-carbon seamless pipes and alloy structural steel pipes in low-carbon species are mainly cut by shearing. In order to improve the shearing efficiency, the double-cutting is carried out by using a large-tonnage shearing machine; in order to reduce the flattening degree of the end portion of the steel pipe when cutting, the cutting edge is generally formed by a forming blade; for a seamless steel pipe which is prone to shear cracking, shearing The steel pipe was preheated to 300 ° C when cut.
(3) Fracture method: The equipment used is the breaking press. The breaking process is to cut all the holes at the predetermined breaking fluid pipe with the torch, and then put it into the breaking press and break it with a triangular axe. The distance between the two points is 1-4 times the diameter Dp of the tube blank.
(4) Saw cutting method: This cutting method has the best cutting quality and is widely used for alloy steel pipes, high-pressure steel pipes, fluid seamless pipes, especially for the cutting of large-diameter fluid seamless steel pipes and high-alloy steel pipes. The sawing device has a bow saw, a band saw and a circular saw. Cold circular saws with high-speed steel sector blades are used for cold-saw alloy steel tubes; cold circular saws with carbide inserts are used for high-alloy steel saws.
How is the crack of seamless steel tube surface to return a responsibility?
The cleanliness and smoothness of the surface of the seamless steel pipe is a requirement for the selection of a seamless steel pipe. The cleanliness of the surface of the seamless steel pipe has become a key point for the customer to choose. In recent years, it has been valued by many companies. Cracks on the surface of seamless steel pipes are a common phenomenon and a direct cause of low sales. So what are the factors?
First, the raw material factors: the poor quality of the tube blank will appear inside and outside the skin, crusting, cracks, etc.
Second, the temperature factor: the first important process of seamless steel pipe production is heating, poor heating (uneven, insufficient temperature, etc.) will cause internal skin, etc.
Third, the equipment factor: from the beginning of the furnace, each equipment component will affect the final quality of the pipe. For example, if the equipment parts are scratched, it will cause the outer skin and pits; if the punching machine is not smooth, the head of the tube blank will be bitten by water and bite into the head or the inside of the head.
Fourth, the process problem: the process problem is also quite complicated, there are adjustment problems, problems with equipment failure, and the quality of the pipe produced after the wear of the process components (head, guide, rolls, etc.). The problems caused are all-encompassing.
Therefore, there are dozens of possible reasons for the occurrence of a defect. If you do not see the physical object or are not at the production site, it is often difficult to say the specific reasons.
First, the raw material factors: the poor quality of the tube blank will appear inside and outside the skin, crusting, cracks, etc.
Second, the temperature factor: the first important process of seamless steel pipe production is heating, poor heating (uneven, insufficient temperature, etc.) will cause internal skin, etc.
Third, the equipment factor: from the beginning of the furnace, each equipment component will affect the final quality of the pipe. For example, if the equipment parts are scratched, it will cause the outer skin and pits; if the punching machine is not smooth, the head of the tube blank will be bitten by water and bite into the head or the inside of the head.
Fourth, the process problem: the process problem is also quite complicated, there are adjustment problems, problems with equipment failure, and the quality of the pipe produced after the wear of the process components (head, guide, rolls, etc.). The problems caused are all-encompassing.
Therefore, there are dozens of possible reasons for the occurrence of a defect. If you do not see the physical object or are not at the production site, it is often difficult to say the specific reasons.
2018年11月29日星期四
Characteristics and advantages of precision seamless tubes
Features of precision seamless steel pipe:
1. High precision, saving the loss when machining the user's materials.
2. There are many specifications and a wide range of applications.
3. The cold rolled product has high precision, good surface quality and good straightness.
4. The inner diameter of the steel pipe can be made into a hexagon.
5. The performance of the steel pipe is superior and the metal is relatively dense.
Advantages of precision seamless steel pipe:
Compared with solid steel such as round steel, seamless steel pipe has a light weight when it has the same bending and torsional strength. It is an economical section steel and is widely used in the manufacture of structural parts and mechanical parts. Precision steel pipes also have their own characteristics while inheriting the advantages of seamless steel pipes. Precision manufacturing of ring parts can improve material utilization, simplify manufacturing processes, save materials and processing man-hours, such as rolling bearing rings, jacks, etc., and have been widely used in precision steel pipes.
The promotion and application of precision seamless pipes is of great significance for saving steel, improving processing efficiency, reducing processing steps or equipment investment, saving cost and processing time, increasing production volume and material utilization rate, and helping to improve product quality and reduce costs. It is of great significance to improve economic efficiency. Generally, precision seamless pipes are used in industries with high precision requirements, and seamless pipes are mostly used without precision requirements. After all, the price of precision seamless pipes of the same specification is higher than that of seamless pipes.
http://www.xysteelpipe.com/info/Characteristics-and-advantages-of-precision-seamless-tubes-1282-1.htm
1. High precision, saving the loss when machining the user's materials.
2. There are many specifications and a wide range of applications.
3. The cold rolled product has high precision, good surface quality and good straightness.
4. The inner diameter of the steel pipe can be made into a hexagon.
5. The performance of the steel pipe is superior and the metal is relatively dense.
Advantages of precision seamless steel pipe:
Compared with solid steel such as round steel, seamless steel pipe has a light weight when it has the same bending and torsional strength. It is an economical section steel and is widely used in the manufacture of structural parts and mechanical parts. Precision steel pipes also have their own characteristics while inheriting the advantages of seamless steel pipes. Precision manufacturing of ring parts can improve material utilization, simplify manufacturing processes, save materials and processing man-hours, such as rolling bearing rings, jacks, etc., and have been widely used in precision steel pipes.
The promotion and application of precision seamless pipes is of great significance for saving steel, improving processing efficiency, reducing processing steps or equipment investment, saving cost and processing time, increasing production volume and material utilization rate, and helping to improve product quality and reduce costs. It is of great significance to improve economic efficiency. Generally, precision seamless pipes are used in industries with high precision requirements, and seamless pipes are mostly used without precision requirements. After all, the price of precision seamless pipes of the same specification is higher than that of seamless pipes.
http://www.xysteelpipe.com/info/Characteristics-and-advantages-of-precision-seamless-tubes-1282-1.htm
2018年11月28日星期三
Technical requirements for ERW steel pipe
With its special technical production process, ERW steel pipe can be applied in various qualities, wall thicknesses, and diameters of the finished pipes. This would be the contribution of the technical technology. Today, we will discuss the technical requirements of this kind of tube mainly.
Yield strength would have the customized range. For ERW steel pipe, we would control it higher than the J55 up to 173 ~ 206 MPa.
If your tube products under the same size, orientation, minimum size, then we will figure out that relative products can absorb lower than N80 steel grade.
Of course, for the nondestructive testing methods of seamless pipe, coupling stock, welded steel pipe like ERW one would be different from them.
Of course, the color would be different due to the technical requirement’s difference.
http://www.xysteelpipe.com/info/Technical-requirements-for-ERW-steel-pipe-1280-1.htm
Yield strength would have the customized range. For ERW steel pipe, we would control it higher than the J55 up to 173 ~ 206 MPa.
If your tube products under the same size, orientation, minimum size, then we will figure out that relative products can absorb lower than N80 steel grade.
Of course, for the nondestructive testing methods of seamless pipe, coupling stock, welded steel pipe like ERW one would be different from them.
Of course, the color would be different due to the technical requirement’s difference.
http://www.xysteelpipe.com/info/Technical-requirements-for-ERW-steel-pipe-1280-1.htm
Thick wall seamless steel tube knowledg
The thick-walled seamless steel pipe production line is characterized by long production line, many transmission equipment, strict tension control requirements, easy deviation of the strip, and continuous production. During the finish rolling process, the local area enters the upper limit of the non-recrystallization zone and the two-phase zone of the austenitic seamless steel pipe manufacturer in advance. The size and uniformity of the ferrite grains obtained by rolling in the non-recrystallization zone are related to the total deformation amount and the pass reduction rate at the rolling stage.
When the total deformation amount and the pass reduction ratio are larger, the ferrite is obtained. The finer and evener the body grains. The local area, that is, the crack opening and the middle part thereof, enters earlier than the base side due to supercooling, so the ferrite grains of the crack at the opening are finer, the grain size of the matrix is ??not changed much, and the difference between the two causes the rolling crack. .
The continuous hot-dip galvanizing production line of thick-walled seamless steel pipe is divided into three parts: the inlet section, the process section and the inlet section according to the production process. The function of the inlet section is 45# seamless steel pipe to ensure the continuous feeding of the steel strip in the process section. The main equipments include unwinding machine, welding machine, 1#S roll and inlet looper; the process section equipment has 2#S roll, furnace roll, furnace tweezers, zinc pots, air knives, 3#S rolls, this section requires thick-walled seamless steel tubes to run at a constant speed, the galvanized layer is thin and uniform; the inlet section is to roll the zinc-plated steel strip into coils and ensure Continuous production, the main equipment is the inlet looper, 4#S roller, roll front pinch roller, coiler and so on.
At the same time it is also the best choice for liquid transport steel pipes, but as time goes on, the probability of steel pipe damage is also very high. At this time, the role of thick-walled seamless steel pipes became apparent. Thick-walled seamless steel pipe is the main pipe used to transport liquids today. Its strength is higher than that of ordinary steel pipes, corrosion resistance is also enhanced, and the service life is increased by ten times.
In addition, it is the main material for making the drive shaft on the car. After all, the strength of the thick-walled seamless steel pipe is very high, and the manufactured transmission shaft will not be easily deformed, which can completely ensure the safety of driving. It can be seen that the help of thick-walled seamless steel pipes for our lives is also very large.
http://www.xysteelpipe.com/info/Thick-wall-seamless-steel-tube-knowledge-1281-1.htm
When the total deformation amount and the pass reduction ratio are larger, the ferrite is obtained. The finer and evener the body grains. The local area, that is, the crack opening and the middle part thereof, enters earlier than the base side due to supercooling, so the ferrite grains of the crack at the opening are finer, the grain size of the matrix is ??not changed much, and the difference between the two causes the rolling crack. .
The continuous hot-dip galvanizing production line of thick-walled seamless steel pipe is divided into three parts: the inlet section, the process section and the inlet section according to the production process. The function of the inlet section is 45# seamless steel pipe to ensure the continuous feeding of the steel strip in the process section. The main equipments include unwinding machine, welding machine, 1#S roll and inlet looper; the process section equipment has 2#S roll, furnace roll, furnace tweezers, zinc pots, air knives, 3#S rolls, this section requires thick-walled seamless steel tubes to run at a constant speed, the galvanized layer is thin and uniform; the inlet section is to roll the zinc-plated steel strip into coils and ensure Continuous production, the main equipment is the inlet looper, 4#S roller, roll front pinch roller, coiler and so on.
At the same time it is also the best choice for liquid transport steel pipes, but as time goes on, the probability of steel pipe damage is also very high. At this time, the role of thick-walled seamless steel pipes became apparent. Thick-walled seamless steel pipe is the main pipe used to transport liquids today. Its strength is higher than that of ordinary steel pipes, corrosion resistance is also enhanced, and the service life is increased by ten times.
In addition, it is the main material for making the drive shaft on the car. After all, the strength of the thick-walled seamless steel pipe is very high, and the manufactured transmission shaft will not be easily deformed, which can completely ensure the safety of driving. It can be seen that the help of thick-walled seamless steel pipes for our lives is also very large.
http://www.xysteelpipe.com/info/Thick-wall-seamless-steel-tube-knowledge-1281-1.htm
2018年11月25日星期日
LSAW steel pipe production process
LSAW steel pipe is a longitudinally parallel steel pipe. Usually divided into metric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on. The straight seam welded pipe has a simple production process, high production efficiency, low cost, and rapid development. LSAW steel pipe according to the production process can be divided into high-frequency straight seam steel pipe and submerged arc welded straight seam steel pipe. Submerged arc welded straight seam steel pipes are divided into UOE, RBE, and JCOE steel pipes according to their different forming methods. The following describes the most common high-frequency straight seam steel pipe and submerged arc welded straight seam steel pipe forming process.
