At present China's metallurgical industry, the high-pressure boiler pipe mainly used in the detection of 160 mm the following specifications, and most of the traditional eddy current through the coil or a separate sink ultrasonic detection methods. For more than 160 mm seamless steel pipe using the traditional method through the eddy current testing, there are many problems, but also the national standards allowed. If using an independent ultrasonic testing, ultrasonic testing mechanism exists because the surface of a certain depth of the blind, the overall test results can not guarantee the reliability of steel.
Through the coil eddy current probe is a circumferential surface of the pipe surface. Through the use of eddy current coils, the larger the diameter of pipe to be detected, detection of the circumferential area of the coil the greater, the lower signal to noise ratio. It is for this reason, pipe eddy current testing standards, the use of eddy current through the coil of its foreign economic size not greater than 140 mm. In addition, the large-diameter pipe through the type testing, the pipe magnetization and demagnetization and so there is a certain degree of difficulty.
Tank ultrasonic testing is used in the steel spiral forward type, ultrasound probe stationary. It was seized by the sink and the water pipe at the bottom of the full coupling characteristics, to ensure the thickness of the coupling constant. But because ultrasonic detection of internal defects on the surface of the main and sub-surface defects exist blind, preventing detection, coupled with spiral forward type, 12 m long pipe needs for space 30m venues such as inadequate pipe detection method has affected the selection and promotion.
Therefore, the domestic large-diameter steel pipe for testing, generally using magnetic flux leakage or water pressure test. In the country, there is no good performance for large diameter steel pipe magnetic flux leakage detection equipment produced, the use of which is imported. Imported magnetic flux leakage detection equipment is expensive, for the majority of domestic enterprises is difficult to accept; while the hydraulic test inefficient, labor-intensive, especially when the operator is not high sense of responsibility, the water pressure test useless. Visible to achieve large-diameter seamless steel pipe industry, metallurgical testing has become an urgent issue.
Is characterized by large-diameter steel pipe diameter, wall thickness is relatively thick, so take advantage of this feature based on ultrasound and eddy current testing internal surface and subsurface features combine to achieve "blind" testing. Through the use of "in situ pipe rotation detection probe forward combinations", not only to solve detection problems, but also to solve narrow space occupied space.
Monday, July 29, 2013
Welded steel pipe stress corrosion
Currently, the project is widely used welding cooling after annealing disposal to eliminate residual stress, residual stress after welding cooling is an important process of attack, this approach not only a waste of power and simple attack a larger weld residual stresses. Health 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 attack.
Stress corrosion of welded pipes in a particular environment as long as the attack ability, heat treatment after welding is a new skill to eliminate residual stresses. Preheated before welding to the data after heat treatment temperature and the welding process, welding pieces continue to insist that the heating temperature, the welding is completed using its thermal insulation cotton so slow cooling. Useful heat treatment after welding can weld residual stress decrease, and the heat treatment temperature is higher, the better to eliminate residual stresses. Post-weld heat treatment can also be useful for the progress of welded steel stress corrosion ability, after the heat treatment temperature is higher, resistance to stress corrosion ability and progress more obvious.
Stress corrosion cracking is a low-stress brittle cracking. Stress corrosion cracking is a petrochemical equipment, especially oil pipeline welded pipe and piling pipe common cause of failure. Stress corrosion cracking is a lag-related damage and the time, this and similar hydrogen delayed cracking completely. As long as there is stress, stress corrosion cracking attack abilities. Such stress can be applied so that the stress, or the process of welding and processing T residual stress introduced, the etching product may be a result of the expansion wedge effects of stress.
Stress corrosion of welded pipes in a particular environment as long as the attack ability, heat treatment after welding is a new skill to eliminate residual stresses. Preheated before welding to the data after heat treatment temperature and the welding process, welding pieces continue to insist that the heating temperature, the welding is completed using its thermal insulation cotton so slow cooling. Useful heat treatment after welding can weld residual stress decrease, and the heat treatment temperature is higher, the better to eliminate residual stresses. Post-weld heat treatment can also be useful for the progress of welded steel stress corrosion ability, after the heat treatment temperature is higher, resistance to stress corrosion ability and progress more obvious.
Stress corrosion cracking is a low-stress brittle cracking. Stress corrosion cracking is a petrochemical equipment, especially oil pipeline welded pipe and piling pipe common cause of failure. Stress corrosion cracking is a lag-related damage and the time, this and similar hydrogen delayed cracking completely. As long as there is stress, stress corrosion cracking attack abilities. Such stress can be applied so that the stress, or the process of welding and processing T residual stress introduced, the etching product may be a result of the expansion wedge effects of stress.
Widely uses of thermal expansion straight seam steel pipe
thermal expansion of straight seam steel pipe has a range of models, which can be expanded from what to what model are fixed, straight seam steel pipe model and the target model itself to be close to, or pipe break. He is given by high-frequency straight seam steel pipe body hardness decreased heating so then let straight seam steel pipe from the header (header is mold, a narrow one wide, narrow tube is a normal caliber, the thickest section of the target diameter) By slowly on, when the tube completely through after reaching thermal expansion purposes.
Thermal expansion process on the straight seam steel pipe and weld material itself has a high demand, the material must meet the national standard, the carbon content must not be less, or will cause tube breakage, another seam have qualified, or in the process of thermal expansion very easy to disconnect. Thermal expansion is a certain risk. Care workers sometimes the case during thermal expansion rate is not well controlled, and other factors, it is easy to break the tube. After thermal expansion after the pipe, there will be a certain length and thickness shrunk, so in the process of purchasing the original tube, try to buy some little thicker wall thickness, and length slightly longer, so as to ensure that the thermal expansion of the walls after thickness and length to achieve the project's requirements. Generally straight seam steel pipe thermal expansion for steel.
Straight seam steel pipes are widely used, including water and structure of urban construction and other fields. During use, straight seam steel pipes some general models: can not meet the needs of the project, this time straight seam steel pipe thermal expansion to play a big role, thermal expansion is straight seam steel pipe after treatment by thermal expansion of straight seam steel pipe.
Thermal expansion process on the straight seam steel pipe and weld material itself has a high demand, the material must meet the national standard, the carbon content must not be less, or will cause tube breakage, another seam have qualified, or in the process of thermal expansion very easy to disconnect. Thermal expansion is a certain risk. Care workers sometimes the case during thermal expansion rate is not well controlled, and other factors, it is easy to break the tube. After thermal expansion after the pipe, there will be a certain length and thickness shrunk, so in the process of purchasing the original tube, try to buy some little thicker wall thickness, and length slightly longer, so as to ensure that the thermal expansion of the walls after thickness and length to achieve the project's requirements. Generally straight seam steel pipe thermal expansion for steel.
Straight seam steel pipes are widely used, including water and structure of urban construction and other fields. During use, straight seam steel pipes some general models: can not meet the needs of the project, this time straight seam steel pipe thermal expansion to play a big role, thermal expansion is straight seam steel pipe after treatment by thermal expansion of straight seam steel pipe.
Sunday, July 28, 2013
The importance of seamless welding defect detection
Seamless hollow sections, a large number of channels for transporting fluids, such as the transportation of oil, natural gas, coal gas, water and some solid materials, pipes and so on. Steel pipe and solid steel bar, etc. compared to the same torsional strength in bending, lighter, is an economic cross-section steel, widely used in the manufacture of structural parts and mechanical parts, such as piling pipe, automotive drive shafts, bicycle rack and construction using steel scaffolding.
In addition, with the Beijing seamless manufacturing annular parts, can improve material utilization, simplify the manufacturing process, saving material and machining time, such as bearing rings, jack sets, has been widely used to make steel. Steel or a variety of conventional weapons indispensable material, barrel, barrel, etc. to make steel. By cross-sectional shape of the pipe can be divided into tube and shaped tubes. Since the perimeter of equal conditions, the maximum area of a circle with a circular tube can carry more fluid.
Magnetic particle testing or penetrant testing can effectively find seamless surface cracks, folds, double skin, hairline, pinholes and other surface defects. For ferromagnetic materials, magnetic particle inspection method should be preferred, because of its high detection sensitivity; For non-ferromagnetic material, such as stainless steel seamless pipe, then a penetration assay.
Reserved resection margin when both ends is small, causes the detection apparatus, both ends of the head may not be effectively detected, and ends there is most likely the site of cracks or other defects. If there is a potential end tendency to crack, the installation of the weld heat affected also possible to make the potential crack. Therefore, it should be noted that certain areas of the welded tube detection, to detect defects in steel tip extensions.
In addition, with the Beijing seamless manufacturing annular parts, can improve material utilization, simplify the manufacturing process, saving material and machining time, such as bearing rings, jack sets, has been widely used to make steel. Steel or a variety of conventional weapons indispensable material, barrel, barrel, etc. to make steel. By cross-sectional shape of the pipe can be divided into tube and shaped tubes. Since the perimeter of equal conditions, the maximum area of a circle with a circular tube can carry more fluid.
Magnetic particle testing or penetrant testing can effectively find seamless surface cracks, folds, double skin, hairline, pinholes and other surface defects. For ferromagnetic materials, magnetic particle inspection method should be preferred, because of its high detection sensitivity; For non-ferromagnetic material, such as stainless steel seamless pipe, then a penetration assay.
Reserved resection margin when both ends is small, causes the detection apparatus, both ends of the head may not be effectively detected, and ends there is most likely the site of cracks or other defects. If there is a potential end tendency to crack, the installation of the weld heat affected also possible to make the potential crack. Therefore, it should be noted that certain areas of the welded tube detection, to detect defects in steel tip extensions.
Friday, July 26, 2013
Post weld heat treatment on the stress corrosion resistance welded steel pipe impact
Welded steel pipe stress corrosion only in certain circumstances take place, it also has some of the following characteristics: (a) only if there is 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. (2) Stress corrosion cracking is a lag time-related damage, which is completely similar to delayed cracking and hydrogen. (3) Stress corrosion cracking is a low-stress brittle fracture.Stress corrosion cracking is a petrochemical equipment, especially oil pipeline - a common cause of failure of welded tube. Due to stress corrosion cracking occurred unpredictability, so the petrochemical industry, the biggest hidden dangers. 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. 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. 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. PWHT welded steel pipe can effectively improve the resistance to stress corrosion, after the heat treatment temperature is higher, increasing resistance to stress corrosion is more significant.
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. 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. PWHT welded steel pipe can effectively improve the resistance to stress corrosion, after the heat treatment temperature is higher, increasing resistance to stress corrosion is more significant.
Large diameter spiral steel pipe for liquid transfer applications with a range
Spiral steel pipe manufacturing method into their large diameter spiral steel pipe and spiral steel two kinds. Spiral welded pipe with high-quality carbon steel or alloy steel, hot-rolled, cold-rolled (pull) of the points. Large diameter spiral pipe is rolled into a tube-shaped steel plates on the seam or spiral seam welded together, in the manufacturing method, is divided into low pressure liquid delivery welded steel pipe, spiral welded steel pipe, straight welded steel pipe, welded pipe, etc. . Spiral welded pipe can be used for a variety of liquids, gas pipelines and so on. Welded pipes can be used for water pipes, gas pipes, heating pipes.
Large diameter spiral steel pipe is the industrial, construction and other industries widely used kind of steel. It is a strip coil as raw material, often warm extrusion molding, with automatic double-sided submerged arc welding process wire spiral welded steel pipe. Mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction.
Large diameter spiral steel pipe 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. It is in the transportation of gas, transportation has played a significant role. Large diameter spiral pipe pressure transmission fluid with spiral submerged arc welded pipe is mainly used to transport oil, natural gas pipelines; pressure transmission fluid with frequency spiral welded steel pipes, lap welding method with high frequency welding for Order pressure fluid transfer frequency spiral welded steel pipe. Strong pressure steel, plastic, and easy welding and machining molding; generally low pressure liquid delivery spiral submerged arc welded pipe, using double-sided automatic submerged arc welding or welding into the legal system for water, gas, air and steam low pressure liquid delivery SAW pipe.
Large diameter spiral steel pipe is the industrial, construction and other industries widely used kind of steel. It is a strip coil as raw material, often warm extrusion molding, with automatic double-sided submerged arc welding process wire spiral welded steel pipe. Mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction.
Large diameter spiral steel pipe 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. It is in the transportation of gas, transportation has played a significant role. Large diameter spiral pipe pressure transmission fluid with spiral submerged arc welded pipe is mainly used to transport oil, natural gas pipelines; pressure transmission fluid with frequency spiral welded steel pipes, lap welding method with high frequency welding for Order pressure fluid transfer frequency spiral welded steel pipe. Strong pressure steel, plastic, and easy welding and machining molding; generally low pressure liquid delivery spiral submerged arc welded pipe, using double-sided automatic submerged arc welding or welding into the legal system for water, gas, air and steam low pressure liquid delivery SAW pipe.
High-frequency welded pipe welding speed and performance of rust
In general, high-frequency welded pipe during welding, the welding quality and welding speed are related. As the heating time can be shortened, the time the metal oxide shortened, therefore, the quality of the welding speed and the welding speed with increased.
If the welding speed is reduced, so that the heating zone will not only wider, but also with the molten zone width and change the heat input and thus the formation of burrs is large, so the high-frequency welded pipe, the welding equipment and the unit should be means the maximum allowable speed according to different specifications and varieties select the appropriate welding speed.
In order to achieve high-frequency welded pipe rust the desired effect, according to the choice of materials abrasive surface hardness and high frequency welded pipe extent of corrosion, surface roughness, for reasonable operation. Meanwhile, in order to achieve the desired effect of rust, for single-layer epoxy, two or three layers polyethylene coating should be mixed abrasive grit and steel shot to operate.
If the welding speed is reduced, so that the heating zone will not only wider, but also with the molten zone width and change the heat input and thus the formation of burrs is large, so the high-frequency welded pipe, the welding equipment and the unit should be means the maximum allowable speed according to different specifications and varieties select the appropriate welding speed.
In order to achieve high-frequency welded pipe rust the desired effect, according to the choice of materials abrasive surface hardness and high frequency welded pipe extent of corrosion, surface roughness, for reasonable operation. Meanwhile, in order to achieve the desired effect of rust, for single-layer epoxy, two or three layers polyethylene coating should be mixed abrasive grit and steel shot to operate.
The deficiency of straight seam welded pipe
In general, large-diameter welded pipe used in industrial and civil construction electrical, plumbing, fire protection and supporting structure are widely used. Because of this pipe making, using rolled strip, winding shape, along this line weld process, and therefore they should not customarily referred to as "high-frequency welded pipe."
