Cold drawn steel pipe is a pipe, that is, its production process according to a different classification, different from the hot-rolled (expansion) tube, while the high-precision cold drawn precision steel product features refers to the so-called high-precision drawing within outer diameter accuracy (tolerance range) strict external surface finish, roundness, straightness good precision steel tube uniform wall thickness. In raw wool tube or pipe flaring through the process of drawing multi-pass processing, usually in the 0.5 ~ 100T single chain or double chain drawing machine on. Cold drawn steel pipe whose diameter can go to 6mm, wall thickness can be 0.25mm, outer diameter thin-walled tube to 5mm thickness less than 0.25mm size, precision and surface quality are much better than hot-rolled (expansion) tubes, but by the process constraints, the diameter and the length are subject to certain restrictions. Precision cold drawn steel tube is drawn through large-tonnage hydraulic machine pull system produced can be used directly or through honing, scrapers used after hydraulic (pneumatic) cylinder. Of precision cold drawn steel industry after 20 years of practice, product quality and technical performance has reached world advanced countries, and has been widely used in engineering machinery, plastic machinery, textile, printing machinery, automotive shock absorbers, oil pumping pumps and concrete cylinders and other industries.
The product was a little honing, it can be directly used as hydraulic, pneumatic cylinder cylinder tube. The traditional hydraulic, pneumatic cylinder body tube of the production process is the use of hot-rolled seamless steel pipe, using boring ─ ─ rolling joint cutting process, the production process, a lot of metal waste was cut into chips, but also consume a lot of power. With China's industrial and technological development, the hydraulic cylinder technology has been widely used, according to incomplete statistics, the country each year requires a variety of specifications of the hydraulic cylinder about 380 meters, follow the old technology production of hydraulic cylinders, has been difficult to adapt production development.
Fine precision cold drawn steel pipe is a new high-skill energy-saving products. Recently, to take the technology to produce fine item has been commonly used in domestic steel hydraulic, pneumatic cylinders, coal mine bracket (pillars), oil pump pipe, jacks and other production areas. Precision cold drawn precision steel tubes to promote the use of steel for the thrifty, progressive processing efficiency, diligence and energy, reducing the hydraulic cylinder, the cylinder processing equipment investment is important.
Tuesday, June 4, 2013
Spiral Pipe stress corrosion cracking causes and preventive measures
Spiral steel construction and family life is a common pipe, which shine in many industries. Here's what the spiral pipe stress corrosion cracking causes and protective measures.
Spiral Pipe Stress corrosion cracking is a lag time-related damage, which is completely similar to delayed cracking and hydrogen. Stress corrosion cracking is a low-stress brittle fracture. Spiral Pipe stress corrosion only in certain circumstances take place, only exists stress (especially tensile stress) only when the stress corrosion cracking. This stress can be applied stress, T or introduced during welding and processing the residual stress corrosion products can also be caused by the action of the expansion wedge stress. Stress corrosion cracking is a petrochemical equipment, especially oil pipes with spiral steel pipe common cause of failure. Due to stress corrosion cracking occurred unpredictability, so the petrochemical industry, the biggest hidden dangers. In the petrochemical and nuclear industries such as equipment, most of the stress caused by stress corrosion cracking is caused by the residual tensile stress, it is often superimposed on stress at work. Mainly from the device residual stresses produced during the welding residual stresses. Stress corrosion cracking is a necessary condition for coexistence of tensile stress and corrosive media, the tensile stress is an important condition for stress corrosion.
Currently, the project is widely used welding cooling after annealing treatment to eliminate residual stress, while cooling after welding residual stress is an important process, this approach is not only a waste of energy and easy to produce larger welding residual stresses. Heat treatment after welding is a new technique to eliminate the residual stress. Preheated before welding the material to a heat treatment temperature after the welding process and welding pieces of heating was continued to maintain this temperature, the soldering is completed using heat insulation cotton to its slow cooling. This method can effectively reduce residual stress and improve the stress corrosion resistance of metals. Heat treatment after welding can reduce the residual stress, and heat treatment temperature is higher, the better to eliminate the residual stress. Post weld heat treatment can effectively improve the spiral pipe stress corrosion resistance, heat treatment temperature is higher, increasing resistance to stress corrosion is more significant.