1. Striking: After the steel plate used for manufacturing large-diameter submerged-arc welded straight-joint steel pipes enters the production line, full-plate ultrasonic inspection is first performed;
2. Milling edge: Through the edge milling machine, the two edges of the steel plate are double-sided milled to achieve the required plate width, plate edge parallelism and groove shape;
3. Pre-bend: Pre-bending machine for pre-bending the edge so that the edge of the board has a curvature that meets the requirements;
4. Forming: Firstly, half of the pre-bent steel plate is stamped and stamped into a "J" shape on a JCO forming machine. The other half of the steel plate is also bent and pressed into a "C" shape to form an opening. The "O" shape
5. Pre-welding: After the formation of straight seam welded steel pipe joints and continuous welding using gas shielded welding (MAG);
6. Internal welding: Use vertical multi-wire submerged arc welding (up to four wires) to weld inside the straight seam steel pipe;
7. Outer welding: Use vertical multi-wire submerged arc welding to weld outside LSAW steel pipe;
8. Ultrasonic inspection I: 100% inspection of the internal and external welds of the longitudinal welded steel pipe and the base metal on both sides of the weld;
9. X-ray inspection I: 100% X-ray industrial television inspection of the inner and outer welds, using image processing systems to ensure the detection sensitivity;
10. Expanded diameter: The full-length of the submerged-arc welded straight seam steel pipe is expanded to improve the dimensional accuracy of the steel pipe, and the distribution of the internal stress of the steel pipe is improved;
11. Hydraulic pressure test: The root diameter of the expanded steel pipe is tested on the hydrostatic testing machine to ensure that the steel pipe meets the required test pressure. The machine has automatic recording and storage functions;
12. Chamfering: After passing the inspection, the steel pipe is processed by the pipe end to reach the required pipe end groove size;
13. Ultrasonic inspection II: Ultrasonic inspection is performed one by one again to check for defects that may occur in straight seam welded steel pipes after diameter expansion and water pressure.
14. X-ray examination II: X-ray industrial television inspection and tube-end weld seam examination of steel tubes after diameter expansion and hydrostatic pressure testing;
15. Tube end magnetic particle inspection: This inspection is performed to find the tube end defects;
16. Anti-corrosion and coating: The qualified steel pipe is anti-corrosion and coating according to the user's requirements.
1. Striking: After the steel plate used for manufacturing large-diameter submerged-arc welded straight-joint steel pipes enters the production line, full-plate ultrasonic inspection is first performed;
2. Milling edge: Through the edge milling machine, the two edges of the steel plate are double-sided milled to achieve the required plate width, plate edge parallelism and groove shape;
3. Pre-bend: Pre-bending machine for pre-bending the edge so that the edge of the board has a curvature that meets the requirements;
4. Forming: Firstly, half of the pre-bent steel plate is stamped and stamped into a "J" shape on a JCO forming machine. The other half of the steel plate is also bent and pressed into a "C" shape to form an opening. The "O" shape
5. Pre-welding: After the formation of straight seam welded steel pipe joints and continuous welding using gas shielded welding (MAG);
6. Internal welding: Use vertical multi-wire submerged arc welding (up to four wires) to weld inside the straight seam steel pipe;
7. Outer welding: Use vertical multi-wire submerged arc welding to weld outside LSAW steel pipe;
8. Ultrasonic inspection I: 100% inspection of the internal and external welds of the longitudinal welded steel pipe and the base metal on both sides of the weld;
9. X-ray inspection I: 100% X-ray industrial television inspection of the inner and outer welds, using image processing systems to ensure the detection sensitivity;
10. Expanded diameter: The full-length of the submerged-arc welded straight seam steel pipe is expanded to improve the dimensional accuracy of the steel pipe, and the distribution of the internal stress of the steel pipe is improved;
11. Hydraulic pressure test: The root diameter of the expanded steel pipe is tested on the hydrostatic testing machine to ensure that the steel pipe meets the required test pressure. The machine has automatic recording and storage functions;
12. Chamfering: After passing the inspection, the steel pipe is processed by the pipe end to reach the required pipe end groove size;
13. Ultrasonic inspection II: Ultrasonic inspection is performed one by one again to check for defects that may occur in straight seam welded steel pipes after diameter expansion and water pressure.
14. X-ray examination II: X-ray industrial television inspection and tube-end weld seam examination of steel tubes after diameter expansion and hydrostatic pressure testing;
15. Tube end magnetic particle inspection: This inspection is performed to find the tube end defects;
16. Anti-corrosion and coating: The qualified steel pipe is anti-corrosion and coating according to the user's requirements.
SSAW steel pipe technology
Production process of ssaw steel pipe: based on strip coil as raw material, often warm extrusion molding, automatic double-wire double-sided submerged arc welding process welding spiral seam steel pipe.
(1) Raw materials are steel coils, welding wire, and flux. Have to go through rigorous physical and chemical tests before investing.
(2) For the butt-end welding of steel strips, single-wire or double-wire submerged arc welding is used, and after the coils are made into steel pipes, automatic submerged arc welding is used to make up the welding.
(3) Before forming, the steel strip is leveled, trimmed, edged, surface cleaned and pre-flanged.
(4) The electric contact pressure gauge is used to control the pressure of the compression cylinders on both sides of the conveyor to ensure the smooth delivery of the strip.
(5) External control or internal control roll forming.
(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, the amount of misalignment, and the weld gap are all strictly controlled.
(7) The inner and outer welds are all welded by single-wire or double-wire submerged arc welding using the Lincoln Electric Welder of the United States, thereby obtaining a stable welding specification.
(8) Welded welds were all inspected by an online continuous ultrasonic automatic flaw tester to ensure non-destructive testing coverage of 100% spiral welds. If there are defects, they will be automatically alarmed and painted. The production workers will adjust the process parameters at any time to eliminate defects in time.
(9) Using an air plasma cutter to cut the steel pipe into single pieces.
(10) After cutting into a single steel pipe, a strict first inspection system shall be carried out for each of the first three pipes of each batch to inspect the mechanical properties, chemical composition, fusion condition, surface quality of steel pipes, and non-destructive testing to ensure the pipe-making process. Qualified before they can officially put into production.
(11) Where there is a continuous sound wave flaw detection mark on the weld, after manual ultrasonic and X-ray review, if there is a defect, after repair, it shall undergo a non-destructive test again until it is confirmed that the defect has been eliminated.
(12) The butt joints of the butt welds and the intersections with the spiral welds of the steel strip are all examined by X-ray television or film.
(13) Each pipe is hydrostatically tested and the pressure is radial sealed. The test pressure and time are strictly controlled by the steel pipe hydraulic pressure testing device. Test parameters are automatically printed and recorded.
(14) End-of-pipe machining is performed so that the verticality of the end face, the groove angle and the blunt edge are accurately controlled.
(1) Raw materials are steel coils, welding wire, and flux. Have to go through rigorous physical and chemical tests before investing.
(2) For the butt-end welding of steel strips, single-wire or double-wire submerged arc welding is used, and after the coils are made into steel pipes, automatic submerged arc welding is used to make up the welding.
(3) Before forming, the steel strip is leveled, trimmed, edged, surface cleaned and pre-flanged.
(4) The electric contact pressure gauge is used to control the pressure of the compression cylinders on both sides of the conveyor to ensure the smooth delivery of the strip.
(5) External control or internal control roll forming.
(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, the amount of misalignment, and the weld gap are all strictly controlled.
(7) The inner and outer welds are all welded by single-wire or double-wire submerged arc welding using the Lincoln Electric Welder of the United States, thereby obtaining a stable welding specification.
(8) Welded welds were all inspected by an online continuous ultrasonic automatic flaw tester to ensure non-destructive testing coverage of 100% spiral welds. If there are defects, they will be automatically alarmed and painted. The production workers will adjust the process parameters at any time to eliminate defects in time.
(9) Using an air plasma cutter to cut the steel pipe into single pieces.
(10) After cutting into a single steel pipe, a strict first inspection system shall be carried out for each of the first three pipes of each batch to inspect the mechanical properties, chemical composition, fusion condition, surface quality of steel pipes, and non-destructive testing to ensure the pipe-making process. Qualified before they can officially put into production.
(11) Where there is a continuous sound wave flaw detection mark on the weld, after manual ultrasonic and X-ray review, if there is a defect, after repair, it shall undergo a non-destructive test again until it is confirmed that the defect has been eliminated.
(12) The butt joints of the butt welds and the intersections with the spiral welds of the steel strip are all examined by X-ray television or film.
(13) Each pipe is hydrostatically tested and the pressure is radial sealed. The test pressure and time are strictly controlled by the steel pipe hydraulic pressure testing device. Test parameters are automatically printed and recorded.
(14) End-of-pipe machining is performed so that the verticality of the end face, the groove angle and the blunt edge are accurately controlled.
LSAW Steel Pipe vs SSAW Steel Pipe
1, Difference between lsaw steel pipe and ssaw steel pipe in production process
LSAW steel pipe is a longitudinally parallel steel pipe. Usually divided into metric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on. The straight seam welded pipe has a simple production process, high production efficiency, low cost, and rapid development. SSAW steel pipe is a coiled steel pipe made from strip coils as the raw material, which is often warm extruded and welded by an automatic double wire double-sided submerged arc welding process.
The strength of the ssaw steel pipe is generally higher than that of the lsaw steel pipe. A narrower blank can be used to produce a larger diameter pipe, and a blank having a different diameter can be produced from a blank of the same width. During the forming process, the steel plate is uniformly deformed, the residual stress is small, and the surface is free of scratches. The processed spiral steel pipe has greater flexibility in the range of diameters and wall thicknesses, especially in the production of high-grade thick-walled pipes, especially small- and medium-caliber thick-walled pipes, which have unparalleled advantages over other technologies and can satisfy users. More requirements on the specifications of spiral steel pipe. The use of advanced double-sided submerged arc welding technology can achieve welding in the best position. It is not prone to defects such as misalignment, welding deviation and incomplete penetration, and it is easy to control the welding quality. However, compared with the straight seam pipe of the same length, the length of the weld seam increases by 30 to 100%, and the production speed is low.
2, Difference between lsaw steel pipe and ssaw steel pipe in security analysis
LSAW steel pipe is mainly subjected to residual stress caused by inhomogeneous cooling. Residual stress is the stress of internal self-phase equilibrium under no external force. Hot rolled section steel of various sections has such residual stress. The larger the section size of general steel, the greater the residual stress is. Although the residual stress is self-balanced, it still has certain influence on the performance of steel components under external forces. For example, it may have adverse effects on deformation, stability, and fatigue resistance; after welding, The non-metallic inclusions inside the straight seam steel pipe are pressed into thin slices, and the delamination phenomenon occurs. The delamination weakens the performance of the straight seam steel pipe in the thickness direction, and there is a possibility of interlayer tearing when the weld seam shrinks. The local strain induced by weld shrinkage often reaches several times of the yield point strain, which is much larger than the strain caused by the load. In addition, the lsaw steel pipe will inevitably have many T-welds, so the probability of welding defects is also greatly improved. Moreover, the welding residual stress at the T-weld is large, and the weld metal is often in a three-dimensional stress state, increasing the possibility of cracking.
SSAW steel pipe with spiral weld distribution, long weld, especially in the dynamic conditions of welding, the weld is too late to leave the molding point of cooling, easy to produce welding hot cracks. The direction of the crack is parallel to the weld and is at a certain angle to the axis of the steel tube, typically between 30-70°. This angle is just in line with the shear failure angle, so its bending, tensile, compressive and torsional resistance is far inferior to the LSAW pipe. At the same time, due to the limitation of the welding position, the resulting saddle shape and ridge-shaped welding seam influence Beautiful. In addition, during the construction process, the intersecting line welds at the spiral welded parent pipe joints split the spiral joints and generate larger welding stress, which greatly weakens the safety performance of the components. Therefore, the non-destructive testing of the spiral welded pipe joints should be strengthened. Ensure welding quality, otherwise spiral submerged arc welded pipe should not be used in important steel structure occasions.
