First, difference between the production process
ERW pipe is the hot-rolled coil through the continuous roll forming, the use of high-frequency current skin effect and proximity effects, so that the plate edge of the hot melt, squeezing the roller pressure to the role of pressure welding achieve production. Therefore, the residual stress of the erw pipe is small, and the residual stress is further released and reduced through the processes of heat treatment, sizing, straightening and water pressure of the weld. Practice has proved that, erw pipe in the storage and use of residual stress on the pipe does not affect. Without any wire, the weld is physically and chemically identical to the plate. The quality of the erw pipe depends on the quality of the sheet.
SAW pipe through the unit screw spiral welding together, the plate through the spiral rotation, so that the geometric stress more complex, and some even reached the yield limit of the steel, spiral pipe after the formation of a larger residual stress, the residual stress is tensile stress. The steel by the internal pressure, the wall also produces a circumferential tensile stress, the two superposition, so that steel can withstand capacity weak. More insecure during use. Steel plates are welded together by a wire with a chemical composition that is prone to air bubbles and weld bead cracks during the welding process. So that the weld and base metal in the physical properties and chemical composition of the apparent difference. Easily in the weld with the base metal joints have a great concentration of stress. In the welding process, thermal effects, and high hardness.
Second, difference between raw materials
The raw materials used by erw pipe are all hot-rolled coils produced by regular manufacturers with relatively stable chemical composition and physical properties.
Most of the raw materials used in the spiral pipe mill are low-grade hot-rolled steel strip, with unstable chemical composition, physical properties and internal defects and impurities.
Third, the procurement costs and procurement difficulties
Spiral steel pipe production of large-scale steel pipe plant of petroleum and petrochemical systems, the advantages are mainly concentrated in the manufacture of large-diameter steel pipe, the manufacturing cost is relatively low. However, for small and medium caliber (Φ114mm ~ Φ355.6mm) steel pipe, the manufacturing cost is higher, averaging 8% ~ 15% higher than ERW pipe.
Large-scale spiral pipe plant often do not produce small and medium-sized spiral pipe, procurement more difficult. Medium and small diameter erw pipe, due to the large number of manufacturers, is very easy to purchase.
Fourth, pipe geometry
1, ERW pipe geometry of the higher accuracy; and spiral welded pipe geometry accuracy is low, resulting in the construction of the site weld girth difficulties.
2, ERW pipe weld coefficient is 100%; spiral welded pipe weld coefficient of 130% -200%. The weld length of spiral pipe is much longer than that of erw pipe, and the incidence of defects also increases synchronously.
3, ERW pipe weld height remaining close to zero, the naked eye is not visible; spiral steel pipe on the outside surface must leave about 0.3 mm height (which is determined by the production process). The weld seam is so high that there is a gap between the steel pipe coating (3PE) and the pipe body, which makes the corrosion resistance of the steel pipe greatly reduced.
4, Due to the spiral welded pipe remaining high, the transmission of high-speed fluid there will be a greater disturbance, increase the flow resistance and reduce pipeline delivery efficiency. ERW pipe wall smooth, then there is no such problem.
Five, other differences
ERW pipe compression performance is higher than the spiral pipe.
http://www.xysteelpipe.com/info/Difference-between-saw-and-erw-pipe-712-1.htm
2017年12月28日星期四
Advantages and disadvantages of eddy current
Eddy current testing features are as follows:
Advantages of eddy current testing
1.When test, the coil does not require contact with the workpiece, but also without the coupling medium, so the detection speed.
2. The workpiece surface or near surface defects, high detection sensitivity, and in a certain range with good linearity indication, can be used for quality management and control.
3. At high temperature, the workpiece narrow area, deep-hole wall (including the wall) for testing.
4. Measure the thickness of the metal coating or non-metallic coating.
5. Detect eddy currents can cause non-metallic materials, such as graphite.
6. The test signal is electrical signal, can be digitized, easy to store, reproduce and data comparison and processing.
Disdvantages of eddy current testing
1. The object must be conductive material, only for detecting metal surface defects.
2. The detection depth and detection sensitivity are contradictory to a material for ET, according to the material, the surface state, the test criteria for comprehensive consideration, and then determine the test program and technical parameters.
3. Through-type coil for ET, the specific location of the circle where the defect can not be determined.
4. Rotating probe ET can locate, but the detection speed is slow.
http://www.xysteelpipe.com/info/Advantages-and-disadvantages-of-eddy-current-713-1.htm
Advantages of eddy current testing
1.When test, the coil does not require contact with the workpiece, but also without the coupling medium, so the detection speed.
2. The workpiece surface or near surface defects, high detection sensitivity, and in a certain range with good linearity indication, can be used for quality management and control.
3. At high temperature, the workpiece narrow area, deep-hole wall (including the wall) for testing.
4. Measure the thickness of the metal coating or non-metallic coating.
5. Detect eddy currents can cause non-metallic materials, such as graphite.
6. The test signal is electrical signal, can be digitized, easy to store, reproduce and data comparison and processing.
Disdvantages of eddy current testing
1. The object must be conductive material, only for detecting metal surface defects.
2. The detection depth and detection sensitivity are contradictory to a material for ET, according to the material, the surface state, the test criteria for comprehensive consideration, and then determine the test program and technical parameters.
3. Through-type coil for ET, the specific location of the circle where the defect can not be determined.
4. Rotating probe ET can locate, but the detection speed is slow.
http://www.xysteelpipe.com/info/Advantages-and-disadvantages-of-eddy-current-713-1.htm
I am steel pipe
I'm a steel pipe. I feel that life is not unreasonable so long as one can scrape along from day to day. For surely, human would happy for the good work of steel pipe when they need water pipe like ERW steel pipe. I think it best to wait in patience for the day of the high quality steel pipe for good life service.
Compared with such complexities, steel pipes are truly simple. If we need to transport water, we transport; if we need to transport oil, we transport; if we need to be repaired, we are repaired at the shopping store; if we need to change the standards to satisfy the customer's demands, we change; if we feel tired, we cry and break and there is no work anymore. Thus we never keep thinks like diaries.
We can be replaced in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction. Among steel pipes, we have main occupations of work, work, work and then repair, then die...
http://www.xysteelpipe.com/info/I-am-steel-pipe-714-1.htm
Compared with such complexities, steel pipes are truly simple. If we need to transport water, we transport; if we need to transport oil, we transport; if we need to be repaired, we are repaired at the shopping store; if we need to change the standards to satisfy the customer's demands, we change; if we feel tired, we cry and break and there is no work anymore. Thus we never keep thinks like diaries.
We can be replaced in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction. Among steel pipes, we have main occupations of work, work, work and then repair, then die...
http://www.xysteelpipe.com/info/I-am-steel-pipe-714-1.htm
Precautions for Installation of Carbon Seamless Steel Pipe
(1) Carbon seamless steel pipe should be carefully installed before the following carefully checked to ensure the quality of pipe and pipe.
A. Check the factory and pipe fittings factory certificate, quality certificate or test records, test records and other technical information, and should comply with existing national standards.
B. Check the quality marks of the pipe and fittings, expansion joint to meet the technical document and the current national standard. If there is any problem, replace or take the measures.
C. Check the quality of the outer surface of the pipe and pipe fittings, wall thickness should be consistent with national standards. The ellipticity is not allowed to exceed the specified range. No cracks, no shrinkage, no slag, no folding, no heavy skin, no trachoma, no pinhole, no more than the thickness of the local pit tolerance, no bumps and other quality problems, and the tube Internal and external surface without serious corrosion when the pipe and pipe fittings qualified.
(2) When the pipe surface rust less number of pipes can not be used when the number of hand-rust, the general hand-rust is a wire brush, wire cloth, emery cloth and other friction, remove the rust on the pipe surface, and then dry cotton yarn Wipe or clean, so that the pipe surface exposed metallic luster.
(3) When the pipe surface rust more, and the larger number of pipes and generally use mechanical rust or sand blasting rust or pickling rust. Pickling rust rust when the general use of sulfuric acid or hydrochloric acid.
(4) Brush the surface of the pipe type of anti-rust paint should be selected according to design requirements, commonly used red lead rust paint, epoxy paint, etc., the surface finish is generally blending paint.
Before painting, clean the surface of the pipe clean dust, dirt, burr, oil and water. Brush should be uniform coating, do not leak coating, brush the paint after the eligibility criteria for attachment firmly, no flaking, no wrinkles, no bubbles, no leakage coating, no damage and other defects.
A. Check the factory and pipe fittings factory certificate, quality certificate or test records, test records and other technical information, and should comply with existing national standards.
B. Check the quality marks of the pipe and fittings, expansion joint to meet the technical document and the current national standard. If there is any problem, replace or take the measures.