Besides, the spiral steel pipe is mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, is the development of 20 key products. For the transport of liquids: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, buildings and other structures tube.
Spiral Pipe Stress corrosion cracking is a lag time-related damage, which is completely similar to delayed cracking and hydrogen. Stress corrosion cracking is a low-stress brittle fracture. Spiral Pipe stress corrosion only in certain circumstances take place, only exists stress (especially tensile stress) only when the stress corrosion cracking. This stress can be applied stress, T or introduced during welding and processing the residual stress corrosion products can also be caused by the action of the expansion wedge stress. Stress corrosion cracking is a petrochemical equipment, especially oil pipes with spiral steel pipe common cause of failure. Due to stress corrosion cracking occurred unpredictability, so the petrochemical industry, the biggest hidden dangers. In the petrochemical and nuclear industries such as equipment, most of the stress caused by stress corrosion cracking is caused by the residual tensile stress, it is often superimposed on stress at work. Mainly from the device residual stresses produced during the welding residual stresses. Stress corrosion cracking is a necessary condition for coexistence of tensile stress and corrosive media, the tensile stress is an important condition for stress corrosion.
Currently, the project is widely used welding cooling after annealing treatment to eliminate residual stress, while cooling after welding residual stress is an important process, this approach is not only a waste of energy and easy to produce larger welding residual stresses. Heat treatment after welding is a new technique to eliminate the residual stress. Preheated before welding the material to a heat treatment temperature after the welding process and welding pieces of heating was continued to maintain this temperature, the soldering is completed using heat insulation cotton to its slow cooling. This method can effectively reduce residual stress and improve the stress corrosion resistance of metals. Heat treatment after welding can reduce the residual stress, and heat treatment temperature is higher, the better to eliminate the residual stress. Post weld heat treatment can effectively improve the spiral pipe stress corrosion resistance, heat treatment temperature is higher, increasing resistance to stress corrosion is more significant.
Besides, the spiral steel pipe is mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, is the development of 20 key products. For the transport of liquids: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, buildings and other structures tube.
Advantages and disadvantages of spiral steel pipe
Spiral pipe defects in the vast majority concentrated in the weld and heat affected zone, weld defects occur long it means that the probability of large, long-term constraints which is more widely used spiral welded main reason, but also has long vexed spiral pipe and straight seam pipe, especially when compared with the UOE steel pipe whose superior problem. Spiral pipe manufacturing technology development today, we should be fully and accurately evaluated and compared to rediscover long spiral weld problems. Also in use, the tube of the main stress direction, i.e. the axial direction of tube defects equivalent pipe length smaller than the straight seam; Second, because pipeline are rolled steel, impact toughness greater anisotropy, cis rolling CVN value of the direction perpendicular to the rolling direction than CVN value three times higher. Straight seam pipe stress suffered by the main shock resistance precisely perpendicular to the lowest pipe direction, and then staggered spiral steel pipe direction lowest impact resistance, so that the disadvantage of a long spiral weld transformed into advantage.
Although the spiral steel pipe is mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, is the development of 20 key products. For the transport of liquids: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, buildings and other structures tube. However, the spiral in the welding process there are some inherent defects.
The specific requirements of the steel strip coil is forward weldability of steel, reducing the sulfur content in the steel pipe to improve the toughness and arrestability are beneficial. While also reducing sulfide inclusions to the swap, forward of steel crack resistance. The phosphorus content in the hot strip is as low as possible, because the phosphorus on the steel toughness and weldability are a hazard, thus reducing the phosphorus content can move weldability, can increase the amount of added titanium, vanadium niobium content spiral during welding weld defects may occur, so that welding defects affect the quality of the spiral, resulting in reduced service life or the spiral can be used. Generally, the spiral weld defects and porosity, and cracks undercut phenomenon.
