First, difference between the production process
ERW pipe is the hot-rolled coil through the continuous roll forming, the use of high-frequency current skin effect and proximity effects, so that the plate edge of the hot melt, squeezing the roller pressure to the role of pressure welding achieve production. Therefore, the residual stress of the erw pipe is small, and the residual stress is further released and reduced through the processes of heat treatment, sizing, straightening and water pressure of the weld. Practice has proved that, erw pipe in the storage and use of residual stress on the pipe does not affect. Without any wire, the weld is physically and chemically identical to the plate. The quality of the erw pipe depends on the quality of the sheet.
SAW pipe through the unit screw spiral welding together, the plate through the spiral rotation, so that the geometric stress more complex, and some even reached the yield limit of the steel, spiral pipe after the formation of a larger residual stress, the residual stress is tensile stress. The steel by the internal pressure, the wall also produces a circumferential tensile stress, the two superposition, so that steel can withstand capacity weak. More insecure during use. Steel plates are welded together by a wire with a chemical composition that is prone to air bubbles and weld bead cracks during the welding process. So that the weld and base metal in the physical properties and chemical composition of the apparent difference. Easily in the weld with the base metal joints have a great concentration of stress. In the welding process, thermal effects, and high hardness.
Second, difference between raw materials
The raw materials used by erw pipe are all hot-rolled coils produced by regular manufacturers with relatively stable chemical composition and physical properties.
Most of the raw materials used in the spiral pipe mill are low-grade hot-rolled steel strip, with unstable chemical composition, physical properties and internal defects and impurities.
Third, the procurement costs and procurement difficulties
Spiral steel pipe production of large-scale steel pipe plant of petroleum and petrochemical systems, the advantages are mainly concentrated in the manufacture of large-diameter steel pipe, the manufacturing cost is relatively low. However, for small and medium caliber (Φ114mm ~ Φ355.6mm) steel pipe, the manufacturing cost is higher, averaging 8% ~ 15% higher than ERW pipe.
Large-scale spiral pipe plant often do not produce small and medium-sized spiral pipe, procurement more difficult. Medium and small diameter erw pipe, due to the large number of manufacturers, is very easy to purchase.
Fourth, pipe geometry
1, ERW pipe geometry of the higher accuracy; and spiral welded pipe geometry accuracy is low, resulting in the construction of the site weld girth difficulties.
2, ERW pipe weld coefficient is 100%; spiral welded pipe weld coefficient of 130% -200%. The weld length of spiral pipe is much longer than that of erw pipe, and the incidence of defects also increases synchronously.
3, ERW pipe weld height remaining close to zero, the naked eye is not visible; spiral steel pipe on the outside surface must leave about 0.3 mm height (which is determined by the production process). The weld seam is so high that there is a gap between the steel pipe coating (3PE) and the pipe body, which makes the corrosion resistance of the steel pipe greatly reduced.
4, Due to the spiral welded pipe remaining high, the transmission of high-speed fluid there will be a greater disturbance, increase the flow resistance and reduce pipeline delivery efficiency. ERW pipe wall smooth, then there is no such problem.
Five, other differences
ERW pipe compression performance is higher than the spiral pipe.
http://www.xysteelpipe.com/info/Difference-between-saw-and-erw-pipe-712-1.htm
2017年12月28日星期四
Advantages and disadvantages of eddy current
Eddy current testing features are as follows:
Advantages of eddy current testing
1.When test, the coil does not require contact with the workpiece, but also without the coupling medium, so the detection speed.
2. The workpiece surface or near surface defects, high detection sensitivity, and in a certain range with good linearity indication, can be used for quality management and control.
3. At high temperature, the workpiece narrow area, deep-hole wall (including the wall) for testing.
4. Measure the thickness of the metal coating or non-metallic coating.
5. Detect eddy currents can cause non-metallic materials, such as graphite.
6. The test signal is electrical signal, can be digitized, easy to store, reproduce and data comparison and processing.
Disdvantages of eddy current testing
1. The object must be conductive material, only for detecting metal surface defects.
2. The detection depth and detection sensitivity are contradictory to a material for ET, according to the material, the surface state, the test criteria for comprehensive consideration, and then determine the test program and technical parameters.