3, Difference between lsaw steel pipe and ssaw steel pipe in the scope of application
LSAW pipe adopts double-side submerged arc welding process. Welding under static conditions, the quality of the weld is high, the weld is short, and the probability of defects is very small. The steel pipe expands through full-length, has a good pipe shape, and is precise in size. The steel pipe has a wide wall thickness range and a wide range of pipe diameters. It is suitable for supporting columns, ultra-large span building structures, such as buildings, bridges, dams, and offshore platforms, as well as wind-resistant and earthquake-resistant structures. Pole mast structure. Spiral steel pipe is a kind of steel commonly used in industry, construction and other industries. Mainly used in tap water projects, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction.
In summary, we can see that the two different types of welded seam pipes have their own characteristics and have different advantages according to different applications.
LSAW steel pipe is a longitudinally parallel steel pipe. Usually divided into metric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on. The straight seam welded pipe has a simple production process, high production efficiency, low cost, and rapid development. SSAW steel pipe is a coiled steel pipe made from strip coils as the raw material, which is often warm extruded and welded by an automatic double wire double-sided submerged arc welding process.
The strength of the ssaw steel pipe is generally higher than that of the lsaw steel pipe. A narrower blank can be used to produce a larger diameter pipe, and a blank having a different diameter can be produced from a blank of the same width. During the forming process, the steel plate is uniformly deformed, the residual stress is small, and the surface is free of scratches. The processed spiral steel pipe has greater flexibility in the range of diameters and wall thicknesses, especially in the production of high-grade thick-walled pipes, especially small- and medium-caliber thick-walled pipes, which have unparalleled advantages over other technologies and can satisfy users. More requirements on the specifications of spiral steel pipe. The use of advanced double-sided submerged arc welding technology can achieve welding in the best position. It is not prone to defects such as misalignment, welding deviation and incomplete penetration, and it is easy to control the welding quality. However, compared with the straight seam pipe of the same length, the length of the weld seam increases by 30 to 100%, and the production speed is low.
2, Difference between lsaw steel pipe and ssaw steel pipe in security analysis
LSAW steel pipe is mainly subjected to residual stress caused by inhomogeneous cooling. Residual stress is the stress of internal self-phase equilibrium under no external force. Hot rolled section steel of various sections has such residual stress. The larger the section size of general steel, the greater the residual stress is. Although the residual stress is self-balanced, it still has certain influence on the performance of steel components under external forces. For example, it may have adverse effects on deformation, stability, and fatigue resistance; after welding, The non-metallic inclusions inside the straight seam steel pipe are pressed into thin slices, and the delamination phenomenon occurs. The delamination weakens the performance of the straight seam steel pipe in the thickness direction, and there is a possibility of interlayer tearing when the weld seam shrinks. The local strain induced by weld shrinkage often reaches several times of the yield point strain, which is much larger than the strain caused by the load. In addition, the lsaw steel pipe will inevitably have many T-welds, so the probability of welding defects is also greatly improved. Moreover, the welding residual stress at the T-weld is large, and the weld metal is often in a three-dimensional stress state, increasing the possibility of cracking.
SSAW steel pipe with spiral weld distribution, long weld, especially in the dynamic conditions of welding, the weld is too late to leave the molding point of cooling, easy to produce welding hot cracks. The direction of the crack is parallel to the weld and is at a certain angle to the axis of the steel tube, typically between 30-70°. This angle is just in line with the shear failure angle, so its bending, tensile, compressive and torsional resistance is far inferior to the LSAW pipe. At the same time, due to the limitation of the welding position, the resulting saddle shape and ridge-shaped welding seam influence Beautiful. In addition, during the construction process, the intersecting line welds at the spiral welded parent pipe joints split the spiral joints and generate larger welding stress, which greatly weakens the safety performance of the components. Therefore, the non-destructive testing of the spiral welded pipe joints should be strengthened. Ensure welding quality, otherwise spiral submerged arc welded pipe should not be used in important steel structure occasions.
3, Difference between lsaw steel pipe and ssaw steel pipe in the scope of application
LSAW pipe adopts double-side submerged arc welding process. Welding under static conditions, the quality of the weld is high, the weld is short, and the probability of defects is very small. The steel pipe expands through full-length, has a good pipe shape, and is precise in size. The steel pipe has a wide wall thickness range and a wide range of pipe diameters. It is suitable for supporting columns, ultra-large span building structures, such as buildings, bridges, dams, and offshore platforms, as well as wind-resistant and earthquake-resistant structures. Pole mast structure. Spiral steel pipe is a kind of steel commonly used in industry, construction and other industries. Mainly used in tap water projects, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction.
In summary, we can see that the two different types of welded seam pipes have their own characteristics and have different advantages according to different applications.
Uses of Casing Coupling
The casing is mainly used to support the wellbore during and after drilling to ensure the normal operation of the entire oil well after the drilling process is completed. Different types of casing used in oil production: The surface oil casing is used to protect the well from contamination by shallow water and shallow gas layers and to support the wellhead equipment and maintain the other layers of the casing. Technical casing is used to separate the pressures at different levels so that the drilling fluid can be circulated and the production casing can be protected.
In order to install anti-blasting devices, leak-proof devices and tail pipes in wells. Oil reservoir casing drains oil and natural gas from the reservoir beneath the surface and is used to protect the well and stratify the drilling mud. When the oil casing is produced, the outer diameter is usually 114.3 mm to 508 mm. Domestic casing according to SY/T 6194-96 regulations, casing length is not fixed, its range of 8-13m. But no less than 6m can be provided, the number of which must not exceed 20%.
The inner and outer surfaces of the sleeve must not have folds, hair lines, separations, cracks, folds, and scabs. These defects should be completely removed, and the depth of removal should not exceed 12.5% of the nominal wall thickness. Couplings shall not have defects such as folds, hairline, separation, cracks, pleats, and scabs on the outer surface of the coupling. The surface of the threads of the casing and coupling should be smooth. No burrs, tears, and enough breakage of the threads will affect the strength and other defects of the tight connection.
In order to install anti-blasting devices, leak-proof devices and tail pipes in wells. Oil reservoir casing drains oil and natural gas from the reservoir beneath the surface and is used to protect the well and stratify the drilling mud. When the oil casing is produced, the outer diameter is usually 114.3 mm to 508 mm. Domestic casing according to SY/T 6194-96 regulations, casing length is not fixed, its range of 8-13m. But no less than 6m can be provided, the number of which must not exceed 20%.
The inner and outer surfaces of the sleeve must not have folds, hair lines, separations, cracks, folds, and scabs. These defects should be completely removed, and the depth of removal should not exceed 12.5% of the nominal wall thickness. Couplings shall not have defects such as folds, hairline, separation, cracks, pleats, and scabs on the outer surface of the coupling. The surface of the threads of the casing and coupling should be smooth. No burrs, tears, and enough breakage of the threads will affect the strength and other defects of the tight connection.
Hydrostatic Pressure Test Casing Pipe
The hydrostatic pressure test of casing pipe is an indispensable part of the production process of the steel pipe. Its role is to test the anti-leakage performance of the steel pipe under standard test pressure and regulation time. Like radiographs, ultrasonics, and other flaw detection techniques, it is an important means of testing the overall quality of steel tubes.
The popular description is to fill the pipe with water and test its ability to maintain the specified pressure without leaking or breaking under pressure. Its operations include three steps: flushing, pressure testing and water control.
API-5CT standard for hydrostatic pressure test
1. The hydrostatic pressure test value of coupling and threaded pipe is the lowest value of the hydrostatic test pressure of the flat end pipe, the maximum hydrostatic pressure test pressure of the coupling, and the internal pressure leakage resistance, but the standard maximum pressure is 69MPa and the pressure is calculated. The value is generally rounded to the nearest 0.5 MPa.
2. According to API requirements, the hydrostatic test pressure measuring device should be calibrated within 4 months before each use.
3. If the customer has special requirements, a higher pressure test pressure can be selected.
4. Hydrostatic pressure test Leakage is the basis for rejection.
5. Except where otherwise agreed between the purchaser and the manufacturer, hydrostatic pressure testing is not required for coupling blanks, coupling materials, nearby materials, or Q125 steel pup joints.
The popular description is to fill the pipe with water and test its ability to maintain the specified pressure without leaking or breaking under pressure. Its operations include three steps: flushing, pressure testing and water control.
API-5CT standard for hydrostatic pressure test
1. The hydrostatic pressure test value of coupling and threaded pipe is the lowest value of the hydrostatic test pressure of the flat end pipe, the maximum hydrostatic pressure test pressure of the coupling, and the internal pressure leakage resistance, but the standard maximum pressure is 69MPa and the pressure is calculated. The value is generally rounded to the nearest 0.5 MPa.
2. According to API requirements, the hydrostatic test pressure measuring device should be calibrated within 4 months before each use.
3. If the customer has special requirements, a higher pressure test pressure can be selected.
4. Hydrostatic pressure test Leakage is the basis for rejection.
5. Except where otherwise agreed between the purchaser and the manufacturer, hydrostatic pressure testing is not required for coupling blanks, coupling materials, nearby materials, or Q125 steel pup joints.
Heat Treatment Technology of Casing Pipe
27MnCrV steel AC1 = 736 °C, AC3 = 810 °C, sub-temperature quenching heating temperature between 740-810 °C selected. Sub-temperature quenching selection of heating temperature 780 °C, quenching and heating of the holding time 15min; tempering temperature after the selection of 630 °C, tempering heating holding time 50min. Since the sub-temperature quenching is heated in the α+γ two-phase region, quenching is performed in the state where the retained ferrite is partially dissolved, and the toughness is improved while maintaining high strength.
At the same time, the low-temperature quenching is lower than the conventional temperature, reducing the quenching stress, thereby reducing the quenching deformation, thus ensuring the smooth operation of the heat treatment production, and providing a very good raw material for subsequent wire processing and the like.
At present, the process has been applied to the processing plant of Magnon Steel, and the warranty data shows that after heat treatment, the yield strength Rt0.6 of the steel pipe is 820-860MPa, the tensile strength Rm is 910-940MPa, and the impact toughness Akv is 65-85J. , The resistance to destruction is 100% qualified. The data shows that the 27MnCrV steel pipe is a very good high-grade casing pipe, on the other hand, it also shows that the sub-temperature quenching process is an excellent method to avoid high-temperature brittleness in the production of steel products.
At the same time, the low-temperature quenching is lower than the conventional temperature, reducing the quenching stress, thereby reducing the quenching deformation, thus ensuring the smooth operation of the heat treatment production, and providing a very good raw material for subsequent wire processing and the like.
At present, the process has been applied to the processing plant of Magnon Steel, and the warranty data shows that after heat treatment, the yield strength Rt0.6 of the steel pipe is 820-860MPa, the tensile strength Rm is 910-940MPa, and the impact toughness Akv is 65-85J. , The resistance to destruction is 100% qualified. The data shows that the 27MnCrV steel pipe is a very good high-grade casing pipe, on the other hand, it also shows that the sub-temperature quenching process is an excellent method to avoid high-temperature brittleness in the production of steel products.
What are the disadvantages of hot and cold rolling processes for seamless tubes
Hot rolled and cold rolled (dial) seamless tubes
1. The cross-section of the cold-rolled seamless pipe is partially embossed, and then the bearing capacity of the bar can be fully utilized; and the hot-rolled steel does not agree with the section of the section.
2. The causes of residual stress in hot-rolled seamless square tubes and cold-rolled sections are different, so the dispersion on the sections is also very different. The residual stress distribution on the section of the cold-formed thin-walled steel is a tortuous type, and the residual stress distribution on the section of the hot-drawn steel or welded steel is a film type.
3. The freely changing stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsional function of hot-rolled steel is better than that of cold-rolled steel. Cold-rolled seamless pipe cold-rolled seamless steel pipe refers to steel that is processed into various types by cold drawing, cold bending, cold drawing and other cold working at normal temperature.