Spiral bubble defect: During spiral welding, the weld bead in the center of bubble defects occur this situation, the main reason is that in the course of the welding of hydrogen is left in the form of bubbles within the metal. In the welding process, we need to remove the oil inside the weld, water and other ingredients, but also the need to do drying, removal of moisture, so that hydrogen gas will not remain in the inside seam. During the welding process the welding current can be avoided to increase the generation of bubbles.
Spiral undercut phenomenon: When the v-shaped groove weld edges appear, and along the weld centerline arise, it means there has been undercut. Generally undercut because of current, voltage and welding speed inappropriate, therefore, in the welding process requires control your speed, so as to effectively avoid undercut phenomenon.
Spiral cracks: spiral cracks may be produced due to the direction of the spiral seam problem spiral in order to effectively prevent the generation of cracks in the welding process, the welding process need to operate in strict accordance with the job.
Although the spiral steel pipe is mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, is the development of 20 key products. For the transport of liquids: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, buildings and other structures tube. However, the spiral in the welding process there are some inherent defects.
The specific requirements of the steel strip coil is forward weldability of steel, reducing the sulfur content in the steel pipe to improve the toughness and arrestability are beneficial. While also reducing sulfide inclusions to the swap, forward of steel crack resistance. The phosphorus content in the hot strip is as low as possible, because the phosphorus on the steel toughness and weldability are a hazard, thus reducing the phosphorus content can move weldability, can increase the amount of added titanium, vanadium niobium content spiral during welding weld defects may occur, so that welding defects affect the quality of the spiral, resulting in reduced service life or the spiral can be used. Generally, the spiral weld defects and porosity, and cracks undercut phenomenon.
Spiral bubble defect: During spiral welding, the weld bead in the center of bubble defects occur this situation, the main reason is that in the course of the welding of hydrogen is left in the form of bubbles within the metal. In the welding process, we need to remove the oil inside the weld, water and other ingredients, but also the need to do drying, removal of moisture, so that hydrogen gas will not remain in the inside seam. During the welding process the welding current can be avoided to increase the generation of bubbles.
Spiral undercut phenomenon: When the v-shaped groove weld edges appear, and along the weld centerline arise, it means there has been undercut. Generally undercut because of current, voltage and welding speed inappropriate, therefore, in the welding process requires control your speed, so as to effectively avoid undercut phenomenon.
Spiral cracks: spiral cracks may be produced due to the direction of the spiral seam problem spiral in order to effectively prevent the generation of cracks in the welding process, the welding process need to operate in strict accordance with the job.
Friday, May 31, 2013
The quality of Tube billet has a influence on seamless steel pipe
The quality of the tube is an important factor in the decision quality seamless steel pipe. In order to ensure the normal perforation process and access to high-quality seamless steel pipe, tube geometry must be low magnification and the surface state and put forward strict requirements.
Tube diameter is too large, or through the large oval, make the piercing bite when conditions deteriorate, but also because of excessive compression tube diameter and to promote the production within the fold.
Mainly refers to the internal organization of shrinkage and center porosity, the accumulation of non-metallic inclusions and gas content, etc. Such stringent requirements, with the use of seamless steel tubes and carbon steel pipe varies.
The most important is the quality of the surface of the tube, because of any defect in the tube to the finished product will be seamless, but also defective parts often leads to stress concentration, defects by plastic deformation will deepen, lengthen.
To sum up in order to produce high-quality seamless steel pipe products, the good quality tube is a crucial step.
Tube diameter is too large, or through the large oval, make the piercing bite when conditions deteriorate, but also because of excessive compression tube diameter and to promote the production within the fold.
Mainly refers to the internal organization of shrinkage and center porosity, the accumulation of non-metallic inclusions and gas content, etc. Such stringent requirements, with the use of seamless steel tubes and carbon steel pipe varies.
The most important is the quality of the surface of the tube, because of any defect in the tube to the finished product will be seamless, but also defective parts often leads to stress concentration, defects by plastic deformation will deepen, lengthen.
