Pre-finishing technology is the large diameter welding thick-walled spiral pipe production of oil and gas pipelines in the more advanced technology.
The first step in the pre-bonding method using fine production of spiral welded pipe, which was followed by gas welding continuously welded steel strip on the molding machine, pre-weld tube consequent plasma cutting machine cut into a predetermined length of pipe the second step is a pre-welded steel pipe after finish welding production line delivery to internal and external multi-wire submerged arc welding fine.
Spiral welded pipe welding two-step pre-finishing production technology Yuan has obvious advantages compared with conventional one-step spiral welded pipe production due to pre-finish welding submerged arc welding speed constraints, the forming and welding separately, an effective solution to the forming and welding problems between mutual interference. full advantage of forming and welding their own characteristics, to achieve a combination of high-speed molding and multi-unit welding, making a molding production line can simultaneously a number of fine welding production line offers to be welded steel pipe, thereby greatly increasing the production efficiency. in addition, since steel forming and submerged arc welding fine separately, on both sides of the pre-weld pipe beveling relatively stable, easy to get high-quality welds.
2019年3月25日星期一
Seamless steel tube as the advantages of pipeline transport materials
According to the size of the caliber, there is also a clear distinction between the use of seamless steel tubes. From the current market point of view, there are more than ten sizes of seamless steel tubes. In order to meet the needs of the market, its production scale is still In the continuous expansion, talking about this type of pipe material, more is used as a material for pipe transportation, so more is the use of large-diameter seamless steel pipes, such large-sized steel pipes, Many problems can be avoided during transportation.
Compared with ordinary welded steel pipes, the safety of seamless steel pipes used as pipe transportation materials is very high, which is one of the advantages of this type of pipe material. The thickness of the pipe wall is also different depending on the specific application. If it is used as a material for transporting oil and natural gas, the pipe wall will generally be thicker, which can effectively avoid the transportation process. In the case of a leak that occurs, this type of pipe material is constantly evolving at the level of the manufacturing process.
Seamless steel tubes are highly utilized in the market and are also widely used in the industrial sector. This type of piping material has a high market price/performance ratio and is therefore very popular in the market. Among the many steel pipe materials, the advantages of seamless steel pipe are obvious, and more are used as materials for fluid and gas transportation. Pipe transportation is an environmentally intensive transportation mode. In modern society, pipe belt transportation It is already a very common way of transporting, so the materials needed for pipeline transportation also get a good market space.
If it is used as a material for pipeline transportation, it is necessary to consider the applicability of such pipeline material before exiting. It is necessary to consider from the viewpoint of mechanical properties to see if this type of pipeline material meets the actual requirements. It is also used in the construction sector. The transportation of groundwater also requires the use of seamless steel pipes.
http://www.xysteelpipe.com/info/Seamless-steel-tube-as-the-advantages-of-pipeline-transport-materials-1353-1.htm
Compared with ordinary welded steel pipes, the safety of seamless steel pipes used as pipe transportation materials is very high, which is one of the advantages of this type of pipe material. The thickness of the pipe wall is also different depending on the specific application. If it is used as a material for transporting oil and natural gas, the pipe wall will generally be thicker, which can effectively avoid the transportation process. In the case of a leak that occurs, this type of pipe material is constantly evolving at the level of the manufacturing process.
Seamless steel tubes are highly utilized in the market and are also widely used in the industrial sector. This type of piping material has a high market price/performance ratio and is therefore very popular in the market. Among the many steel pipe materials, the advantages of seamless steel pipe are obvious, and more are used as materials for fluid and gas transportation. Pipe transportation is an environmentally intensive transportation mode. In modern society, pipe belt transportation It is already a very common way of transporting, so the materials needed for pipeline transportation also get a good market space.
If it is used as a material for pipeline transportation, it is necessary to consider the applicability of such pipeline material before exiting. It is necessary to consider from the viewpoint of mechanical properties to see if this type of pipeline material meets the actual requirements. It is also used in the construction sector. The transportation of groundwater also requires the use of seamless steel pipes.
http://www.xysteelpipe.com/info/Seamless-steel-tube-as-the-advantages-of-pipeline-transport-materials-1353-1.htm
2019年3月24日星期日
Forming technology of seamless pipe fittings
What are the main types of seamless pipe fittings forming technology:
1. Hot extrusion method
Before the extrusion, it is necessary to carry out machining pretreatment of the blank. When the seamless pipe fittings with a diameter of 100 mm or less are extruded, the equipment investment is small, the material waste is small, and the technology is relatively mature. However, once the pipe diameter is increased, hot extrusion requires large tonnage and high power equipment, and the corresponding control system is also upgraded.
2, Hot piercing rolling method
Hot piercing and rolling is mainly based on longitudinal rolling and cross rolling. Vertical rolling and rolling is mainly limited to dynamic mandrel rolling mill rolling, small frame limiting mandrel rolling mill rolling, three-roller limiting mandrel rolling mill rolling and floating mandrel rolling mill rolling. These methods have high production efficiency, low metal consumption, good product quality, advanced control systems, and increasingly widespread applications. The cross-rolling and rolling method is also widely used in the production of small-sized seamless pipes with low input, short process, suitable for small batches, multiple varieties, multiple specifications and high precision.
3, Hot push expansion method
The push-expanding and expanding equipment is simple, the cost is low, the maintenance is convenient, the economy is durable, and the product specifications are changed flexibly. If it is necessary to prepare a large-diameter elbow and the like, only some accessories need to be added. It is suitable for the production of medium and thin wall thick large diameter seamless steel pipe, and can also produce thick wall pipe which does not exceed the equipment capacity.
http://www.xysteelpipe.com/info/Forming-technology-of-seamless-pipe-fittings-1352-1.htm
1. Hot extrusion method
Before the extrusion, it is necessary to carry out machining pretreatment of the blank. When the seamless pipe fittings with a diameter of 100 mm or less are extruded, the equipment investment is small, the material waste is small, and the technology is relatively mature. However, once the pipe diameter is increased, hot extrusion requires large tonnage and high power equipment, and the corresponding control system is also upgraded.