C. Check the quality of the outer surface of the pipe and pipe fittings, wall thickness should be consistent with national standards. The ellipticity is not allowed to exceed the specified range. No cracks, no shrinkage, no slag, no folding, no heavy skin, no trachoma, no pinhole, no more than the thickness of the local pit tolerance, no bumps and other quality problems, and the tube Internal and external surface without serious corrosion when the pipe and pipe fittings qualified.
(2) When the pipe surface rust less number of pipes can not be used when the number of hand-rust, the general hand-rust is a wire brush, wire cloth, emery cloth and other friction, remove the rust on the pipe surface, and then dry cotton yarn Wipe or clean, so that the pipe surface exposed metallic luster.
(3) When the pipe surface rust more, and the larger number of pipes and generally use mechanical rust or sand blasting rust or pickling rust. Pickling rust rust when the general use of sulfuric acid or hydrochloric acid.
(4) Brush the surface of the pipe type of anti-rust paint should be selected according to design requirements, commonly used red lead rust paint, epoxy paint, etc., the surface finish is generally blending paint.
Before painting, clean the surface of the pipe clean dust, dirt, burr, oil and water. Brush should be uniform coating, do not leak coating, brush the paint after the eligibility criteria for attachment firmly, no flaking, no wrinkles, no bubbles, no leakage coating, no damage and other defects.
Hardness Test of 40Cr Carbon Seamless Steel Tubes
American Standard carbon seamless steel pipe conduct mechanical performance testing. Mechanical properties of test methods are divided into two categories, one is the tensile test, one is the hardness test.
Tensile tests are made of seamless steel tube samples, the tensile test machine will pull the specimen to the fracture, and then measured one or more mechanical properties, usually only the determination of tensile strength, yield strength, elongation and rate of reduction in area. Tensile test is the most basic metal mechanical properties of test methods, almost all of the metal materials, as long as the mechanical properties are required, are provided for tensile testing. In particular, tensile tests are the only means of testing the mechanical properties of materials that are not easily tested for their hardness.
Hardness test is a hard indenter according to the provisions of the conditions slowly pressed into the sample surface, and then test indentation depth or size, in order to determine the size of the hardness of the material. Hardness test is the mechanical properties of materials testing the most simple, the most rapid and easiest to implement the method. Hardness test is non-destructive, the hardness value of the material and the tensile strength value between the approximate conversion relationship. The hardness of the material can be converted into tensile strength value, which has great practical significance.
As the tensile test is not easy to test, and converted from the hardness to the intensity is very convenient, so more and more people only test the hardness of the material and less test its strength. In particular, due to the hardness of manufacturing technology advances and innovation, some of the original can not directly test the hardness of materials, such as seamless steel tubes, stainless steel, etc., are now possible to directly test the hardness. Therefore, there is a tendency to gradually replace the tensile test with a hardness test.
Tensile tests are made of seamless steel tube samples, the tensile test machine will pull the specimen to the fracture, and then measured one or more mechanical properties, usually only the determination of tensile strength, yield strength, elongation and rate of reduction in area. Tensile test is the most basic metal mechanical properties of test methods, almost all of the metal materials, as long as the mechanical properties are required, are provided for tensile testing. In particular, tensile tests are the only means of testing the mechanical properties of materials that are not easily tested for their hardness.
Hardness test is a hard indenter according to the provisions of the conditions slowly pressed into the sample surface, and then test indentation depth or size, in order to determine the size of the hardness of the material. Hardness test is the mechanical properties of materials testing the most simple, the most rapid and easiest to implement the method. Hardness test is non-destructive, the hardness value of the material and the tensile strength value between the approximate conversion relationship. The hardness of the material can be converted into tensile strength value, which has great practical significance.
As the tensile test is not easy to test, and converted from the hardness to the intensity is very convenient, so more and more people only test the hardness of the material and less test its strength. In particular, due to the hardness of manufacturing technology advances and innovation, some of the original can not directly test the hardness of materials, such as seamless steel tubes, stainless steel, etc., are now possible to directly test the hardness. Therefore, there is a tendency to gradually replace the tensile test with a hardness test.
2017年12月27日星期三
Carbon Seamless Steel Pipe Connection Method
Carbon seamless steel pipe connections are many ways, now commonly used in several ways:
Different connections, because of its production principle of the different areas in its application are also different, in general, there is a common point that is easy to install, solid and reliable. Here are some of the more common way to do a brief description of the connection:
1. Compression: the pipe inserted into the tube of the mouth, tightened by the nut, with a spiral force to the mouth of the casing through the sealing ring compression, the role of sealing, complete piping connections.
2. Welding: the end of the pipe processing groove, with manual or automatic welding of the pipe to do ring welding.
3 flange type: the flange and pipe for the ring welding, with fast clip or bolt fastening, so that the flange between the sealing gasket role in the completion of piping connections.
4. Clamping type: the pipeline into the tube with a special installation tool to pipe the wall card into a hexagonal, the internal seal is also transformed into hexagonal.
5. Taper thread: is the external thread and pipe for the TIG welding, threaded pipe fittings to tapered thread connection from the role of sealing to complete the piping connection.
Different connections, because of its production principle of the different areas in its application are also different, in general, there is a common point that is easy to install, solid and reliable. Here are some of the more common way to do a brief description of the connection:
1. Compression: the pipe inserted into the tube of the mouth, tightened by the nut, with a spiral force to the mouth of the casing through the sealing ring compression, the role of sealing, complete piping connections.
2. Welding: the end of the pipe processing groove, with manual or automatic welding of the pipe to do ring welding.
3 flange type: the flange and pipe for the ring welding, with fast clip or bolt fastening, so that the flange between the sealing gasket role in the completion of piping connections.
4. Clamping type: the pipeline into the tube with a special installation tool to pipe the wall card into a hexagonal, the internal seal is also transformed into hexagonal.
5. Taper thread: is the external thread and pipe for the TIG welding, threaded pipe fittings to tapered thread connection from the role of sealing to complete the piping connection.
Manufacturing Process of Carbon Seamless Steel Pipe
According to different production methods of carbon seamless steel pipe can be divided into hot-rolled tube, cold-rolled tube, drawing tube, extrusion tube.
1.Hot-rolled seamless pipe is generally in the automatic production of rolling mill unit. The solid tube blank is inspected and removed from the surface defects, cut into the required length, in the tube end of the perforation end of the centering, and then sent to the heating furnace heating, perforation in the punching machine. In the perforation at the same time continue to rotate and move, in the role of the roll and the head, the tube gradually formed within the cavity, called the capillary. And then sent to the automatic rolling machine to continue rolling. And finally by the whole machine are the whole wall thickness, by sizing machine diameter, to specifications. The use of continuous rolling mill production of hot-rolled seamless steel pipe is a more advanced method.
2.If you want to get smaller and better quality of seamless tubes, must be cold-rolled, cold drawn or a combination of the two methods. Cold rolling is usually carried out on a two-roll mill, in which the steel pipe is rolled in an annular orifice formed by a tapered hole and a non-moving tapered head. Cold drawing is usually carried out on single-chain or double-chain cold drawing machines of 0.5 to 100T.
3.the extrusion method is to heat a good tube on a closed cylinder, squeeze rods and extrusion rod with the movement, so that extrusion from the smaller hole in the extrusion die. This method can produce smaller diameter steel pipe.
1.Hot-rolled seamless pipe is generally in the automatic production of rolling mill unit. The solid tube blank is inspected and removed from the surface defects, cut into the required length, in the tube end of the perforation end of the centering, and then sent to the heating furnace heating, perforation in the punching machine. In the perforation at the same time continue to rotate and move, in the role of the roll and the head, the tube gradually formed within the cavity, called the capillary. And then sent to the automatic rolling machine to continue rolling. And finally by the whole machine are the whole wall thickness, by sizing machine diameter, to specifications. The use of continuous rolling mill production of hot-rolled seamless steel pipe is a more advanced method.
2.If you want to get smaller and better quality of seamless tubes, must be cold-rolled, cold drawn or a combination of the two methods. Cold rolling is usually carried out on a two-roll mill, in which the steel pipe is rolled in an annular orifice formed by a tapered hole and a non-moving tapered head. Cold drawing is usually carried out on single-chain or double-chain cold drawing machines of 0.5 to 100T.
3.the extrusion method is to heat a good tube on a closed cylinder, squeeze rods and extrusion rod with the movement, so that extrusion from the smaller hole in the extrusion die. This method can produce smaller diameter steel pipe.