Longitudinal as large diameter pipes are used, generally spiral welding production process, avoiding the Longitudinal defects, but also the pipe material weldability indicators affecting product quality is a major factor. Longitudinal in the production of large diameter, because of its large size jokes by processing machinery and processes, the effects will inevitably have some defects such as concentricity goods, smooth surface, surface finish appearance of these targets.
Relatively speaking, small diameter pipe, using this technology production, technology is relatively simple, relatively easy to control defects, and a large-diameter welded tube was difficult to control, prone to cavities, weld, welding defects and other indicators, and may exceed originally expected.
Longitudinal as large diameter pipes are used, generally spiral welding production process, avoiding the Longitudinal defects, but also the pipe material weldability indicators affecting product quality is a major factor. Longitudinal in the production of large diameter, because of its large size jokes by processing machinery and processes, the effects will inevitably have some defects such as concentricity goods, smooth surface, surface finish appearance of these targets.
Relatively speaking, small diameter pipe, using this technology production, technology is relatively simple, relatively easy to control defects, and a large-diameter welded tube was difficult to control, prone to cavities, weld, welding defects and other indicators, and may exceed originally expected.
Frequency welded pipe welding process
The process is the first high-frequency welded pipe uncoiling, flattening, on the head and tail cut, weld on steel with the right looper material storage, you can shape it. After molding is welded, remove burrs, its inspection, pipe straightening, and finally hydrostatic testing, flaw detection, all work ready after that finished it.
Typically, high-frequency welded pipe welding process welding speed is the main parameters, the speed and the heating system, weld deformation speed, and the speed of crystallization are all mutual relations. Frequency welded pipe welding quality also with welding speed and progressive.
This is because the high-frequency welded to shorten heating time, leaving the edge of the heated zone width is narrowed, greatly limits shortening the time of forming a metal oxide. If the welding speed is too low, it will not only widens the heating zone, but also with the input of the molten zone width and change into heat, a large burr is formed inside, resulting in problems.
Typically, high-frequency welded pipe welding process welding speed is the main parameters, the speed and the heating system, weld deformation speed, and the speed of crystallization are all mutual relations. Frequency welded pipe welding quality also with welding speed and progressive.
This is because the high-frequency welded to shorten heating time, leaving the edge of the heated zone width is narrowed, greatly limits shortening the time of forming a metal oxide. If the welding speed is too low, it will not only widens the heating zone, but also with the input of the molten zone width and change into heat, a large burr is formed inside, resulting in problems.
Tuesday, July 23, 2013
The main production methods of large diameter welded pipe
Used to transport large diameter pipes, manufactured using various welding methods, such as using electric arc welding under flux layer, the contact resistance welding, flash welding and other welding and high frequency currents. Press the seam can be divided into straight seam welded and spiral welded two ways, straight seam welding production process is composed of the following main steps: forming tube within the model to make double-sided welding, welded tube imposed on small expanding.
The method currently used is the most complete with a huge three-step molding production press with die no longitudinal joints 12 meters long pipe, and the shape and size are very accurate. The gas pipeline is the most common method used solvent layer under the double seam welding speeds of up to 140 ^ -150 m / hour. Soldering should be repaired weld, then cut the head and pipe sizing. The modern sizing method is applied to the inner pipe hydraulic diameter to the expansion diameter of 1.5-2.5% pots, fixed length to diameter, on the other hand to improve the yield limit of about 20%.
Nickel is an excellent corrosion-resistant materials, which is an important alloying element in steel. Nickel is the formation of austenite in the steel elements, but to obtain pure carbon-nickel austenitic steels, nickel volume to reach 24%; whereas only 27% of nickel when the steel corrosion in certain media Corrosion can significantly changed. So Nickel alone can not constitute a stainless steel. However, both nickel and chromium present in the stainless steel, the nickel-containing stainless steel, but has many valuable properties. Based on the above case shows, nickel as an alloying element in stainless steel effect, is that it enables high-chromium steel tissue changes, so that the corrosion resistance of stainless steel and obtain certain improved process performance.
The method currently used is the most complete with a huge three-step molding production press with die no longitudinal joints 12 meters long pipe, and the shape and size are very accurate. The gas pipeline is the most common method used solvent layer under the double seam welding speeds of up to 140 ^ -150 m / hour. Soldering should be repaired weld, then cut the head and pipe sizing. The modern sizing method is applied to the inner pipe hydraulic diameter to the expansion diameter of 1.5-2.5% pots, fixed length to diameter, on the other hand to improve the yield limit of about 20%.
Nickel is an excellent corrosion-resistant materials, which is an important alloying element in steel. Nickel is the formation of austenite in the steel elements, but to obtain pure carbon-nickel austenitic steels, nickel volume to reach 24%; whereas only 27% of nickel when the steel corrosion in certain media Corrosion can significantly changed. So Nickel alone can not constitute a stainless steel. However, both nickel and chromium present in the stainless steel, the nickel-containing stainless steel, but has many valuable properties. Based on the above case shows, nickel as an alloying element in stainless steel effect, is that it enables high-chromium steel tissue changes, so that the corrosion resistance of stainless steel and obtain certain improved process performance.
Jet blasting of spiral piling pipe
Also known as spiral or helical spiral piling pipe, is a low-carbon steel or low alloy steel strip at a certain angle of the helix (called molding angle) rolled into a tube and then welded together to form a tube it can be a narrow strip production of large diameter steel pipe.
Rust is the result of high-power spray jet vane motor driven high-speed reverse, the grit, steel shot, wire segments, abrasive minerals under the effect of centrifugal force on the pipe exterior spray and disposal, can completely eliminate rust, oxides and dirt and steel in the abrasive impact and ferocity under the effect of friction, but also to reach the needs of the average roughness.
Spray rust, can extend the appearance of physical adsorption tube effect, and can enhance the appearance of the pipe coating mechanical adhesion effect. Consequently, the pipeline corrosion spray rust rust fantasy method. Generally, blasting (sand ) rust inside the tube first appearance for disposal, blasting (sand) is mainly used for pipe surface rust surface disposal.
Rust is the result of high-power spray jet vane motor driven high-speed reverse, the grit, steel shot, wire segments, abrasive minerals under the effect of centrifugal force on the pipe exterior spray and disposal, can completely eliminate rust, oxides and dirt and steel in the abrasive impact and ferocity under the effect of friction, but also to reach the needs of the average roughness.
Spray rust, can extend the appearance of physical adsorption tube effect, and can enhance the appearance of the pipe coating mechanical adhesion effect. Consequently, the pipeline corrosion spray rust rust fantasy method. Generally, blasting (sand ) rust inside the tube first appearance for disposal, blasting (sand) is mainly used for pipe surface rust surface disposal.
Hot extrusion production process of steel pipe
Hot extrusion process meets stringent product standards, widely used in military, nuclear power, petrochemical, and other cutting-edge areas of aviation and a variety of stainless steel tubes, high-quality high-temperature corrosion steel pipe, steel pipe and other steel titanium and titanium alloy products. These high-quality, high-precision, difficult deformation of specialty steel products, its production processes often require special smelting, casting, rolling, forging production and R & D capabilities, and includes cold rolling, heat treatment process including a series of tube processing capacity. Core areas of hot piercing and hot extrusion production process need to build a complete production line, a broad product line includes: pretreatment tube offline, online pre-heating and heating tube, inner tube, the outer surface of the glass powder lubrication after heat perforation / reaming, after reheating and the inner and outer surfaces of the glass powder lubricant into the hot extrusion process and thermal pressure I saw after cutting, hot extruded steel tube (long tube by heat sawing online after) by a roller transported to the background, and then heat quenched or cooled in the cooling bed. Depending on technical requirements for products, hot extruded pipe after production using continuous production process, but also through rolling, straightening, shot blasting, degreasing, pickling processes to deal with.
With the worldwide high-end seamless piping market recovery and the country's economic strength gradually increased, steel hot extrusion production process ushered in a new round of development opportunities. Hot extruded pipe production process using hot extrusion method with three-stress deformation in the metal density is good, homogeneous, suitable for almost all varieties of steel production, particularly in the high-alloy steels difficult to deformation and various special-shaped production of the tube section has a special processing advantages.
With the worldwide high-end seamless piping market recovery and the country's economic strength gradually increased, steel hot extrusion production process ushered in a new round of development opportunities. Hot extruded pipe production process using hot extrusion method with three-stress deformation in the metal density is good, homogeneous, suitable for almost all varieties of steel production, particularly in the high-alloy steels difficult to deformation and various special-shaped production of the tube section has a special processing advantages.
Monday, July 22, 2013
Moisture rust removal of spiral piling pipe
Currently the main use of rust on the steel wire brushes and other tools to be polished appearance, spiral piling pipe with plain bars is the difference between appearance with longitudinal ribs and transverse ribs.
Spiral piling pipe cleaning and preheating can remove loose or warped oxide, rust, welding slag. Hand tools rust can reach Sa2 grade power tools rust Sa3 level can be achieved, if attached to a solid iron oxide steel exterior skin, the effect is not ideal tools rust, anti-corrosion construction required to reach the depth of anchor pattern. Acid by solvent, emulsion cleaning fluid pressure welded tube exterior to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the appearance of the steel rust, oxide, flux, etc., so the corrosion production only as an adjunct. Generally use two methods to do chemical and electrolytic pickling treatment, pipeline corrosion using only chemical pickling can descaling, rust, old paint, sometimes used as a sand blasting after reprocessing. Although chemical cleaning can achieve a certain surface cleanliness and roughness, but the anchor pattern shallow, but easy on the spiral steel stacking pollute the environment.
Cleaning methods used to remove grease and fouling steel exterior, spiral steel pipe in spray (throwing) shot before treatment. Using the tube furnace preheated to 40 to 60 ℃, dry stick appearance of the steel pipe. Spray (throwing) shot deal, due to pressure transmission fluid with frequency spiral welded steel pipe appearance without grease and other dirt, rust can enhance the effect of the dry pipe appearance but also conducive to steel shot, steel grit and rust and oxidation the separation of the skin, so that the low pressure fluid rust welded steel pipe cleaner appearance.
Spiral piling pipe cleaning and preheating can remove loose or warped oxide, rust, welding slag. Hand tools rust can reach Sa2 grade power tools rust Sa3 level can be achieved, if attached to a solid iron oxide steel exterior skin, the effect is not ideal tools rust, anti-corrosion construction required to reach the depth of anchor pattern. Acid by solvent, emulsion cleaning fluid pressure welded tube exterior to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the appearance of the steel rust, oxide, flux, etc., so the corrosion production only as an adjunct. Generally use two methods to do chemical and electrolytic pickling treatment, pipeline corrosion using only chemical pickling can descaling, rust, old paint, sometimes used as a sand blasting after reprocessing. Although chemical cleaning can achieve a certain surface cleanliness and roughness, but the anchor pattern shallow, but easy on the spiral steel stacking pollute the environment.
Cleaning methods used to remove grease and fouling steel exterior, spiral steel pipe in spray (throwing) shot before treatment. Using the tube furnace preheated to 40 to 60 ℃, dry stick appearance of the steel pipe. Spray (throwing) shot deal, due to pressure transmission fluid with frequency spiral welded steel pipe appearance without grease and other dirt, rust can enhance the effect of the dry pipe appearance but also conducive to steel shot, steel grit and rust and oxidation the separation of the skin, so that the low pressure fluid rust welded steel pipe cleaner appearance.
Spiral piling pipe technology features and applications
Spiral piling pipe technical characteristics and applications. Spiral welded steel pipe with reliability and adaptability varieties, spiral steel pipe plant in recent years, the proportion of the number stabilized at 42% to 45% or so. Especially adapted to the production of thick-walled steel and alloy steel.
Spiral steel pipe is mainly used for reinforced concrete building elements of the skeleton. Usually with two longitudinal ribs uniformly distributed along the length of the transverse ribs. Rebar is a small section steel, spiral steel pipe with plain bars is the difference between appearance with longitudinal ribs and transverse ribs. Requires the use of a certain degree of mechanical strength, bending properties and process welding performance. Billets as feedstock production spiral disposition by sedation melting carbon steel or low alloy steel, hot-rolled steel scrap forming, normalizing or rolled condition.
Spiral piling pipe technical features include: high investment, high interest rates, complex manufacturing process, a large wall thickness and ovality tolerance. The fact sheet welded tube deep processing products, prices of similar conditions, the spiral steel pipe market competitiveness and increase its reliability, as from time to time to improve the quality of steel and welded raise the level of technical equipment, the local spiral pipe occupy market, there is the possibility of substitution welded pipe, but only a very limited field.
Spiral steel pipe is mainly used for reinforced concrete building elements of the skeleton. Usually with two longitudinal ribs uniformly distributed along the length of the transverse ribs. Rebar is a small section steel, spiral steel pipe with plain bars is the difference between appearance with longitudinal ribs and transverse ribs. Requires the use of a certain degree of mechanical strength, bending properties and process welding performance. Billets as feedstock production spiral disposition by sedation melting carbon steel or low alloy steel, hot-rolled steel scrap forming, normalizing or rolled condition.
Spiral piling pipe technical features include: high investment, high interest rates, complex manufacturing process, a large wall thickness and ovality tolerance. The fact sheet welded tube deep processing products, prices of similar conditions, the spiral steel pipe market competitiveness and increase its reliability, as from time to time to improve the quality of steel and welded raise the level of technical equipment, the local spiral pipe occupy market, there is the possibility of substitution welded pipe, but only a very limited field.
Non-destructive testing in the role of spiral welded pipe production
Nondestructive testing technology, also known as non-destructive testing techniques. It is the use of certain physical properties of the substance or group defective structure bound to the differential changes in physical phenomenon, without damage, the detected object does not damage the performance and shape of the premise, by measuring these changes understanding and evaluation of plant material to be detected, the nature of products and equipment components, status, quality, or internal structure of a particular detection technique.
In a small spiral welded tube production process, the role of non-destructive testing are two points; First, raw materials, semi-finished products, rife provides continuous, real-time process quality control, especially spiral pipe welding quality control and production process quality (such as heat treatment, expansion diameter, flat head and hydrostatic test or defects caused by the expansion of the original defect), timely detection of primitive and production processes of various defects and this appears to be controlled to prevent does not meet the quality requirements of raw materials / semi-finished products into the next process ; Second, Liu pipe small defects accurate qualitative and quantitative and positioning, thus providing guidance disposed of; three are based on the acceptance of non-standard vague to the production of spiral welded pipe for quality grading, to meet different customer needs. Yuan right detection technology allows us the safest and most economical way to health and the use of wide spiral welded pipe products.