Strengths: fast forming speed, high output value, and no damage to the coating, can be made into a variety of cross-sections to meet the needs of the conditions; cold rolling can cause large plastic deformation of the steel, and then improve the yield of the steel point.
Defect:
1. Although there is no hot plastic shrinkage during the forming process, there is still residual stress in the cross section, which inevitably affects the characteristics of the whole steel and part of the steel;
2. The cold-rolled steel profile is generally an open section, so that the freeness of the section changes less. It is simple to change when it is bent. It is simple to show bending and torsion when pressed, and the torsion resistance is poor.
3. The wall thickness of cold-rolled steel is small, and there is no thickening at the corner of the joint of the plate. The ability to gather loads is weak.
http://www.xysteelpipe.com/info/What-are-the-disadvantages-of-hot-and-cold-rolling-processes-for-seamless-tubes-1279-1.htm
1. The cross-section of the cold-rolled seamless pipe is partially embossed, and then the bearing capacity of the bar can be fully utilized; and the hot-rolled steel does not agree with the section of the section.
2. The causes of residual stress in hot-rolled seamless square tubes and cold-rolled sections are different, so the dispersion on the sections is also very different. The residual stress distribution on the section of the cold-formed thin-walled steel is a tortuous type, and the residual stress distribution on the section of the hot-drawn steel or welded steel is a film type.
3. The freely changing stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsional function of hot-rolled steel is better than that of cold-rolled steel. Cold-rolled seamless pipe cold-rolled seamless steel pipe refers to steel that is processed into various types by cold drawing, cold bending, cold drawing and other cold working at normal temperature.
Strengths: fast forming speed, high output value, and no damage to the coating, can be made into a variety of cross-sections to meet the needs of the conditions; cold rolling can cause large plastic deformation of the steel, and then improve the yield of the steel point.
Defect:
1. Although there is no hot plastic shrinkage during the forming process, there is still residual stress in the cross section, which inevitably affects the characteristics of the whole steel and part of the steel;
2. The cold-rolled steel profile is generally an open section, so that the freeness of the section changes less. It is simple to change when it is bent. It is simple to show bending and torsion when pressed, and the torsion resistance is poor.
3. The wall thickness of cold-rolled steel is small, and there is no thickening at the corner of the joint of the plate. The ability to gather loads is weak.
http://www.xysteelpipe.com/info/What-are-the-disadvantages-of-hot-and-cold-rolling-processes-for-seamless-tubes-1279-1.htm
2018年11月15日星期四
How to Bend the Square Tube Bending Machine without Wrinkle
There are some steps about how to bend the square tube bending machine not o be wrinkled:
1. Clamp (clamping) part of the tube must be clamped, if not clamping, it will wrinkle.
2. If the clamping clamp, but also wrinkled, pay attention to the diameter of the mold (round mold) shape, the outer mold should be outside the drum, so that the inner wall of the square tube into a little, so the tube deformation is stable.
3. At the same time pay attention to secondary mold and die diameter distance, not too tight or too loose.
4. Solve the above problems or not, it is necessary to adjust the shape of the core, the use of joint through the core, and adjust the distance of the through the core.
5. Adjust the joint through the core or wrinkled, remember to install wrinkle-free mold, try bending slower, timely adjustment of the core lift length and wrinkle-free mold location.
6. If this still does not work, especially for thin-walled stainless steel square tubes or aluminum square tubes, fine sand may be required to ensure high-quality
1. Clamp (clamping) part of the tube must be clamped, if not clamping, it will wrinkle.
2. If the clamping clamp, but also wrinkled, pay attention to the diameter of the mold (round mold) shape, the outer mold should be outside the drum, so that the inner wall of the square tube into a little, so the tube deformation is stable.
3. At the same time pay attention to secondary mold and die diameter distance, not too tight or too loose.
4. Solve the above problems or not, it is necessary to adjust the shape of the core, the use of joint through the core, and adjust the distance of the through the core.
5. Adjust the joint through the core or wrinkled, remember to install wrinkle-free mold, try bending slower, timely adjustment of the core lift length and wrinkle-free mold location.
6. If this still does not work, especially for thin-walled stainless steel square tubes or aluminum square tubes, fine sand may be required to ensure high-quality
Production Process of Large Diameter Thick-walled Square Tube
Production process of large diameter thick-walled square tube are as follows:
The first step: Raw materials that strip, wire, flux. In the input before going through a rigorous physical and chemical testing.
The second step: The end of the strip butt joint, the use of single or double wire submerged arc welding, rolled into large diameter thick-walled square tube automatic submerged arc welding.
The third step: Before forming, strip through leveling, trimming, planing, surface cleaning and conveying to the bending treatment.
The fourth step: The use of electric contact pressure gauge control conveyor pressure on both sides of the press to ensure a smooth strip delivery.
The five step: The use of external control or roller molding.
The six step: Large-diameter thick-walled square tube weld seam gap control device used to ensure the weld gap to meet the welding requirements, pipe diameter, the wrong side of the amount and weld gap have been strictly controlled.
The seventh step: Large-diameter thick-walled square tube wall welding is divided into internal and external welding, are used by the United States Lincoln welding machine for single-wire or double-wire submerged arc welding to obtain a stable welding specifications.
The eighth step: Weld large-diameter thick-walled square tube welded continuous online ultrasonic testing after injury, to ensure that 100% of the spiral weld non-destructive testing coverage. If there are defects, automatic alarm and spray mark, the production workers so adjust the process parameters at any time, promptly eliminate defects.
The nine step: The air plasma cutting machine will be cut into large single-tube thick-walled square tube.
The first step: Raw materials that strip, wire, flux. In the input before going through a rigorous physical and chemical testing.
The second step: The end of the strip butt joint, the use of single or double wire submerged arc welding, rolled into large diameter thick-walled square tube automatic submerged arc welding.
The third step: Before forming, strip through leveling, trimming, planing, surface cleaning and conveying to the bending treatment.
The fourth step: The use of electric contact pressure gauge control conveyor pressure on both sides of the press to ensure a smooth strip delivery.
The five step: The use of external control or roller molding.
The six step: Large-diameter thick-walled square tube weld seam gap control device used to ensure the weld gap to meet the welding requirements, pipe diameter, the wrong side of the amount and weld gap have been strictly controlled.
The seventh step: Large-diameter thick-walled square tube wall welding is divided into internal and external welding, are used by the United States Lincoln welding machine for single-wire or double-wire submerged arc welding to obtain a stable welding specifications.
The eighth step: Weld large-diameter thick-walled square tube welded continuous online ultrasonic testing after injury, to ensure that 100% of the spiral weld non-destructive testing coverage. If there are defects, automatic alarm and spray mark, the production workers so adjust the process parameters at any time, promptly eliminate defects.
The nine step: The air plasma cutting machine will be cut into large single-tube thick-walled square tube.
Difference between Stainless Steel Seamless Pipe and Carbon Steel Seamless Pipe
The so-called difference between stainless steel seamless pipe and carbon steel seamless pipe, stainless steel and carbon steel mainly refers to the difference in the design rules, that is, the design rules of these two types of steel are not universal.
These differences are summarized as follows: The design rules of stainless steel can not be used for carbon steel because there are 3 fundamental differences between stainless steel and carbon steel:
First, when cold working stainless steel produce work hardening, for example, when bending anisotropy, namely: the horizontal and vertical performance are different. The strength increased by cold working can be utilized, but if the bending area is small compared to the total area and negligible, the increase in strength can improve the safety factor to a certain extent.
Second, the shape of the stress / strain curve is different. The elastic limit of stainless steel is about 50% of the yield stress. The yield stress is lower than the yield stress of medium carbon steel in terms of the minimum specified in the standard.
Third, stainless steel does not yield point, usually ó0.2 that yield stress is considered equivalent.
These differences are summarized as follows: The design rules of stainless steel can not be used for carbon steel because there are 3 fundamental differences between stainless steel and carbon steel:
First, when cold working stainless steel produce work hardening, for example, when bending anisotropy, namely: the horizontal and vertical performance are different. The strength increased by cold working can be utilized, but if the bending area is small compared to the total area and negligible, the increase in strength can improve the safety factor to a certain extent.
Second, the shape of the stress / strain curve is different. The elastic limit of stainless steel is about 50% of the yield stress. The yield stress is lower than the yield stress of medium carbon steel in terms of the minimum specified in the standard.
Third, stainless steel does not yield point, usually ó0.2 that yield stress is considered equivalent.
Reasons for corrosion of 304 stainless steel seamless tube
Metal of 304 stainless steel seamless pipe and oxygen in the atmosphere to react, the appearance will form an oxide film. However, the iron oxide formed on a common carbon steel pipe is continuously oxidized, causing the corrosion to continuously expand, and as a result, pores are formed. Such good stainless steel seamless pipes are damaged. We can use galvanized paint or oxidation-resistant metals such as zinc, nickel and chrome to coat the carbon steel. However, as we expected, this maintenance is only a layer of maintenance film, assuming the maintenance layer is damaged, the steel will begin to be eroded. The corrosion resistance of stainless steel depends on chromium. Chromium is part of the steel composition. When chromium is combined with steel, the type of oxide in the surface changes to a surface oxide similar to pure chromium metal. This tightly adhering chromium-rich oxide maintains the appearance and avoids further oxidation.
Heat treatment process includes heating, insulation, cooling, etc., this is done in order to reduce the deformation of the metal forming process due to hardening and other shortcomings, the processing of deformed pipe back to before processing, so that performance is improved.
Now the most common heat treatment tools, including electric furnace and refire furnace; commonly seen control method is automatic temperature control mode.
Different 304 stainless steel seamless pipe fittings require different heat treatment, and not all the deformation of the tools have to be heat treatment, usually low-carbon steel pipe fittings, the final temperature of not less than 723 ℃, then you can not heat treatment, if below this temperature or above 1000 degrees celsius heat treatment should be carried out.
Heat treatment process includes heating, insulation, cooling, etc., this is done in order to reduce the deformation of the metal forming process due to hardening and other shortcomings, the processing of deformed pipe back to before processing, so that performance is improved.
Now the most common heat treatment tools, including electric furnace and refire furnace; commonly seen control method is automatic temperature control mode.
Different 304 stainless steel seamless pipe fittings require different heat treatment, and not all the deformation of the tools have to be heat treatment, usually low-carbon steel pipe fittings, the final temperature of not less than 723 ℃, then you can not heat treatment, if below this temperature or above 1000 degrees celsius heat treatment should be carried out.
Precautions for welding of 304 stainless steel pipe
Precautions for welding of 304 stainless steel pipe are as follows:
1, The use of vertical external power supply, DC positive polarity (wire connected negative).
2, Generally suitable for the welding of sheet 6mm below, with the appearance of weld appearance, welding deformation of a small amount of features.
3, The protective gas is argon, purity of 99.99%. When the welding current is 50 ~ 50A, argon flow rate is 8 ~ 0L / min, when the current is 50 ~ 250A, argon flow rate is 2 ~ 5L / min.
4, Tungsten protruding from the gas nozzle to the length of 4 ~ 5mm is better, in the fillet welding and other poor shielding is 2 ~ 3mm, deep groove where it is 5 ~ 6mm, the nozzle to the work of the general distance more than 5mm.
5, In order to prevent the emergence of welding pores, weld rust, oil, etc. must be cleaned.
6, The welding arc length, welding ordinary steel, preferably 2 ~ 4mm, and welding stainless steel to ~ 3mm is better, too long, the protection is not good.
7, The docking base, in order to prevent the back of the bottom weld is oxidized, the back also need to implement gas protection.
8, In order to make the argon well protect the welding pool, and to facilitate the welding operation, the tungsten centerline and welding workpieces should generally maintain 80 ~ 85 ° angle, filler wire and workpiece surface angle should be as small as possible, Generally 0 & deg; left and right.