Weld Defect on Stress Cracking of Large Diameter Steel Pipe Coating
In order to ensure the quality of extruded polyethylene coating, the standard stipulates the large diameter steel pipe weld I ≤ 2.5mm, and the weld should be smooth transition. For some steel pipe into the plant, if the weld over the high standard or weld surface there are burr, sharp bump welding, scaly welding wave, arc crater, splash, undercut and other defects, because such defects can be in the plastic surface layer left significant disability, the cooling shrinkage residual stress will be further concentrated in the disability, and lead to the plastic layer of the initial crack. At this point, only a small amount of the compressive stress (converted from the residual stress) at the two tips of the formed crack can be developed rapidly. Regardless of the factors that cause the crack, once formed will continue to develop until the accumulation of plastic within the residual stress relaxation to less than the crack stress required for the development.
Quality Inspection Standard and Operation Process of Cold Drawn Carbon Seamless Steel Pipe
Quality inspection standard and operation process of cold drawn carbon seamless steel pipe are following below:
Production characteristics of the cold drawn tube is from the input to the finished product,which is usually processed through a number of cold deformation and produce hardening, and thus the entire production process by a number of preparatory processes and deformation processes, and has the characteristics of reciprocating cycle, and thus more processes , The production cycle is long, metal consumption, production efficiency is low, the general scale of production are not large.
Cold-rolled, cold-drawn or cold-rolled and cold-drawn combination of cold processing methods is to produce the entire package of equipment combinations, which is the hot-rolled pipe or welded pipe for deep processing unit.
According to the metal processing performance, pipe size, quality requirements and investment and efficiency to choose a different processing methods and the corresponding auxiliary processes. Cold-rolled cold drawn tube of the basic processes are:
(1) The supply of pipe material, the pipe used for hot-rolled or semi-finished product pipe, extrusion pipe and welded pipe;
(2) Pipe preparation, including inspection, bundling, pickling, washing, washing, and in, drying,coating lubricants;
(3) Cold (cold or cold drawing);
(4) Finished product finishing including heat treatment, straightening, sampling, cutting head and tail, inspection (manual inspection and a variety of testing), hydraulic test, oil, packaging, storage and so on. The contents of different products finishing different.
Production characteristics of the cold drawn tube is from the input to the finished product,which is usually processed through a number of cold deformation and produce hardening, and thus the entire production process by a number of preparatory processes and deformation processes, and has the characteristics of reciprocating cycle, and thus more processes , The production cycle is long, metal consumption, production efficiency is low, the general scale of production are not large.
Cold-rolled, cold-drawn or cold-rolled and cold-drawn combination of cold processing methods is to produce the entire package of equipment combinations, which is the hot-rolled pipe or welded pipe for deep processing unit.
According to the metal processing performance, pipe size, quality requirements and investment and efficiency to choose a different processing methods and the corresponding auxiliary processes. Cold-rolled cold drawn tube of the basic processes are:
(1) The supply of pipe material, the pipe used for hot-rolled or semi-finished product pipe, extrusion pipe and welded pipe;
(2) Pipe preparation, including inspection, bundling, pickling, washing, washing, and in, drying,coating lubricants;
(3) Cold (cold or cold drawing);
(4) Finished product finishing including heat treatment, straightening, sampling, cutting head and tail, inspection (manual inspection and a variety of testing), hydraulic test, oil, packaging, storage and so on. The contents of different products finishing different.
Effect of Mechanical Expanding of Double Submerged Arc Welding Longitudinal Seam Steel Pipe
At present, the long-distance transportation of oil and natural gas mainly adopts pipeline. Long-distance pipeline pipeline used in the main spiral pipe submerged arc welded pipe(ssaw steel pipe) and double submerged arc welded straight steel pipe(dsaw steel pipe). As the spiral submerged arc welded pipe is based on strip as raw material, wall thickness is limited, in addition to the existence of spiral submerged arc welded pipe longer, greater residual stress, weld reliability is poor and difficult to overcome the shortcomings of dense population area and reliability requirements of the region, large diameter straight seam submerged arc welded pipe has been gradually replaced by spiral submerged arc welded pipe.
Expanded diameter is a large diameter straight seam submerged arc welded pipe production to ensure the quality of an important process, the standard pipe line pipe submerged arc welded pipe must be expanded process.
1, Effectively improve the dimensional accuracy of steel pipe
At present, there are mainly UO, RB, JCO, C and Hu-Metal for the forming of LSAW steel pipes. The steel pipes produced by these five kinds of molding methods have different geometrical accuracy. As the straight seam submerged arc welding in the tube side of the inside and outside welding, and thus under the action of thermal stress in the steel pipe to be bending deformation, and the longitudinal part of the weld shrinkage larger, so that the straightness of steel pipe is seriously affected; In addition, these five kinds of forming the production of steel pipe, the oval are large, especially JCO and C forming steel pipe. Therefore, we must increase the diameter, the whole circle and other processes to improve the geometric accuracy of steel pipe.
2, Reduce or eliminate in the pipe, the test process caused by the Bauschinger effect
As the steel pipe in the process of forming and testing will produce the Bauschinger effect, so that the yield strength decreased, and the expansion of steel in the cold hardened, expanded diameter can improve the yield strength of steel, thus reducing the strength to achieve steel requirements while increasing the level of waste caused by sheet metal.
3, The elimination of steel pipe forming and welding residual stress
Cold expansion can eliminate the residual stress caused by forming and welding, and improve the distribution of stress in the steel pipe, so as to avoid the occurrence of hydrogen embrittlement and crack in the steel pipe stress concentration area due to the transportation of H2S in oil or natural gas.
In addition, the diameter of the welding quality and welding performance is also a good test.
Expanded diameter is a large diameter straight seam submerged arc welded pipe production to ensure the quality of an important process, the standard pipe line pipe submerged arc welded pipe must be expanded process.
1, Effectively improve the dimensional accuracy of steel pipe
At present, there are mainly UO, RB, JCO, C and Hu-Metal for the forming of LSAW steel pipes. The steel pipes produced by these five kinds of molding methods have different geometrical accuracy. As the straight seam submerged arc welding in the tube side of the inside and outside welding, and thus under the action of thermal stress in the steel pipe to be bending deformation, and the longitudinal part of the weld shrinkage larger, so that the straightness of steel pipe is seriously affected; In addition, these five kinds of forming the production of steel pipe, the oval are large, especially JCO and C forming steel pipe. Therefore, we must increase the diameter, the whole circle and other processes to improve the geometric accuracy of steel pipe.
2, Reduce or eliminate in the pipe, the test process caused by the Bauschinger effect
As the steel pipe in the process of forming and testing will produce the Bauschinger effect, so that the yield strength decreased, and the expansion of steel in the cold hardened, expanded diameter can improve the yield strength of steel, thus reducing the strength to achieve steel requirements while increasing the level of waste caused by sheet metal.
3, The elimination of steel pipe forming and welding residual stress
Cold expansion can eliminate the residual stress caused by forming and welding, and improve the distribution of stress in the steel pipe, so as to avoid the occurrence of hydrogen embrittlement and crack in the steel pipe stress concentration area due to the transportation of H2S in oil or natural gas.
In addition, the diameter of the welding quality and welding performance is also a good test.
2017年12月17日星期日
How to detect the quality of spiral steel pipe factory
Spiral steel pipe in the factory should do before the mechanical performance test and flattening test and flaring test, and to meet the requirements of the standard requirements.
Spiral steel pipe quality testing methods are as follows:
1, From the surface to judge, that is, in the appearance of inspection. The appearance of the welded joint inspection is a simple procedure and a wide range of inspection methods, is an important part of the finished product inspection, mainly to find the weld surface defects and size of the deviation. Generally through the naked eye observation, with the standard model, gauge and magnifying glass and other tools for testing. If there is a defect on the surface of the weld, there may be a defect in the weld.
2, The physical method of inspection: the physical test method is the use of some physical phenomena for testing or testing methods. Materials or parts of the internal defects of the inspection, are generally used non-destructive testing methods. Non-destructive testing of ultrasonic testing, ray detection, penetration testing, magnetic detection and so on.
3, The strength of the pressure vessel test: pressure vessel, in addition to sealing test, but also for strength test. Commonly there are two kinds of hydraulic pressure test and air pressure test. They are able to test the weld densities of containers and pipes working under pressure. Pneumatic test is more sensitive and faster than hydraulic pressure test, while the product after the test without drainage, especially for difficult drainage products. But the risk of testing than the hydraulic test. During the test, the corresponding safety and technical measures must be observed to prevent accidents during the test.
4, Compactness test: the storage of liquid or gas welding containers, the weld is not dense defects, such as penetrating cracks, pores, slag, not penetration and loose tissue, etc., can be used to find the compact test. Densification test methods are: kerosene test, water test, water test and so on.