3. Through-type coil for ET, the specific location of the circle where the defect can not be determined.
4. Rotating probe ET can locate, but the detection speed is slow.
http://www.xysteelpipe.com/info/Advantages-and-disadvantages-of-eddy-current-713-1.htm
Advantages of eddy current testing
1.When test, the coil does not require contact with the workpiece, but also without the coupling medium, so the detection speed.
2. The workpiece surface or near surface defects, high detection sensitivity, and in a certain range with good linearity indication, can be used for quality management and control.
3. At high temperature, the workpiece narrow area, deep-hole wall (including the wall) for testing.
4. Measure the thickness of the metal coating or non-metallic coating.
5. Detect eddy currents can cause non-metallic materials, such as graphite.
6. The test signal is electrical signal, can be digitized, easy to store, reproduce and data comparison and processing.
Disdvantages of eddy current testing
1. The object must be conductive material, only for detecting metal surface defects.
2. The detection depth and detection sensitivity are contradictory to a material for ET, according to the material, the surface state, the test criteria for comprehensive consideration, and then determine the test program and technical parameters.
3. Through-type coil for ET, the specific location of the circle where the defect can not be determined.
4. Rotating probe ET can locate, but the detection speed is slow.
http://www.xysteelpipe.com/info/Advantages-and-disadvantages-of-eddy-current-713-1.htm
I am steel pipe
I'm a steel pipe. I feel that life is not unreasonable so long as one can scrape along from day to day. For surely, human would happy for the good work of steel pipe when they need water pipe like ERW steel pipe. I think it best to wait in patience for the day of the high quality steel pipe for good life service.
Compared with such complexities, steel pipes are truly simple. If we need to transport water, we transport; if we need to transport oil, we transport; if we need to be repaired, we are repaired at the shopping store; if we need to change the standards to satisfy the customer's demands, we change; if we feel tired, we cry and break and there is no work anymore. Thus we never keep thinks like diaries.
We can be replaced in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction. Among steel pipes, we have main occupations of work, work, work and then repair, then die...
http://www.xysteelpipe.com/info/I-am-steel-pipe-714-1.htm
Compared with such complexities, steel pipes are truly simple. If we need to transport water, we transport; if we need to transport oil, we transport; if we need to be repaired, we are repaired at the shopping store; if we need to change the standards to satisfy the customer's demands, we change; if we feel tired, we cry and break and there is no work anymore. Thus we never keep thinks like diaries.
We can be replaced in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction. Among steel pipes, we have main occupations of work, work, work and then repair, then die...
http://www.xysteelpipe.com/info/I-am-steel-pipe-714-1.htm
Precautions for Installation of Carbon Seamless Steel Pipe
(1) Carbon seamless steel pipe should be carefully installed before the following carefully checked to ensure the quality of pipe and pipe.
A. Check the factory and pipe fittings factory certificate, quality certificate or test records, test records and other technical information, and should comply with existing national standards.
B. Check the quality marks of the pipe and fittings, expansion joint to meet the technical document and the current national standard. If there is any problem, replace or take the measures.
C. Check the quality of the outer surface of the pipe and pipe fittings, wall thickness should be consistent with national standards. The ellipticity is not allowed to exceed the specified range. No cracks, no shrinkage, no slag, no folding, no heavy skin, no trachoma, no pinhole, no more than the thickness of the local pit tolerance, no bumps and other quality problems, and the tube Internal and external surface without serious corrosion when the pipe and pipe fittings qualified.
(2) When the pipe surface rust less number of pipes can not be used when the number of hand-rust, the general hand-rust is a wire brush, wire cloth, emery cloth and other friction, remove the rust on the pipe surface, and then dry cotton yarn Wipe or clean, so that the pipe surface exposed metallic luster.
(3) When the pipe surface rust more, and the larger number of pipes and generally use mechanical rust or sand blasting rust or pickling rust. Pickling rust rust when the general use of sulfuric acid or hydrochloric acid.
(4) Brush the surface of the pipe type of anti-rust paint should be selected according to design requirements, commonly used red lead rust paint, epoxy paint, etc., the surface finish is generally blending paint.
Before painting, clean the surface of the pipe clean dust, dirt, burr, oil and water. Brush should be uniform coating, do not leak coating, brush the paint after the eligibility criteria for attachment firmly, no flaking, no wrinkles, no bubbles, no leakage coating, no damage and other defects.
A. Check the factory and pipe fittings factory certificate, quality certificate or test records, test records and other technical information, and should comply with existing national standards.