Spiral welded pipe manufacturing in the most commonly used non-destructive testing methods of food: ray inspection (only T), ultrasonic testing (uT), penetrant testing (FP), eddy current testing, magnetic particle testing (MT) and so on. This is also the first developed Chia conventional detection methods.
In a small spiral welded tube production process, the role of non-destructive testing are two points; First, raw materials, semi-finished products, rife provides continuous, real-time process quality control, especially spiral pipe welding quality control and production process quality (such as heat treatment, expansion diameter, flat head and hydrostatic test or defects caused by the expansion of the original defect), timely detection of primitive and production processes of various defects and this appears to be controlled to prevent does not meet the quality requirements of raw materials / semi-finished products into the next process ; Second, Liu pipe small defects accurate qualitative and quantitative and positioning, thus providing guidance disposed of; three are based on the acceptance of non-standard vague to the production of spiral welded pipe for quality grading, to meet different customer needs. Yuan right detection technology allows us the safest and most economical way to health and the use of wide spiral welded pipe products.
Spiral welded pipe manufacturing in the most commonly used non-destructive testing methods of food: ray inspection (only T), ultrasonic testing (uT), penetrant testing (FP), eddy current testing, magnetic particle testing (MT) and so on. This is also the first developed Chia conventional detection methods.
External spiral steel works
Whatever the mechanical equipment has their own works, how it works is to allow us to better understand its work, and our awareness of it. Spiral steel pipe is a pipe commonly used in construction, then there is a outside spiral Pipe seldom been learned.
External spiral steel pipe is rolled tubes or other processing methods in its inner and outer spiral pattern formed on the surface of a highly efficient heat transfer tubes. External spiral steel pipe strengthen the role of the media outside the clothing aspect medium flows through the shell externally threaded tube surface, the outer thread edge layer-to-layer flow generated disturbance, thinning of the boundary layer thickness, on the other hand reflects the increased heat transfer area external thread; combined result, so that the tube has a high heat transfer when the external spiral steel pipe for evaporating when the unit can increase the number of bubble formation on the surface, to improve the boiling heat transfer, to further reduce resistance and improve the condensation heat transfer efficiency.
Spiral steel fluid flowing inside and outside the inner spiral pattern by obstacles and guide the fluid hampered and guided along the spiral pattern rotating part only; another part of the fluid from the outer spiral axial flow. Inner spiral pattern projection of the cis rotating helical spiral fluid shock fluid flowing axially outer edge. former boundary layer thinning beneficial effect; role of the latter axially outer spiral heat exchange fluid flowing in the other heat exchange area larger than the original tubes and process heat transfer area and processes, which can speed up the body wall to fluid heat transfer. combined result of two effects, the effect of heat transfer tube has been strengthened.
External spiral steel pipe is rolled tubes or other processing methods in its inner and outer spiral pattern formed on the surface of a highly efficient heat transfer tubes. External spiral steel pipe strengthen the role of the media outside the clothing aspect medium flows through the shell externally threaded tube surface, the outer thread edge layer-to-layer flow generated disturbance, thinning of the boundary layer thickness, on the other hand reflects the increased heat transfer area external thread; combined result, so that the tube has a high heat transfer when the external spiral steel pipe for evaporating when the unit can increase the number of bubble formation on the surface, to improve the boiling heat transfer, to further reduce resistance and improve the condensation heat transfer efficiency.
Spiral steel fluid flowing inside and outside the inner spiral pattern by obstacles and guide the fluid hampered and guided along the spiral pattern rotating part only; another part of the fluid from the outer spiral axial flow. Inner spiral pattern projection of the cis rotating helical spiral fluid shock fluid flowing axially outer edge. former boundary layer thinning beneficial effect; role of the latter axially outer spiral heat exchange fluid flowing in the other heat exchange area larger than the original tubes and process heat transfer area and processes, which can speed up the body wall to fluid heat transfer. combined result of two effects, the effect of heat transfer tube has been strengthened.
Spiral pipe extrusion pressure control
The strength of the spiral steel pipe is generally higher than the straight seam welded pipe and straight seam welded pipe development too fast, the cost is low, two kinds of steel pipes have advantages also is different, so the applicable scope is also different.
The two edges of the heating tube to the welding temperature in the extrusion press roll, a common mutual penetration of the metal grains, crystals, and ultimately form a strong weld. If the pressing force is too small, a common number of crystals is small, the weld metal strength decreases, the force will produce cracks; if the extrusion pressure is excessive, the molten weld metal is extruded, not only reduces the the weld strength, and will generate a lot of internal and external burrs, and even cause defects such as seam welding ride.
Spiral Pipe uses: 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.
The two edges of the heating tube to the welding temperature in the extrusion press roll, a common mutual penetration of the metal grains, crystals, and ultimately form a strong weld. If the pressing force is too small, a common number of crystals is small, the weld metal strength decreases, the force will produce cracks; if the extrusion pressure is excessive, the molten weld metal is extruded, not only reduces the the weld strength, and will generate a lot of internal and external burrs, and even cause defects such as seam welding ride.
Spiral Pipe uses: 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.
Wednesday, July 17, 2013
How to maintain and repair for spiral pipe in winter
Spiral steel pipe plant in the winter protection methods: you can use a professional pipe curing agent regularly sewer cleaning and disinfection, sterilization, to keep water pipes clear, avoiding pipeline to become a breeding ground for germs. Clean the pipes, the pipes to use a professional maintenance products, in order to achieve sterilization, odor and clean anti-clogging effect. Maintenance dredging in the selection of products and products, pay attention to the safety of products, try to select the sterilization rate, by the professional authority detection products.
Drain should choose a manufacturer names, brand and specifications of qualified products. Water supply pipe with threaded connections, the connection should be at its exposed threads, promptly after installation card holder tube, pipe and fittings or valves should be connected between the firm, without any loose. Piping installed, check to pass water, with visual and feel method to check for leaks. See all faucets, valves are installed flat, open is flexible, water is smooth, without leakage. Check the meter is functioning properly.
Clean drains on the family, to master the correct way, to adhere to prevention, good sewer routine maintenance work. In the family home decoration, avoiding water supply, drainage channels leakage occurs is the best
Drain should choose a manufacturer names, brand and specifications of qualified products. Water supply pipe with threaded connections, the connection should be at its exposed threads, promptly after installation card holder tube, pipe and fittings or valves should be connected between the firm, without any loose. Piping installed, check to pass water, with visual and feel method to check for leaks. See all faucets, valves are installed flat, open is flexible, water is smooth, without leakage. Check the meter is functioning properly.
Clean drains on the family, to master the correct way, to adhere to prevention, good sewer routine maintenance work. In the family home decoration, avoiding water supply, drainage channels leakage occurs is the best
Cold-rolled steel and large diameter spiral pipe distinction
Currently seamless increasingly competitive market, because by its manufacturing process constraints, seamless steel pipe production costs have been high, resulting in the gradual decline of its economic benefits.
Seamless hollow sections, a large number of channels for transporting fluids, steel pipe and solid bar, etc. compared to large diameter spiral steel pipe, the same torsional strength in bending, lighter, is an economic cross-section of large diameter spiral pipe , widely used in the manufacture of structural parts and mechanical parts, such as drill pipe,piling pipe, automotive drive shafts, bicycle frames and construction using steel scaffolding.
Weld quality directly determines the quality of large diameter spiral pipe, is a large-diameter spiral pipe and seamless biggest difference lies. Large diameter spiral steel pipe in two-sided submerged arc welding, the carbon can not be eliminated straight sets crevices, welds, and the mother just converge together, and not completely fused into one, unable to withstand the test of time and pressure. Hot stretch reducing the double submerged arc welded tube even after the overall temperature of 800 degrees after heating, the overall annealing, and then open the change process, through this series of processes, the weld performance has the same parent organization, completely melting as a whole, well done from a seam to seamless transition.
Of course, the difference between the two is not just limited to the above two points, but illustrates the large diameter spiral steel pipe and hot stretch reducing pipe there are still significant differences. The latter in the large diameter spiral pipe has conducted on the basis of clear internal and external burrs online, the overall heating type variable and a series of new technical processing, enabling Tianjin 316L stainless steel tube which has been a qualitative leap in the field of high pressure common use, and can only be limited to large diameter spiral pipe water under low pressure gas transmission.
Different processes resulting in differences in product quality, reducing thermal stress in double submerged arc welded steel pipe after also carried out a large-diameter spiral pipe are no external burr removal process online. The presence of burrs affect the flow of fluid inside the tube, burrs blocking the normal flow of fluid, to produce swirl. According to principles of fluid mechanics, the weld must increase local compression, discontinuity of the large diameter spiral pipe safety factor is also greatly reduced, hot stretch reducing steel production process to take full account of the risks that exist burr, burr to limit Clear, making it uniform thickness, seamless appearance with no difference. So from this point of view, hot stretch reducing pipe joints from having also completed a seamless transition to.
Seamless hollow sections, a large number of channels for transporting fluids, steel pipe and solid bar, etc. compared to large diameter spiral steel pipe, the same torsional strength in bending, lighter, is an economic cross-section of large diameter spiral pipe , widely used in the manufacture of structural parts and mechanical parts, such as drill pipe,piling pipe, automotive drive shafts, bicycle frames and construction using steel scaffolding.
Weld quality directly determines the quality of large diameter spiral pipe, is a large-diameter spiral pipe and seamless biggest difference lies. Large diameter spiral steel pipe in two-sided submerged arc welding, the carbon can not be eliminated straight sets crevices, welds, and the mother just converge together, and not completely fused into one, unable to withstand the test of time and pressure. Hot stretch reducing the double submerged arc welded tube even after the overall temperature of 800 degrees after heating, the overall annealing, and then open the change process, through this series of processes, the weld performance has the same parent organization, completely melting as a whole, well done from a seam to seamless transition.
Of course, the difference between the two is not just limited to the above two points, but illustrates the large diameter spiral steel pipe and hot stretch reducing pipe there are still significant differences. The latter in the large diameter spiral pipe has conducted on the basis of clear internal and external burrs online, the overall heating type variable and a series of new technical processing, enabling Tianjin 316L stainless steel tube which has been a qualitative leap in the field of high pressure common use, and can only be limited to large diameter spiral pipe water under low pressure gas transmission.
Different processes resulting in differences in product quality, reducing thermal stress in double submerged arc welded steel pipe after also carried out a large-diameter spiral pipe are no external burr removal process online. The presence of burrs affect the flow of fluid inside the tube, burrs blocking the normal flow of fluid, to produce swirl. According to principles of fluid mechanics, the weld must increase local compression, discontinuity of the large diameter spiral pipe safety factor is also greatly reduced, hot stretch reducing steel production process to take full account of the risks that exist burr, burr to limit Clear, making it uniform thickness, seamless appearance with no difference. So from this point of view, hot stretch reducing pipe joints from having also completed a seamless transition to.
Application of large diameter spiral pipe
Currently, spiral steel pipe widely used in engineering cooling after annealing treatment to eliminate residual stress, while cooling after welding residual stress is an important process, this approach is both extravagant energy and easily 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 stresses, progressive metal resistance to stress corrosion performance.
Spiral steel pipe used in different industries, according to certain production processing and manufacturing processes and production together, be able to show the construction of an important role and value. Spiral plant due to increasingly higher bearing pressure pipelines, using the premise of increasingly demanding, and to try to extend the life of the pipeline. Despite the economic crisis, but the large-diameter spiral steel pipe company cited argument is resuming development, to meet a better tomorrow. Large diameter spiral pipe in the transportation of gas, transportation has played a significant role. Large diameter spiral steel pipe is mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction piling pipe, is the development of the 20 key products.
Spiral steel pipe used in different industries, according to certain production processing and manufacturing processes and production together, be able to show the construction of an important role and value. Spiral plant due to increasingly higher bearing pressure pipelines, using the premise of increasingly demanding, and to try to extend the life of the pipeline. Despite the economic crisis, but the large-diameter spiral steel pipe company cited argument is resuming development, to meet a better tomorrow. Large diameter spiral pipe in the transportation of gas, transportation has played a significant role. Large diameter spiral steel pipe is mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction piling pipe, is the development of the 20 key products.
Sunday, July 14, 2013
How to avoid large diameter spiral pipe corrosion
All metals and reaction of oxygen in the atmosphere, the surface oxide film. Unfortunately, in the iron oxide formed on carbon steel proceed oxidation, corrosion continues to expand, forming holes. You can use paint or oxidation-resistant metal (eg, zinc, nickel and chromium) plating to ensure the steel surface, but, as people know, this protection is only a film. If the protective layer is damaged, the following steel began to rust. Large diameter spiral steel pipe corrosion resistance depends on corrosion, coal tar epoxy anticorrosive is one of the components, so the protection methods vary.
Strengthen the anti-corrosion paint material reaches level, large diameter spiral pipe atmospheric corrosion resistance can significantly increase, but higher strength corrosion, although still improve corrosion resistance, but not obvious. The reason is used for large diameter spiral steel pipe anti-corrosion processing of the processing, the change in the type of surface oxide became similar to the large diameter spiral pipe is formed on the surface of the metal oxide. This tight adhesion of large diameter spiral pipe oxide protective surface to prevent further oxidation. This oxide layer is very thin, it can be seen through the large diameter spiral steel pipe surface natural luster, making large-diameter spiral pipe has a unique surface. Moreover, if the surface is damaged, the exposed surface of large diameter spiral pipe and atmospheric reaction to self-repair, re-formation of this oxide "passive film" and continue to play a protective role. Therefore, all of the large diameter spiral pipe elements have a common characteristic, corrosion prevention of corrosion is the best way.
Strengthen the anti-corrosion paint material reaches level, large diameter spiral pipe atmospheric corrosion resistance can significantly increase, but higher strength corrosion, although still improve corrosion resistance, but not obvious. The reason is used for large diameter spiral steel pipe anti-corrosion processing of the processing, the change in the type of surface oxide became similar to the large diameter spiral pipe is formed on the surface of the metal oxide. This tight adhesion of large diameter spiral pipe oxide protective surface to prevent further oxidation. This oxide layer is very thin, it can be seen through the large diameter spiral steel pipe surface natural luster, making large-diameter spiral pipe has a unique surface. Moreover, if the surface is damaged, the exposed surface of large diameter spiral pipe and atmospheric reaction to self-repair, re-formation of this oxide "passive film" and continue to play a protective role. Therefore, all of the large diameter spiral pipe elements have a common characteristic, corrosion prevention of corrosion is the best way.