5, Hydrostatic test Each steel pipe should be hydrostatic test without leakage phenomenon, the test pressure by the test P = 2ST / D where the S-hydrostatic test test stress Mpa, hydrostatic test test stress by the corresponding The strip standard specifies 60% of the minimum yield. Regulator time: D <508 test pressure holding time of not less than 5 seconds; D ≥ 508 test pressure retention time of not less than 10 seconds.
6, Non-destructive testing of steel pipe welding seam, steel head weld and ring joints should be X-ray or ultrasonic testing. For helical welds of steel for combustible ordinary fluid delivery, a 100% SX-ray or ultrasonic test shall be carried out. The spiral welds of steel pipes for general fluid delivery such as water, sewage, air, heating steam shall be subjected to X-ray or Ultrasonic examination checks (20%).
According to the results of spiral steel pipe inspection, spiral steel pipe is usually divided into three categories: qualified goods, rework and waste. Qualified refers to the appearance of quality and quality of the quality of the relevant standards or delivery acceptance of technical conditions of the spiral steel pipe; Refurbished goods refers to the appearance of quality and internal quality is not fully meet the standards and acceptance of the bar, but to allow rework, rework after the standard and acceptance conditions Of the spiral steel pipe; scrap refers to the appearance of quality and quality of the internal failure, does not allow rework or rework after still fail to meet the standard and acceptance conditions of the spiral steel pipe.
Waste is divided into two kinds of waste and waste. Internal waste refers to the waste steel pipe found in the foundry or foundry workshop. The waste material found after the delivery of the spiral steel pipe is usually exposed to mechanical processing, heat treatment or use. The economic loss caused by it is far Much larger than the inside. In order to reduce the external waste, batch production of spiral steel pipe in the factory before the best sampling test heat treatment and rough processing, as far as possible in the spiral steel pipe plant found in the potential spiral steel pipe defects in order to take the necessary early remedial instructions.
Spiral steel pipe quality testing methods are as follows:
1, From the surface to judge, that is, in the appearance of inspection. The appearance of the welded joint inspection is a simple procedure and a wide range of inspection methods, is an important part of the finished product inspection, mainly to find the weld surface defects and size of the deviation. Generally through the naked eye observation, with the standard model, gauge and magnifying glass and other tools for testing. If there is a defect on the surface of the weld, there may be a defect in the weld.
2, The physical method of inspection: the physical test method is the use of some physical phenomena for testing or testing methods. Materials or parts of the internal defects of the inspection, are generally used non-destructive testing methods. Non-destructive testing of ultrasonic testing, ray detection, penetration testing, magnetic detection and so on.
3, The strength of the pressure vessel test: pressure vessel, in addition to sealing test, but also for strength test. Commonly there are two kinds of hydraulic pressure test and air pressure test. They are able to test the weld densities of containers and pipes working under pressure. Pneumatic test is more sensitive and faster than hydraulic pressure test, while the product after the test without drainage, especially for difficult drainage products. But the risk of testing than the hydraulic test. During the test, the corresponding safety and technical measures must be observed to prevent accidents during the test.
4, Compactness test: the storage of liquid or gas welding containers, the weld is not dense defects, such as penetrating cracks, pores, slag, not penetration and loose tissue, etc., can be used to find the compact test. Densification test methods are: kerosene test, water test, water test and so on.
5, Hydrostatic test Each steel pipe should be hydrostatic test without leakage phenomenon, the test pressure by the test P = 2ST / D where the S-hydrostatic test test stress Mpa, hydrostatic test test stress by the corresponding The strip standard specifies 60% of the minimum yield. Regulator time: D <508 test pressure holding time of not less than 5 seconds; D ≥ 508 test pressure retention time of not less than 10 seconds.
6, Non-destructive testing of steel pipe welding seam, steel head weld and ring joints should be X-ray or ultrasonic testing. For helical welds of steel for combustible ordinary fluid delivery, a 100% SX-ray or ultrasonic test shall be carried out. The spiral welds of steel pipes for general fluid delivery such as water, sewage, air, heating steam shall be subjected to X-ray or Ultrasonic examination checks (20%).
According to the results of spiral steel pipe inspection, spiral steel pipe is usually divided into three categories: qualified goods, rework and waste. Qualified refers to the appearance of quality and quality of the quality of the relevant standards or delivery acceptance of technical conditions of the spiral steel pipe; Refurbished goods refers to the appearance of quality and internal quality is not fully meet the standards and acceptance of the bar, but to allow rework, rework after the standard and acceptance conditions Of the spiral steel pipe; scrap refers to the appearance of quality and quality of the internal failure, does not allow rework or rework after still fail to meet the standard and acceptance conditions of the spiral steel pipe.
Waste is divided into two kinds of waste and waste. Internal waste refers to the waste steel pipe found in the foundry or foundry workshop. The waste material found after the delivery of the spiral steel pipe is usually exposed to mechanical processing, heat treatment or use. The economic loss caused by it is far Much larger than the inside. In order to reduce the external waste, batch production of spiral steel pipe in the factory before the best sampling test heat treatment and rough processing, as far as possible in the spiral steel pipe plant found in the potential spiral steel pipe defects in order to take the necessary early remedial instructions.
Difference between ASTM and ASME Standard
ASTM material standards are developed by the American Society for Materials and Testing, ASTM material standards can include the chemical, mechanical, physical and electrical properties of the material. These standards include both a description of test methods to be performed on building materials, and the size and shape that these materials are to take. Building materials like concrete can be required by local law to meet ASTM standards before being used in construction. Among ASTM A53 and ASTM A106 are widely used.
ASME is the standard of the American Society of Mechanical Engineers. ASME material specifications are based on those published by the ASTM, AWS and other recognized national and international standards. ASME standards are legally required when building infrastructure like bridges, power plant piping and boilers. Among ASME b16.5 are widely used.
ASTM is responsible for the development and re-enactment of standards for all types of old and new materials. Because it is the test and materials association.
ASME is to selectively absorb and filter these standards for the relevant works used, and to be modified to improve.
ASTM is the US material standard, similar to the domestic GB713
ASME is a design specification, but ASME is a complete system.
ASME is the standard of the American Society of Mechanical Engineers. ASME material specifications are based on those published by the ASTM, AWS and other recognized national and international standards. ASME standards are legally required when building infrastructure like bridges, power plant piping and boilers. Among ASME b16.5 are widely used.
ASTM is responsible for the development and re-enactment of standards for all types of old and new materials. Because it is the test and materials association.
ASME is to selectively absorb and filter these standards for the relevant works used, and to be modified to improve.
ASTM is the US material standard, similar to the domestic GB713
ASME is a design specification, but ASME is a complete system.
Steel delivery status and heat treatment requirements
Other countries and ISO stainless steel standards are provided for hot-rolled (forged) steel, in addition to heating pressure processing steel, the general heat treatment delivery (heat treatment requirements need to be specified in the contract). After heat treatment, according to the requirements, to conduct pickling, shot peening or turning peeling and other surface treatment or surface finishing. For cold-rolled or cold-drawn steel, or cold working conditions, or cold processing after heat treatment, pickling or shot blasting, or heat treatment after the formation, grinding, polishing, or further to varying degrees of hardening processing and other state delivery.
ISO and EN, DIN standards, the delivery status of steel should be according to the production and processing methods and surface conditions of several different types of combinations, more scientific and reasonable, conducive to the implementation of standards.
With regard to the heat treatment system, in addition to the ASTM standard, national and ISO standards specify the heat treatment system for each grade delivery steel or the heat treatment system for measuring mechanical properties. Only the ASTM standard, in addition to precipitation hardening steel, in the steel standard is generally not for each grade of heat treatment system for specific provisions, only provisions of heat treatment types (such as annealing, co-solution or aging), all kinds of steel heat treatment requirements Varieties of the general technical requirements of the standard described in the standard.
ISO and EN, DIN standards, the delivery status of steel should be according to the production and processing methods and surface conditions of several different types of combinations, more scientific and reasonable, conducive to the implementation of standards.
With regard to the heat treatment system, in addition to the ASTM standard, national and ISO standards specify the heat treatment system for each grade delivery steel or the heat treatment system for measuring mechanical properties. Only the ASTM standard, in addition to precipitation hardening steel, in the steel standard is generally not for each grade of heat treatment system for specific provisions, only provisions of heat treatment types (such as annealing, co-solution or aging), all kinds of steel heat treatment requirements Varieties of the general technical requirements of the standard described in the standard.
2017年12月15日星期五
Strong as steel support by spiral welded pipe
Lots of department in countries of transportation would build new, high-rise bridge to relieve traffic pressure. And thus the bridge's service life would be important for engineers' project. So materials choosing has a necessary role during the building and spiral welded pipe would be a nice option for engineers nowadays.