9, Wind and ventilation. Windy areas, be sure to take the measures to block the network, while indoors should take appropriate ventilation measures.
1, The use of vertical external power supply, DC positive polarity (wire connected negative).
2, Generally suitable for the welding of sheet 6mm below, with the appearance of weld appearance, welding deformation of a small amount of features.
3, The protective gas is argon, purity of 99.99%. When the welding current is 50 ~ 50A, argon flow rate is 8 ~ 0L / min, when the current is 50 ~ 250A, argon flow rate is 2 ~ 5L / min.
4, Tungsten protruding from the gas nozzle to the length of 4 ~ 5mm is better, in the fillet welding and other poor shielding is 2 ~ 3mm, deep groove where it is 5 ~ 6mm, the nozzle to the work of the general distance more than 5mm.
5, In order to prevent the emergence of welding pores, weld rust, oil, etc. must be cleaned.
6, The welding arc length, welding ordinary steel, preferably 2 ~ 4mm, and welding stainless steel to ~ 3mm is better, too long, the protection is not good.
7, The docking base, in order to prevent the back of the bottom weld is oxidized, the back also need to implement gas protection.
8, In order to make the argon well protect the welding pool, and to facilitate the welding operation, the tungsten centerline and welding workpieces should generally maintain 80 ~ 85 ° angle, filler wire and workpiece surface angle should be as small as possible, Generally 0 & deg; left and right.
9, Wind and ventilation. Windy areas, be sure to take the measures to block the network, while indoors should take appropriate ventilation measures.
2018年11月5日星期一
Special treatment for large diameter steel pipe
If your customer has affection on large diameter steel pipe, no matter ERW steel pipe or LSAW type, you would figure out the advantages for it. Thus, you will finally figure out the special treatment for large diameter steel pipe.
In order to achieve the standards like API, we know that large diameter pipe would have strict production process. Thus, it can serve on the engineering project like bridge piling, underwater piling, piling high-rise buildings.
With its good adhesion, corrosion resistance, and other traits, we will make large diameter steel tube improve traffic and transportation efficiency, reduce delivery pressure loss.
Coating solvent-free is another character, no leaking substances, and thus will not contaminate the transmission medium, thus ensuring fluid purity and hygiene at -40 ℃ to +80 ℃ range can be used alternately hot and cold cycles, aging, no cracks, which can in cold areas such harsh environments.
In order to achieve the standards like API, we know that large diameter pipe would have strict production process. Thus, it can serve on the engineering project like bridge piling, underwater piling, piling high-rise buildings.
With its good adhesion, corrosion resistance, and other traits, we will make large diameter steel tube improve traffic and transportation efficiency, reduce delivery pressure loss.
Coating solvent-free is another character, no leaking substances, and thus will not contaminate the transmission medium, thus ensuring fluid purity and hygiene at -40 ℃ to +80 ℃ range can be used alternately hot and cold cycles, aging, no cracks, which can in cold areas such harsh environments.
Main steel grade for API 5CT steel pipe
API 5CT steel tube belongs to API casing. No matter seamless steel pipe or welded type, it is mainly used among the structural retainer for the walls of oil, gas wells. Today, our main topic would focus on main steel grade of it.
The main steel grade of API 5CT would conclude the following five types.
API 5CT J55;
API 5CT K55;
API 5CT N80;
API 5CT L80;
API 5CT P110.
With its special characters, we will figure out that the basic size for this steel pipeline.
Outer Dimensions: 6.0mm–219.0mm;
Wall Thickness: 1.0mm–30 mm;
Length: max 12000mm.
The main steel grade of API 5CT would conclude the following five types.
API 5CT J55;
API 5CT K55;
API 5CT N80;
API 5CT L80;
API 5CT P110.
With its special characters, we will figure out that the basic size for this steel pipeline.
Outer Dimensions: 6.0mm–219.0mm;
Wall Thickness: 1.0mm–30 mm;
Length: max 12000mm.
The importance of heat treatment to steel pipe production
We cannot ignore any detail during the steel pipe’s production process as all of them would finally determine the quality of seamless or ERW steel pipe. Today, you can hear the importance of heat treatment for steel pipe production.
It needs a microstructure even for heat treatment’s control that allows abrasion resistant steel to have a high hardness, thus, we can get high quality steel pipe with this material. This is accomplished, in part, by adding the proper alloying elements. Except this one, we still need to focus on the heating and a rapid quenching process to form microstructures such as martensite and bainite which gives the steel the required high hardness values. For more information about the heat treatment, welcome to have a view in our factory.
It needs a microstructure even for heat treatment’s control that allows abrasion resistant steel to have a high hardness, thus, we can get high quality steel pipe with this material. This is accomplished, in part, by adding the proper alloying elements. Except this one, we still need to focus on the heating and a rapid quenching process to form microstructures such as martensite and bainite which gives the steel the required high hardness values. For more information about the heat treatment, welcome to have a view in our factory.
Requirement of rust - proof layer of petroleum steel pipeline
Oil transportation, no matter by seamless steel pipe or welded tubes, has high demand for pipeline itself. Today, the special topic would be focus on demands of the rust layer for oil steel tubes.
The affecting factors for the oil pipeline would conclude transport conditions, long or short distance; open dump time, rust varnish and so on. And how can we ignore the bug during the transportation? This need steel pipes have properties of good construction performance, security, environmental protection, quick drying; bright, transparent film and so on. Thus, we will adopt anti-rust layer with good weather resistance; impact, bumps and impact damage during handling and transport of the oil pipeline, there factor, anti-rust layer should have good impact resistance; the operation of shipping, hot and humid zones, anti-rust layer should have good moisture resistance, salt spray resistance.
The affecting factors for the oil pipeline would conclude transport conditions, long or short distance; open dump time, rust varnish and so on. And how can we ignore the bug during the transportation? This need steel pipes have properties of good construction performance, security, environmental protection, quick drying; bright, transparent film and so on. Thus, we will adopt anti-rust layer with good weather resistance; impact, bumps and impact damage during handling and transport of the oil pipeline, there factor, anti-rust layer should have good impact resistance; the operation of shipping, hot and humid zones, anti-rust layer should have good moisture resistance, salt spray resistance.
Identification Of Seamed Steel Pipes And Seamless Steel Pipes
The steel pipe is divided into two major categories according to the molding method and the manufacturing method. The seamless steel pipe and the welded pipe (the welded pipe is what you call the seamed steel pipe). Seamless steel tubes can be further divided into hot rolled and cold rolled cold drawn tubes. The welded pipe can be further divided into a lsaw steel pipe and a ssaw steel pipe. The seam here does not mean that there are gaps, but the steel pipe has weld marks. After the treatment, the welder is difficult to see.
The two are divided according to the processing form. The seamed steel pipe is generally welded. The seamless steel pipe has two methods of cold drawing and hot drawing. The carbon steel pipe is in terms of material, and the galvanized pipe is the surface of the welded pipe after the production. Galvanized treatment. Popular: the conveyor carrier requires high, such as pressure, environment, maintenance, corrosion, temperature, etc. with seamless steel pipe. For pressure and temperature requirements, there are seam steel pipes, such as domestic water pipes and gas pipes.
The easiest way to identify the two is to look at the look. There are seam steel pipes, there will be a welded straight line, or the surface is polished. There is also straightness, uneven thickness, and it can't be tested. Some tubes with seamless steel pipe are annealed to the weld, eliminating the residual stress of the weld, making the weld equivalent to the base metal, and its pressure range is basically equivalent to that of the seamless pipe. However, some seamless steel pipes which are welded or rolled with the jointed steel pipe are mainly small-sized pipes. These pipes are only seamless pipes in terms of shape, and their essence is not very good. It is a pressure test.
http://www.xysteelpipe.com/info/Identification-Of-Seamed-Steel-Pipes-And-Seamless-Steel-Pipes-1263-1.htm
The two are divided according to the processing form. The seamed steel pipe is generally welded. The seamless steel pipe has two methods of cold drawing and hot drawing. The carbon steel pipe is in terms of material, and the galvanized pipe is the surface of the welded pipe after the production. Galvanized treatment. Popular: the conveyor carrier requires high, such as pressure, environment, maintenance, corrosion, temperature, etc. with seamless steel pipe. For pressure and temperature requirements, there are seam steel pipes, such as domestic water pipes and gas pipes.
The easiest way to identify the two is to look at the look. There are seam steel pipes, there will be a welded straight line, or the surface is polished. There is also straightness, uneven thickness, and it can't be tested. Some tubes with seamless steel pipe are annealed to the weld, eliminating the residual stress of the weld, making the weld equivalent to the base metal, and its pressure range is basically equivalent to that of the seamless pipe. However, some seamless steel pipes which are welded or rolled with the jointed steel pipe are mainly small-sized pipes. These pipes are only seamless pipes in terms of shape, and their essence is not very good. It is a pressure test.
http://www.xysteelpipe.com/info/Identification-Of-Seamed-Steel-Pipes-And-Seamless-Steel-Pipes-1263-1.htm
2018年10月25日星期四
Testing the mechanical and technological properties of seamless steel tube
In order to verify the mechanical properties of seamless steel pipe to meet the requirements of the standard, the test sample of seamless steel pipe mechanical performance should be prepared carefully. Mechanical property test includes tensile strength, yield strength, elongation, impact energy and so on. Process performance test includes flattening test, flaring test, hydrostatic testing, curling trials, cold bend test, perforation test. These test items are based on different standards and different uses of seamless steel tubes.
Non-destructive testing of seamless steel pipe
Under the premise of not damaging the specimen, NDT refers to carry out inspection and testing to internal and surface structure, properties, status of specimen with physical or chemical methods, advanced technology and equipment. The development of non destructive testing technology has experienced three stages: Nondestructive detection, nondestructive testing and nondestructive evaluation.
Nondestructive detection is the name of the early stage, and the meaning is to detect and detect defects; Nondestructive testing is the name of the current stage, its meaning is not only to detect defects, but also to detect some other information, such as the structure, nature, status, etc.; And nondestructive evaluation (NDE) is one which is entered or is entering a new stage, it requires not only the defects are found, but also detection test pieces of the structure, properties, status, and access more comprehensive and more accurate, comprehensive information, such as defects associated with the shape, size, location, orientation, inclusions, tissue defect, residual stress force of information. It is necessary to combined with imaging technology, automation technology, and computer data analysis and processing technology, and mechanics of materials, and other fields of knowledge, and gives a comprehensive and accurate evaluation of the quality and performance of the test piece or product.
Non-destructive testing of seamless steel pipe
Under the premise of not damaging the specimen, NDT refers to carry out inspection and testing to internal and surface structure, properties, status of specimen with physical or chemical methods, advanced technology and equipment. The development of non destructive testing technology has experienced three stages: Nondestructive detection, nondestructive testing and nondestructive evaluation.
Nondestructive detection is the name of the early stage, and the meaning is to detect and detect defects; Nondestructive testing is the name of the current stage, its meaning is not only to detect defects, but also to detect some other information, such as the structure, nature, status, etc.; And nondestructive evaluation (NDE) is one which is entered or is entering a new stage, it requires not only the defects are found, but also detection test pieces of the structure, properties, status, and access more comprehensive and more accurate, comprehensive information, such as defects associated with the shape, size, location, orientation, inclusions, tissue defect, residual stress force of information. It is necessary to combined with imaging technology, automation technology, and computer data analysis and processing technology, and mechanics of materials, and other fields of knowledge, and gives a comprehensive and accurate evaluation of the quality and performance of the test piece or product.
Hot Rolling Treatment and Cold Stretching Treatment
After hot rolling or casting, the steel is no longer specialized for heat treatment and deliver directly after cooling, that is called hot rolling treatment. The terminal temperature of hot rolled is generally 800 to 900 degrees Celsius. After that, steel is generally cooling in the air, thus the state is equivalent to normalizing treatment. Due to the terminal temperature is high or low, different from normalizing heating temperature controlled strictly, The fluctuation of steel with hot rolling is greater than normalizing treatment on structure and properties.