B. Check the quality marks of the pipe and fittings, expansion joint to meet the technical document and the current national standard. If there is any problem, replace or take the measures.
C. Check the quality of the outer surface of the pipe and pipe fittings, wall thickness should be consistent with national standards. The ellipticity is not allowed to exceed the specified range. No cracks, no shrinkage, no slag, no folding, no heavy skin, no trachoma, no pinhole, no more than the thickness of the local pit tolerance, no bumps and other quality problems, and the tube Internal and external surface without serious corrosion when the pipe and pipe fittings qualified.
(2) When the pipe surface rust less number of pipes can not be used when the number of hand-rust, the general hand-rust is a wire brush, wire cloth, emery cloth and other friction, remove the rust on the pipe surface, and then dry cotton yarn Wipe or clean, so that the pipe surface exposed metallic luster.
(3) When the pipe surface rust more, and the larger number of pipes and generally use mechanical rust or sand blasting rust or pickling rust. Pickling rust rust when the general use of sulfuric acid or hydrochloric acid.
(4) Brush the surface of the pipe type of anti-rust paint should be selected according to design requirements, commonly used red lead rust paint, epoxy paint, etc., the surface finish is generally blending paint.
Before painting, clean the surface of the pipe clean dust, dirt, burr, oil and water. Brush should be uniform coating, do not leak coating, brush the paint after the eligibility criteria for attachment firmly, no flaking, no wrinkles, no bubbles, no leakage coating, no damage and other defects.
Hardness Test of 40Cr Carbon Seamless Steel Tubes
American Standard carbon seamless steel pipe conduct mechanical performance testing. Mechanical properties of test methods are divided into two categories, one is the tensile test, one is the hardness test.
Tensile tests are made of seamless steel tube samples, the tensile test machine will pull the specimen to the fracture, and then measured one or more mechanical properties, usually only the determination of tensile strength, yield strength, elongation and rate of reduction in area. Tensile test is the most basic metal mechanical properties of test methods, almost all of the metal materials, as long as the mechanical properties are required, are provided for tensile testing. In particular, tensile tests are the only means of testing the mechanical properties of materials that are not easily tested for their hardness.
Hardness test is a hard indenter according to the provisions of the conditions slowly pressed into the sample surface, and then test indentation depth or size, in order to determine the size of the hardness of the material. Hardness test is the mechanical properties of materials testing the most simple, the most rapid and easiest to implement the method. Hardness test is non-destructive, the hardness value of the material and the tensile strength value between the approximate conversion relationship. The hardness of the material can be converted into tensile strength value, which has great practical significance.
As the tensile test is not easy to test, and converted from the hardness to the intensity is very convenient, so more and more people only test the hardness of the material and less test its strength. In particular, due to the hardness of manufacturing technology advances and innovation, some of the original can not directly test the hardness of materials, such as seamless steel tubes, stainless steel, etc., are now possible to directly test the hardness. Therefore, there is a tendency to gradually replace the tensile test with a hardness test.
Tensile tests are made of seamless steel tube samples, the tensile test machine will pull the specimen to the fracture, and then measured one or more mechanical properties, usually only the determination of tensile strength, yield strength, elongation and rate of reduction in area. Tensile test is the most basic metal mechanical properties of test methods, almost all of the metal materials, as long as the mechanical properties are required, are provided for tensile testing. In particular, tensile tests are the only means of testing the mechanical properties of materials that are not easily tested for their hardness.
Hardness test is a hard indenter according to the provisions of the conditions slowly pressed into the sample surface, and then test indentation depth or size, in order to determine the size of the hardness of the material. Hardness test is the mechanical properties of materials testing the most simple, the most rapid and easiest to implement the method. Hardness test is non-destructive, the hardness value of the material and the tensile strength value between the approximate conversion relationship. The hardness of the material can be converted into tensile strength value, which has great practical significance.
As the tensile test is not easy to test, and converted from the hardness to the intensity is very convenient, so more and more people only test the hardness of the material and less test its strength. In particular, due to the hardness of manufacturing technology advances and innovation, some of the original can not directly test the hardness of materials, such as seamless steel tubes, stainless steel, etc., are now possible to directly test the hardness. Therefore, there is a tendency to gradually replace the tensile test with a hardness test.