Development of straight seam double submerged arc welded steel pipes in related fields
First of all that, because of various factors, including the double-sided submerged arc welding straight seam steel pipe on its own merits, but also according to the actual needs of the industry in recent years, two-sided submerged arc welding straight seam steel pipe in the related areas of development is considerable! Steel structure is a new type of energy saving building system, known as the 21st century "green building." Sided submerged arc welding straight seam steel pipe is a light weight, high strength, good
seismic performance, energy saving, can be recycled using load-bearing steel structures, in line with the development of energy efficient buildings and sustained and healthy economic development. The biggest advantage is the steel structure brings people to the building, supports, bearer of the functional requirements, visual requirements and efficiency requirements perfectly together.
And according to the relevant knowledge: In the field of application of large diameter steel, thick-walled, high-grade steel straight seam double submerged arc welded steel tube, steel structures absorb foreign marine equipment and port of advanced design concepts, with emphasis on the development of steel as a structure, in addition to used in construction areas, and mature marine equipment used in port areas, quickly gained international industry and peer recognition, and achieved substantial results. In addition, the steel structure of superiority over other structures, available from member section properties, mechanical behavior, economic and other aspects contrast drawn. Steel structure with its own superior performance in recent years is the rapid development of applications involving almost all steel construction fields.
seismic performance, energy saving, can be recycled using load-bearing steel structures, in line with the development of energy efficient buildings and sustained and healthy economic development. The biggest advantage is the steel structure brings people to the building, supports, bearer of the functional requirements, visual requirements and efficiency requirements perfectly together.
And according to the relevant knowledge: In the field of application of large diameter steel, thick-walled, high-grade steel straight seam double submerged arc welded steel tube, steel structures absorb foreign marine equipment and port of advanced design concepts, with emphasis on the development of steel as a structure, in addition to used in construction areas, and mature marine equipment used in port areas, quickly gained international industry and peer recognition, and achieved substantial results. In addition, the steel structure of superiority over other structures, available from member section properties, mechanical behavior, economic and other aspects contrast drawn. Steel structure with its own superior performance in recent years is the rapid development of applications involving almost all steel construction fields.
Common sense of spiral steel pipe
Spiral steel pipe is the industrial, construction and other industries widely used kind of steel. It is a strip coil as raw material, often warm extrusion molding, with automatic double-sided submerged arc welding process wire spiral welded steel tube. Mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction. Spiral steel pipe 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. It is in the transportation of gas, transportation has played a significant role. Spiral steel pipe pressure transmission fluid with spiral submerged arc welded pipe is mainly used to transport oil, natural gas pipelines; pressure transmission fluid with frequency spiral welded steel pipes, lap welding method with high frequency welding, pressure fluid transport frequency spiral welded steel pipe. Strong pressure steel, plastic, and easy welding and machining molding; generally low pressure liquid delivery spiral submerged arc welded pipe, using double-sided automatic submerged arc welding or welding into the legal system for water, gas, air and steam low pressure liquid delivery SAW pipe.
Longitudinal generally is higher than its strength, which can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight pipe joints than weld length of 30 to 100%, and lower production rate. Therefore, the smaller diameter pipe is mostly a straight seam welded, large diameter spiral welded pipe is mostly used steel tube and solid steel bar, etc. compared to the same torsional strength in bending, lighter, is an economic cross-section steel, widely used in the manufacture of structural parts and mechanical parts, construction using steel scaffolding. With steel pipe manufacturing annular parts, can improve material utilization, simplify the manufacturing process, saving material and machining time, such as bearing rings, jack sets, has been widely used to make steel. Steel or a variety of conventional weapons indispensable material, barrel, barrel, etc. to make steel. By cross-sectional shape of the pipe can be divided into tube and shaped tubes. Since the perimeter of equal conditions, the maximum area of a circle with a circular tube can carry more fluid. In addition, the circular cross section to withstand internal or external radial pressure, the stress is uniform.
Longitudinal generally is higher than its strength, which can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight pipe joints than weld length of 30 to 100%, and lower production rate. Therefore, the smaller diameter pipe is mostly a straight seam welded, large diameter spiral welded pipe is mostly used steel tube and solid steel bar, etc. compared to the same torsional strength in bending, lighter, is an economic cross-section steel, widely used in the manufacture of structural parts and mechanical parts, construction using steel scaffolding. With steel pipe manufacturing annular parts, can improve material utilization, simplify the manufacturing process, saving material and machining time, such as bearing rings, jack sets, has been widely used to make steel. Steel or a variety of conventional weapons indispensable material, barrel, barrel, etc. to make steel. By cross-sectional shape of the pipe can be divided into tube and shaped tubes. Since the perimeter of equal conditions, the maximum area of a circle with a circular tube can carry more fluid. In addition, the circular cross section to withstand internal or external radial pressure, the stress is uniform.
Application analysis of large diameter dredge pipe
Large diameter steel pipe is mainly used to clean dredged sediment transport, mud and other debris mixed steel pipes, whose products include steel pipe dredging, dredging spiral steel pipe, spiral pipe dredging, dredging pipe, harbor dredging pipe and so on. Dredging steel products are widely used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, etc., can be used for liquid transport, gas transportation, as structures, piling pipe.
Dredging of large diameter steel pipe is a good product in the steel products, widely used in industry in different applications and use of the production process is the dredging tube has an extremely strict production standards, to the use of certain methods and means of processing and technology production, production quality and reliable raw
material used in the production process and production, production and use can show significant performance and role in certain market sectors to fully demonstrate good performance advantage, play a certain reliability and value.
Dredging of large diameter steel pipe is a good product in the steel products, widely used in industry in different applications and use of the production process is the dredging tube has an extremely strict production standards, to the use of certain methods and means of processing and technology production, production quality and reliable raw
material used in the production process and production, production and use can show significant performance and role in certain market sectors to fully demonstrate good performance advantage, play a certain reliability and value.
Friday, July 12, 2013
Elimination of cold drawn seamless steel pipe breakage
Foreign precision cold drawn seamless steel is generally added to the metal alloy material way to improve the performance of the cold drawn seamless steel tubes, are required to stress annealing, to eliminate the residual stress material, to improve the organization of materials, improve the plasticity of the material, thus preventing seamless fracture failure occurs purposes.
At present, cold drawn seamless steel tubes are made of ordinary 45 # or 20 # steel 27SiMn steel, cold drawn deformed through the metal strength; however, it is at the expense of metal ductility, toughness for the price. Precision cold drawn seamless steel is its high dimensional accuracy and high strength properties and based on the market, it must ensure that the amount of deformation in a certain range, in order to maximize the performance of materials, to reduce the material adversely affected.
Cold drawn seamless steel pipe deformation is too small to reach the surface finish and dimensional accuracy requirements, but also unable to reach members of the strength index; deformation is too large, seamless plasticity, toughness decreases too much, but the grain is pulled excessively elongate, forming a fibrous tissue, a significant anisotropy metals. Cold drawn seamless steel tube in the axial direction, parallel to the elongate direction of the grain, the intensity increased; cold drawn seamless radially perpendicular to the elongated direction of the grain, but lower strength, and maximum stress of the hydraulic cylinder is present in the radial direction of seamless, so much distortion on the performance of fully drawn tubes unfavorable.
For steel and fibrous tissue appears dislocations, vacancies and other crystal defects are generally taken annealing or normalizing heat treatment methods to eliminate them. The purpose is to refine the grain annealing to remove tissue defects, reduce hardness, improved ductility, but also facilitate cold. Cold drawn seamless steel pipe production, annealing equipment is indispensable, therefore, to develop an appropriate annealing process is to ensure that cold drawn seamless organization qualified defective product is not a necessary condition for a fracture. If the manufacturers in order to unilaterally reduce production costs, reduce the annealing process is bound to adversely affect the quality of products.
At present, cold drawn seamless steel tubes are made of ordinary 45 # or 20 # steel 27SiMn steel, cold drawn deformed through the metal strength; however, it is at the expense of metal ductility, toughness for the price. Precision cold drawn seamless steel is its high dimensional accuracy and high strength properties and based on the market, it must ensure that the amount of deformation in a certain range, in order to maximize the performance of materials, to reduce the material adversely affected.
Cold drawn seamless steel pipe deformation is too small to reach the surface finish and dimensional accuracy requirements, but also unable to reach members of the strength index; deformation is too large, seamless plasticity, toughness decreases too much, but the grain is pulled excessively elongate, forming a fibrous tissue, a significant anisotropy metals. Cold drawn seamless steel tube in the axial direction, parallel to the elongate direction of the grain, the intensity increased; cold drawn seamless radially perpendicular to the elongated direction of the grain, but lower strength, and maximum stress of the hydraulic cylinder is present in the radial direction of seamless, so much distortion on the performance of fully drawn tubes unfavorable.
For steel and fibrous tissue appears dislocations, vacancies and other crystal defects are generally taken annealing or normalizing heat treatment methods to eliminate them. The purpose is to refine the grain annealing to remove tissue defects, reduce hardness, improved ductility, but also facilitate cold. Cold drawn seamless steel pipe production, annealing equipment is indispensable, therefore, to develop an appropriate annealing process is to ensure that cold drawn seamless organization qualified defective product is not a necessary condition for a fracture. If the manufacturers in order to unilaterally reduce production costs, reduce the annealing process is bound to adversely affect the quality of products.
The application of submerged arc welding in oil and piling
Welding technology has been widely applied in the oil industry and piling pipe and played an increasingly important role. For coiled tubing drilling, the weakest of the bottom hole assembly (BHA) that is dangerous section of the welds. In recent years, with the development of welding technology, coiled tubing manufacturer application of new technologies to improve the welding process, and improve the pipeline performance. Coiled tubing from the past "pipe on the tube end butt spiral submerged arc welded technology alternative. The immediate advantage of the spiral submerged arc welding is to weld the spiral-shaped distribution, greatly increase the axial strength of the tubing, coiled tubing reliability has also been significantly improved.
Submerged arc welding principle and characteristics - submerged arc welding arc as a heat source. The submerged arc welding when the arc is burning in the granular layer to melt the solder under the coverage of the arc is not exposed, and thus called the submerged arc welding. Welding arc burning between the wire and the workpiece. Arc hot wire end and the arc near the base metal and flux melting. Molten metal formed in the weld pool, molten flux as slag. The arc to move forward, the arc force in the bath of liquid metal into the weld pool behind the. In the subsequent cooling process, this part of the liquid metal solidified into a weld. The slag is solidified into a slag shell covering on the weld surface. Slag in addition to the mechanical protection role of the weld pool and weld metal from the welding process, the molten metal, the metallurgical reaction, thus affecting the chemical composition of the weld metal. Submerged arc welding, the welder parts and wires were connected to the welding power poles. Wire by sliding contact with the contact tip and power connections. Welding circuit including the welding power source, connection cable, tip, wire arc, molten pool, work and other sectors. Continue to melt the wire end in the electric arc thermal effect, which wire should be sent in a continuous manner, in order to maintain the stability of the welding process is continuous. Wire feeding speed wire melting rate to the balance.
In addition, spiral submerged arc welded in the oil industry and piling is also reflected in the drilling of casing (surface casing, intermediate casing, etc.)
Submerged arc welding principle and characteristics - submerged arc welding arc as a heat source. The submerged arc welding when the arc is burning in the granular layer to melt the solder under the coverage of the arc is not exposed, and thus called the submerged arc welding. Welding arc burning between the wire and the workpiece. Arc hot wire end and the arc near the base metal and flux melting. Molten metal formed in the weld pool, molten flux as slag. The arc to move forward, the arc force in the bath of liquid metal into the weld pool behind the. In the subsequent cooling process, this part of the liquid metal solidified into a weld. The slag is solidified into a slag shell covering on the weld surface. Slag in addition to the mechanical protection role of the weld pool and weld metal from the welding process, the molten metal, the metallurgical reaction, thus affecting the chemical composition of the weld metal. Submerged arc welding, the welder parts and wires were connected to the welding power poles. Wire by sliding contact with the contact tip and power connections. Welding circuit including the welding power source, connection cable, tip, wire arc, molten pool, work and other sectors. Continue to melt the wire end in the electric arc thermal effect, which wire should be sent in a continuous manner, in order to maintain the stability of the welding process is continuous. Wire feeding speed wire melting rate to the balance.
In addition, spiral submerged arc welded in the oil industry and piling is also reflected in the drilling of casing (surface casing, intermediate casing, etc.)
Spiral piling pipe rainy season rust
As the spiral piling pipe are stored in the open, but when in use, most of them are buried in the ground, so it is easy to rust, rusty after the spiral, usually by chemical and electrolytic pickling two ways to divide rust.
However, if it is buried in the ground coil is generally used for chemical pickling process, chemical pickling can remove rust and old paint. However, it should be noted that although the chemical pickling able to clean the surface of the spiral tube, but its anchor pattern shallow, but also likely to cause environmental pollution, therefore, under normal circumstances, does not recommend the use of chemical cleaning. Especially during the rainy season, some customers to the factory guard and saw a layer of rust on the steel pipe is considered poor quality, this idea is wrong, in fact, this is a normal chemical reaction. In order to solve some problems concerning rust spiral, spiral steel pipe factory introduced a spiral corrosion, corrosion spiral spiral pipe in the processing time, joined the anti-corrosion technology. Tube can be more effectively prevent corrosion during use, can be very effective anti-corrosion steel block or slow down rusting.
However, if it is buried in the ground coil is generally used for chemical pickling process, chemical pickling can remove rust and old paint. However, it should be noted that although the chemical pickling able to clean the surface of the spiral tube, but its anchor pattern shallow, but also likely to cause environmental pollution, therefore, under normal circumstances, does not recommend the use of chemical cleaning. Especially during the rainy season, some customers to the factory guard and saw a layer of rust on the steel pipe is considered poor quality, this idea is wrong, in fact, this is a normal chemical reaction. In order to solve some problems concerning rust spiral, spiral steel pipe factory introduced a spiral corrosion, corrosion spiral spiral pipe in the processing time, joined the anti-corrosion technology. Tube can be more effectively prevent corrosion during use, can be very effective anti-corrosion steel block or slow down rusting.
Elimination of cold drawn seamless steel pipe breakage
Foreign precision cold drawn seamless tube is generally added to the metal alloy material way to improve the performance of the cold drawn seamless steel tubes, are required to stress annealing, to eliminate the residual stress material, to improve the organization of materials, improve the plasticity of the material, thus preventing seamless fracture failure occurs purposes.
At present, cold drawn seamless steel tubes are made of ordinary 45 # or 20 # steel 27SiMn steel, cold drawn deformed through the metal strength; however, it is at the expense of metal ductility, toughness for the price. Precision cold drawn seamless steel is its high dimensional accuracy and high strength properties and based on the market, it must ensure that the amount of deformation in a certain range, in order to maximize the performance of materials, to reduce the material adversely affected.