The surface of steel with hot rolling is covered with a layer of iron oxide, which has a certain corrosion resistance. Therefore, requirements of storage and transportation is less strict than that of cold stretching and large and medium steel plate can be stored in the open yard.
Hot rolling treatment and cold stretching treatment
The steel, which is through cold stretching, without any heat treatment and direct delivery, is known as cold stretching. Compared with the state of hot rolled, cold stretching steel has high precision, good surface quality and higher mechanical properties. Due to the surface of steel with cold stretching is without oxide layer covered, and there are a lot of internal stress, it is extremely easy to suffer corrosion or rust. As a result, the packaging and storage of steel with cold stretching have strict requirements. It’s generally to be kept in the warehouse and the warehouse temperature and humidity should be pay attention.
The surface of steel with hot rolling is covered with a layer of iron oxide, which has a certain corrosion resistance. Therefore, requirements of storage and transportation is less strict than that of cold stretching and large and medium steel plate can be stored in the open yard.
Hot rolling treatment and cold stretching treatment
The steel, which is through cold stretching, without any heat treatment and direct delivery, is known as cold stretching. Compared with the state of hot rolled, cold stretching steel has high precision, good surface quality and higher mechanical properties. Due to the surface of steel with cold stretching is without oxide layer covered, and there are a lot of internal stress, it is extremely easy to suffer corrosion or rust. As a result, the packaging and storage of steel with cold stretching have strict requirements. It’s generally to be kept in the warehouse and the warehouse temperature and humidity should be pay attention.
The Application Range of LSAW Steel Pipe
LSAW (LSAW-Longitudinal Submerged Arc Welded) was invented in 1940, a new welding method, welding hand in front of it and the same place it is to protect the use of slag, but this residue is not a skin electrode medicine . Straight seam double submerged arc welding and manual welding the same place it is to protect the use of slag, but this residue is not a skin electrode medicine, is dedicated melting out of the welding flux. The welding system consists of a funnel drug loading of the welding flux through a pipeline to be welded to the front. The second difference is the use of welding, using wire, because the wire can be continuously sent; electrode, we gotta burn a welding electrode head and gave a throw, and the operation was stopped, for welding and then welded.
The application range :
LSAW steel pipe diameter in the range between 406 ~ 1600mm, in exceptional cases even more, the ratio of wall thickness and diameter of about 0.06 to 0.08. Modern foreign technology can produce pipe up to 100mm wall thickness of pipe.
Industrial production of steel plate or straight seam steel pipe only a few ways, the principle difference is the method of forming steel pipe, steel pipe after forming the follow-up process is basically the same. Methodological principles of forming the weld depends on the distribution of steel, according to the distribution of the pipes to weld two basic forms: straight seam and spiral seam steel pipe. Corresponding to this, straight seam welded pipe production into the production and the production of spiral seam pipe. Straight seam and spiral seam steel pipe the most widely used method is submerged arc welding (SAW), its good quality, high productivity, technology is mature and stable. Currently, straight seam steel pipe widely used abroad following range: air land and sea transport, water and oil trunk pipelines; transport chemicals and chemical products of stainless steel tube; marine industrial structure with a tube; boiler manufacturing and special purpose pipe structural tube.
The application range :
LSAW steel pipe diameter in the range between 406 ~ 1600mm, in exceptional cases even more, the ratio of wall thickness and diameter of about 0.06 to 0.08. Modern foreign technology can produce pipe up to 100mm wall thickness of pipe.
Industrial production of steel plate or straight seam steel pipe only a few ways, the principle difference is the method of forming steel pipe, steel pipe after forming the follow-up process is basically the same. Methodological principles of forming the weld depends on the distribution of steel, according to the distribution of the pipes to weld two basic forms: straight seam and spiral seam steel pipe. Corresponding to this, straight seam welded pipe production into the production and the production of spiral seam pipe. Straight seam and spiral seam steel pipe the most widely used method is submerged arc welding (SAW), its good quality, high productivity, technology is mature and stable. Currently, straight seam steel pipe widely used abroad following range: air land and sea transport, water and oil trunk pipelines; transport chemicals and chemical products of stainless steel tube; marine industrial structure with a tube; boiler manufacturing and special purpose pipe structural tube.
Quality control method of LSAW steel pipe
Large diameter LSAW steel pipe with its large wall thickness, good material, processing technology and stability, has become the first choice of steel large oil and gas transmission project at present at home and abroad. LSAW steel pipe in large diameter welded joints, the weld and heat affected zone is the most easy to produce all kinds of defects, and welding undercut, porosity, slag inclusion, incomplete fusion, lack of penetration, overip, burn, welding crack is the main form of welding defects, it is often the origin of the LSAW steel pipe the quality accident.
Quality control measures:
1. 1) before the welding quality control to quality first good raw materials, can be officially entered the construction site after passing inspection, and resolutely put an end to the use of substandard steel.
2) followed by the management of welding materials. Check whether the welding materials for qualified products, storage and baking system is executed, issued by the welding material surface is clean without rust, the electrode is intact, there is no mildew.
3) again is the welding area clean management. Check the welding area clean quality, no water, oil, rust and other dirt film, which plays an important role in avoiding weld external defects.
4) select the appropriate welding methods, welding principle should be applied, after the implementation of welding test.
2. 1) quality control in welding according to welding procedure review of welding wire and flux specifications are correct, to prevent misuse of wire and flux caused by welding quality accident.
2) to supervise the welding environment, welding environment is not good (when the temperature is below 0 DEG C, the relative humidity is greater than 90%) to take corresponding measures after welding at.
3) to test the pre groove size before welding, including clearance, edge, angle and the wrong port meets the technical requirements.
4) used in the welding process and automatic submerged arc welding current, welding voltage, welding speed and other parameters are correct.
5) supervision personnel in the submerged arc welding automatic welding and make full use of the pipe end arc plate length, and enhance the efficiency of the use of welding arc plate, which helps to improve the welding quality of tube end.
6) personnel in the supervision of welding repair welding is clean, whether the first slag has been completely processing joint, whether there is oil, rust, slag, water, paint and dirt groove.
Quality control measures:
1. 1) before the welding quality control to quality first good raw materials, can be officially entered the construction site after passing inspection, and resolutely put an end to the use of substandard steel.
2) followed by the management of welding materials. Check whether the welding materials for qualified products, storage and baking system is executed, issued by the welding material surface is clean without rust, the electrode is intact, there is no mildew.
3) again is the welding area clean management. Check the welding area clean quality, no water, oil, rust and other dirt film, which plays an important role in avoiding weld external defects.
4) select the appropriate welding methods, welding principle should be applied, after the implementation of welding test.
2. 1) quality control in welding according to welding procedure review of welding wire and flux specifications are correct, to prevent misuse of wire and flux caused by welding quality accident.
2) to supervise the welding environment, welding environment is not good (when the temperature is below 0 DEG C, the relative humidity is greater than 90%) to take corresponding measures after welding at.
3) to test the pre groove size before welding, including clearance, edge, angle and the wrong port meets the technical requirements.
4) used in the welding process and automatic submerged arc welding current, welding voltage, welding speed and other parameters are correct.
5) supervision personnel in the submerged arc welding automatic welding and make full use of the pipe end arc plate length, and enhance the efficiency of the use of welding arc plate, which helps to improve the welding quality of tube end.
6) personnel in the supervision of welding repair welding is clean, whether the first slag has been completely processing joint, whether there is oil, rust, slag, water, paint and dirt groove.
The Difference Between Galvanized Pipe And Seamless Pipe
Hot-dip galvanized steel pipe: reacts a molten metal with an iron matrix to produce an alloy layer, thereby combining the substrate and the plating layer. Hot-dip galvanizing is to pickle the steel pipe first, in order to remove the iron oxide on the surface of the steel pipe, after pickling, it is washed by ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then fed. Hot dip plating tank.
Hot-dip galvanizing has the advantages of uniform plating, strong adhesion and long service life. The complex physical and chemical anti-galvanized steel pipe of the hot-dip galvanized steel pipe base and the molten plating solution shall form a corrosion-resistant structure of a zinc-iron alloy layer. The alloy layer is integrated with the pure zinc layer and the steel pipe base. Therefore, its corrosion resistance is strong.
Hot-dip galvanized seamless steel pipe: the galvanizing amount is very small, only 10-50g/m2, and its corrosion resistance is much worse than that of hot-dip galvanized pipe. Regular galvanized pipe manufacturers use quenched galvanized pipes as water and gas pipes. The galvanized layer of the cold-galvanized steel pipe is an electroplated layer, and the zinc layer and the steel pipe matrix are independently layered. The zinc layer is thin, and the zinc layer is simply attached to the steel pipe base and is easy to fall off. Therefore, its corrosion resistance is poor. In newly built houses, the use of cold-galvanized steel pipes as water supply pipes is prohibited.
The difference between galvanized pipe and seamless pipe:
1. Efficient and environmentally friendly, non-toxic, non-polluting, non-corrosive, not only has the function of pickling, corrosion and fog suppression, but also has the effect of derusting and high-efficiency degreasing. It does not produce toxic or harmful substances during use, which reduces air pollution, is beneficial to the health of operators and improves the working environment of the workshop.
The existing pickling process has large consumption of hydrochloric acid, large acid mist, and short waste acid discharge cycle, and the product can be recycled after being added in a small amount during use, and can be used in the acid during use. Most of the ferrous chloride is converted into iron oxide and precipitated, which greatly prolongs the discharge cycle of the waste liquid.
2. There is no “over-etching” and “rust embrittlement” in the process of derusting. There is no “weight loss” phenomenon when steel materials are immersed for a long time.
3. Strong derusting ability, good effect, fast speed (descaling speed can be adjusted according to needs) General floating rust can be removed in about 5 minutes, significantly better than the current pickling process.
4. The workpiece after descaling with this product has a strong rust-removing adhesion to the zinc layer during galvanizing. The finish is good, and it is obviously superior to the pure hydrochloric acid pickled workpiece.
5. The cost of descaling is lower than the cost of existing pickling (the product can be extended for more than four times after adding this product in the acid solution).
6. The derusting speed can be adjusted in the range of 1min-60min. Generally, the floating rust can be removed within 3 minutes, and the heavy rust can be removed within 30 minutes. Depending on the size of the steel surface, the degree of corrosion and the number of steel grades, the rust of 20-100 tons of material can be removed per ton of rust removal liquid.
http://www.xysteelpipe.com/info/The-Difference-Between-Galvanized-Pipe-And-Seamless-Pipe-1307-1.htm
Hot-dip galvanizing has the advantages of uniform plating, strong adhesion and long service life. The complex physical and chemical anti-galvanized steel pipe of the hot-dip galvanized steel pipe base and the molten plating solution shall form a corrosion-resistant structure of a zinc-iron alloy layer. The alloy layer is integrated with the pure zinc layer and the steel pipe base. Therefore, its corrosion resistance is strong.
Hot-dip galvanized seamless steel pipe: the galvanizing amount is very small, only 10-50g/m2, and its corrosion resistance is much worse than that of hot-dip galvanized pipe. Regular galvanized pipe manufacturers use quenched galvanized pipes as water and gas pipes. The galvanized layer of the cold-galvanized steel pipe is an electroplated layer, and the zinc layer and the steel pipe matrix are independently layered. The zinc layer is thin, and the zinc layer is simply attached to the steel pipe base and is easy to fall off. Therefore, its corrosion resistance is poor. In newly built houses, the use of cold-galvanized steel pipes as water supply pipes is prohibited.
The difference between galvanized pipe and seamless pipe:
1. Efficient and environmentally friendly, non-toxic, non-polluting, non-corrosive, not only has the function of pickling, corrosion and fog suppression, but also has the effect of derusting and high-efficiency degreasing. It does not produce toxic or harmful substances during use, which reduces air pollution, is beneficial to the health of operators and improves the working environment of the workshop.