2, Hot piercing rolling method
Hot piercing and rolling is mainly based on longitudinal rolling and cross rolling. Vertical rolling and rolling is mainly limited to dynamic mandrel rolling mill rolling, small frame limiting mandrel rolling mill rolling, three-roller limiting mandrel rolling mill rolling and floating mandrel rolling mill rolling. These methods have high production efficiency, low metal consumption, good product quality, advanced control systems, and increasingly widespread applications. The cross-rolling and rolling method is also widely used in the production of small-sized seamless pipes with low input, short process, suitable for small batches, multiple varieties, multiple specifications and high precision.
3, Hot push expansion method
The push-expanding and expanding equipment is simple, the cost is low, the maintenance is convenient, the economy is durable, and the product specifications are changed flexibly. If it is necessary to prepare a large-diameter elbow and the like, only some accessories need to be added. It is suitable for the production of medium and thin wall thick large diameter seamless steel pipe, and can also produce thick wall pipe which does not exceed the equipment capacity.
http://www.xysteelpipe.com/info/Forming-technology-of-seamless-pipe-fittings-1352-1.htm
2019年3月21日星期四
Long distance pipeline construction welding problem
At present, the domestic long-distance pipeline construction usually "under the cellulose type electrode to weld, cellulose type electrode root welding + self shielded flux cored wire semi-automatic welding and STT root pass + self shielded flux cored wire semi-automatic welding" process, welding easy question that arises is:
1, Slag
Reason: Because they use a long-distance pipeline under flux cored wire semi-automatic welding process to be filled, cover up, when a semi-automatic welding process equipment intermittent fault, often top wire phenomenon, then wear a wire into the bath, when melt instant re-ignited after rapid cooling pool, the weld was often wrapped with metal debris, or slag, produced slag.
Measures: Before root weld groove should carefully cleaning, filling, be careful when you clean up the slag cover pass.
2, Stomatal
Cause: The filling layer porosity is mainly due to self-protection cored semiautomatic welding arc voltage caused by excessive.
Action: In the welding process, to select the appropriate arc voltage and wire feed speed, to maintain a certain length of wire out, next to the vertical welding to control the proper welding speed.
3, Roots of incomplete penetration
Cause: The main group of the gap is too small or too thick blunt edge.
Measures: Before welding serious and group weld grinding, to ensure wire or rod can be smoothly inserted into the groove when the root weld root; root weld can not occur when the hole when dissolved, grinding out the root gap applications and appropriately adjust the welding parameters .
4, Crack
The reason: to force the group to crack when often lead solder.
Measures: 1) to avoid forcible Group; 2) preheat, a modest increase in root weld bead thickness, immediately after the completion of the root weld heat welding, filling, capping.
5, Burn
Reason: Because the root bead is too thin or improper welding parameters.
Measures: not too thin root bead to 3mm thick appropriate; root welding process parameters is not too much; to stop welding immediately after burn, to be grinding out bevel angle and root gap, and then re-root welding, heat welding To complete this procedure.
1, Slag
Reason: Because they use a long-distance pipeline under flux cored wire semi-automatic welding process to be filled, cover up, when a semi-automatic welding process equipment intermittent fault, often top wire phenomenon, then wear a wire into the bath, when melt instant re-ignited after rapid cooling pool, the weld was often wrapped with metal debris, or slag, produced slag.
Measures: Before root weld groove should carefully cleaning, filling, be careful when you clean up the slag cover pass.
2, Stomatal
Cause: The filling layer porosity is mainly due to self-protection cored semiautomatic welding arc voltage caused by excessive.
Action: In the welding process, to select the appropriate arc voltage and wire feed speed, to maintain a certain length of wire out, next to the vertical welding to control the proper welding speed.
3, Roots of incomplete penetration
Cause: The main group of the gap is too small or too thick blunt edge.
Measures: Before welding serious and group weld grinding, to ensure wire or rod can be smoothly inserted into the groove when the root weld root; root weld can not occur when the hole when dissolved, grinding out the root gap applications and appropriately adjust the welding parameters .
4, Crack
The reason: to force the group to crack when often lead solder.
Measures: 1) to avoid forcible Group; 2) preheat, a modest increase in root weld bead thickness, immediately after the completion of the root weld heat welding, filling, capping.
5, Burn
Reason: Because the root bead is too thin or improper welding parameters.
Measures: not too thin root bead to 3mm thick appropriate; root welding process parameters is not too much; to stop welding immediately after burn, to be grinding out bevel angle and root gap, and then re-root welding, heat welding To complete this procedure.
Precision pipe length measurement method
According to the technological requirements of different manufacturers, precision tubes length measurement systems with a variety of length measurement methods. There are the following:
1, The grating length measurement
The basic principle is: the outer ends of precision tubes are provided two fixed length of the grating, the use of rodless cylinder driven grating near precision tubes ends, using light interference to achieve precise measurement of the length of the tube.
It is characterized by high accuracy. But the scale is expensive and difficult to maintain, the impact of dust and vibration is very sensitive site.
2, The camera length measurement
Camera length measurement is the use of image processing to achieve precision tubes length measurement, the principle is equidistant series of photoelectric switches installed in the precision roller conveyor tube a certain period, the increase in light and camera on the other section. When precision tubes through this region may be determined by the precision tube length cameras capture an image on the screen at a position based on a photoelectric switch.
Features are available for online measurement, precision tubes can be obtained by measuring the length of the data when long area, no interval. Shortage is: If you do not ad hoc light source, precision tubes will be subject to interference outside light, but after using the light due to the ad hoc precision tubes after chamfered tube end while the high brightness light reflection is very strong, is likely to cause reading errors.
3, The encoder measuring length
The principle is to install the encoder in the cylinder at the cylinder to promote the use of precision tubes in rollers movement on the other side of the mounting equidistant series of photoelectric switches, precision tubes is met when the photoelectric switch cylinders push the tube end, from the recording encoding readings, converted the stroke of cylinder, so you can calculate the length of the precision tubes.
Characterized by the need to raise precision tubes measuring length. In addition, there are certain photoelectric switch detects an error, you may need to be fully measured.