Buried under the waters of every bridge is spiral welded pipe. Why spiral-welded steel pipe? As it is most often used in water delivery for the bride due to its less cost than other steel pipes like seamless steel pipe, but with high quality on water delivery. In addition, it also excels as drilled shaft casing pipe used in the formation of cast-in-place concrete piles. Spiral welded pipe did a really good job getting product out the door on a tight schedule, making sure everything was staged and ready to go when we needed it. With the strong steel support, the quality of the bridge would be here for customers.
http://www.xysteelpipe.com/info/Strong-as-steel-support-by-spiral-welded-pipe-672-1.htm
Buried under the waters of every bridge is spiral welded pipe. Why spiral-welded steel pipe? As it is most often used in water delivery for the bride due to its less cost than other steel pipes like seamless steel pipe, but with high quality on water delivery. In addition, it also excels as drilled shaft casing pipe used in the formation of cast-in-place concrete piles. Spiral welded pipe did a really good job getting product out the door on a tight schedule, making sure everything was staged and ready to go when we needed it. With the strong steel support, the quality of the bridge would be here for customers.
http://www.xysteelpipe.com/info/Strong-as-steel-support-by-spiral-welded-pipe-672-1.htm
Open the door of knowledge of steel pipe
Why are you keeping the curiosity door locked? Why are you keep the knowledge door for steel pipe locked? Now entering the world of ERW steel pipe would be the required lesson for clients and buyers.
Seamless steel pipe, ERW steel pipe, LSAW steel pipe are the most common used standard steel pipe nowadays. They are part of tubular goods which are manufactured to different specifications like the round steel pipe and square steel pipe, different standards such as API 5L, API 5CT, ASTM A252, ASTM 53, EN10217, EN10219, BS, JIS, IS just for SSAW steel pipe. Of course, pipes are sold also by various sizes from 1/8" to 72". Welded pipe like ERW steel pipe and seamless steel pipe would be the common types among all the steel pipes. Welded pipe is also called ERW (Electric Resistance Welded) pipe. Most common specification for welded carbon steel pipe is A53. Seamless pipe is made by process that requires no welding. Most common specification for seamless carbon steel pipe is A106B.
http://www.xysteelpipe.com/info/Open-the-door-of-knowledge-of-steel-pipe-673-1.htm
Seamless steel pipe, ERW steel pipe, LSAW steel pipe are the most common used standard steel pipe nowadays. They are part of tubular goods which are manufactured to different specifications like the round steel pipe and square steel pipe, different standards such as API 5L, API 5CT, ASTM A252, ASTM 53, EN10217, EN10219, BS, JIS, IS just for SSAW steel pipe. Of course, pipes are sold also by various sizes from 1/8" to 72". Welded pipe like ERW steel pipe and seamless steel pipe would be the common types among all the steel pipes. Welded pipe is also called ERW (Electric Resistance Welded) pipe. Most common specification for welded carbon steel pipe is A53. Seamless pipe is made by process that requires no welding. Most common specification for seamless carbon steel pipe is A106B.
http://www.xysteelpipe.com/info/Open-the-door-of-knowledge-of-steel-pipe-673-1.htm
Accurate reference provide a guide to your choice of seamless steel pipe
It is the common sense for your answer when supplier of seamless steel pipe asks which kind of thickness you need. As we all know that different thickness parameters would have different function for various steel pipes.
Here are standards of thickness for commonly used seamless steel pipe:
General structure and mechanical structure seamless steel pipe would adopt (GB / T8162-2008).
You can choose fluid transportation steel pipe with (GB / T8163-2008) if you need to transport water, oil and gas.
If you use steel pipe for producing various structures of low and medium pressure boiler superheated steam pipes, boiling water pipes and superheated steam locomotive boiler pipes, arch pipe High-quality carbon structural steel hot-rolled and cold drawn (rolled) seamless steel pipes, it is better to use low and medium pressure seamless steel pipe with (GB3087-2008).
Seamless steel pipe for high pressure boiler (GB5310-2008) would choose a high-quality carbon steel, alloy steel and stainless steel heat-resistant steel seamless pipe for heating surface of water pipe boilers with high pressure and above.
http://www.xysteelpipe.com/info/Accurate-reference-provide-a-guide-to-your-choice-of-seamless-steel-pipe-674-1.htm
Here are standards of thickness for commonly used seamless steel pipe:
General structure and mechanical structure seamless steel pipe would adopt (GB / T8162-2008).
You can choose fluid transportation steel pipe with (GB / T8163-2008) if you need to transport water, oil and gas.
If you use steel pipe for producing various structures of low and medium pressure boiler superheated steam pipes, boiling water pipes and superheated steam locomotive boiler pipes, arch pipe High-quality carbon structural steel hot-rolled and cold drawn (rolled) seamless steel pipes, it is better to use low and medium pressure seamless steel pipe with (GB3087-2008).
Seamless steel pipe for high pressure boiler (GB5310-2008) would choose a high-quality carbon steel, alloy steel and stainless steel heat-resistant steel seamless pipe for heating surface of water pipe boilers with high pressure and above.
http://www.xysteelpipe.com/info/Accurate-reference-provide-a-guide-to-your-choice-of-seamless-steel-pipe-674-1.htm
2017年12月14日星期四
The main difference between cold drawn seamless steel pipe and finish rolling seamless steel pipe
Process equipment distinction: cold drawn seamless steel pipe is usually 0.5 ~ 100T single-chain or double-chain cold drawn machine. Finished seamless steel tubes are usually carried out on a two-roll mill where the steel pipe is rolled in a ring-shaped bore formed by a variable cross-section round hole and a stationary tapered head.
Production of the product difference: cold drawn seamless steel pipe can produce thin wall thickness of the cold drawn steel pipe, cold drawn shaped steel pipe, such as plum tube, hexagonal tube, bread tube, etc .; finishing seamless steel pipe relative to the wall thickness range Large, can now finish rolling 0.8-40mm.
Wall thickness deviation difference: cold-drawn seamless steel pipe without cold-rolled seamless steel pipe wall thickness deviation is small, so cold-rolled precision seamless steel pipe for the requirements of wall thickness, diameter size deviation of the strict customers, choose cold rolling better.
Production of the product difference: cold drawn seamless steel pipe can produce thin wall thickness of the cold drawn steel pipe, cold drawn shaped steel pipe, such as plum tube, hexagonal tube, bread tube, etc .; finishing seamless steel pipe relative to the wall thickness range Large, can now finish rolling 0.8-40mm.
Wall thickness deviation difference: cold-drawn seamless steel pipe without cold-rolled seamless steel pipe wall thickness deviation is small, so cold-rolled precision seamless steel pipe for the requirements of wall thickness, diameter size deviation of the strict customers, choose cold rolling better.
Why does oil drilling choose thick-walled seamless steel tubes?
Oil is now the world's most important energy, its use is very extensive, a lot of equipment need to use oil can be normal operation. For example, we often use cars, aircraft, generators and so on. If there is no oil, then our life will be a very big change.
So now, oil drilling has been carried out in the uninterrupted. In the oil drilling time, thick-walled seamless steel pipe with this material is widely used. Many people can be more puzzled, thick-walled seamless steel pipe is hollow, its strength should be small, not as good as the use of solid steel column.
Indeed, the solid steel column compared to thick-walled seamless steel pipe, its strength is much higher. However, the strength of thick-walled seamless steel tubes is still very strong, the most important thing is that it has a very big advantage, that is, its vibration is very small. After all, thick-walled seamless steel pipe is hollow, in the drilling time, it can be a good transfer impact force, so that the drill to maintain a smooth, for oil drilling, is the best choice.
So now, oil drilling has been carried out in the uninterrupted. In the oil drilling time, thick-walled seamless steel pipe with this material is widely used. Many people can be more puzzled, thick-walled seamless steel pipe is hollow, its strength should be small, not as good as the use of solid steel column.
Indeed, the solid steel column compared to thick-walled seamless steel pipe, its strength is much higher. However, the strength of thick-walled seamless steel tubes is still very strong, the most important thing is that it has a very big advantage, that is, its vibration is very small. After all, thick-walled seamless steel pipe is hollow, in the drilling time, it can be a good transfer impact force, so that the drill to maintain a smooth, for oil drilling, is the best choice.
Installation of spiral seam steel pipe
1. Repair mouth
In order to ensure the quality of the welding, the welding is carried out before the full inspection and correction, so that the pipe end, bevel angle, blunt edge, roundness, etc., are in line with the requirements of the interface size, individual steel pipe needs In the field to do groove processing, the use of gas welding cutting, remove the slag and then grinding with a grinding wheel.
Counter operation procedures are: check the interface connector size → clear chamber → determine and adjust the longitudinal seam of the steel pipe staggered position → the first pipeline straight → adjust the gap size of the counterparts → leveling the mouth → straight → straight line → spot welding
2. Welding
Interface welding using arc welding, once down the base, two times to survive, each weld are welded once, each layer of welding lead-off arc to be staggered.