Cold drawn seamless steel pipe deformation is too small to reach the surface finish and dimensional accuracy requirements, but also unable to reach members of the strength index; deformation is too large, seamless plasticity, toughness decreases too much, but the grain is pulled excessively elongate, forming a fibrous tissue, a significant anisotropy metals. Cold drawn seamless steel tube in the axial direction, parallel to the elongate direction of the grain, the intensity increased; cold drawn seamless radially perpendicular to the elongated direction of the grain, but lower strength, and maximum stress of the hydraulic cylinder is present in the radial direction of seamless, so much distortion on the performance of fully drawn tubes unfavorable.
For steel and fibrous tissue appears dislocations, vacancies and other crystal defects are generally taken annealing or normalizing heat treatment methods to eliminate them. The purpose is to refine the grain annealing to remove tissue defects, reduce hardness, improved ductility, but also facilitate cold. Cold drawn seamless steel pipe production, annealing equipment is indispensable, therefore, to develop an appropriate annealing process is to ensure that cold drawn seamless organization qualified defective product is not a necessary condition for a fracture. If the manufacturers in order to unilaterally reduce production costs, reduce the annealing process is bound to adversely affect the quality of products.
At present, cold drawn seamless steel tubes are made of ordinary 45 # or 20 # steel 27SiMn steel, cold drawn deformed through the metal strength; however, it is at the expense of metal ductility, toughness for the price. Precision cold drawn seamless steel is its high dimensional accuracy and high strength properties and based on the market, it must ensure that the amount of deformation in a certain range, in order to maximize the performance of materials, to reduce the material adversely affected.
Cold drawn seamless steel pipe deformation is too small to reach the surface finish and dimensional accuracy requirements, but also unable to reach members of the strength index; deformation is too large, seamless plasticity, toughness decreases too much, but the grain is pulled excessively elongate, forming a fibrous tissue, a significant anisotropy metals. Cold drawn seamless steel tube in the axial direction, parallel to the elongate direction of the grain, the intensity increased; cold drawn seamless radially perpendicular to the elongated direction of the grain, but lower strength, and maximum stress of the hydraulic cylinder is present in the radial direction of seamless, so much distortion on the performance of fully drawn tubes unfavorable.
For steel and fibrous tissue appears dislocations, vacancies and other crystal defects are generally taken annealing or normalizing heat treatment methods to eliminate them. The purpose is to refine the grain annealing to remove tissue defects, reduce hardness, improved ductility, but also facilitate cold. Cold drawn seamless steel pipe production, annealing equipment is indispensable, therefore, to develop an appropriate annealing process is to ensure that cold drawn seamless organization qualified defective product is not a necessary condition for a fracture. If the manufacturers in order to unilaterally reduce production costs, reduce the annealing process is bound to adversely affect the quality of products.
Uses of precision seamless tube
It is a precision seamless cold drawn or hot processed through a high-precision steel material. Because precision steel outer wall oxide layer to withstand high pressure without leakage, high-precision, high-quality finish, cold deformation, flaring, flattening without cracks a bit, so the main pneumatic or hydraulic components used in the production of products, such as cylinder or cylinder, which can be seamless, there are also welded pipe.
Precision seamless mostly machinery manufacturers procurement, used to make some of the parts, a very wide range of applications. Precision seamless features are so many, such as high-precision, high pressure, cold deformation, flaring flattening without cracks, high-quality finish, scale, etc., against the pull, fight with good mechanical properties, high precision to mechanical processing saves processing time user feed loss, and many specifications, the application range is very wide, steel superior performance comparison, relatively dense metal, but can also be made pipe diameter hexagonal. Precision seamless pipe, compared with the general, in bending and torsional strength is consistent, comparable lighter weight, is an economic cross-section steel, manufacture of structural parts and mechanical parts industry for more use. Precision seamless and seamless compared to their advantage is the same, but with the same precision seamless own merits, for the manufacture of annular parts, but also can improve utilization, simplify processes, etc., like the jack sets are using precision seamless tube manufacturing. Precision Steel can not only improve efficiency, but also can reduce the manufacturing processes and equipment investment, cost savings and working hours, increased production and utilization of materials, but also can help improve product quality, reduce costs, companies can improve economic efficiency, but precision seamless tube seamless than the average price but also high point.
Precision seamless mostly machinery manufacturers procurement, used to make some of the parts, a very wide range of applications. Precision seamless features are so many, such as high-precision, high pressure, cold deformation, flaring flattening without cracks, high-quality finish, scale, etc., against the pull, fight with good mechanical properties, high precision to mechanical processing saves processing time user feed loss, and many specifications, the application range is very wide, steel superior performance comparison, relatively dense metal, but can also be made pipe diameter hexagonal. Precision seamless pipe, compared with the general, in bending and torsional strength is consistent, comparable lighter weight, is an economic cross-section steel, manufacture of structural parts and mechanical parts industry for more use. Precision seamless and seamless compared to their advantage is the same, but with the same precision seamless own merits, for the manufacture of annular parts, but also can improve utilization, simplify processes, etc., like the jack sets are using precision seamless tube manufacturing. Precision Steel can not only improve efficiency, but also can reduce the manufacturing processes and equipment investment, cost savings and working hours, increased production and utilization of materials, but also can help improve product quality, reduce costs, companies can improve economic efficiency, but precision seamless tube seamless than the average price but also high point.
Thursday, July 11, 2013
Welding speed and rust performance of high-frequency welded pipe
In general, high-frequency welded pipe during welding, the welding quality and welding speed are related. As the heating time can be shortened, the time the metal oxide shortened, therefore, the quality of the welding speed and the welding speed with increased.
If the welding speed is reduced, so that the heating zone will not only wider, but also with the molten zone width and change the heat input and thus the formation of burrs is large, so the high-frequency welded pipe, the welding equipment and the unit should be means the maximum allowable speed according to different specifications and varieties select the appropriate welding speed.
In order to achieve high-frequency welded pipe rust the desired effect, according to the choice of materials abrasive surface hardness and high frequency welded pipe extent of corrosion, surface roughness, for reasonable operation. Meanwhile, in order to achieve the desired effect of rust, for single-layer epoxy, two or three layers polyethylene coating should be mixed abrasive grit and steel shot to operate.
If the welding speed is reduced, so that the heating zone will not only wider, but also with the molten zone width and change the heat input and thus the formation of burrs is large, so the high-frequency welded pipe, the welding equipment and the unit should be means the maximum allowable speed according to different specifications and varieties select the appropriate welding speed.
In order to achieve high-frequency welded pipe rust the desired effect, according to the choice of materials abrasive surface hardness and high frequency welded pipe extent of corrosion, surface roughness, for reasonable operation. Meanwhile, in order to achieve the desired effect of rust, for single-layer epoxy, two or three layers polyethylene coating should be mixed abrasive grit and steel shot to operate.
Performance and application of welded pipe
For the welded pipe, the quality of the weld is to determine the performance of the main factors that are seen in the winter heating water pipe or pipes are to be frozen explosion things, in general, where the burst are generally weld.
The seamless tube Longitudinal resistance and scope of its application. Longitudinal if you want to develop rapidly, it is important to achieve a seamless way, through the seamless pipe, the pipe manufacturer can not only improve the efficiency, but also can greatly jiangdu costs of users, so it is economically viable. Therefore, seamless pipes of its development is an inevitable trend. In water engineering, chemical industry, agriculture irrigation, urban construction, Longitudinal has widely used, but also can be transported as a liquid water supply, drainage, as a gas, vapor and other gases in transport, as docks, roads, building structure tube. In short, Longitudinal activities in modern life, have been widely used, is indispensable.
The seamless tube Longitudinal resistance and scope of its application. Longitudinal if you want to develop rapidly, it is important to achieve a seamless way, through the seamless pipe, the pipe manufacturer can not only improve the efficiency, but also can greatly jiangdu costs of users, so it is economically viable. Therefore, seamless pipes of its development is an inevitable trend. In water engineering, chemical industry, agriculture irrigation, urban construction, Longitudinal has widely used, but also can be transported as a liquid water supply, drainage, as a gas, vapor and other gases in transport, as docks, roads, building structure tube. In short, Longitudinal activities in modern life, have been widely used, is indispensable.
High frequency welded pipe welding process
The process is the first high-frequency welded pipe uncoiling, flattening, on the head and tail cut, weld on steel with the right looper material storage, you can shape it. After molding is welded, remove burrs, its inspection, pipe straightening, and finally hydrostatic testing, flaw detection, all work ready after that finished it.
Typically, high-frequency welded pipe welding process welding speed is the main parameters, the speed and the heating system, weld deformation speed, and the speed of each crystal are all related. Frequency welded pipe welding quality also with welding speed and progressive. This is because the high-frequency welded to shorten heating time, leaving the edge of the heated zone width is narrowed, greatly limits shortening the time of forming a metal oxide. If the welding speed is too low, it will not only widens the heating zone, but also with the input of the molten zone width and change into heat, a large burr is formed inside, resulting in problems.
Typically, high-frequency welded pipe welding process welding speed is the main parameters, the speed and the heating system, weld deformation speed, and the speed of each crystal are all related. Frequency welded pipe welding quality also with welding speed and progressive. This is because the high-frequency welded to shorten heating time, leaving the edge of the heated zone width is narrowed, greatly limits shortening the time of forming a metal oxide. If the welding speed is too low, it will not only widens the heating zone, but also with the input of the molten zone width and change into heat, a large burr is formed inside, resulting in problems.
Straight seam steel pipe corrosion
Straight seam steel pipe joints get rid of corrosion passivation of iron and aluminum in dilute HNO3 or dilute H2SO4 solution can be quickly dissolved, but in concentrated HNO3 or dissolved in concentrated H2SO4 appearance almost completely halted, ordinary carbon steel pipe rust very briefly, if the steel participate in excess Ni, Cr, stainless steel has become a. Metal or alloy by a number of factors influence significantly enhanced chemical stability, appearance, known as passivation. By some of the passivation agent (chemicals) are caused by the appearance of metal passivation called chemical passivation. Such as concentrated HNO3, concentrated H2SO4, HClO3, K2Cr2O7, KMnO4 and other oxidants can make metal passivation. A reactive metal or alloy, during chemical activity greatly decreased, and the appearance of a precious metal condition, called passivation. Because the effects of the media generated metal corrosion products if a fine layout constitute a film, tight appearance of the metal cover, changing the apparent condition of the metal, the metal to the positive electrode potential Fangxiang Yue greatly changed, and a corrosion resistant passive.
Straight seam steel pipe get rid of corrosion of metal passivation, its electrode potential move in the positive direction, so that it lost its original features, such as passivation of iron in copper can not displace copper. In addition, the electrochemical approach also allows metal passivation, as will be placed in H2SO4 solution Fe as the anode, the anode with impressed current polarization, the choice of instruments will certainly increase the potential extent of iron, Fe on the passivation.
Straight seam steel pipe get rid of corrosion of metal passivation, its electrode potential move in the positive direction, so that it lost its original features, such as passivation of iron in copper can not displace copper. In addition, the electrochemical approach also allows metal passivation, as will be placed in H2SO4 solution Fe as the anode, the anode with impressed current polarization, the choice of instruments will certainly increase the potential extent of iron, Fe on the passivation.
The status of spiral steel pipe
Spiral steel pipe under the impact of high-speed fluid, the protective film damage, break at the bare metal accelerate corrosion. If the fluid contains solid particles, spiral steel pipe corrosion and wear is even more serious. Spiral steel pipe surface by high velocity impact and turbulence of the fluid-like, and to abrasion and corrosion damage, known corrosion and wear. Its exterior features are: localized grooves, corrugated, round and valleys shaped, usually show directionality. Exposed to the movement of fluid in equipment such as: pipes, tees, valves, blowers, centrifuges, impellers, heat exchangers, exhaust duct, etc. can have an impact corrosion. Soft metals such as copper and lead more serious.
You can choose to prevent the impact corrosion resistance, wear better materials, such as Alloy 20 is better than 18/8 stainless steel, 90Cu/10Ni superior 70Cu/30Ni (sea water), but also improve the design, changing the environment, or coating and cathodic protection. Impact corrosion occurred in parts of the fluid to change direction. Such as elbows, tees, cyclone separator, container and inlet tube relative to the site.
You can choose to prevent the impact corrosion resistance, wear better materials, such as Alloy 20 is better than 18/8 stainless steel, 90Cu/10Ni superior 70Cu/30Ni (sea water), but also improve the design, changing the environment, or coating and cathodic protection. Impact corrosion occurred in parts of the fluid to change direction. Such as elbows, tees, cyclone separator, container and inlet tube relative to the site.
Longitudinal welded pipe fracture
The study found that people when the temperature drops below a certain temperature value, the data will be found to brittle state, the impact absorbed energy decreased, a phenomenon known as cold brittleness, high strength metallic materials brittle fracture occurred in low stress process, the data is far from homogeneous isotropic tissue organization have cracks, there will be inclusions, porosity and other defects, which are a material can be seen in the micro-cracks. Therefore, the design also according to the operating temperature of components to select cold-brittle transition temperature with the appropriate information.
Generally data are assumed to be homogeneous isotropic continuous analysis that this approach is based on the design of safe, and sometimes accidental breakage incidents. As hot-rolled tube defects such as cracks or high-precision cold drawn tube is made after the tank, cold drawn seamless. Breakage occurs during use, almost no plastic deformation occurs, in general are brittle fracture. Brittle fracture caused by a variety of reasons, such as: precipitates on the grain boundaries, regardless of the intensity ratio of the matrix strength strong or weak, are all causes cracks; grain boundary segregation of inclusions also cause fracture; addition, even in far less than the yield limit alternating loads can also cause fatigue fracture phenomena.
Generally data are assumed to be homogeneous isotropic continuous analysis that this approach is based on the design of safe, and sometimes accidental breakage incidents. As hot-rolled tube defects such as cracks or high-precision cold drawn tube is made after the tank, cold drawn seamless. Breakage occurs during use, almost no plastic deformation occurs, in general are brittle fracture. Brittle fracture caused by a variety of reasons, such as: precipitates on the grain boundaries, regardless of the intensity ratio of the matrix strength strong or weak, are all causes cracks; grain boundary segregation of inclusions also cause fracture; addition, even in far less than the yield limit alternating loads can also cause fatigue fracture phenomena.
Wednesday, July 10, 2013
Detection method of straight seam piling pipe after weld reinforcement
Straight seam piling pipe finished weld reinforcement detection methods are mainly the following:
First, the physical method for testing: testing the physical phenomena is measured using some physical or testing methods. Material or workpiece internal defects of the inspection, are generally used NDT methods. There are currently NDT ultrasonic testing, radiography, penetrant testing, magnetic testing and so on.