To sum up in order to produce high-quality seamless steel pipe products, the good quality tube is a crucial step.
Thursday, May 30, 2013
Spiral welded pipe flaw detection testing
Spiral welded pipe steel is heated to quenching above the critical temperature, holding time, then quickly into the quenching agent, so that the temperature suddenly decreased, the critical cooling rate greater than the speed of rapid cooling, to obtain the martensite imbalance based organization heat treatment method. Quench can increase the strength and hardness of steel, but to reduce its plasticity. In China, good performance is still not suitable for large-diameter steel pipe produced magnetic flux leakage testing equipment, use of which is imported. Imports of magnetic flux leakage testing equipment is expensive for the majority of domestic enterprises difficult to accept.
The end of April this year, U.S. exports to China its most important oil pipeline starts "dual" survey, involving more than $ 2.6 billion, more than the tires safeguard the two billion U.S. dollars. Spiral welded pipe strength is generally higher than the Longitudinal, can produce a narrower diameter than the blank large pipe, you can also use the same width of billet production of different pipe diameters. API-5L (American Petroleum Institute, also known as line pipe; but with the same length of straight seam tubes, weld length of 30 to 100%, and the production rate is low. Generally spiral low-pressure fluid transport submerged arc welded pipe, double-sided or single-sided submerged arc automatic welding method as for water, gas, air and steam.
Past two years, including spiral pipe specifications, including a Sino-US trade friction and the weight of industry the hardest hit, the U.S. has several GB of steel products to China spiral pipe size weight "double reverse", the value of the case the case of seamless steel tube about four billion U.S. dollars, the U.S. International Trade Kunshan Teflon tube to the same italian decision is very high.
Quenching pipe commonly used quenching agents are: water, oil, alkali and salt solution, and so on. Oil pipe imported from Japan for more than half of total imports. Spiral welded pipe(SAWL pipe) for testing at home and abroad, the general magnetic or pressure leakage test. Spiral welded pipe strength is generally higher than the Longitudinal, can narrow billet production with a larger diameter pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight seam pipe compared to the weld length of 30 to 100, and a lower production rate. Therefore, the smaller diameter pipe actually use straight seam welding, large diameter spiral welded pipe is mostly used.
The end of April this year, U.S. exports to China its most important oil pipeline starts "dual" survey, involving more than $ 2.6 billion, more than the tires safeguard the two billion U.S. dollars. Spiral welded pipe strength is generally higher than the Longitudinal, can produce a narrower diameter than the blank large pipe, you can also use the same width of billet production of different pipe diameters. API-5L (American Petroleum Institute, also known as line pipe; but with the same length of straight seam tubes, weld length of 30 to 100%, and the production rate is low. Generally spiral low-pressure fluid transport submerged arc welded pipe, double-sided or single-sided submerged arc automatic welding method as for water, gas, air and steam.
Past two years, including spiral pipe specifications, including a Sino-US trade friction and the weight of industry the hardest hit, the U.S. has several GB of steel products to China spiral pipe size weight "double reverse", the value of the case the case of seamless steel tube about four billion U.S. dollars, the U.S. International Trade Kunshan Teflon tube to the same italian decision is very high.
Quenching pipe commonly used quenching agents are: water, oil, alkali and salt solution, and so on. Oil pipe imported from Japan for more than half of total imports. Spiral welded pipe(SAWL pipe) for testing at home and abroad, the general magnetic or pressure leakage test. Spiral welded pipe strength is generally higher than the Longitudinal, can narrow billet production with a larger diameter pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight seam pipe compared to the weld length of 30 to 100, and a lower production rate. Therefore, the smaller diameter pipe actually use straight seam welding, large diameter spiral welded pipe is mostly used.