4, Improved length measuring encoder
This method is an indirect measurement, by measuring the distance between two end precision tubes with the respective reference point indirectly measured precision tube length. In the precision tubes both ends of the measuring station set up a long car, the initial position is zero position, spacing L. Then move the editor precision tube length to each end of the distance traveled (L2, L3), L-L2-L3, is the length of the precision tubes.
1, The grating length measurement
The basic principle is: the outer ends of precision tubes are provided two fixed length of the grating, the use of rodless cylinder driven grating near precision tubes ends, using light interference to achieve precise measurement of the length of the tube.
It is characterized by high accuracy. But the scale is expensive and difficult to maintain, the impact of dust and vibration is very sensitive site.
2, The camera length measurement
Camera length measurement is the use of image processing to achieve precision tubes length measurement, the principle is equidistant series of photoelectric switches installed in the precision roller conveyor tube a certain period, the increase in light and camera on the other section. When precision tubes through this region may be determined by the precision tube length cameras capture an image on the screen at a position based on a photoelectric switch.
Features are available for online measurement, precision tubes can be obtained by measuring the length of the data when long area, no interval. Shortage is: If you do not ad hoc light source, precision tubes will be subject to interference outside light, but after using the light due to the ad hoc precision tubes after chamfered tube end while the high brightness light reflection is very strong, is likely to cause reading errors.
3, The encoder measuring length
The principle is to install the encoder in the cylinder at the cylinder to promote the use of precision tubes in rollers movement on the other side of the mounting equidistant series of photoelectric switches, precision tubes is met when the photoelectric switch cylinders push the tube end, from the recording encoding readings, converted the stroke of cylinder, so you can calculate the length of the precision tubes.
Characterized by the need to raise precision tubes measuring length. In addition, there are certain photoelectric switch detects an error, you may need to be fully measured.
4, Improved length measuring encoder
This method is an indirect measurement, by measuring the distance between two end precision tubes with the respective reference point indirectly measured precision tube length. In the precision tubes both ends of the measuring station set up a long car, the initial position is zero position, spacing L. Then move the editor precision tube length to each end of the distance traveled (L2, L3), L-L2-L3, is the length of the precision tubes.
2019年3月15日星期五
Six Processing Method of Seamless Steel Pipe
Seamless steel tube is the combination of machining and metal pressure processing, processing many ways, within the scope of machining and the like, are common stamping, forging method, roller processing method, rolling method, bulging method, stretching , bending method, and a combination of processing methods, to understand in detail below under:
1, Bulging method: one is placed in the seamless steel pipe rubber, with the top punch compression, so that the sub-convex shaped seamless steel pipe; Another method is forming a hydraulic bulging in the middle of seamless steel tubes filled with liquid child, by fluid pressure seamless steel sub-drum into the desired shape, like we used corrugated seamless steel pipe production is most used in this way.
2, Forging method: using a swaging machine seamless steel pipe end or part of the child to be rushed stretch, reducing the outer diameter, often have a rotary swaging machine, link type, roller.
3, Roller method: Place the core in a seamless steel pipe, the outer periphery with rollers pushing for round edge processing.
4, Rolling method: generally do mandrel, suitable for thick-walled seamless inner circle to the edge.
5, Bending method: There are three methods more commonly used, a method called stretching method, another method called stamping method, and the third is more familiar roller method, there are 3-4 roll, two fixed roll, an adjustment roller, adjust the fixing roller distance, finished seamless steel member is curved. Wider application of this approach, if the production of seamless steel pipe spiral curvature can be increased.
6, Stamping method: punch with seamless steel core with a tapered end will expand to the required size and shape.
1, Bulging method: one is placed in the seamless steel pipe rubber, with the top punch compression, so that the sub-convex shaped seamless steel pipe; Another method is forming a hydraulic bulging in the middle of seamless steel tubes filled with liquid child, by fluid pressure seamless steel sub-drum into the desired shape, like we used corrugated seamless steel pipe production is most used in this way.
2, Forging method: using a swaging machine seamless steel pipe end or part of the child to be rushed stretch, reducing the outer diameter, often have a rotary swaging machine, link type, roller.
3, Roller method: Place the core in a seamless steel pipe, the outer periphery with rollers pushing for round edge processing.
4, Rolling method: generally do mandrel, suitable for thick-walled seamless inner circle to the edge.
5, Bending method: There are three methods more commonly used, a method called stretching method, another method called stamping method, and the third is more familiar roller method, there are 3-4 roll, two fixed roll, an adjustment roller, adjust the fixing roller distance, finished seamless steel member is curved. Wider application of this approach, if the production of seamless steel pipe spiral curvature can be increased.
6, Stamping method: punch with seamless steel core with a tapered end will expand to the required size and shape.
Deformation strengthening of high pressure alloy tube
High-pressure alloy pipe deformation strengthening is using the method of deformation of steel reinforcement. Also known as the strain hardening or work hardening. The strength of the material at the macro (or a whole) the ability to resist deformation (or flow stress). Hardness is the ability of the material to resist plastic deformation localized (whether micro-hardness, Vickers hardness, Rockwell hardness or Brinell hardness). Both have similar corresponding relationship in many cases. Strength of the material, the greater the resistance to plastic deformation, the higher the hardness value. Conversely, the higher the hardness of the material, the material may be due to increased brittleness, its strength is not fully reflected in such strength index value is not high.
For longer subjected to heat treatment, and the use of the material in temperatures well below the recrystallization temperature of the high-pressure alloy pipe steel pipe material (such as low-carbon low-alloy steel), often use cold (cold deformation) so that by means of deformation strengthening to improve strength. Thus, deformation strengthening essence is in the recrystallization temperature of the material in the following cold deformation, with the degree of deformation (strain) is increased, resulting in a high density of dislocations (crystal defects), the higher the dislocation density in the crystal, The greater the degree of enhancement, namely the higher flow stress. After deformation flow stress of steel should not be equal before deformation flow stress plus incremental deformation strengthening flow stress. Use of deformation strengthening to achieve high strength steel products, typical is the high-carbon steel cold-drawn steel wire and low carbon low-alloy duplex steel cold-drawn steel wire.