Density test: Storage containers of liquid or gas welding, the weld is not dense defects, such as penetrating cracks, porosity, slag, incomplete penetration and loose tissue, etc., can be used to find the density test. Density test methods are: kerosene test, ballast water test, water will test.
Judgment on the surface, which is in appearance inspection. Visual inspection of welded joints is a widely used procedure is simple but testing methods, is an important element of product testing is mainly found in the weld surface defects and size bias. Generally observed by the naked eye, with the standard model, gauges and inspection tools such as a magnifying glass. If the weld surface defects, weld defects there may be internal.
Pressure vessel strength testing: pressure vessels, in addition to tightness test, but also a strength test. Common with hydrostatic testing and pressure testing two kinds. They can work under pressure testing containers and piping welds compactness. Pressure test is more sensitive than the hydrostatic test and speed, while testing the product after processing without drainage, drainage problems for products is particularly applicable. But the test is more dangerous than a large hydrostatic test. When tested, it must comply with the appropriate safety precautions to prevent accidents during the test.
First, the physical method for testing: testing the physical phenomena is measured using some physical or testing methods. Material or workpiece internal defects of the inspection, are generally used NDT methods. There are currently NDT ultrasonic testing, radiography, penetrant testing, magnetic testing and so on.
Density test: Storage containers of liquid or gas welding, the weld is not dense defects, such as penetrating cracks, porosity, slag, incomplete penetration and loose tissue, etc., can be used to find the density test. Density test methods are: kerosene test, ballast water test, water will test.
Judgment on the surface, which is in appearance inspection. Visual inspection of welded joints is a widely used procedure is simple but testing methods, is an important element of product testing is mainly found in the weld surface defects and size bias. Generally observed by the naked eye, with the standard model, gauges and inspection tools such as a magnifying glass. If the weld surface defects, weld defects there may be internal.
Pressure vessel strength testing: pressure vessels, in addition to tightness test, but also a strength test. Common with hydrostatic testing and pressure testing two kinds. They can work under pressure testing containers and piping welds compactness. Pressure test is more sensitive than the hydrostatic test and speed, while testing the product after processing without drainage, drainage problems for products is particularly applicable. But the test is more dangerous than a large hydrostatic test. When tested, it must comply with the appropriate safety precautions to prevent accidents during the test.
Spiral steel pipe manufacturing method of insulation technology
Spiral steel pipe thermal insulation method of inhibiting them from the start of a process, such as anti-corrosion coating on the pipe wall plus, loop resistance can be increased, reducing the corrosion current; external DC power supply, so that the soil pipe causing negative potential, the formation of cathodic protection can eliminate anode potential difference, a fundamental process for stopping the anode and cathode. anticorrosion coating rule table, cathodic protection of the rule of law, but once the anti-corrosion coating is damaged, exposed iron parts will accelerate localized corrosion. therefore anti-corrosion coating and cathodic protection is the table of the combined method of treating both, economical and effective. U.S. and other countries have been clearly defined, using the anti-corrosion coating cathodic protection must be used at the same time.
But for the city gas system, due to intensive underground pipe network, external power cathodic protection to other pipeline interference, can cause its own benefit, his family situation of the victims, while using a negative potential than the metal pipe spiral pipe connected with sacrificial anode law does not appear to protect such cases, therefore, the city's gas mains gas should be used to anticorrosion coating combined with sacrificial anode corrosion methods for other non-main pipeline pressure is low, then the anti-corrosion coating method generally used directly .
Buried gas pipeline insulation currently used mainly in the outer layer PE anti-corrosion coating composite structure, epoxy powder, coal tar enamel, coal tar epoxy and PE tape and other five categories. Layer PE composite structure, anti-corrosion epoxy powder coating performance, and therefore the United States and Europe the main buried pipeline anticorrosion coating in our country, from the useful life, maintenance costs and other comprehensive economic factors to consider, generally preferred anti-corrosion coating layer PE composite structure.
But for the city gas system, due to intensive underground pipe network, external power cathodic protection to other pipeline interference, can cause its own benefit, his family situation of the victims, while using a negative potential than the metal pipe spiral pipe connected with sacrificial anode law does not appear to protect such cases, therefore, the city's gas mains gas should be used to anticorrosion coating combined with sacrificial anode corrosion methods for other non-main pipeline pressure is low, then the anti-corrosion coating method generally used directly .
Buried gas pipeline insulation currently used mainly in the outer layer PE anti-corrosion coating composite structure, epoxy powder, coal tar enamel, coal tar epoxy and PE tape and other five categories. Layer PE composite structure, anti-corrosion epoxy powder coating performance, and therefore the United States and Europe the main buried pipeline anticorrosion coating in our country, from the useful life, maintenance costs and other comprehensive economic factors to consider, generally preferred anti-corrosion coating layer PE composite structure.
Spiral piling pipe anti-corrosion technology
Since the quality of the individual spiral piling pipe is relatively large, it must be stacked in the outdoors, but this will be difficult to avoid the sun and rain, so the rusty spiral piling pipe has been plagued by storage time and conditions. So we have the need for knowledge about the spiral welded pipe rust comprehensive answers.
The main use of tools such as a wire brush to polish the surface of the steel, spiral welded pipe cleaning and preheating can remove loose or warped oxide, rust, welding slag. Hand tools rust can reach Sa2 grade power tools rust Sa3 level can be achieved, if the steel surface firmly attached to the iron skin, the effect is not ideal tools rust, anti-corrosion construction required to reach the depth of anchor pattern. Acid by solvent, emulsion cleaning fluid pressure welded steel pipe (pipe) surfaces to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, oxide, flux, etc., Therefore, in the production of corrosion only as an adjunct. Generally use two methods to do chemical and electrolytic pickling treatment, pipeline corrosion using only chemical pickling can descaling, rust, old paint, sometimes used as a sand blasting after reprocessing. Although chemical cleaning can achieve a certain surface cleanliness and roughness, but the anchor pattern shallow, and easy on the environment caused by pollution stacking spiral welded pipe.
The main use of tools such as a wire brush to polish the surface of the steel, spiral welded pipe cleaning and preheating can remove loose or warped oxide, rust, welding slag. Hand tools rust can reach Sa2 grade power tools rust Sa3 level can be achieved, if the steel surface firmly attached to the iron skin, the effect is not ideal tools rust, anti-corrosion construction required to reach the depth of anchor pattern. Acid by solvent, emulsion cleaning fluid pressure welded steel pipe (pipe) surfaces to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, oxide, flux, etc., Therefore, in the production of corrosion only as an adjunct. Generally use two methods to do chemical and electrolytic pickling treatment, pipeline corrosion using only chemical pickling can descaling, rust, old paint, sometimes used as a sand blasting after reprocessing. Although chemical cleaning can achieve a certain surface cleanliness and roughness, but the anchor pattern shallow, and easy on the environment caused by pollution stacking spiral welded pipe.
Tuesday, July 9, 2013
Bending reasons of large diameter piling pipe
Processing large diameter piling pipe to a certain length, then there is certainly a bend in the steel is a phenomenon often encountered and circumstances. Large diameter piling pipe is due to uneven along the longitudinal direction of the pipe at the bottom or on the occurrence of such a curved shape, commonly known as "goose head bent."
The major causes bending, artificial heat checks, the local water caused; straightening improper adjustment, straightening rolls badly worn arising; lifting and transportation of bending caused; sizing machining, assembly and improper adjustment can also be possible.
For the occurrence of large diameter pipe bending, if it is excessive curvature, it can be secondary re-straightening, but if it is unable to straightening of the "goose head bent" removal treatment should be given. In addition, the large diameter steel pipe production process, can not be very accurate due to several rolls in a straight line, so it is easy to bend, the solution is to increase the number of these rollers and distance.
The major causes bending, artificial heat checks, the local water caused; straightening improper adjustment, straightening rolls badly worn arising; lifting and transportation of bending caused; sizing machining, assembly and improper adjustment can also be possible.
For the occurrence of large diameter pipe bending, if it is excessive curvature, it can be secondary re-straightening, but if it is unable to straightening of the "goose head bent" removal treatment should be given. In addition, the large diameter steel pipe production process, can not be very accurate due to several rolls in a straight line, so it is easy to bend, the solution is to increase the number of these rollers and distance.
The method of connecting pipe
In fact, when a pipe connected to a very simple matter, without the need for any special expertise and skills. Only the outer surface of the pipe grooving extruded to a grooved pipe, the pipe will not damage the inner wall structure, which is connected to the unique advantages of pipe.
Technical part of the fine pipe products have been incorporated into the finished product to go, a tube on the connection only takes a few minutes only, the greatest degree of difficulty of the operation simplifies field, saving time, stable quality, improve work efficiency, workers need only a simple training can be work.
Although the use of connection pipe connection technology, construction organization convenient, but need to be equipped complex power cables, cutting tools, etc., which brings a certain complexity, but also increases the leakage and fire hazard may occur. While welding and cutting the resulting weld slag, the fall can not be placed inside of the pipe, easy to plug the device will contaminate water inside the tube.
Technical part of the fine pipe products have been incorporated into the finished product to go, a tube on the connection only takes a few minutes only, the greatest degree of difficulty of the operation simplifies field, saving time, stable quality, improve work efficiency, workers need only a simple training can be work.
Although the use of connection pipe connection technology, construction organization convenient, but need to be equipped complex power cables, cutting tools, etc., which brings a certain complexity, but also increases the leakage and fire hazard may occur. While welding and cutting the resulting weld slag, the fall can not be placed inside of the pipe, easy to plug the device will contaminate water inside the tube.
Sided submerged arc welding straight seam steel pipe technology
Double submerged arc welded (LSAW-Longitudinal Submerged Arc Welded) was invented in 1940, a new welding method, it and the front of the manual welding the same place or the use of slag to protect it, but this is not a slag electrode coating . Straight seam double submerged arc welding and manual welding the same place or the use of slag to protect it, but this is not a slag electrode coating, is designed out of the melting flux. The flux system consists of a funnel filled with flux through a pipeline to be welded to the front. The second difference is not used electrode using wire, because the wire can be continuously sent; electrode, we gotta burn a welding electrode head gave a throw, and the operation was stopped, and then for electrode welding.
In this way, the first advantage is fully automated; second advantage, it is carried out under submerged arc welding, the heat exchange and so it is relatively strong protection performance, higher quality weld out; third advantage as submerged arc welding arc welding flux buried underneath, so it can use a large current, welding efficiency is relatively high, the recent progress of our country's natural gas pipeline project. After wire changed, with the delivery device and the wire coil wire, the wire is continuously sent, this welding process is continuous feeding of the wire and the solder to melt under the coverage of the particulate ignition of the arc, the welding wire, base material and flux melting and evaporation constitute part of a cavity, the cavity inside the arc is stable combustion, so call it submerged arc welding. Arc is buried inside the cavity. Pipe is a high-strength steel, this pipe prefabricated in the factory inside the first paragraph, and then get on the site, in the field welding, this pipeline in the factory production process is the use of submerged arc welding, submerged arc now has become, a double wire submerged arc welding, as well as multi-wire submerged arc welding, to further improve efficiency.
In this way, the first advantage is fully automated; second advantage, it is carried out under submerged arc welding, the heat exchange and so it is relatively strong protection performance, higher quality weld out; third advantage as submerged arc welding arc welding flux buried underneath, so it can use a large current, welding efficiency is relatively high, the recent progress of our country's natural gas pipeline project. After wire changed, with the delivery device and the wire coil wire, the wire is continuously sent, this welding process is continuous feeding of the wire and the solder to melt under the coverage of the particulate ignition of the arc, the welding wire, base material and flux melting and evaporation constitute part of a cavity, the cavity inside the arc is stable combustion, so call it submerged arc welding. Arc is buried inside the cavity. Pipe is a high-strength steel, this pipe prefabricated in the factory inside the first paragraph, and then get on the site, in the field welding, this pipeline in the factory production process is the use of submerged arc welding, submerged arc now has become, a double wire submerged arc welding, as well as multi-wire submerged arc welding, to further improve efficiency.
Production process of hot-rolled seamless steel pipe
Hot-rolled seamless steel ingot is made of perforated or solid tube capillary tube, and then hot rolled steel. Hot-rolled seamless steel tube industry in China has an important position.
Hot-rolled seamless steel tube material is round, after cutting machine processed into 1 m blank, and by conveyor belt to the furnace heating, a temperature of about 1200 degrees Celsius, the fuel is hydrogen or acetylene. Round tube came out after pressure punching machine wear air. After perforation, round tube has been three roll rolling, rolling or extrusion. Squeeze off the tube after sizing. Sizing mill rotating at high speed through a cone drill holes into the billet to form pipe. Pipe diameter from the sizing mill to determine the length of the drill diameter. The pipe sizing after entering the cooling tower through water cooling pipe after cooling, will be straightening.
Steel belt sent by straightening the metal detection machine (or water pressure test) for internal testing. If the pipe internal cracks, bubbles and other problems will be detected. Steel quality even after rigorous hand-selected. Steel quality, the use of spray paint number, size, production batch number. Hanging by a crane into the warehouse.
Hot-rolled seamless steel tube material is round, after cutting machine processed into 1 m blank, and by conveyor belt to the furnace heating, a temperature of about 1200 degrees Celsius, the fuel is hydrogen or acetylene. Round tube came out after pressure punching machine wear air. After perforation, round tube has been three roll rolling, rolling or extrusion. Squeeze off the tube after sizing. Sizing mill rotating at high speed through a cone drill holes into the billet to form pipe. Pipe diameter from the sizing mill to determine the length of the drill diameter. The pipe sizing after entering the cooling tower through water cooling pipe after cooling, will be straightening.
Steel belt sent by straightening the metal detection machine (or water pressure test) for internal testing. If the pipe internal cracks, bubbles and other problems will be detected. Steel quality even after rigorous hand-selected. Steel quality, the use of spray paint number, size, production batch number. Hanging by a crane into the warehouse.
Spiral pipe applications in the construction industry
Spiral steel pipe is the industrial, construction and other industries widely used kind of steel. It is a strip coil as raw material, often warm extrusion molding, with
automatic double-sided submerged arc welding process wire spiral welded steel tube. Mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction.
Spiral steel pipe 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. It is in the transportation of gas, transportation has played a significant role.