The existing pickling process has large consumption of hydrochloric acid, large acid mist, and short waste acid discharge cycle, and the product can be recycled after being added in a small amount during use, and can be used in the acid during use. Most of the ferrous chloride is converted into iron oxide and precipitated, which greatly prolongs the discharge cycle of the waste liquid.
2. There is no “over-etching” and “rust embrittlement” in the process of derusting. There is no “weight loss” phenomenon when steel materials are immersed for a long time.
3. Strong derusting ability, good effect, fast speed (descaling speed can be adjusted according to needs) General floating rust can be removed in about 5 minutes, significantly better than the current pickling process.
4. The workpiece after descaling with this product has a strong rust-removing adhesion to the zinc layer during galvanizing. The finish is good, and it is obviously superior to the pure hydrochloric acid pickled workpiece.
5. The cost of descaling is lower than the cost of existing pickling (the product can be extended for more than four times after adding this product in the acid solution).
6. The derusting speed can be adjusted in the range of 1min-60min. Generally, the floating rust can be removed within 3 minutes, and the heavy rust can be removed within 30 minutes. Depending on the size of the steel surface, the degree of corrosion and the number of steel grades, the rust of 20-100 tons of material can be removed per ton of rust removal liquid.
http://www.xysteelpipe.com/info/The-Difference-Between-Galvanized-Pipe-And-Seamless-Pipe-1307-1.htm
2018年10月16日星期二
How Is The Crack On The Surface Of The Seamless Steel Pipe?
The cleanliness and smoothness of the surface of the seamless steel pipe is a requirement for the selection of a seamless steel pipe. The cleanliness of the surface of the seamless steel pipe has become a key point for the customer to choose. In recent years, it has been valued by many companies. Cracks on the surface of seamless steel pipes are a common phenomenon and a direct cause of low sales. So what are the factors?
First, the raw material factors: the poor quality of the tube blank will appear inside and outside the skin, crusting, cracks, etc.
Second, the temperature factor: the first important process of seamless steel pipe production is heating, poor heating (uneven, insufficient temperature, etc.) will cause internal skin, etc.
Third, the equipment factor: from the beginning of the furnace, each equipment component will affect the final quality of the pipe. For example, if the equipment parts are scratched, it will cause the outer skin and pits; if the punching machine is not smooth, the head of the tube blank will be bitten by water and bite into the head or the inside of the head.
Fourth, the process problem: the process problem is also quite complicated, there are adjustment problems, problems with equipment failure, and the quality of the pipe produced after the wear of the process components (head, guide, rolls, etc.). The problems caused are all-encompassing.
Therefore, there are dozens of possible reasons for the occurrence of a defect. If you do not see the physical object or are not at the production site, it is often difficult to say the specific reasons.
http://www.xysteelpipe.com/info/How-Is-The-Crack-On-The-Surface-Of-The-Seamless-Steel-Pipe-1300-1.htm
First, the raw material factors: the poor quality of the tube blank will appear inside and outside the skin, crusting, cracks, etc.
Second, the temperature factor: the first important process of seamless steel pipe production is heating, poor heating (uneven, insufficient temperature, etc.) will cause internal skin, etc.
Third, the equipment factor: from the beginning of the furnace, each equipment component will affect the final quality of the pipe. For example, if the equipment parts are scratched, it will cause the outer skin and pits; if the punching machine is not smooth, the head of the tube blank will be bitten by water and bite into the head or the inside of the head.
Fourth, the process problem: the process problem is also quite complicated, there are adjustment problems, problems with equipment failure, and the quality of the pipe produced after the wear of the process components (head, guide, rolls, etc.). The problems caused are all-encompassing.
Therefore, there are dozens of possible reasons for the occurrence of a defect. If you do not see the physical object or are not at the production site, it is often difficult to say the specific reasons.
http://www.xysteelpipe.com/info/How-Is-The-Crack-On-The-Surface-Of-The-Seamless-Steel-Pipe-1300-1.htm
2018年10月15日星期一
Advantages of precision seamless steel pipe
1. Precision seamless steel pipe is light weight, high strength, easy for transportation and installation. It is only 1/4 of steel, but the circumferential tensile strength is 180 - 300MPa and the axial tensile strength is 60 - 15OMPa, which is similar to alloy steel. Therefore, the strength is 2 to 3 times of gold steel. So that it can meet different requirements of users, designed to various types of pipeline to withstand internal and external pressure. Precision seamless steel pipe is 12 meters per section, it is easy to install which reduce the cost of lifting and improve the installation speed.
2. Anti-fouling and anti-boring. Precision seamless steel pipe will not be affected by sewage, fungi and other microbial station fester, reduce maintenance costs. Without these pollution, precision seamless steel pipe can be used for a long time. Due to its smooth wall and excellent corrosion resistance, it will not produce scale and microbial, effectively ensure water quality.
3. Good heat resistance, good frost resistance. Below -30 degrees, precision seamless steel pipe still has good toughness and high strength, can be used at the range of 50 ℃ - 80 ℃.
4. Good corrosion resistance. Precision seamless steel pipes can resist acid, alkali, salt, sea water, untreated sewage, corrosive soil or groundwater and erosion of many chemical fluids. Compared to traditional pipes, it generally lasts more than 50 years, which is used in municipal, urban transmission and distribution network. Because precision seamless steel pipe is non-toxic, no rust, tasteless, no secondary pollution to water, no corrosion, they are widely used for drainage industry.
2. Anti-fouling and anti-boring. Precision seamless steel pipe will not be affected by sewage, fungi and other microbial station fester, reduce maintenance costs. Without these pollution, precision seamless steel pipe can be used for a long time. Due to its smooth wall and excellent corrosion resistance, it will not produce scale and microbial, effectively ensure water quality.
3. Good heat resistance, good frost resistance. Below -30 degrees, precision seamless steel pipe still has good toughness and high strength, can be used at the range of 50 ℃ - 80 ℃.
4. Good corrosion resistance. Precision seamless steel pipes can resist acid, alkali, salt, sea water, untreated sewage, corrosive soil or groundwater and erosion of many chemical fluids. Compared to traditional pipes, it generally lasts more than 50 years, which is used in municipal, urban transmission and distribution network. Because precision seamless steel pipe is non-toxic, no rust, tasteless, no secondary pollution to water, no corrosion, they are widely used for drainage industry.
Treatment Technology of Stainless Seamless Steel Pipe
Stainless seamless steel pipes treatment technology refers to the processing of achieving uniform silver, and has a metallic luster. This is generally referred to the production of large stainless seamless steel pipes. Because large stainless seamless steel pipe is manufactured through stamping, folding and welding process, the surface of workpiece has oil, rust, macular, which is neither beautiful, and easy to rust, reducing its stainless steel quality and value.
To make stainless seamless steel pipes achieve the standard, the surface must be finished. After forming matte treatment, that can achieve beautiful appearance, but also improve its anti-corrosion and anti-discoloration performance. After the above method, the corrosion resistance of stainless seamless steel pipes can be increased by 2 to 3 times.
Stainless seamless steel pipes does not rust due to the existence of chromium, nickel components, and then through the matt treatment, not only can eliminate the matrix impurities and iron-rich layer, but also can make chromium on the surface, forming a complete purification film, play a better anti-corrosion effect. According to the complexity of stainless seamless steel pipes and user requirements, we can choose different processing technology, such as mechanical polishing, chemical polishing, electro chemical polishing and other methods to achieve specular gloss.
To make stainless seamless steel pipes achieve the standard, the surface must be finished. After forming matte treatment, that can achieve beautiful appearance, but also improve its anti-corrosion and anti-discoloration performance. After the above method, the corrosion resistance of stainless seamless steel pipes can be increased by 2 to 3 times.
Stainless seamless steel pipes does not rust due to the existence of chromium, nickel components, and then through the matt treatment, not only can eliminate the matrix impurities and iron-rich layer, but also can make chromium on the surface, forming a complete purification film, play a better anti-corrosion effect. According to the complexity of stainless seamless steel pipes and user requirements, we can choose different processing technology, such as mechanical polishing, chemical polishing, electro chemical polishing and other methods to achieve specular gloss.
Welded Steel Pipe for Low Pressure Fluid
Welded steel pipe for low pressure fluid (GB/T3092-1993), also known as general welded pipe, commonly known as the clarined,which used for conveying water, gas, air, oil and steam heating and other general low pressure fluid. steel pipe can be divided into ordinary steel pipe and thicken steel pipe according to the wall thickness. Specifications of steel pipe with nominal diameter (mm) that the nominal diameter is the diameter of the approximation. Customarily used in inches. Welded steel pipe for low pressure fluid directly is used for conveying fluids, but also a lot for low-pressure fluid the original tube of galvanized steel pipes.
Galvanized welded steel pipe for low pressure fluid (GB/T3091-1993), also known as galvanized welded steel pipe, commonly known as white tube, which is used for conveying water, gas, air, oil and steam heating, warm water and other fluids, or other general purpose low-pressure hot-dip galvanized welding (soldering or welding furnace) steel pipe. steel pipe can be divided into ordinary galvanized steel pipe and thicken galvanized steel pipe according to the wall thickness,and according to the pipe form,it be divided into without threaded galvanized steel pipe and threaded galvanized steel pipe. Specifications of steel pipe with nominal diameter (mm) that the nominal diameter is the diameter of the approximation. Customarily used in inches.
General low-frequency fluid transport with spiral seam welded steel pipe (SY5039-83) is a hot-rolled steel strip for the tube volume, temperature often spiral shape, high frequency welding lap welding method for general low pressure liquid delivery Spiral high-frequency welded steel pipe.
General low pressure liquid delivery spiral submerged arc welded pipe (SY5037-83) is a hot-rolled steel strip for the tube volume, temperature often spiral shape, using single-sided or double-sided automatic submerged arc welding method as for water , gas, air and steam is generally low pressure liquid delivery such as submerged arc welding steel pipes.
Galvanized welded steel pipe for low pressure fluid (GB/T3091-1993), also known as galvanized welded steel pipe, commonly known as white tube, which is used for conveying water, gas, air, oil and steam heating, warm water and other fluids, or other general purpose low-pressure hot-dip galvanized welding (soldering or welding furnace) steel pipe. steel pipe can be divided into ordinary galvanized steel pipe and thicken galvanized steel pipe according to the wall thickness,and according to the pipe form,it be divided into without threaded galvanized steel pipe and threaded galvanized steel pipe. Specifications of steel pipe with nominal diameter (mm) that the nominal diameter is the diameter of the approximation. Customarily used in inches.
General low-frequency fluid transport with spiral seam welded steel pipe (SY5039-83) is a hot-rolled steel strip for the tube volume, temperature often spiral shape, high frequency welding lap welding method for general low pressure liquid delivery Spiral high-frequency welded steel pipe.
General low pressure liquid delivery spiral submerged arc welded pipe (SY5037-83) is a hot-rolled steel strip for the tube volume, temperature often spiral shape, using single-sided or double-sided automatic submerged arc welding method as for water , gas, air and steam is generally low pressure liquid delivery such as submerged arc welding steel pipes.
Hot rolled seamless tube of what kind of billet
The birth of the seamless steel pipe is very important for the transportation of gas and oils between the two locations. However, not all pipes can be used for the hot-rolled seamless tube. Then, how could we choose from them?
Concerned about the steel pipe’s categories, functions and piercing methods, we will have strict demands on pipe billet for hot-rolled seamless tube.
First of all, stress conditions would be an important factor for us. Better or lesser amount of deformation perforation method, without affecting pipe performance conditions, the tube surface and internal quality requirements may be slightly lower.
Then, the stress disadvantaged two-roll rotary piercing, if a large amount of deformation perforation, then the tube surface and internal quality have strict requirements.
Of course, we should make sure the high quality of the technical condition. As it would guarantee the production process as the basis for steel pipe’s production.
http://www.xysteelpipe.com/info/Hot-rolled-seamless-tube-of-what-kind-of-billet-1299-1.htm
Concerned about the steel pipe’s categories, functions and piercing methods, we will have strict demands on pipe billet for hot-rolled seamless tube.