A. Pipe joints should be first before the mouth, slag, tube end of the groove angle, blunt edge, clearance, should meet the specifications; not in the gap between the gap welding or welding method to narrow the gap welding.
B. The mouth should be flush with the wall, the length of 300mm long ruler in the order of the inner wall of the interface in order to close the wrong port to allow partial inspection should be 0.2 times the wall thickness, and not more than 2mm.
C. The position of the longitudinal and circumferential welds shall meet the following requirements: The longitudinal weld shall be about 45 ° from the semicircle of the vertical line of the pipe; the welded seam of the reinforced steel pipe and the reinforcement ring shall be in the longitudinal direction Weld staggered, the spacing should not be less than 100mm; reinforcement ring pipe section of the circumferential weld should not be less than 50mm; pipe any location shall not have cross-shaped weld.
D. When positioning welding, the positioning of all weld pads (or grades) should be the same as the official welding, but the electrode diameter optional fine. The welding current of the positioning weld should be chosen to be larger than the formal welding, usually 10% -15% to ensure penetration.
E. Pipe welding: weld quality must meet the relevant provisions of GB50268-97 4.2, the weld should be smooth, uniform width, root penetration, no obvious bump defects and undercut phenomenon, weld reinforcement should be higher than the tube Face about 2 mm, weld the edge of the groove 2-3 mm.
F. Pipe and flange welding, the pipeline should be inserted into the flange two-thirds, the flange and the pipeline should be vertical, the two coincides with the axis.
In order to ensure the quality of the welding, the welding is carried out before the full inspection and correction, so that the pipe end, bevel angle, blunt edge, roundness, etc., are in line with the requirements of the interface size, individual steel pipe needs In the field to do groove processing, the use of gas welding cutting, remove the slag and then grinding with a grinding wheel.
Counter operation procedures are: check the interface connector size → clear chamber → determine and adjust the longitudinal seam of the steel pipe staggered position → the first pipeline straight → adjust the gap size of the counterparts → leveling the mouth → straight → straight line → spot welding
2. Welding
Interface welding using arc welding, once down the base, two times to survive, each weld are welded once, each layer of welding lead-off arc to be staggered.
A. Pipe joints should be first before the mouth, slag, tube end of the groove angle, blunt edge, clearance, should meet the specifications; not in the gap between the gap welding or welding method to narrow the gap welding.
B. The mouth should be flush with the wall, the length of 300mm long ruler in the order of the inner wall of the interface in order to close the wrong port to allow partial inspection should be 0.2 times the wall thickness, and not more than 2mm.
C. The position of the longitudinal and circumferential welds shall meet the following requirements: The longitudinal weld shall be about 45 ° from the semicircle of the vertical line of the pipe; the welded seam of the reinforced steel pipe and the reinforcement ring shall be in the longitudinal direction Weld staggered, the spacing should not be less than 100mm; reinforcement ring pipe section of the circumferential weld should not be less than 50mm; pipe any location shall not have cross-shaped weld.
D. When positioning welding, the positioning of all weld pads (or grades) should be the same as the official welding, but the electrode diameter optional fine. The welding current of the positioning weld should be chosen to be larger than the formal welding, usually 10% -15% to ensure penetration.
E. Pipe welding: weld quality must meet the relevant provisions of GB50268-97 4.2, the weld should be smooth, uniform width, root penetration, no obvious bump defects and undercut phenomenon, weld reinforcement should be higher than the tube Face about 2 mm, weld the edge of the groove 2-3 mm.
F. Pipe and flange welding, the pipeline should be inserted into the flange two-thirds, the flange and the pipeline should be vertical, the two coincides with the axis.
2017年12月6日星期三
Process and application of high precision cold drawn steel pipe
High-precision cold drawn steel pipe is a new type of high-tech energy-saving products. In recent years, the use of this technology to produce precision steel pipe has been widely used in domestic hydraulic, pneumatic cylinder, coal downhole stent (pillar), oil pump tube, jack and other manufacturing areas. High-precision cold drawn precision steel pipe to promote the use of saving steel, improve processing efficiency, energy conservation, reduce the hydraulic cylinder, cylinder processing equipment investment is important.
Cold-drawn way: the production of high-precision cold-drawn tube ─ ─ hydraulic cylinder compared with the traditional cutting process, has the following characteristics:
(1) High production efficiency: the traditional way to produce a diameter of 420 mm, 12 meters long cylinder to be 154 hours, with cold drawing method to produce only 4 minutes.
(2) The high rate of genuine: the boring of the rolling head and play a guiding role in the cutting process, the blank tube due to self-weight deflection, resulting in rolling head and boring tool deviation, resulting in waste. Genuine rate can only reach about 60%, while the cold-drawn method of production, genuine rate of up to 95% or more.
(3) High metal utilization: the traditional boring method of manufacturing cylinder, metal utilization rate of only 50-70%. With the drawing method of production, the metal not only is not cut into iron, but can get 30% extension, metal utilization up to 95%.
(4) Improve the mechanical properties of finished pipe metal: the use of drawing method, so that the blank get more than 30% of the plastic deformation, due to hardening and processing of the finished tube metal strength limit greatly improved. Generally in the finished product tube strength limit increased by 60%.
The production process is as follows: Feed - Appearance inspection - Mechanical cleaning - Mechanical cleaning - Annealing - Straightening - Pipe head processing - Pickling - Neutralization - Washing - Sizing - Saponification - - Pull - Check - Cut - Honing - End Machining - Straightening - Assembly - Pressure Test - Packing
Application:
(1) Engineering hydraulic machinery: such as hydraulic car hanging, excavators, bulldozers, forklifts and so on.
(2) Coal mine hydraulic support: the current production of underground hydraulic support of the 48 companies, high-precision cold-drawn tube of the total demand of about 1.2 million meters.
(3) Hydropower station gate hoist, template machine, especially the Yangtze River Three Gorges Project in the next decade a great demand.
(4) Construction machinery: high-altitude operation of lifting machinery, general construction of the construction can not be separated from the hydraulic machinery.
(5) Petroleum geological tube: the oil field of each year to pump more than 30,000 units, the annual consumption of high-precision tube 20-40 million meters, in addition to this technology can also be used to refine all kinds of drill pipe.
(6) Weapons industry: the military sector is now using spinning method of processing guns, spinning method of low productivity and high cost, with cold drawing method is more appropriate production.
(7) Bearing industry: the current production of rolling bearing ring to round steel as raw material, sliced after stamping made. Large bearing seat will also be hollow bar hollow to make, metal utilization rate of less than 40%, the urgent need for high precision, bearing steel thick-walled pipe.
(8) The automotive industry: 95 years drive shaft with precision pipe 6,000 tons, 10,000 tons of casing and a variety of oil pipeline.
(9) Aviation industry: aluminum alloy landing gear and thick-walled steel pipe.
(10) Jack industry: China's jack manufacturing has considerable strength, export prospects. The production of enterprises at present the use of solid cylinder bar processing, low production efficiency, high material waste, the need for high-precision cold-drawn tube urgent.
(11) Other areas: all kinds of printing and dyeing roller, roller roller with tube, stainless steel tube, aluminum tube, brass, shaped tube and inside and outside the composite pipe, etc. can be used to produce this technology.
Cold-drawn way: the production of high-precision cold-drawn tube ─ ─ hydraulic cylinder compared with the traditional cutting process, has the following characteristics:
(1) High production efficiency: the traditional way to produce a diameter of 420 mm, 12 meters long cylinder to be 154 hours, with cold drawing method to produce only 4 minutes.
(2) The high rate of genuine: the boring of the rolling head and play a guiding role in the cutting process, the blank tube due to self-weight deflection, resulting in rolling head and boring tool deviation, resulting in waste. Genuine rate can only reach about 60%, while the cold-drawn method of production, genuine rate of up to 95% or more.
(3) High metal utilization: the traditional boring method of manufacturing cylinder, metal utilization rate of only 50-70%. With the drawing method of production, the metal not only is not cut into iron, but can get 30% extension, metal utilization up to 95%.
(4) Improve the mechanical properties of finished pipe metal: the use of drawing method, so that the blank get more than 30% of the plastic deformation, due to hardening and processing of the finished tube metal strength limit greatly improved. Generally in the finished product tube strength limit increased by 60%.
The production process is as follows: Feed - Appearance inspection - Mechanical cleaning - Mechanical cleaning - Annealing - Straightening - Pipe head processing - Pickling - Neutralization - Washing - Sizing - Saponification - - Pull - Check - Cut - Honing - End Machining - Straightening - Assembly - Pressure Test - Packing
Application:
(1) Engineering hydraulic machinery: such as hydraulic car hanging, excavators, bulldozers, forklifts and so on.