Spiral steel pipe pressure transmission fluid with spiral submerged arc welded pipe is mainly used to transport oil, natural gas pipeline; pressure transmission fluid with frequency spiral welded steel pipes, lap welding method with high frequency welding, pressure fluid transport frequency spiral welded steel pipe. Strong pressure steel, plastic, and easy welding and machining molding; generally low pressure liquid delivery spiral submerged arc welded pipe, using double-sided automatic submerged arc welding or welding into the legal system for water, gas, air and steam low pressure liquid delivery SAW pipe. Longitudinal generally higher than its strength, can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight pipe joints than weld length of 30 to 100%, and lower production rate. Therefore, the smaller diameter pipe is mostly a straight seam welded, large diameter spiral welded pipe is mostly used steel tube and solid steel bar, etc. compared to the same torsional strength in bending, lighter, is an economic cross-section steel, widely used in the manufacture of structural parts and mechanical parts, construction using steel scaffolding. With steel pipe manufacturing annular parts, can improve material utilization, simplify the manufacturing process, saving material and machining time, such as bearing rings, jack sets, has been widely used to make steel. Steel or a variety of conventional weapons indispensable material, barrel, barrel, etc. to make steel. By cross-sectional shape of the pipe can be divided into tube and shaped tubes. Since the perimeter of equal conditions, the maximum area of a circle with a circular tube can carry more fluid. In addition, the circular cross section to withstand internal or external radial pressure, the stress is uniform. Spiral Pipe closely with our lives, our drainage, exhaust, gas, gas can not be separated with the help of spiral steel pipe.
automatic double-sided submerged arc welding process wire spiral welded steel tube. Mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction.
Spiral steel pipe 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. It is in the transportation of gas, transportation has played a significant role.
Spiral steel pipe pressure transmission fluid with spiral submerged arc welded pipe is mainly used to transport oil, natural gas pipeline; pressure transmission fluid with frequency spiral welded steel pipes, lap welding method with high frequency welding, pressure fluid transport frequency spiral welded steel pipe. Strong pressure steel, plastic, and easy welding and machining molding; generally low pressure liquid delivery spiral submerged arc welded pipe, using double-sided automatic submerged arc welding or welding into the legal system for water, gas, air and steam low pressure liquid delivery SAW pipe. Longitudinal generally higher than its strength, can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight pipe joints than weld length of 30 to 100%, and lower production rate. Therefore, the smaller diameter pipe is mostly a straight seam welded, large diameter spiral welded pipe is mostly used steel tube and solid steel bar, etc. compared to the same torsional strength in bending, lighter, is an economic cross-section steel, widely used in the manufacture of structural parts and mechanical parts, construction using steel scaffolding. With steel pipe manufacturing annular parts, can improve material utilization, simplify the manufacturing process, saving material and machining time, such as bearing rings, jack sets, has been widely used to make steel. Steel or a variety of conventional weapons indispensable material, barrel, barrel, etc. to make steel. By cross-sectional shape of the pipe can be divided into tube and shaped tubes. Since the perimeter of equal conditions, the maximum area of a circle with a circular tube can carry more fluid. In addition, the circular cross section to withstand internal or external radial pressure, the stress is uniform. Spiral Pipe closely with our lives, our drainage, exhaust, gas, gas can not be separated with the help of spiral steel pipe.
Monday, July 8, 2013
Spiral piling pipe butt weld joints crack
Defect is connected by its nature, quantity, causes and there were all located at different extent, weakened the performance of welded joints, and also reduces its welded steel performance.
Spiral piling pipe welding defects, such as porosity, slag, incomplete fusion, incomplete penetration welds and other defects have reduced the cross-sectional dimensions and gold session densification; open type cracks, cracks and weld root interlaminar cracks on the degree of harm more serious. For the weld can be checked by ultrasonic flaw detection, radiography examination, penetrate, magnetic particle, eddy current testing and other means to determine the weld quality is satisfactory, you can also take the appropriate repair measures to eliminate defects, to reach qualified targets. However, non-destructive testing methods can only detect the static quality of the weld, and for the spiral steel pipe welded structure in the course of changes in the quality weld bead is very difficult to implement the pre-detection; while those at risk of defects in the structure before the course gradually exposed, and even lead to catastrophic accidents. Cracks, especially delayed cracking, sudden brittle fracture are some categories of dangerous defects.
Spiral piling pipe welding defects, such as porosity, slag, incomplete fusion, incomplete penetration welds and other defects have reduced the cross-sectional dimensions and gold session densification; open type cracks, cracks and weld root interlaminar cracks on the degree of harm more serious. For the weld can be checked by ultrasonic flaw detection, radiography examination, penetrate, magnetic particle, eddy current testing and other means to determine the weld quality is satisfactory, you can also take the appropriate repair measures to eliminate defects, to reach qualified targets. However, non-destructive testing methods can only detect the static quality of the weld, and for the spiral steel pipe welded structure in the course of changes in the quality weld bead is very difficult to implement the pre-detection; while those at risk of defects in the structure before the course gradually exposed, and even lead to catastrophic accidents. Cracks, especially delayed cracking, sudden brittle fracture are some categories of dangerous defects.
Spiral pipe forming methods and causes internal stress
Spiral welded steel pipe in the petrochemical, heat pipe network and urban water supply and drainage works and piling pipe construction and other fields have a wide range of applications, especially in the long-distance transportation of oil pipeline and natural gas pipelines are more widely used. Oil, gas pipeline network almost all spiral welded steel pipe, with high security, durability and economic rationality. Since the diameter of the spiral welded steel sheet width generally not limited, by a variety of different specifications of the plate width coil manufacture, so no wide plate width of the plate. This gives plate manufacturing, transportation convenience, the use of flat steel strip ratio much lower price, suitable for China's actual situation. Spiral welded steel pipe there is a problem produce elastic recovery after welding steel pipe, steel pipe previously exposed to the equivalent one circumferential tensile stress, the stress will produce stress corrosion and reduced ability of the pressure tube.
Spiral welded steel pipe using a continuous forming, welding fabrication method, is now widely used within and outside deck holds two kinds of molding method, forming rolls and rolls made within (or outside hold rolls) composed of a shaper plate along the arrow fed to the forming device in the direction, while forming the side weld. Molding can be obtained by adjusting the different sizes of the pipe. In order to prevent excessive bending, forming rolls three points of contact with the plate height is generally not much difference, manufacturers have adopted an insufficient amount molding, pipe made within the radius of curvature is to rely on roll (or external hold rolls) formed by the radius of curvature that in within each roll (or external hold rolls) in the elastic and plastic plates are actually mixed deformation. Spiral welded steel pipe cut open along the generatrix direction, there must be a certain amount of circumferential openings, namely the existence of certain steel pipe bomb complex quantity, steel residual stress exists. Since the existence of internal stress, steel external tensile stress, so this will reduce the ability of the pressure tube, increasing the external pipe corrosion, to adversely affect the use of steel. Many studies have discussed in detail the tone type parameters (forming roll positional parameters) on the amount of complex pipe bomb, but the actual parameters and by the whole steel welded steel tube mill parameters, can only be imprecise quantitative analysis. In fact at the various spiral pipe manufacturers are relying on experience, probably forming roller position adjusting parameters, and then producing a steel pipe, steel pipe is cut open along the bus to check whether the amount of the opening meet customer requirements. Is not very important for the steel (such as water pipes) is not limited to the opening size of the steel pipe.
Spiral welded steel pipe using a continuous forming, welding fabrication method, is now widely used within and outside deck holds two kinds of molding method, forming rolls and rolls made within (or outside hold rolls) composed of a shaper plate along the arrow fed to the forming device in the direction, while forming the side weld. Molding can be obtained by adjusting the different sizes of the pipe. In order to prevent excessive bending, forming rolls three points of contact with the plate height is generally not much difference, manufacturers have adopted an insufficient amount molding, pipe made within the radius of curvature is to rely on roll (or external hold rolls) formed by the radius of curvature that in within each roll (or external hold rolls) in the elastic and plastic plates are actually mixed deformation. Spiral welded steel pipe cut open along the generatrix direction, there must be a certain amount of circumferential openings, namely the existence of certain steel pipe bomb complex quantity, steel residual stress exists. Since the existence of internal stress, steel external tensile stress, so this will reduce the ability of the pressure tube, increasing the external pipe corrosion, to adversely affect the use of steel. Many studies have discussed in detail the tone type parameters (forming roll positional parameters) on the amount of complex pipe bomb, but the actual parameters and by the whole steel welded steel tube mill parameters, can only be imprecise quantitative analysis. In fact at the various spiral pipe manufacturers are relying on experience, probably forming roller position adjusting parameters, and then producing a steel pipe, steel pipe is cut open along the bus to check whether the amount of the opening meet customer requirements. Is not very important for the steel (such as water pipes) is not limited to the opening size of the steel pipe.
Manual welding thick-walled steel pipe
Thick-walled steel pipe welding method is the most commonly used manual welding, manual welding is a very common, easy to use welding methods arc length is adjusted by human hands, it depends on the gap between the electrodes and the workpiece the size of the same time, when the carrier as the arc when welding the weld filler material also.
This welding thick-walled steel pipe method is very simple and can be used to weld almost all materials for outdoor use, it has good adaptability, even in the underwater use have no problem. Most welders can TIG welding electrode welding , the arc length determined by the human hand: when you change the gap electrode and the workpiece, you have to change the length of the arc, in most cases, welding using direct current, the arc electrode both as carrier and also as filler weld material from the alloy or non-alloy electrode metal core wire and the electrode coating composition of this layer of coating to protect the weld from air violations, while stabilizing the arc it also caused the formation of slag layer to protect the weld it shape. welding bars to titanium type electrode, but also seal in nature, depending on the coating thickness and composition. titanium rod easy to weld, weld flat appearance. Additionally, welding slag is easy to remove if the rod storage for a long time, must be re-baked roast because moisture from the air will quickly accumulate in the electrode, so says manual welding thick steel is the most commonly used method.
This welding thick-walled steel pipe method is very simple and can be used to weld almost all materials for outdoor use, it has good adaptability, even in the underwater use have no problem. Most welders can TIG welding electrode welding , the arc length determined by the human hand: when you change the gap electrode and the workpiece, you have to change the length of the arc, in most cases, welding using direct current, the arc electrode both as carrier and also as filler weld material from the alloy or non-alloy electrode metal core wire and the electrode coating composition of this layer of coating to protect the weld from air violations, while stabilizing the arc it also caused the formation of slag layer to protect the weld it shape. welding bars to titanium type electrode, but also seal in nature, depending on the coating thickness and composition. titanium rod easy to weld, weld flat appearance. Additionally, welding slag is easy to remove if the rod storage for a long time, must be re-baked roast because moisture from the air will quickly accumulate in the electrode, so says manual welding thick steel is the most commonly used method.
The main large diameter welded pipe production methods
Used to transport large diameter pipe, manufactured using various welding methods, such as using electric arc welding under flux layer, the contact resistance welding, flash welding and other welding and high frequency currents. Press the seam can be divided into straight seam welded and spiral welded two ways, straight seam welding production process is composed of the following main steps: forming tube within the model to make double-sided welding, welded steel tube imposed on small expanding.
The method currently used is the most complete with a huge three-step molding production press with die no longitudinal joints 12 meters long pipe, and the shape and size are very accurate. The gas pipeline is the most common method used solvent layer under the double seam welding speeds of up to 140 ^ -150 m / hour. Soldering should be repaired weld, then cut the head and pipe sizing. The modern sizing method is applied to the inner pipe hydraulic diameter to the expansion diameter of 1.5-2.5% pots, fixed length to diameter, on the other hand to improve the yield limit of about 20%.
Nickel is an excellent corrosion-resistant materials, is an important alloying element in steel. Nickel is the formation of austenite in the steel elements, but to obtain pure carbon-nickel austenitic steels, nickel volume to reach 24%; whereas only 27% of nickel when the steel corrosion in certain media corrosion can significantly changed. So Nickel alone can not constitute a stainless steel. However, both nickel and chromium present in the stainless steel, the nickel-containing stainless steel, but has many valuable properties.
Based on the above case shows, nickel as an alloying element in stainless steel effect, is that it enables high-chromium steel tissue changes, so that the corrosion resistance of stainless steel and obtain certain improved process performance.
The method currently used is the most complete with a huge three-step molding production press with die no longitudinal joints 12 meters long pipe, and the shape and size are very accurate. The gas pipeline is the most common method used solvent layer under the double seam welding speeds of up to 140 ^ -150 m / hour. Soldering should be repaired weld, then cut the head and pipe sizing. The modern sizing method is applied to the inner pipe hydraulic diameter to the expansion diameter of 1.5-2.5% pots, fixed length to diameter, on the other hand to improve the yield limit of about 20%.
Nickel is an excellent corrosion-resistant materials, is an important alloying element in steel. Nickel is the formation of austenite in the steel elements, but to obtain pure carbon-nickel austenitic steels, nickel volume to reach 24%; whereas only 27% of nickel when the steel corrosion in certain media corrosion can significantly changed. So Nickel alone can not constitute a stainless steel. However, both nickel and chromium present in the stainless steel, the nickel-containing stainless steel, but has many valuable properties.
Based on the above case shows, nickel as an alloying element in stainless steel effect, is that it enables high-chromium steel tissue changes, so that the corrosion resistance of stainless steel and obtain certain improved process performance.
Polyethylene shrink sleeve anti-corrosion steel pipe fittings in the interface of the application
Also called heat-shrinkable polyethylene heat shrink tape, polyethylene heat shrinkable tape, by radiation cross-linked polyethylene sheet material (substrate) and specialty hot melt composite made of corrosion-resistant materials, mainly for the manufacture of heat shrinkable tape anti-corrosion steel pipe. Divided into cylindrical tablets with a fixed structure (often called corrugated type or open type heat shrinkable sleeve) and band structure two kinds of commonly used styles, shrinkage ge; 15. The radiation crosslinking of modified polyethylene sheet material (substrate) and ordinary polyethylene, high mechanical strength, and long life, corrosion resistance, aging resistance, resistance to environmental stress cracking, composite heat melt adhesive has strong bonding and good sealing characteristics, is ideal for making anti-corrosion steel pipe anti-corrosion materials, anti-corrosion steel pipe is mainly used 3pe for some reason can not produce a very good substitute corrosion process or corrosion at the interface .
Mainly used in oil, gas, chemical, city gas pipeline network and other anti-corrosion steel pipe mending, mending and interfaces, elbows, tees, etc. wound antiseptic; insulation pipe (stuck pipe) drainage and other engineering PE, PVC pipe joint seals fixed and so on. Different uses for the project, with a variety of specifications of specific products, divided into anticorrosion mouth, interfaces fixed, water seepage type, rust protection type, and other categories, customers can choose according to actual engineering requirements. With high mechanical strength, anti-aging ability, good sealing performance, corrosion-resistant, easy to use, save labor and many other advantages.