With the increase of the degree of deformation, material strength and hardness higher and higher, but its ductility and toughness are often getting lower and lower, more and more brittle, which requires tough to take appropriate measures to improve the situation. Internal induced in the martensitic phase transformation phase cooling for hardening, its physical essence, it also belongs to deformation strengthening, but this time not from the external deformation, but the process of martensitic transformation from crystal High-density place itself shear generated by mistake.
For longer subjected to heat treatment, and the use of the material in temperatures well below the recrystallization temperature of the high-pressure alloy pipe steel pipe material (such as low-carbon low-alloy steel), often use cold (cold deformation) so that by means of deformation strengthening to improve strength. Thus, deformation strengthening essence is in the recrystallization temperature of the material in the following cold deformation, with the degree of deformation (strain) is increased, resulting in a high density of dislocations (crystal defects), the higher the dislocation density in the crystal, The greater the degree of enhancement, namely the higher flow stress. After deformation flow stress of steel should not be equal before deformation flow stress plus incremental deformation strengthening flow stress. Use of deformation strengthening to achieve high strength steel products, typical is the high-carbon steel cold-drawn steel wire and low carbon low-alloy duplex steel cold-drawn steel wire.
With the increase of the degree of deformation, material strength and hardness higher and higher, but its ductility and toughness are often getting lower and lower, more and more brittle, which requires tough to take appropriate measures to improve the situation. Internal induced in the martensitic phase transformation phase cooling for hardening, its physical essence, it also belongs to deformation strengthening, but this time not from the external deformation, but the process of martensitic transformation from crystal High-density place itself shear generated by mistake.
Precision pipeline corrosion detection
1, The coating inspection and acceptance:
① surface coating during the construction and after construction, painting had to deal with the workpiece is protected against dust and other debris flying.
② treatment after coating, the coating should be consistent colors, sharp color bright, wrinkle-free skin, blistering, sagging, holidays and other defects.
③ measuring coating film thickness, film thickness was measured using contact-type film thickness, the film thickness is generally 3:00 thickness measurement, the mean value.
2, Quality Inspection
① quality testing using sample testing ways depending on design requirements.
② by visual inspection by the root. Cover layer surface should be uniform, smooth, no bubbles, wrinkles, protruding tumor and uneven hem overlay defects
③ film thickness was measured using magnetic thickness, measured at intervals of 1.5 m on a single precision light pipe at both ends and in the middle of the circumference of a little, the film thickness should meet two 85%: that 85% of the thickness of the measuring point design requirements, amounting to less than the thickness of the measuring points, the minimum should not be less than 85% of the design thickness;
④ with pinhole tester checks pinholes, if found pinholes, sanding with sandpaper grinding machine painted up;
⑤ insufficient film thickness or pinholes, after curing repair should be reviewed, the failure to repair again until qualified;
⑥ adhesion check, use a rigid tool draw an angle on the coating to cut 60 to conduct random checks, shall be classified through direct coating substrates, draw mouth taped portion, tear tape hindsight scratches, Tu layer should be no peeling. You may also have to be checked under the same conditions on the painting template.
① surface coating during the construction and after construction, painting had to deal with the workpiece is protected against dust and other debris flying.
② treatment after coating, the coating should be consistent colors, sharp color bright, wrinkle-free skin, blistering, sagging, holidays and other defects.
③ measuring coating film thickness, film thickness was measured using contact-type film thickness, the film thickness is generally 3:00 thickness measurement, the mean value.
2, Quality Inspection
① quality testing using sample testing ways depending on design requirements.
② by visual inspection by the root. Cover layer surface should be uniform, smooth, no bubbles, wrinkles, protruding tumor and uneven hem overlay defects
③ film thickness was measured using magnetic thickness, measured at intervals of 1.5 m on a single precision light pipe at both ends and in the middle of the circumference of a little, the film thickness should meet two 85%: that 85% of the thickness of the measuring point design requirements, amounting to less than the thickness of the measuring points, the minimum should not be less than 85% of the design thickness;
④ with pinhole tester checks pinholes, if found pinholes, sanding with sandpaper grinding machine painted up;
⑤ insufficient film thickness or pinholes, after curing repair should be reviewed, the failure to repair again until qualified;
⑥ adhesion check, use a rigid tool draw an angle on the coating to cut 60 to conduct random checks, shall be classified through direct coating substrates, draw mouth taped portion, tear tape hindsight scratches, Tu layer should be no peeling. You may also have to be checked under the same conditions on the painting template.
The strip width deviation affects the quality of welded steel tubes
Frequency welded pipe production process, affecting the quality of the elements have more than one pipe, the main raw materials, welding technology and roll count which is beginning to adjust.
Key to look at raw geometric dimensions. Strip geometry affect the quality of the steel strip width when less than the allowable deviation, the extrusion pressure welded steel pipe is reduced, making the pipe weld welding is not strong, cracks or open tube. When the width of the strip is greater than the tolerance, the pressing force is increased when the welded steel pipe, steel pipe welds appear beak, lap welding and other welding defects or burrs. Therefore, the fluctuation width of the strip, not only affects the accuracy of the outside diameter of the steel pipe, but also seriously affect the surface quality of the steel pipe.
Requirements for the same section thickness difference does not exceed the predetermined value of the steel pipe, which requires a high degree of uniformity of the wall thickness of steel pipe, fluctuations in the thickness of the strip, the same volume will be transferred to the wall thickness of the permissible value of finished steel strip thickness difference exceeds the difference so that a large number of steel thickness exceeds the allowable deviation and sentenced to waste. Fluctuations in the thickness of the finished steel thickness only affects the accuracy. Meanwhile, since the strip thickness varies, the steel pipe during welding, extrusion pressure and welding temperature instability, resulting in unstable weld quality steel welding.
In addition, since the internal steel sandwich material defects exist, impurities, such as trachoma, is a major factor affecting the quality of steel. Therefore, before steel welding, to check each roll strip surface quality and geometry of the strip quality does not meet standards, not production, so as to avoid unnecessary losses.