(2) Coal mine hydraulic support: the current production of underground hydraulic support of the 48 companies, high-precision cold-drawn tube of the total demand of about 1.2 million meters.
(3) Hydropower station gate hoist, template machine, especially the Yangtze River Three Gorges Project in the next decade a great demand.
(4) Construction machinery: high-altitude operation of lifting machinery, general construction of the construction can not be separated from the hydraulic machinery.
(5) Petroleum geological tube: the oil field of each year to pump more than 30,000 units, the annual consumption of high-precision tube 20-40 million meters, in addition to this technology can also be used to refine all kinds of drill pipe.
(6) Weapons industry: the military sector is now using spinning method of processing guns, spinning method of low productivity and high cost, with cold drawing method is more appropriate production.
(7) Bearing industry: the current production of rolling bearing ring to round steel as raw material, sliced after stamping made. Large bearing seat will also be hollow bar hollow to make, metal utilization rate of less than 40%, the urgent need for high precision, bearing steel thick-walled pipe.
(8) The automotive industry: 95 years drive shaft with precision pipe 6,000 tons, 10,000 tons of casing and a variety of oil pipeline.
(9) Aviation industry: aluminum alloy landing gear and thick-walled steel pipe.
(10) Jack industry: China's jack manufacturing has considerable strength, export prospects. The production of enterprises at present the use of solid cylinder bar processing, low production efficiency, high material waste, the need for high-precision cold-drawn tube urgent.
(11) Other areas: all kinds of printing and dyeing roller, roller roller with tube, stainless steel tube, aluminum tube, brass, shaped tube and inside and outside the composite pipe, etc. can be used to produce this technology.
P92 high pressure boiler tubes based on P91 steel
P92 high pressure boiler tube is based on the P91 steel, using a variety of ways to strengthen the research and development of good high temperature strength and creep resistance of the new ferrite heat-resistant alloy steel pipe. It is the highest use of high temperature compared to P91, P91 in the manufacture of large power plant boiler metal wall temperature and pressure higher part of the head and steam pipe instead.
Due to tungsten, molybdenum compound solutions, reinforced multi-reinforcement devices, P92 performance tests for P91 difficult mill equipment are quite large, and the rolling range of temperature selection is narrow. The team members of the technical center, on the basis of summing up past experience, rolled the high alloy tube system technology, fully considering the production capacity of the equipment, the production process conditions, and actively explored the two tubes of the assel rolling unit to improve the heating system, optimize the process parameters, tool configuration and deformation of the distribution, in strict accordance with the unit's internal control standards of production, the successful rolling Φ168 × 30mmP92 high pressure boiler tube.
Due to tungsten, molybdenum compound solutions, reinforced multi-reinforcement devices, P92 performance tests for P91 difficult mill equipment are quite large, and the rolling range of temperature selection is narrow. The team members of the technical center, on the basis of summing up past experience, rolled the high alloy tube system technology, fully considering the production capacity of the equipment, the production process conditions, and actively explored the two tubes of the assel rolling unit to improve the heating system, optimize the process parameters, tool configuration and deformation of the distribution, in strict accordance with the unit's internal control standards of production, the successful rolling Φ168 × 30mmP92 high pressure boiler tube.
Performance of P91 steel
P91 steel is to fill the pearlite heat-resistant steel and austenitic heat-resistant steel 600 ~ 650 ℃ between the temperature area of the new soda water pipeline steel, are martensitic heat-resistant steel, the maximum temperature of 650 ℃, the actual On the basis of the original 9Cr-1Mo steel added V, Nb, N and other strengthening elements, the formation of a new type of deterioration of steel.
P91 welding performance
P91 steel can be arc welded according to existing methods, including welding by means of argon welding (TIG). The choice of electrodes and flux should be made as close as possible to the chemical composition of the weld and the base metal so that the weld metal has the same or better creep and lasting strength as the base material. As the steel is not sensitive to hot cracking, pre-heating to 150 ~ 200 ℃ before welding will not appear cracks, and with a variety of steel, such as P22 steel (pearlitic heat-resistant steel), X20CrMoV121 (martensite hot steel) and TP304H (austenitic heat-resistant steel) and other steel welding, the following describes the welding of P91 steel:
A) P91 steel and P91 steel welding, the choice of 9Cr-1Mo (T9) or improved 9Cr-1Mo (T91) electrode, wall thickness greater than 25 mm using the latter, the preheating temperature of 200 ℃, after welding slowly Cooled to room temperature and then tempered at temperatures above 730 °C;
B) P91 steel and 10CrMo910 welding, the welding material to match with the 10CrMo910, 730 ℃ after the release of stress should be cooled in the air 2 h, because the two parts of the welding parts of a decarburization area, if the use of 10CrMo910 electrode welding, To ensure that the carbon content of welding metal is high enough to meet the requirements of lasting strength;
C) P91 steel and P22 steel welding, the electrode can be used 2.25Cr-1Mo electrode, preheating temperature of 200 ℃, after welding slowly cooled to room temperature, and then 700 ~ 725 ℃ tempering, but also in the P91 steel side Welding 5Cr1-1Mo electrode, and then welding with the P22 steel;
D) P91 steel and X20CrMoV121 welding, the use of two matching welding materials, such as P91 steel electrode, preheating temperature of 250 ℃, after welding slowly cooled to 80 ~ 100 ℃, above 750 ℃ temperature tempering;
E) P91 steel and TP304H welding, with Inconel 182Ni-based alloy electrode, preheating temperature of 200 ℃, after welding to room temperature, at 700 ~ 730 ℃ tempering.
Above the heat treatment temperature after welding depends on the pipe wall thickness, small diameter pipe treatment 0.5 h, large diameter pipe to the wall thickness every 25 mm treatment 1 h. Because P91 creep strength is high, under the same conditions, the pipe wall thickness is thinner than that of P22 steel, and the amount of metal filled with weld is relatively small, but P91 steel is sensitive to weld type IV crack. Therefore, it is necessary to minimize the P91 steel Of the system stress, the wall thickness of more than 12.5 mm of the pipe, the requirements of the cold after welding to 100 ℃ or more tempering.
P91 welding performance
P91 steel can be arc welded according to existing methods, including welding by means of argon welding (TIG). The choice of electrodes and flux should be made as close as possible to the chemical composition of the weld and the base metal so that the weld metal has the same or better creep and lasting strength as the base material. As the steel is not sensitive to hot cracking, pre-heating to 150 ~ 200 ℃ before welding will not appear cracks, and with a variety of steel, such as P22 steel (pearlitic heat-resistant steel), X20CrMoV121 (martensite hot steel) and TP304H (austenitic heat-resistant steel) and other steel welding, the following describes the welding of P91 steel:
A) P91 steel and P91 steel welding, the choice of 9Cr-1Mo (T9) or improved 9Cr-1Mo (T91) electrode, wall thickness greater than 25 mm using the latter, the preheating temperature of 200 ℃, after welding slowly Cooled to room temperature and then tempered at temperatures above 730 °C;
B) P91 steel and 10CrMo910 welding, the welding material to match with the 10CrMo910, 730 ℃ after the release of stress should be cooled in the air 2 h, because the two parts of the welding parts of a decarburization area, if the use of 10CrMo910 electrode welding, To ensure that the carbon content of welding metal is high enough to meet the requirements of lasting strength;
C) P91 steel and P22 steel welding, the electrode can be used 2.25Cr-1Mo electrode, preheating temperature of 200 ℃, after welding slowly cooled to room temperature, and then 700 ~ 725 ℃ tempering, but also in the P91 steel side Welding 5Cr1-1Mo electrode, and then welding with the P22 steel;
D) P91 steel and X20CrMoV121 welding, the use of two matching welding materials, such as P91 steel electrode, preheating temperature of 250 ℃, after welding slowly cooled to 80 ~ 100 ℃, above 750 ℃ temperature tempering;
E) P91 steel and TP304H welding, with Inconel 182Ni-based alloy electrode, preheating temperature of 200 ℃, after welding to room temperature, at 700 ~ 730 ℃ tempering.
Above the heat treatment temperature after welding depends on the pipe wall thickness, small diameter pipe treatment 0.5 h, large diameter pipe to the wall thickness every 25 mm treatment 1 h. Because P91 creep strength is high, under the same conditions, the pipe wall thickness is thinner than that of P22 steel, and the amount of metal filled with weld is relatively small, but P91 steel is sensitive to weld type IV crack. Therefore, it is necessary to minimize the P91 steel Of the system stress, the wall thickness of more than 12.5 mm of the pipe, the requirements of the cold after welding to 100 ℃ or more tempering.