Shrink band width of 50mm to 600mm, heat shrinkable tape of any length, the construction site according to the diameter size, the width of cut for any size. This flexibility helps customers reduce inventory waste and construction input costs, facilitate project management. Special specifications can also be used as a belt across the sacrifice.
Mainly used in oil, gas, chemical, city gas pipeline network and other anti-corrosion steel pipe mending, mending and interfaces, elbows, tees, etc. wound antiseptic; insulation pipe (stuck pipe) drainage and other engineering PE, PVC pipe joint seals fixed and so on. Different uses for the project, with a variety of specifications of specific products, divided into anticorrosion mouth, interfaces fixed, water seepage type, rust protection type, and other categories, customers can choose according to actual engineering requirements. With high mechanical strength, anti-aging ability, good sealing performance, corrosion-resistant, easy to use, save labor and many other advantages.
Shrink band width of 50mm to 600mm, heat shrinkable tape of any length, the construction site according to the diameter size, the width of cut for any size. This flexibility helps customers reduce inventory waste and construction input costs, facilitate project management. Special specifications can also be used as a belt across the sacrifice.
Wednesday, July 3, 2013
Ultrasonic testing of welded pipe inspection process
Welded steel pipe, also known as welded pipe, steel sheet or strip is molded after curling welded steel pipe. Welded steel pipe production process is simple, high production efficiency, variety specifications, equipment owned small, but generally less than seamless strength. Since the 1930s, along with high-quality strip steel rolling production as well as the rapid development of welding and inspection technology, continuously improve the quality welds, welded steel pipe increasing varieties and specifications, and in more and more areas instead of a non- pipe joints. Press the seam welded steel pipe into the form of longitudinally and spirally welded pipe.
Longitudinal production process is simple, high efficiency, low cost, rapid development. Spiral Welded Longitudinal generally higher than, can narrow the billet production of large diameter steel pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight pipe joints than weld length of 30 to 100%, and lower production rate. Therefore, the smaller diameter pipe is mostly a straight seam welded, large diameter spiral welded pipe is mostly used. Although welded pipe production line is quality assurance, but also have some small problems inevitably arise, so pipe testing done at the factory areas is essential, it can be said is crucial.
General common pipe weld defects: pores, slag, incomplete penetration, lack of fusion and cracks. So far there is not a mature approach to the nature of defects accurately judge, but according to a defect on the screen to get the shape of the wave and the reflected wave height changes combined with the location of defects and welding a comprehensive assessment of the defect judgment.
Longitudinal production process is simple, high efficiency, low cost, rapid development. Spiral Welded Longitudinal generally higher than, can narrow the billet production of large diameter steel pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight pipe joints than weld length of 30 to 100%, and lower production rate. Therefore, the smaller diameter pipe is mostly a straight seam welded, large diameter spiral welded pipe is mostly used. Although welded pipe production line is quality assurance, but also have some small problems inevitably arise, so pipe testing done at the factory areas is essential, it can be said is crucial.
General common pipe weld defects: pores, slag, incomplete penetration, lack of fusion and cracks. So far there is not a mature approach to the nature of defects accurately judge, but according to a defect on the screen to get the shape of the wave and the reflected wave height changes combined with the location of defects and welding a comprehensive assessment of the defect judgment.
Spiral piling pipe principal stress direction
In use process, spiral piling pipe principal stress direction, that indeed equivalent defective pipe axis length smaller than a straight seam pipe; Secondly, because pipeline are rolled steel, toughness greater isotropic, rolling along CVN value of the direction perpendicular to the rolling direction than CVN value three times higher.
Using wire brushes and other tools for steel suspension polished appearance, to remove loose or warped oxide, rust, welding slag. Hand open tools rust can reach Sa2 grade power tools rust Sa3 level can be reached, if the appearance of adhering solid steel iron skin, tools rust effect is not fantasy, anti-corrosion construction requests reach the depth of anchor pattern pickling. Straight seam welded pipe suffered precisely perpendicular to the principal stress impact to the lowest pipe direction, while spiral steel pipe is staggered a minimum impact to the direction of the spiral weld pipe changed to the advantage of long upwind. Spiral steel pipe anti-corrosion method is also a process from which restrain the hands. If the pipe wall plus anti-corrosion coating, can increase the loop resistance, adding corrosion current; external DC power supply, so that the soil pipe constitutes a negative potential, constitute cathodic protection can eliminate the potential difference between anode and cathode, anode and cathode from basically abort the process aborted. Rule of law, anti-corrosion coating table, cathodic protection law standard. But once the anti-corrosion coating is damaged, partially exposed iron will slow localized corrosion. Therefore, anti-corrosion coating and cathodic protection phase separation is the way to rid the table of the economic and void.
Using wire brushes and other tools for steel suspension polished appearance, to remove loose or warped oxide, rust, welding slag. Hand open tools rust can reach Sa2 grade power tools rust Sa3 level can be reached, if the appearance of adhering solid steel iron skin, tools rust effect is not fantasy, anti-corrosion construction requests reach the depth of anchor pattern pickling. Straight seam welded pipe suffered precisely perpendicular to the principal stress impact to the lowest pipe direction, while spiral steel pipe is staggered a minimum impact to the direction of the spiral weld pipe changed to the advantage of long upwind. Spiral steel pipe anti-corrosion method is also a process from which restrain the hands. If the pipe wall plus anti-corrosion coating, can increase the loop resistance, adding corrosion current; external DC power supply, so that the soil pipe constitutes a negative potential, constitute cathodic protection can eliminate the potential difference between anode and cathode, anode and cathode from basically abort the process aborted. Rule of law, anti-corrosion coating table, cathodic protection law standard. But once the anti-corrosion coating is damaged, partially exposed iron will slow localized corrosion. Therefore, anti-corrosion coating and cathodic protection phase separation is the way to rid the table of the economic and void.
The physical phenomena of submerged arc welding
Currently, submerged arc welding is widely used in the spiral steel pipe as a welding technology. The principle is the use of submerged arc welding of heat, and manual arc welding is different: submerged arc welding wire is exposed, the above does not paint, Submerged arc welding fluxes are pre indeed be welded at the shop, submerged arc welding wire into the flux, the arc is burning under the flux.
The formation process of submerged arc welding wire and the workpiece, press the start button is pressed after the power of the moment the wire and the workpiece, wire Withdrawing arc ignition, welding carriage to move forward, under the conveying wire continuously maintain arc flux layer under the burning arc weld pool formed below. Around the arc, flux melted to form a cavity. The voids and pool continues to advance, and the rear metal solidification bath to form a continuous weld. Since this process is carried out under the flux, so we can not see with the naked eye. By means of X-ray photography can be seen.
As the spiral pipe welding using submerged arc welding technology, in addition to such high production efficiency; production auxiliary less time, saving time for welding; welding conditions clean and no spatter, saving clean-up time; weld quality is high. But also for the delivery of spiral welded pipe plant provides the necessary conditions for making large spiral pipe production time is guaranteed, so is still widely used with.
The formation process of submerged arc welding wire and the workpiece, press the start button is pressed after the power of the moment the wire and the workpiece, wire Withdrawing arc ignition, welding carriage to move forward, under the conveying wire continuously maintain arc flux layer under the burning arc weld pool formed below. Around the arc, flux melted to form a cavity. The voids and pool continues to advance, and the rear metal solidification bath to form a continuous weld. Since this process is carried out under the flux, so we can not see with the naked eye. By means of X-ray photography can be seen.
As the spiral pipe welding using submerged arc welding technology, in addition to such high production efficiency; production auxiliary less time, saving time for welding; welding conditions clean and no spatter, saving clean-up time; weld quality is high. But also for the delivery of spiral welded pipe plant provides the necessary conditions for making large spiral pipe production time is guaranteed, so is still widely used with.
How to control the quality of spiral piling pipe
Spiral piling pipe is low carbon steel or low alloy steel strip at a certain angle rolled into a spiral tube, and then welded together to form the tube, which can be produced with a narrow strip of large diameter pipe. Spiral single-sided and double-sided welding welding, pipe should ensure that hydrostatic test, weld tensile strength and cold performance to meet the requirements. In welding and soldering are used Lincoln welding machine for single or double wire submerged arc welding, thereby obtaining a stable welding specifications. After welding the weld line continuous ultrasonic injury checks to ensure 100% coverage of non-destructive testing of welds spiral. If defective, automatic alarm and spraying tags, production workers so adjusting the process parameters, and remove defects.
Heating operation is the second key is to try to cut the number of oxide. Especially in hot kneading elbow, something life expectancy from the pipe surface quality and kneading leave, pleading even more severe. Such as heat with the stove, according to their effect, divided into two kinds of furnaces and reheating; former for the fabric is heated from room temperature to the processing temperature; which is used during the processing of billets reheated to the required processing temperature. There are many ways the furnace, but the primary use of the annular furnace. This has an annular hearth furnace, which can slowly shift along the bottom of the blank from the entrance into the radial direction, reverse one can be used at the outlet of the heating and soaking temperature to the rules one kind of stove. This heating operation is the key to uniformly heat the billet to a temperature suitable for processing. Since a great impact on the quality piercing, that is, perforation processing temperatures are important condition affecting the quality, it is generally to processing of piercing the billet temperature control.
Heating operation is the second key is to try to cut the number of oxide. Especially in hot kneading elbow, something life expectancy from the pipe surface quality and kneading leave, pleading even more severe. Such as heat with the stove, according to their effect, divided into two kinds of furnaces and reheating; former for the fabric is heated from room temperature to the processing temperature; which is used during the processing of billets reheated to the required processing temperature. There are many ways the furnace, but the primary use of the annular furnace. This has an annular hearth furnace, which can slowly shift along the bottom of the blank from the entrance into the radial direction, reverse one can be used at the outlet of the heating and soaking temperature to the rules one kind of stove. This heating operation is the key to uniformly heat the billet to a temperature suitable for processing. Since a great impact on the quality piercing, that is, perforation processing temperatures are important condition affecting the quality, it is generally to processing of piercing the billet temperature control.
Spiral piling pipe rust treatment
After piling pipe rusty spiral wire brushes and other tools used primarily for steel surface sanding, cleaning and preheat coil can remove loose or warped oxide, rust, welding slag. Hand tools rust can reach Sa2 grade power tools rust Sa3 level can be achieved, if the coil firmly attached to the surface of the oxide scale, the effect is not ideal tools rust, anti-corrosion construction required to reach the depth of anchor pattern.
In traditional applications based on the new application has been added, which makes the usefulness of spiral steel pipe more fruitful, and also reduces the cost of the use of spiral pipe. Radio frequency sensors to provide 200 volts, 50 amps of electricity flowing through spiral pipe flow, experimental samples by induction heating effect.
Coil itself does not get hot, but the experimental samples will be significantly fever. In the heating temperature exceeds arc melting machine, radio frequency sensors will provide more control so that scientists can adjust the specific alloy composition ratio. Strong pressure spiral pipe, plastic, and easy welding and machining molding; generally low pressure liquid delivery spiral submerged arc welded spiral steel pipe (SY5037-83), using double-sided automatic submerged arc welding or welding into the legal system for water, gas, air and steam. Spiral steel pipe market demand both fast growth trend without chaos will not fundamentally changed. Spiral steel pipe market can keep chaos hub depends on the rapid development of changes in demand. Currently, the macroeconomic regulation and control by the policy level, the future will bring some market growth rate slows down.
In traditional applications based on the new application has been added, which makes the usefulness of spiral steel pipe more fruitful, and also reduces the cost of the use of spiral pipe. Radio frequency sensors to provide 200 volts, 50 amps of electricity flowing through spiral pipe flow, experimental samples by induction heating effect.
Coil itself does not get hot, but the experimental samples will be significantly fever. In the heating temperature exceeds arc melting machine, radio frequency sensors will provide more control so that scientists can adjust the specific alloy composition ratio. Strong pressure spiral pipe, plastic, and easy welding and machining molding; generally low pressure liquid delivery spiral submerged arc welded spiral steel pipe (SY5037-83), using double-sided automatic submerged arc welding or welding into the legal system for water, gas, air and steam. Spiral steel pipe market demand both fast growth trend without chaos will not fundamentally changed. Spiral steel pipe market can keep chaos hub depends on the rapid development of changes in demand. Currently, the macroeconomic regulation and control by the policy level, the future will bring some market growth rate slows down.
How to avoid large-caliber spiral piling pipe corrosion-resistant
All metals and reaction of oxygen in the atmosphere, the surface oxide film. Unfortunately, in the iron oxide formed on carbon steel proceed oxidation, corrosion continues to expand, forming holes. You can use paint or oxidation-resistant metal (eg, zinc, nickel and chromium) plating to ensure the steel surface, but, as people know, this protection is only a film. If the protective layer is damaged, the following steel began to rust. Large diameter spiral piling pipe corrosion resistance depends on corrosion, corrosion epoxy coal tar is one of the components, so the protection methods vary.
Strengthen the anti-corrosion paint material reaches level, large diameter spiral pipe atmospheric corrosion resistance can significantly increase, but higher strength corrosion, although still improve corrosion resistance, but not obvious. The reason is used for large diameter spiral steel pipe anti-corrosion processing of the processing, the change in the type of surface oxide became similar to the large diameter spiral piling pipe is formed on the surface of the metal oxide. This tight adhesion of large diameter spiral pipe oxide protective surface to prevent further oxidation. This oxide layer is very thin, it can be seen through the large diameter spiral piling pipe natural luster surface, so that large diameter spiral pipe has a unique surface. Moreover, if the surface is damaged, the exposed surface of large diameter spiral pipe and atmospheric reaction to self-repair, re-formation of this oxide "passive film" and continue to play a protective role.
Therefore, all of the large diameter spiral pipe elements have a common characteristic, corrosion prevention of corrosion is the best way.
Strengthen the anti-corrosion paint material reaches level, large diameter spiral pipe atmospheric corrosion resistance can significantly increase, but higher strength corrosion, although still improve corrosion resistance, but not obvious. The reason is used for large diameter spiral steel pipe anti-corrosion processing of the processing, the change in the type of surface oxide became similar to the large diameter spiral piling pipe is formed on the surface of the metal oxide. This tight adhesion of large diameter spiral pipe oxide protective surface to prevent further oxidation. This oxide layer is very thin, it can be seen through the large diameter spiral piling pipe natural luster surface, so that large diameter spiral pipe has a unique surface. Moreover, if the surface is damaged, the exposed surface of large diameter spiral pipe and atmospheric reaction to self-repair, re-formation of this oxide "passive film" and continue to play a protective role.
Therefore, all of the large diameter spiral pipe elements have a common characteristic, corrosion prevention of corrosion is the best way.
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