How to save energy for transporting fluid spiral steel pipe
Transmission fluid temperature is reduced to seize the autumn seasonal changes, to take reasonable open to stop running the cooling tower fan and pump room axial fans used to cool the work of measures to effectively reduce the power consumption. According to the professional management department's forecast, alone, can reduce the monthly cost of nearly 10 million. In the daily production run in 15 units (sets) cooling tower fan while running at full capacity, the total power per hour 1600kW, is a veritable big power. As steelmaking systems, continuous casting systems for water supply medium have special requirements, especially fine steel smelting, the water medium temperature control for stable product quality and develop new kinds of steel plays a vital role.
It also can be used to open the outdoor temperature and reasonable to stop the fan, to reduce power consumption, energy conservation purposes. Active users with points for each production line to get in touch, in-depth understanding of the specific requirements of the water temperature to determine the most reasonable range to meet production needs, while achieving cost reduction and efficiency purposes. Taking advantage of seasonal changes and outdoor temperature at night reduce the characteristics of staff on duty at the production site to track real-time detection of medium temperature water delivery method of data, timely adjustment of operating the fan, the fan running to minimize the number of units. Week has halved the number of running fans, power consumption is also reduced by half.
Like the steel pipe for transporting fluid, normally it is spiral pipe. besides, the spiral steel pipe also can be as piling pipe.
It also can be used to open the outdoor temperature and reasonable to stop the fan, to reduce power consumption, energy conservation purposes. Active users with points for each production line to get in touch, in-depth understanding of the specific requirements of the water temperature to determine the most reasonable range to meet production needs, while achieving cost reduction and efficiency purposes. Taking advantage of seasonal changes and outdoor temperature at night reduce the characteristics of staff on duty at the production site to track real-time detection of medium temperature water delivery method of data, timely adjustment of operating the fan, the fan running to minimize the number of units. Week has halved the number of running fans, power consumption is also reduced by half.
Like the steel pipe for transporting fluid, normally it is spiral pipe. besides, the spiral steel pipe also can be as piling pipe.
Friday, May 24, 2013
The technical requirment and quality inspection of ERW steel pipe
According to GB3092 "welded steel pipe low pressure liquid delivery" standard provisions, the nominal pipe diameter 6 ~ 150mm, nominal wall thickness of 2.0 ~ 6.0mm, the length of pipe is usually 4 to 10 meters, can be cut to length or times foot length of the factory. Steel surface quality should be smooth, does not allow folding, cracks, delamination, lap welding defects exist. Pipe wall thickness of the surface to allow no more than the negative deviation Scratch, scratch, weld dislocation, burns and scarring and other minor defects. Thickening and wall thickness to allow the weld seam welding bars in existence.
Welded steel pipe and mechanical tests should be done flattening test, and flaring test, and to meet the standard requirements. Pipe should be able to withstand a certain pressure, when necessary, 2.5Mpa pressure test, for a minute without leakage. Allows the use of eddy current testing in lieu of hydrostatic testing. Eddy current testing according to GB7735 "pipe eddy current test method" standard. Eddy current method is to probe the rack, testing and maintaining 3 ~ 5mm from the weld, by the rapid movement of the weld pipe comprehensive scanning, eddy current testing signal by the automatic processing and automatic sorting, achieve the purpose of testing.
After testing the pipe with the required length flying saw cutting, frame by turning off the assembly line. Pipe ends should be flat chamfer, marking, hexagonal tubes tied product packaging factory.
Welded steel pipe and mechanical tests should be done flattening test, and flaring test, and to meet the standard requirements. Pipe should be able to withstand a certain pressure, when necessary, 2.5Mpa pressure test, for a minute without leakage. Allows the use of eddy current testing in lieu of hydrostatic testing. Eddy current testing according to GB7735 "pipe eddy current test method" standard. Eddy current method is to probe the rack, testing and maintaining 3 ~ 5mm from the weld, by the rapid movement of the weld pipe comprehensive scanning, eddy current testing signal by the automatic processing and automatic sorting, achieve the purpose of testing.
After testing the pipe with the required length flying saw cutting, frame by turning off the assembly line. Pipe ends should be flat chamfer, marking, hexagonal tubes tied product packaging factory.
Subscribe to:
Posts (Atom)