Key to look at raw geometric dimensions. Strip geometry affect the quality of the steel strip width when less than the allowable deviation, the extrusion pressure welded steel pipe is reduced, making the pipe weld welding is not strong, cracks or open tube. When the width of the strip is greater than the tolerance, the pressing force is increased when the welded steel pipe, steel pipe welds appear beak, lap welding and other welding defects or burrs. Therefore, the fluctuation width of the strip, not only affects the accuracy of the outside diameter of the steel pipe, but also seriously affect the surface quality of the steel pipe.
Requirements for the same section thickness difference does not exceed the predetermined value of the steel pipe, which requires a high degree of uniformity of the wall thickness of steel pipe, fluctuations in the thickness of the strip, the same volume will be transferred to the wall thickness of the permissible value of finished steel strip thickness difference exceeds the difference so that a large number of steel thickness exceeds the allowable deviation and sentenced to waste. Fluctuations in the thickness of the finished steel thickness only affects the accuracy. Meanwhile, since the strip thickness varies, the steel pipe during welding, extrusion pressure and welding temperature instability, resulting in unstable weld quality steel welding.
In addition, since the internal steel sandwich material defects exist, impurities, such as trachoma, is a major factor affecting the quality of steel. Therefore, before steel welding, to check each roll strip surface quality and geometry of the strip quality does not meet standards, not production, so as to avoid unnecessary losses.
Difference between small diameter welded pipe and stainless steel pipe
The small-diameter welded pipe is also called a small-diameter welded steel pipe, and is a steel pipe which is formed by welding a steel plate or a strip steel after being crimped. The small-diameter welded pipe has simple production process, high production efficiency, many varieties and specifications, and low equipment, but the general strength is lower than that of seamless steel pipe. Since the 1930s, with the rapid development of high-quality strip continuous rolling production and the advancement of welding and inspection technology, the quality of welds has been continuously improved, and the specifications of small-diameter welded pipes have been increasing, and they have been replaced in more and more fields. Seamless steel pipe. Welded steel pipes are divided into straight welded pipes and spiral welded pipes in the form of welds.
The billet used is steel plate or strip steel, which is divided into furnace welded pipe, electric welding (resistance welded) pipe and automatic arc welded pipe due to different welding processes. Due to the different welding forms, it is divided into straight seam welded pipe and spiral welded pipe. Because of its shape, it is divided into round welded pipes and special-shaped (square, flat, etc.) welded pipes.
The small-diameter welded pipe has a simple production process, high production efficiency, low cost and rapid development. The strength of the spiral welded pipe is generally higher than that of the straight welded pipe. It is possible to produce a welded pipe with a larger diameter by using a narrow blank, and it is also possible to produce a welded pipe having a different pipe diameter with a blank of the same width. However, compared with the straight pipe of the same length, the weld length is increased by 30 to 100%, and the production speed is low. Therefore, most of the smaller diameter welded pipes are straight seam welded, and the large diameter welded pipes are mostly spiral welded.
Supplement: The small-diameter welded pipe is welded with strip steel, so it has no high seamless steel pipe in its original position.
The difference between small diameter welded pipe and stainless steel pipe:
1. The former is a steel pipe made by welding a steel plate or a strip steel after being crimped. The latter is made by ingoting a steel ingot or a solid tube blank, and then making it by hot rolling, cold rolling or cold drawing.
2. The strength of the small diameter welded pipe is lower than that of the stainless steel pipe. The production process is simple, the production efficiency is high, the variety specifications and specifications, and the equipment cost are small. As the quality of the weld seam is continuously improved, the variety specifications of the small-diameter welded pipe are increasing, and the stainless steel pipe is replaced in many fields.
3. The blank used for the small-diameter welded pipe is steel plate or strip steel, and the narrow billet is produced.
4. Small-diameter welded pipes are mainly used for oil and natural gas transmission pipelines. The stainless steel tube has a hollow section and is light in weight. It is an economical section steel and is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile drive shafts, bicycle frames, and steel scaffolding used in construction.
5. The rolling direction of the small-diameter welded pipe vertical coil is not the direction of the vertical steel pipe axis, and the rolling direction of the stainless steel pipe is perpendicular to the axial direction of the steel pipe. The crack resistance of the small-diameter welded pipe material is better than that of the stainless steel pipe.
http://www.xysteelpipe.com/info/Difference-between-small-diameter-welded-pipe-and-stainless-steel-pipe-1346-1.htm
The billet used is steel plate or strip steel, which is divided into furnace welded pipe, electric welding (resistance welded) pipe and automatic arc welded pipe due to different welding processes. Due to the different welding forms, it is divided into straight seam welded pipe and spiral welded pipe. Because of its shape, it is divided into round welded pipes and special-shaped (square, flat, etc.) welded pipes.
The small-diameter welded pipe has a simple production process, high production efficiency, low cost and rapid development. The strength of the spiral welded pipe is generally higher than that of the straight welded pipe. It is possible to produce a welded pipe with a larger diameter by using a narrow blank, and it is also possible to produce a welded pipe having a different pipe diameter with a blank of the same width. However, compared with the straight pipe of the same length, the weld length is increased by 30 to 100%, and the production speed is low. Therefore, most of the smaller diameter welded pipes are straight seam welded, and the large diameter welded pipes are mostly spiral welded.
Supplement: The small-diameter welded pipe is welded with strip steel, so it has no high seamless steel pipe in its original position.
The difference between small diameter welded pipe and stainless steel pipe:
1. The former is a steel pipe made by welding a steel plate or a strip steel after being crimped. The latter is made by ingoting a steel ingot or a solid tube blank, and then making it by hot rolling, cold rolling or cold drawing.
2. The strength of the small diameter welded pipe is lower than that of the stainless steel pipe. The production process is simple, the production efficiency is high, the variety specifications and specifications, and the equipment cost are small. As the quality of the weld seam is continuously improved, the variety specifications of the small-diameter welded pipe are increasing, and the stainless steel pipe is replaced in many fields.