2017年12月27日星期三
Carbon Seamless Steel Pipe Connection Method
Carbon seamless steel pipe connections are many ways, now commonly used in several ways:
Different connections, because of its production principle of the different areas in its application are also different, in general, there is a common point that is easy to install, solid and reliable. Here are some of the more common way to do a brief description of the connection:
1. Compression: the pipe inserted into the tube of the mouth, tightened by the nut, with a spiral force to the mouth of the casing through the sealing ring compression, the role of sealing, complete piping connections.
2. Welding: the end of the pipe processing groove, with manual or automatic welding of the pipe to do ring welding.
3 flange type: the flange and pipe for the ring welding, with fast clip or bolt fastening, so that the flange between the sealing gasket role in the completion of piping connections.
4. Clamping type: the pipeline into the tube with a special installation tool to pipe the wall card into a hexagonal, the internal seal is also transformed into hexagonal.
5. Taper thread: is the external thread and pipe for the TIG welding, threaded pipe fittings to tapered thread connection from the role of sealing to complete the piping connection.
Different connections, because of its production principle of the different areas in its application are also different, in general, there is a common point that is easy to install, solid and reliable. Here are some of the more common way to do a brief description of the connection:
1. Compression: the pipe inserted into the tube of the mouth, tightened by the nut, with a spiral force to the mouth of the casing through the sealing ring compression, the role of sealing, complete piping connections.
2. Welding: the end of the pipe processing groove, with manual or automatic welding of the pipe to do ring welding.
3 flange type: the flange and pipe for the ring welding, with fast clip or bolt fastening, so that the flange between the sealing gasket role in the completion of piping connections.
4. Clamping type: the pipeline into the tube with a special installation tool to pipe the wall card into a hexagonal, the internal seal is also transformed into hexagonal.
5. Taper thread: is the external thread and pipe for the TIG welding, threaded pipe fittings to tapered thread connection from the role of sealing to complete the piping connection.
Manufacturing Process of Carbon Seamless Steel Pipe
According to different production methods of carbon seamless steel pipe can be divided into hot-rolled tube, cold-rolled tube, drawing tube, extrusion tube.
1.Hot-rolled seamless pipe is generally in the automatic production of rolling mill unit. The solid tube blank is inspected and removed from the surface defects, cut into the required length, in the tube end of the perforation end of the centering, and then sent to the heating furnace heating, perforation in the punching machine. In the perforation at the same time continue to rotate and move, in the role of the roll and the head, the tube gradually formed within the cavity, called the capillary. And then sent to the automatic rolling machine to continue rolling. And finally by the whole machine are the whole wall thickness, by sizing machine diameter, to specifications. The use of continuous rolling mill production of hot-rolled seamless steel pipe is a more advanced method.
2.If you want to get smaller and better quality of seamless tubes, must be cold-rolled, cold drawn or a combination of the two methods. Cold rolling is usually carried out on a two-roll mill, in which the steel pipe is rolled in an annular orifice formed by a tapered hole and a non-moving tapered head. Cold drawing is usually carried out on single-chain or double-chain cold drawing machines of 0.5 to 100T.
3.the extrusion method is to heat a good tube on a closed cylinder, squeeze rods and extrusion rod with the movement, so that extrusion from the smaller hole in the extrusion die. This method can produce smaller diameter steel pipe.
1.Hot-rolled seamless pipe is generally in the automatic production of rolling mill unit. The solid tube blank is inspected and removed from the surface defects, cut into the required length, in the tube end of the perforation end of the centering, and then sent to the heating furnace heating, perforation in the punching machine. In the perforation at the same time continue to rotate and move, in the role of the roll and the head, the tube gradually formed within the cavity, called the capillary. And then sent to the automatic rolling machine to continue rolling. And finally by the whole machine are the whole wall thickness, by sizing machine diameter, to specifications. The use of continuous rolling mill production of hot-rolled seamless steel pipe is a more advanced method.
2.If you want to get smaller and better quality of seamless tubes, must be cold-rolled, cold drawn or a combination of the two methods. Cold rolling is usually carried out on a two-roll mill, in which the steel pipe is rolled in an annular orifice formed by a tapered hole and a non-moving tapered head. Cold drawing is usually carried out on single-chain or double-chain cold drawing machines of 0.5 to 100T.
3.the extrusion method is to heat a good tube on a closed cylinder, squeeze rods and extrusion rod with the movement, so that extrusion from the smaller hole in the extrusion die. This method can produce smaller diameter steel pipe.
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