First of all, stress conditions would be an important factor for us. Better or lesser amount of deformation perforation method, without affecting pipe performance conditions, the tube surface and internal quality requirements may be slightly lower.
Then, the stress disadvantaged two-roll rotary piercing, if a large amount of deformation perforation, then the tube surface and internal quality have strict requirements.
Of course, we should make sure the high quality of the technical condition. As it would guarantee the production process as the basis for steel pipe’s production.
http://www.xysteelpipe.com/info/Hot-rolled-seamless-tube-of-what-kind-of-billet-1299-1.htm
2018年9月28日星期五
Corrosion conditions of stainless steel seamless tubes
Stainless steel seamless pipe of metal and oxygen react in the atmosphere, in the appearance will form an oxide film. However, the oxidation of the iron oxide formed on the ordinary carbon steel pipe continuously causes the corrosion to be enlarged, and as a result, the pores are formed. If stainless steel seamless tube is damaged, we can use paint or oxidation-resistant metal such as zinc, nickel and chromium plating to cover the appearance of carbon steel, but, this maintenance is a layer of maintenance film, if the maintenance layer is damaged, the steel will corrosion. The corrosion resistance of stainless steel depends on the chromium, chromium is a part of steel composition, chrome on steel combined treatment, will change the appearance of the oxide type similar to pure chromium metal surface oxide. This tightly adhered chromium-rich oxide maintains the appearance and avoids further oxidation.
Heat treatment process includes heating, insulation, cooling, etc. This is done in order to reduce the deformation of the metal forming process hardening and other deficiencies, so that the deformation of the pipe after processing to restore the performance, to improve its performance.
Now the most common heat treatment tools include electric furnace and reverberatory furnace; common control mode is automatic temperature control mode.
Different stainless steel seamless pipe fittings on the heat treatment requirements are different, and not all deformation of the tools must be heat-treated, usually the final temperature of low-carbon steel pipe fittings is not less than 723 ℃, then you can not heat treatment, if lower than this temperature or the temperature above 1000 degrees celsius should be heat treatment.
Heat treatment process includes heating, insulation, cooling, etc. This is done in order to reduce the deformation of the metal forming process hardening and other deficiencies, so that the deformation of the pipe after processing to restore the performance, to improve its performance.
Now the most common heat treatment tools include electric furnace and reverberatory furnace; common control mode is automatic temperature control mode.
Different stainless steel seamless pipe fittings on the heat treatment requirements are different, and not all deformation of the tools must be heat-treated, usually the final temperature of low-carbon steel pipe fittings is not less than 723 ℃, then you can not heat treatment, if lower than this temperature or the temperature above 1000 degrees celsius should be heat treatment.
The Damaged Form of LSAW Steel Pipe Surface
LSAW steel pipe is formed by the surface layer of very thin and strong stability of fine chromium-rich oxide film (protective film), to prevent the continued infiltration of oxygen atoms, to oxidation, and access to anti-corrosion ability. If there is some reason, this film was the constant destruction, air or liquid oxygen or metal atoms will continue to penetrate the iron atom out from the constant analysis of the formation of loose iron oxide, metal surface corrosion will be constantly . This surface film in the form of a lot of damage, more common in everyday life are summarized as follows:
1. LSAW steel pipe surface deposit product with other metals containing dust particles or heterogeneous metal fixtures in the humid air, and stainless steel fixtures between the condensate, the two together into a micro-battery, causing the electric chemical reactions, protective film is damaged, call it that electrochemical corrosion.
2. Straight pipe surface adhesion organic juice (such as vegetables, soup, sputum, etc.), oxygen in the water case, constitutes organic acids, organic acids long is the corrosion of metal surfaces.
3. LSAW steel pipe surface adhesion with acid, alkali, salts (such as a wall decoration lye, lime splash), causing localized corrosion.
4. In a polluted air (which contain a large number of sulfide, carbon dioxide, nitrogen oxide atmosphere), the case of condensed water to form sulfuric acid, nitric acid, acetic acid solution point, cause chemical corrosion.
1. LSAW steel pipe surface deposit product with other metals containing dust particles or heterogeneous metal fixtures in the humid air, and stainless steel fixtures between the condensate, the two together into a micro-battery, causing the electric chemical reactions, protective film is damaged, call it that electrochemical corrosion.
2. Straight pipe surface adhesion organic juice (such as vegetables, soup, sputum, etc.), oxygen in the water case, constitutes organic acids, organic acids long is the corrosion of metal surfaces.
3. LSAW steel pipe surface adhesion with acid, alkali, salts (such as a wall decoration lye, lime splash), causing localized corrosion.
4. In a polluted air (which contain a large number of sulfide, carbon dioxide, nitrogen oxide atmosphere), the case of condensed water to form sulfuric acid, nitric acid, acetic acid solution point, cause chemical corrosion.
Function of stainless steel tube
Stainless steel pipe materials are various. There are a number of different types of stainless steel pipes classified by the ratio of strength and weight. Architects can choose all kinds of stainless steel pipes according to the building structure requirements. In order to help you have a better understanding of the stainless steel pipe function, this passage will divide the functions of stainless steel pipe into five categories. Now, we will explain them one by one. The first category we are going to mention about stainless steel pipe function is in water supply and drainage system. We all know that heat makes objects expand and cold makes it contract.
Because the temperatures of a year are changing according to different seasons, the intensity of the pipes used in water supply and drainage system should be excellent. Stainless steel pipes rightly meet the requirements. The second category we are going to talk about the stainless steel pipe function is in hydraulic system. The pipes used to convey oil, gas or stream should be corrosion resistance. Sometimes, the fluid is rusty. Or the gases are flammable or combustible. So plastic pipes or ordinary pipes are not suitable for conveying these objects. The function of stainless steel pipes is to protect the safety.
The third category we are going to deal with the stainless steel pipe function is in city heat supply. Stainless steel pipes can support reciprocating motion at axial direction. Thus, it is the ideal material for city heat supply. Besides, stainless steel pipes can be used in various pipe networks of heat addition. The fourth category we are going to mention of the stainless steel pipe function is in chemical engineering. Such as API steel pipe. In pipe laying projects, stainless steel pipes can help the process of cold and heat compensating action proceed. The fifth category we are going to talk about the stainless steel pipe function is pipe installation. The stainless steel pipes are widely used in the building of power station, oil field, chemical industry and so on. Sometimes, they are used as conveying pipes. Other time it is used as decorations. Because the stainless steel pipes are shiny and beautiful, they are widely used various areas.
Because the temperatures of a year are changing according to different seasons, the intensity of the pipes used in water supply and drainage system should be excellent. Stainless steel pipes rightly meet the requirements. The second category we are going to talk about the stainless steel pipe function is in hydraulic system. The pipes used to convey oil, gas or stream should be corrosion resistance. Sometimes, the fluid is rusty. Or the gases are flammable or combustible. So plastic pipes or ordinary pipes are not suitable for conveying these objects. The function of stainless steel pipes is to protect the safety.
The third category we are going to deal with the stainless steel pipe function is in city heat supply. Stainless steel pipes can support reciprocating motion at axial direction. Thus, it is the ideal material for city heat supply. Besides, stainless steel pipes can be used in various pipe networks of heat addition. The fourth category we are going to mention of the stainless steel pipe function is in chemical engineering. Such as API steel pipe. In pipe laying projects, stainless steel pipes can help the process of cold and heat compensating action proceed. The fifth category we are going to talk about the stainless steel pipe function is pipe installation. The stainless steel pipes are widely used in the building of power station, oil field, chemical industry and so on. Sometimes, they are used as conveying pipes. Other time it is used as decorations. Because the stainless steel pipes are shiny and beautiful, they are widely used various areas.
Large diameter seamless steel pipe cutting method
Large diameter seamless steel pipe is over 1000MM, which is made from steel ingot or solid tube, and then processed by hot rolling or cold rolling. Sometimes, the seamless steel pipes is long or short while using. Short seamless steel pipes can be welded, long seamless steel pipes can be cut off. Here are three methods of cutting large diameter seamless steel pipes to proper length to meet industry needs.
1. By saw machine
Saw machine can make neat section which is convenient for welding. The disadvantage is low efficiency.
2. By gas cutting
Though gas cutting is fast, the disadvantage is presented notched surface which is not good for construction.
3. By cnc cutting machine
By cnc cutting machine, seamless steel pipes manufacturers will not save a lot cost but also can obtain smooth section of seamless steel pipe which has not much difference from cutting by saw machine.
1. By saw machine
Saw machine can make neat section which is convenient for welding. The disadvantage is low efficiency.
2. By gas cutting
Though gas cutting is fast, the disadvantage is presented notched surface which is not good for construction.
3. By cnc cutting machine
By cnc cutting machine, seamless steel pipes manufacturers will not save a lot cost but also can obtain smooth section of seamless steel pipe which has not much difference from cutting by saw machine.
What is Low Carbon Steel Pipe
Low carbon steel pipe known as mild steel pipe and carbon content from 0.10% to 0.30% in low-carbon steel is easy to accept all kinds of processing such as forging, welding and cutting, commonly used in the manufacturing chain, rivets, bolts, axis. The carbon content of less than 0.25% carbon steel, because of its low intensity, low hardness and soft, it is also known as mild steel pipes. It includes the majority of ordinary carbon steel pipe and part of high-quality carbon structural steel, mostly used in engineering structures without heat treatment, and some by carburizing and other heat treatment is used for wear-resistant mechanical parts.
Low carbon steel pipe annealed structure of ferrite and pearlite, the lower its strength and hardness, good ductility and toughness. Therefore, the cold good form ability and can use methods such as crimping, bending, stamping, cold forming. This structural steel pipe has good weld ability. Low carbon content of low carbon steel hardness is low, the poor machinability of normalizing treatment can improve machinability. Low-carbon steel pipes have a greater tendency of aging, both quench aging and the tendency to deformation aging tendencies. When the steel from high temperature and rapid cooling, the ferrite scratch carbon, nitrogen supersaturation at room temperature can slow the formation of iron carbonitride material, and thus improve the strength and hardness of the steel pipe, reduce the ductility and toughness of this phenomenon known as the quench aging. Low carbon steel quenching and air cooling will produce aging. Low-carbon steel large number of dislocations generated by deformation, the elastic interaction from the carbon and nitrogen atoms with dislocations in the ferrite, carbon, nitrogen atoms gather around the dislocations Line. This carbon, nitrogen atom and the dislocation line combination that old Coriolis air mass (Ke lop air mass). It will make the strength and hardness of the steel to improve the ductility and toughness decreased, a phenomenon known as the deformation aging. Deformation than the quench aging on the ductility and toughness of low carbon steel pipe greater harm evident in the tensile curve of the low-carbon steel and lower yield point.
Low carbon steel pipe annealed structure of ferrite and pearlite, the lower its strength and hardness, good ductility and toughness. Therefore, the cold good form ability and can use methods such as crimping, bending, stamping, cold forming. This structural steel pipe has good weld ability. Low carbon content of low carbon steel hardness is low, the poor machinability of normalizing treatment can improve machinability. Low-carbon steel pipes have a greater tendency of aging, both quench aging and the tendency to deformation aging tendencies. When the steel from high temperature and rapid cooling, the ferrite scratch carbon, nitrogen supersaturation at room temperature can slow the formation of iron carbonitride material, and thus improve the strength and hardness of the steel pipe, reduce the ductility and toughness of this phenomenon known as the quench aging. Low carbon steel quenching and air cooling will produce aging. Low-carbon steel large number of dislocations generated by deformation, the elastic interaction from the carbon and nitrogen atoms with dislocations in the ferrite, carbon, nitrogen atoms gather around the dislocations Line. This carbon, nitrogen atom and the dislocation line combination that old Coriolis air mass (Ke lop air mass). It will make the strength and hardness of the steel to improve the ductility and toughness decreased, a phenomenon known as the deformation aging. Deformation than the quench aging on the ductility and toughness of low carbon steel pipe greater harm evident in the tensile curve of the low-carbon steel and lower yield point.
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