3. The blank used for the small-diameter welded pipe is steel plate or strip steel, and the narrow billet is produced.
4. Small-diameter welded pipes are mainly used for oil and natural gas transmission pipelines. The stainless steel tube has a hollow section and is light in weight. It is an economical section steel and is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile drive shafts, bicycle frames, and steel scaffolding used in construction.
5. The rolling direction of the small-diameter welded pipe vertical coil is not the direction of the vertical steel pipe axis, and the rolling direction of the stainless steel pipe is perpendicular to the axial direction of the steel pipe. The crack resistance of the small-diameter welded pipe material is better than that of the stainless steel pipe.
http://www.xysteelpipe.com/info/Difference-between-small-diameter-welded-pipe-and-stainless-steel-pipe-1346-1.htm
2019年3月7日星期四
Analysis of the reason of the wrong side of straight joint steel pipe
Straight seam steel pipe production, the wrong side have occurred, many influencing factors. In practice, often by a dry wrong side super differential leaving the steel pipe downgrade. Cause analysis thus produces the wrong side of straight pipe joints and prevention measures are necessary.
1, Strip steel camber is caused by the wrong side of the most important factors. In forming the spiral welded pipe, steel strip camber angle will constantly change shape, leading to changes in the weld gap, resulting in open seam, wrong side or even take sides. Seriously affecting the quality of the steel, so the observation strip coil-camber situations after, by controlling the vertical rolls so that the disc can be cut and removal of part of camber angle forming the continuous control and corrective camber of the strip is the reduction in the production process effective way of generating the wrong side.
2, Due to poor not trimming the strip head and tail shape and size precision, easy to cause docking strip hard bend caused by the wrong side.
3, Strip head and tail butt welding weld reinforcement is large, when the over-molding, if not handled properly, likely to cause greater wrong side.
1, Strip steel camber is caused by the wrong side of the most important factors. In forming the spiral welded pipe, steel strip camber angle will constantly change shape, leading to changes in the weld gap, resulting in open seam, wrong side or even take sides. Seriously affecting the quality of the steel, so the observation strip coil-camber situations after, by controlling the vertical rolls so that the disc can be cut and removal of part of camber angle forming the continuous control and corrective camber of the strip is the reduction in the production process effective way of generating the wrong side.
2, Due to poor not trimming the strip head and tail shape and size precision, easy to cause docking strip hard bend caused by the wrong side.
3, Strip head and tail butt welding weld reinforcement is large, when the over-molding, if not handled properly, likely to cause greater wrong side.
Exotic Advantages Of Spiral Submerged Arc Pipe
The spiral submerged arc pipe is divided into three layers from the inside to the outside. The working steel pipe layer is generally made of seamless pipe (gb8163-87) and spiral welded pipe (gb9711-88). According to the planning and customer requirements. SY t5038-92) and straight seam welded pipe (gb3092-93). After the appearance of the steel pipe is advanced by the shot blasting process, the corrosion grade of the steel pipe can reach the level of gb8923-1988 SA2, and the roughness of the surface can reach the specification of gb6060.5-88 R = 12.5 microns.
The polyurethane insulation layer is formed by injection molding a rigid polyurethane foam into a cavity between the steel pipe and the outer jacket by a high pressure foaming machine. This is the so-called tube foaming process. Its function is waterproof, the second is insulation, and the third is to support the weight of the heat network. When the medium temperature is: 50 ° C, 120 ° C, a rigid polyurethane foam insulation layer is used. High-density polyethylene protective layer Prefabricated black (yellow) plastic pipe with a certain wall thickness, its function is to protect the mechanical hard disk damage of the polyurethane insulation layer, and the second is anti-corrosion and waterproof.
The spiral pipe is used for heating (refrigeration) project, and its heat sealing effect is remarkable. It is directly used for direct burial, which not only saves energy but also reduces dross, and does not occupy the environment and beautify the environment. It is used for oil and gas transportation, can meet the requirements of long-distance transportation, avoid operation and protection, meet the requirements of heat preservation and antifreeze, reduce heating equipment, and is particularly convenient for installation and shorten the construction period.
When used for geothermal and hot spring transportation, the cooling requirements can be satisfied and the long loss can be reached. Applicable to water conservancy, mining and other areas, to meet the requirements of cold, antifreeze, anti-corrosion. In addition, the transportation of chemical raw materials has a wide use space. In total, the polyurethane direct insulation pipe has the advantages of energy saving, anti-corrosion, cold, and economical beauty. In addition, it has been widely used throughout the country and is well received by users.
Polyurethane insulation pipe adopts polyurethane insulation characteristics: the thermal conductivity is small, and the thermal conductivity of polyurethane foam is the lowest in the insulation data, which can minimize the heat loss of the data. Waterproof, anti-corrosion, high old: Because the closed cell rate of polyurethane foam is over 92%, the use of polyurethane foam as the insulation layer of buried pipeline can not only play the role of thermal insulation, but also can be used to avoid water, moisture, etc. Soaking of various corrosive liquids and gases to prevent microbial growth and development.
http://www.xysteelpipe.com/info/Exotic-Advantages-Of-Spiral-Submerged-Arc-Pipe-1341-1.htm
The polyurethane insulation layer is formed by injection molding a rigid polyurethane foam into a cavity between the steel pipe and the outer jacket by a high pressure foaming machine. This is the so-called tube foaming process. Its function is waterproof, the second is insulation, and the third is to support the weight of the heat network. When the medium temperature is: 50 ° C, 120 ° C, a rigid polyurethane foam insulation layer is used. High-density polyethylene protective layer Prefabricated black (yellow) plastic pipe with a certain wall thickness, its function is to protect the mechanical hard disk damage of the polyurethane insulation layer, and the second is anti-corrosion and waterproof.
The spiral pipe is used for heating (refrigeration) project, and its heat sealing effect is remarkable. It is directly used for direct burial, which not only saves energy but also reduces dross, and does not occupy the environment and beautify the environment. It is used for oil and gas transportation, can meet the requirements of long-distance transportation, avoid operation and protection, meet the requirements of heat preservation and antifreeze, reduce heating equipment, and is particularly convenient for installation and shorten the construction period.
