Usually in steel processing, lsaw steel pipe preheated deformation method, what does the following new legislation pipe Xiaobian to explain and I hope that we have a deeper understanding of straight pipe joints of methods and techniques. First, reasonable selection. Precision messy mold material should choose a good micro-deformation of steel on steel carbide segregation serious mold should be a reasonable casting and heat treatment quenching and tempering, solution heat treatment on a large double refining and casting mold steel can not be carried out. Reasonable choice of heating temperature control heating rate, on messy precision molds can be heated slowly, preheating and other methods to reduce the mold uniform heating heat deformation. Second, the correct operation of the heat treatment process and reasonable heat treatment process is also a useful way to reduce messy precision mold deformation. Deformation reason messy precision molds are often messy, but we only need to master the rules of the deformation, to analyze the attack reason, the choice of methods to avoid abnormal deformation of the mold can be reduced, and also can be controlled. Third, precision molds to be messy pre-heat treatment, machining process to eliminate the remaining episodes of stress. Precision messy mold, when conditions allow, try to use cryogenic vacuum heating process and hardening after quenching. Mold hardness in ensuring the premise, try to use pre-cooling, grading cooling or quenching temperature quenching process. Fourth, mold planning is depicted to be reasonable, not too poor thickness, shape to be symmetrical with respect to large deformation mold deformation to master the rules, set aside allowance, on large, sophisticated planning messy mold can be used in combination. For some messy precision molds can be used pre-heat treatment, aging heat treatment, quenching and nitriding to control the accuracy of the mold. When mold repair blisters, porosity, wear and other defects, selection of cold welding and other small heat-affected patch repair equipment, to prevent deformation during the attack.

In order to better control the quality of welds, the concept of inclusion weld crack index. Mainly weld strength, ductility humanoid or shortage caused. When there is the impact toughness of small inclusions seam welding, only when the two relatively close to the wall of the steel pipe crushed metal, weld cracking is likely to emerge. To reduce weld cracking, the need to improve the toughness of the weld, the weld reduce inclusions. So how to reduce the weld inclusions it? First, to improve the purity of the raw material, reducing P, S content, reduced content of inclusions. Second, check the strip edge bumps, whether stained with rust, dirt, these are not conducive to the discharge of molten metal, is likely to cause the weld inclusions. Again, uneven thickness, glitches and drum kits are likely to cause fluctuations in the welding current, affecting the quality of welding.

First, ssaw steel pipe production test, there had been no detection of spiral steel pipe through the wall with a large hole phenomenon MFL method. Management and human factors aside, technically should probe into the scoreboard and to guard against. For the method can be used MFL stuck deep surface defects, there has been no clear conclusion. It has a relationship with the instrument and probe performance and defect size and shape. Since the detection of high speed through the coil ET method is widely used for many years to detect spiral steel quality, especially its compactness. Second, the use of proven, it is difficult to ferromagnetic spiral pipe stuck in the crack-like defects, so the high standards of ET, using the probe coil ET method. In addition, the ET method can actually stuck his face hidden deep lack of such a simple question, it seems so far not formed a clear consensus. Third, spiral pipe often produced "outside the fold" such defects, a lot of eddy current probe instrument and often can not be found. Often outside off to the naked eye visible, but not the only instrument ET alarm embarrassing phenomenon. Since the emergence of sector-type vortex phase alarm device, this situation has been fundamentally changed. Fourth, select the appropriate instrument with the probe and adjust it correctly, it is still an important issue can not be ignored. Another important factor is the reliability of the natural angle of the tube surface defects. Theoretical and experimental studies have shown: When the orientation of artificial groove along the thickness direction of the outer surface of the tube angle is 30 degrees, that can not be detected by MFL parallel to the surface defects, such as class stratification defect.

SSAW steel pipe into the steel unit, multi-channel roll rolling strip gradually rolled up, a gap is formed with an opening round tube, squeeze rollers reduction adjustment, the weld gap control at 1 ~ 3mm, and the weld ends flush. Spiral Pipe is a strip coil as raw material, often warm extrusion molding, automatic double wire-sided spiral submerged arc welded steel pipe technology. 1, Hardness refers to the metal object is harder to push and the contact surface wear caused by plastic deformation resistance, commonly used test methods Brinell hardness test, Rockwell hardness test, Vickers hardness test. 2, The selection of lubricants, low temperature should be chosen viscosity (low), the load should be selected large viscosity (high), the movement speed should be selected high viscosity (low) it is. 3, Single rod side of the piston in the hydraulic cylinder, piston rod, and therefore the effective active area of the piston cylinder two chambers are not equal, the larger diameter of the piston rod, the effective area of the piston effect greater the difference between the three sides. 4, Steel welded pipe is made blank, have collectively produced welds steel processing line equipment. 5, The applied voltage and the resistance of the metallic conductors irrelevant. 6, The hydraulic system from the power system, execution system, control system, auxiliary system composed of four parts. 7, There are two ways to achieve a rolling bearing preload, ie radial and axial preload preload. 8, Manufacture high precision, complex shape of the blade and cutting tool for steel, the material should be used carbon tool steel. 9, If an object in space without any constraints, there should be six degrees of freedom. 10, does not destroy the performance and integrity by checking material or article, and method for detecting defects is called non-destructive testing.

According to the test indicated the relevant US research institutions, large diameter spiral pipe with large-caliber Longitudinal course of a same level, but the ssaw steel pipe has a high impact toughness. Large diameter spiral pipe blast occurred as positive weld suffered stress and the resultant stress is relatively small, blasting the mouth is generally not originated in the spiral weld, but whether it is still the yield pressure burst pressure, spiral welded pipe are lower than the straight seam pipe. Large diameter spiral weld pipe is generally degree helix angle, so the spiral weld resultant stress is bursting Longitudinal principal stress test also shows the deformation rate was significantly greater than the spiral steel pipe blasting the mouth ring Longitudinal. According submerged arc welding process delineated, each weld should have the arc at the place and extinction, but in each Longitudinal welding girth, unable to meet the premise, thereby extinction may have more at multi weld defects. In an interview with the pipe internal pressure, typically produces two main stress on the wall, ie the radial stress and axial stress. Followed by increasing the diameter of the steel pipe, the steel grade improvement, the greater the occurrence of ductile fracture tip steady expansion trend. Because the transfer line output volume changes, the actual disposal process, the pipe is subject to random alternating load effect. Low cycle of fatigue strength solution pipe for determining life of the pipeline is of great significance. Under the same operating pressure, spiral welded pipe than Longitudinal unified diameter wall thickness can be reduced.