Seamless steel pipe precision requirements
(A) Seamless steel pipe size accuracy
In order to determine the position of the shaft, it is usually required for its dimensional accuracy (IT5 ~ IT7). The accuracy of the journal size of the assembly drive is generally low (IT6 ~ IT9).
(B) Seamless steel pipe geometry accuracy
The geometric shape accuracy of the shaft parts refers mainly to the roundness, the cylindrical degree, etc. of the journal, outer cone, Mohs cone, etc., and should be limited to the tolerance range. 40Cr seamless steel pipe with high accuracy requirements of the inner and outer circular surface, the drawings should be marked on the allowable deviation.
(C) Seamless steel pipe position accuracy
The positional accuracy requirements of the shaft parts are determined primarily by the position and function of the shaft in the machine. It is usually necessary to ensure that the journal of the drive body is required to coax the support journal, otherwise it will affect the transmission accuracy of the transmission (gear, etc.) and produce noise. The axis of normal accuracy, the radial runout of the support shaft with respect to the support journal is generally 0.01 to 0.03 mm, and the high precision shaft (e.g., the main shaft) is usually 0.001 to 0.005 mm.
(D) Seamless steel pipe surface roughness
In general, the surface roughness of the shaft diameter is Ra2.5 ~ 0.63μm, and the surface roughness of the supporting shaft diameter is 40.63 ~ 0.16μm with the 40Cr seamless steel tube bearing.
In order to determine the position of the shaft, it is usually required for its dimensional accuracy (IT5 ~ IT7). The accuracy of the journal size of the assembly drive is generally low (IT6 ~ IT9).
(B) Seamless steel pipe geometry accuracy
The geometric shape accuracy of the shaft parts refers mainly to the roundness, the cylindrical degree, etc. of the journal, outer cone, Mohs cone, etc., and should be limited to the tolerance range. 40Cr seamless steel pipe with high accuracy requirements of the inner and outer circular surface, the drawings should be marked on the allowable deviation.
(C) Seamless steel pipe position accuracy
The positional accuracy requirements of the shaft parts are determined primarily by the position and function of the shaft in the machine. It is usually necessary to ensure that the journal of the drive body is required to coax the support journal, otherwise it will affect the transmission accuracy of the transmission (gear, etc.) and produce noise. The axis of normal accuracy, the radial runout of the support shaft with respect to the support journal is generally 0.01 to 0.03 mm, and the high precision shaft (e.g., the main shaft) is usually 0.001 to 0.005 mm.
(D) Seamless steel pipe surface roughness
In general, the surface roughness of the shaft diameter is Ra2.5 ~ 0.63μm, and the surface roughness of the supporting shaft diameter is 40.63 ~ 0.16μm with the 40Cr seamless steel tube bearing.
Processing Technology of Thin-wall Seamless Tube Parts
Thin-walled seamless pipe parts because of its compact structure, light weight, saving materials and other characteristics, in the industrial sector is increasingly widely used. However, due to thin-walled thin-walled seamless pipe parts of low strength, poor rigidity, easy to deformation during processing, it is difficult to ensure the accuracy of parts processing, thin-walled parts processing difficult to become a prominent problem. The factors that affect the machining accuracy of thin-walled seamless pipe parts are many, the machine tool, the tool, the workpiece and the workpiece clamping, cutting process cutting force, cutting heat and so will cause the parts processing error. Thin-walled seamless pipe parts, processing more difficult, especially the processing of the hole, because of in the cutting process, parts by the role of cutting force, prone to deformation. Resulting in elliptical or middle small, two large "waist" phenomenon. In addition, thin-walled parts because of poor heat dissipation during processing, easy to produce thermal deformation, the size and shape error can not meet the requirements of the drawings, so that parts of the shape and error increases, not easy to ensure the quality of parts processing. How to reduce the impact of cutting force on the deformation of the workpiece, so as to fully consider the impact of process problems on the quality of parts processing, the workpiece clamping, tool geometry, cutting the amount of procedures such as the preparation of the test, effectively To overcome the thin-walled parts in the process of deformation, to ensure the processing accuracy.
Characteristics of thin-walled parts: According to the technical requirements of the drawings, the workpiece material using seamless steel pipe for processing, the hole and the outer wall of the surface roughness Ra1.6, can be achieved with the turning. But the cylindrical diameter of the hole 0.03 for thin-walled seamless pipe parts in terms of requirements are relatively high, in mass production, the process route is roughly: cutting - heat treatment - car end - car outer - car hole - quality inspection.
Characteristics of thin-walled parts: According to the technical requirements of the drawings, the workpiece material using seamless steel pipe for processing, the hole and the outer wall of the surface roughness Ra1.6, can be achieved with the turning. But the cylindrical diameter of the hole 0.03 for thin-walled seamless pipe parts in terms of requirements are relatively high, in mass production, the process route is roughly: cutting - heat treatment - car end - car outer - car hole - quality inspection.
Notes of cold drawn precision steel pipe
Cold-drawn precision steel pipe with internal and external wall without oxidation layer, to withstand high pressure without leakage, high precision, high finish, cold bending is not deformed, flared flat no cracks, the surface has been anti-rust treatment, etc., mainly for mechanical structure , Hydraulic equipment and automotive motorcycles pneumatic or hydraulic components, such as cylinders or cylinders.
The basic process of cold drawing is: hot-rolled capillary; capillary inspection, grinding; capillary pickling; after pickling pickling; cold drawn; fine pull straight before the line; pickling, lubrication; Processing;
Production need to pay attention to control:
1, Capillary
Capillary wall thickness to be uniform, less inside and outside the surface defects; to configure the external surface polishing and hole defect cleaning equipment.
2, Re-examination
Compared with ordinary cold drawn steel pipe, cold drawn precision steel pipe production increased the hot-rolled capillary pickling re-inspection process, mainly to ensure that the outer surface of the capillary without folding, cracks and other defects, excluding the inner surface of the fold, Dumplings and other defects of the capillary.
3, Tools
General cold drawn precision steel pipe production tools used in the surface finish requirements Ra0.4 above, dimensional accuracy of H3 or more, hardness requirements above HRC70. At the same time require the drawing process can not appear head or die sticky steel phenomenon.
4, Annealing
Annealing is a very important step in the production of all the cold drawn tubes. The quality of the annealing affects both the performance of the steel pipe and the removal of the scale. Cold drawn precision steel pipe needs to be equipped with no oxidation bright annealing furnace equipment.
5, Pickling
Precision steel pipe in the acid pickling process is easy to form Fe2O3, Fe3O4-based "black slag", in the subsequent production of the formation of surface dark spots. Fe2O3, Fe3O4 soluble in hydrochloric acid, in order to prevent the formation of dark spots in the acid pool by adding 5-10g / l of NaCl.
6, Lubrication
Should be used as a lubricant lubricant, this lubrication and phosphating plus lubrication (saponification) compared to a significant difference, drawn out of the iron tube showing the true nature of the iron matrix, both high gloss and cold rolled like a beautiful appearance color.
The basic process of cold drawing is: hot-rolled capillary; capillary inspection, grinding; capillary pickling; after pickling pickling; cold drawn; fine pull straight before the line; pickling, lubrication; Processing;
Production need to pay attention to control:
1, Capillary
Capillary wall thickness to be uniform, less inside and outside the surface defects; to configure the external surface polishing and hole defect cleaning equipment.
2, Re-examination
Compared with ordinary cold drawn steel pipe, cold drawn precision steel pipe production increased the hot-rolled capillary pickling re-inspection process, mainly to ensure that the outer surface of the capillary without folding, cracks and other defects, excluding the inner surface of the fold, Dumplings and other defects of the capillary.
3, Tools
General cold drawn precision steel pipe production tools used in the surface finish requirements Ra0.4 above, dimensional accuracy of H3 or more, hardness requirements above HRC70. At the same time require the drawing process can not appear head or die sticky steel phenomenon.
4, Annealing
Annealing is a very important step in the production of all the cold drawn tubes. The quality of the annealing affects both the performance of the steel pipe and the removal of the scale. Cold drawn precision steel pipe needs to be equipped with no oxidation bright annealing furnace equipment.
5, Pickling
Precision steel pipe in the acid pickling process is easy to form Fe2O3, Fe3O4-based "black slag", in the subsequent production of the formation of surface dark spots. Fe2O3, Fe3O4 soluble in hydrochloric acid, in order to prevent the formation of dark spots in the acid pool by adding 5-10g / l of NaCl.
6, Lubrication
Should be used as a lubricant lubricant, this lubrication and phosphating plus lubrication (saponification) compared to a significant difference, drawn out of the iron tube showing the true nature of the iron matrix, both high gloss and cold rolled like a beautiful appearance color.
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