When used for geothermal and hot spring transportation, the cooling requirements can be satisfied and the long loss can be reached. Applicable to water conservancy, mining and other areas, to meet the requirements of cold, antifreeze, anti-corrosion. In addition, the transportation of chemical raw materials has a wide use space. In total, the polyurethane direct insulation pipe has the advantages of energy saving, anti-corrosion, cold, and economical beauty. In addition, it has been widely used throughout the country and is well received by users.
Polyurethane insulation pipe adopts polyurethane insulation characteristics: the thermal conductivity is small, and the thermal conductivity of polyurethane foam is the lowest in the insulation data, which can minimize the heat loss of the data. Waterproof, anti-corrosion, high old: Because the closed cell rate of polyurethane foam is over 92%, the use of polyurethane foam as the insulation layer of buried pipeline can not only play the role of thermal insulation, but also can be used to avoid water, moisture, etc. Soaking of various corrosive liquids and gases to prevent microbial growth and development.
http://www.xysteelpipe.com/info/Exotic-Advantages-Of-Spiral-Submerged-Arc-Pipe-1341-1.htm
2019年3月6日星期三
Measures of Boiler Tube Defects in the Low-pressure Control
Through the low-pressure boiler tube tracking the number of times the foot found concentrated in the steel tube reported injured end of the first, twice feet (from the end of the inner tube 25m), closely related to the capillary head borax oxide accumulation, low-pressure boiler tube defects in capillary higher rates of front rolling to appear. Through the above analysis we can draw the following conclusions:
1, The presence of perforated capillary end effects in addition to bad oxidation issues that need to be improved.
2, When present on the surface in the rolling rack rolling work plan tract defects, it needs to be addressed from the start hole, lubrication improvement.
3, Save higher overall machine diameter ratio of blank pipe in the presence of genetic defects can not be completely eliminated during rolling.
To reduce and control deficiencies, should take the following improvements:
1, A head injury ranging from the production of 30 will change, eliminate off by head generated.
2, The production of low-pressure boiler tubes use no injuries mandrel, the mandrel to eliminate defects produced.
3, Pre-production of the perforated roller and guide from distance measurements to ensure ovality coefficient control within the range of process requirements.
4, Machine Save Save walls rate increased to 10 - 15% (formerly 5 - 8%).
5, Finishing temperature controlled at above 860 ℃, temperature increase reheating 5--8 section (1020 +/- 10) ℃, according to Zhang Save high-pressure water descaling the outer surface of the control situation in 8--18MPa, improving Zhang Save outlet velocity to 5.5m / s or more.
6, The choice of phosphate instead of sodium sulfide as the main additive borax is due to iron oxide react with the phosphate to form a melt, reducing rolling gather the inner surface of the roll bite at the time of Rolling was to reduce internal scarring and draw Road produced by chance.
7, Continue to follow the inner surface state and the actual measurement data analysis anatomy stuck pipe rolling after rolling on the first two pass design improvements made mature ideas, design principles and elements, improved rolling 185,151 Pass Design , to reduce the total elongation factor, reducing the process Zhang Save reducing the rate of single machine purposes, improve the surface roughness in the steel pipe.
8, Under the existing conditions improve research mandrel stopper speed way.
Through the above measures, the process gradually fixed, low pressure boiler tubes injuries has been effectively controlled, inspection pass rate stability, an average of 95.5%.
1, The presence of perforated capillary end effects in addition to bad oxidation issues that need to be improved.
2, When present on the surface in the rolling rack rolling work plan tract defects, it needs to be addressed from the start hole, lubrication improvement.
3, Save higher overall machine diameter ratio of blank pipe in the presence of genetic defects can not be completely eliminated during rolling.
To reduce and control deficiencies, should take the following improvements:
1, A head injury ranging from the production of 30 will change, eliminate off by head generated.
2, The production of low-pressure boiler tubes use no injuries mandrel, the mandrel to eliminate defects produced.
3, Pre-production of the perforated roller and guide from distance measurements to ensure ovality coefficient control within the range of process requirements.
4, Machine Save Save walls rate increased to 10 - 15% (formerly 5 - 8%).
5, Finishing temperature controlled at above 860 ℃, temperature increase reheating 5--8 section (1020 +/- 10) ℃, according to Zhang Save high-pressure water descaling the outer surface of the control situation in 8--18MPa, improving Zhang Save outlet velocity to 5.5m / s or more.
6, The choice of phosphate instead of sodium sulfide as the main additive borax is due to iron oxide react with the phosphate to form a melt, reducing rolling gather the inner surface of the roll bite at the time of Rolling was to reduce internal scarring and draw Road produced by chance.
7, Continue to follow the inner surface state and the actual measurement data analysis anatomy stuck pipe rolling after rolling on the first two pass design improvements made mature ideas, design principles and elements, improved rolling 185,151 Pass Design , to reduce the total elongation factor, reducing the process Zhang Save reducing the rate of single machine purposes, improve the surface roughness in the steel pipe.
8, Under the existing conditions improve research mandrel stopper speed way.
Through the above measures, the process gradually fixed, low pressure boiler tubes injuries has been effectively controlled, inspection pass rate stability, an average of 95.5%.
Large - caliber seamless steel pipe testing technology
In the field of detection technology, large diameter seamless steel pipe refers to the diameter larger than 160 mm. Large-diameter seamless steel pipe is important material ofpetroleum, chemical, thermal, boiler, machinery, and hydraulic industry, etc. With the development of national economy, our country during the period of "11th five-year plan", greatly increasing demand for seamless steel pipe, and presents the development trend of large diameter significantly. Especially for corrosion resistance, resistance to squeeze oil well pipe and large diameter high pressure boiler tube and high quality oil cracking pipe, petroleum and petrochemical pipeline, etc., will be as countries increase as demand for energy infrastructure investment hot spot. Thus, to ensure the quality of products nondestructive testing put forward the methods and techniques on the new topic.
At present, China's metallurgical industry for high pressure boiler seamless steel pipe detection mainly applied in phi 160 mm below the specification, and adopting the traditional eddy current flaw detection coil or independent water trough type ultrasonic testing method. For more than 160 mm seamless steel pipe through the traditional type eddy current method is used for testing, there exist many problems, also not allowed to the national standard. If use the ultrasonic testing of independence, due to the ultrasonic detection mechanism of the existence of certain depth on the surface of blind area, can't be guaranteed the reliability of test results as a whole.
Through the coil of eddy current detection is a circle on the surface of the steel pipe surface. In use through the coil, eddy current flaw detection of tested steel tube diameter, the greater the coil detection, the greater the peripheral area of the lower SNR. It is for this reason, steel pipe eddy current inspection standard, adopt through the coil, eddy current flaw detection of its foreign economic size shall not be greater than 140 mm. In addition, in the large diameter steel pipe through the type testing, the steel tube of magnetization and demagnetization, there is certain difficulty.
Water tank type ultrasonic testing is to use steel pipe spiral advancing, ultrasonic probe fixed. By the sink and checked the characteristics of the steel pipe full of water at the bottom of the coupling, ensure that the thickness of the coupling layer remains the same. But for ultrasonic detection of internal defects on the surface of main surface defects exist blind area and time, lead to cannot detect, coupled with the spiral advancing, 30 m to 12 m long steel pipe need to occupy a space of venue, etc, have been affect the choice of the steel pipe detection method and promotion.
Therefore, testing for large diameter steel pipe at home and abroad, generally using the magnetic flux leakage method or the water pressure experiment. At home, it is no good performance for large diameter steel pipe produced by the magnetic flux leakage detection device, once used to import. Imports of magnetic flux leakage detection device is expensive, difficult to accept for most of the domestic enterprises; And low efficiency of water pressure test, the intensity of labor is big, especially when the operator the sense of responsibility is not high, the water pressure test. Visible, realization of large diameter seamless steel tube inspection has become a subject urgently to be solved in metallurgical steel pipe industry.
At present, China's metallurgical industry for high pressure boiler seamless steel pipe detection mainly applied in phi 160 mm below the specification, and adopting the traditional eddy current flaw detection coil or independent water trough type ultrasonic testing method. For more than 160 mm seamless steel pipe through the traditional type eddy current method is used for testing, there exist many problems, also not allowed to the national standard. If use the ultrasonic testing of independence, due to the ultrasonic detection mechanism of the existence of certain depth on the surface of blind area, can't be guaranteed the reliability of test results as a whole.
Through the coil of eddy current detection is a circle on the surface of the steel pipe surface. In use through the coil, eddy current flaw detection of tested steel tube diameter, the greater the coil detection, the greater the peripheral area of the lower SNR. It is for this reason, steel pipe eddy current inspection standard, adopt through the coil, eddy current flaw detection of its foreign economic size shall not be greater than 140 mm. In addition, in the large diameter steel pipe through the type testing, the steel tube of magnetization and demagnetization, there is certain difficulty.
Water tank type ultrasonic testing is to use steel pipe spiral advancing, ultrasonic probe fixed. By the sink and checked the characteristics of the steel pipe full of water at the bottom of the coupling, ensure that the thickness of the coupling layer remains the same. But for ultrasonic detection of internal defects on the surface of main surface defects exist blind area and time, lead to cannot detect, coupled with the spiral advancing, 30 m to 12 m long steel pipe need to occupy a space of venue, etc, have been affect the choice of the steel pipe detection method and promotion.
Therefore, testing for large diameter steel pipe at home and abroad, generally using the magnetic flux leakage method or the water pressure experiment. At home, it is no good performance for large diameter steel pipe produced by the magnetic flux leakage detection device, once used to import. Imports of magnetic flux leakage detection device is expensive, difficult to accept for most of the domestic enterprises; And low efficiency of water pressure test, the intensity of labor is big, especially when the operator the sense of responsibility is not high, the water pressure test. Visible, realization of large diameter seamless steel tube inspection has become a subject urgently to be solved in metallurgical steel pipe industry.
Types of corrosion of seamless steel tubes
Corrosion in the form of seamless steel pipe for buried pipelines are divided into two kinds of localized corrosion and uniform corrosion, localized corrosion mostly dominated, the danger is also the largest. Pipe in the soil erosion process is mainly electrochemical dissolution process, due to the formation of a corrosion cell causing corrosion of the pipe perforation. Press corrosion cell anode and the cathode region of the size of the pitch, but also form a corrosion cell corrosion steel pipe into micro and macro cell corrosion two categories. The so-called micro-cell corrosion, refers to the role of a few millimeters from the pipeline micro-cell or even just a few microns apart anode and cathode consisting caused by corrosion. Its shape is very uniform characteristics, it is also called uniform corrosion. Since the micro-micro anode and cathode separated by very close, so the micro-cell corrosion rate does not depend on the resistivity of the soil, only slightly depends on the anode and cathode electrodes micro process. Micro cell corrosion of buried steel pipe less harmful.
The so-called macro-cell corrosion, galvanic action macro refers pipeline by the distance of a few centimeters or even meters of anode and cathode region composed caused by corrosion. Macrocell corrosion, also known as localized corrosion. Since the anode region and the cathode region far away from the soil medium resistance accounts for a considerable proportion of the corrosion cell circuit total resistance, so the macro cell corrosion speed in addition to the anode and cathode electrode process related, but also with the soil resistivity related. Great soil resistivity can be reduced by the macro cell corrosion speed. That is caused by the macro cell corrosion in buried pipe or a hole in the surface of the plaque-like corrosion, the danger is considerable.
The so-called macro-cell corrosion, galvanic action macro refers pipeline by the distance of a few centimeters or even meters of anode and cathode region composed caused by corrosion. Macrocell corrosion, also known as localized corrosion. Since the anode region and the cathode region far away from the soil medium resistance accounts for a considerable proportion of the corrosion cell circuit total resistance, so the macro cell corrosion speed in addition to the anode and cathode electrode process related, but also with the soil resistivity related. Great soil resistivity can be reduced by the macro cell corrosion speed. That is caused by the macro cell corrosion in buried pipe or a hole in the surface of the plaque-like corrosion, the danger is considerable.
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