If the ssaw steel pipe production process is unreasonable if the machine parameter settings shall not be deemed deviation phenomenon occurs in the production process, especially for large diameter spiral steel pipe, which is often said the wrong side of the phenomenon. For the production of spiral steel pipe processing program has been completed on the wrong side as follows: 1, The position of the wrong side of the polished, then welding 2, If a situation occurs frequently on the wrong side, you can replace the equipment. After Spiral Pipe wrong side analysis of the causes produce the wrong side is very necessary, the following is to produce the wrong side of the common reasons: 1, Strip steel camber is caused by the wrong side of the most important factors. In forming the spiral welded pipe, steel strip camber angle will constantly change shape, leading to changes in the weld gap, resulting in open seam, wrong side or even take sides. 2, Strip head and tail butt welding weld reinforcement is large, when the over-molding, if not handled properly, likely to cause greater wrong side. 3, Due to the poor is not trimming the strip head and tail shape and size precision, easy to cause docking strip hard bend caused by the wrong side. 4, The strip edges in poor condition is another important reason for the wrong side. Therefore, the observation strip coil-camber situations after, by controlling the vertical rolls so that the disc can be cut and removal of part of camber angle forming the continuous control and corrective camber of the strip is the reduction in the production process effective way of generating the wrong side.

1, SSAW steel pipe in different directions taken specimens tensile and impact tests, found that test different directions of yield strength and ultimate strength difference is small, generally only in the 5-10% range, and different direction of the sample cvn values vary greatly, cvn value entirely with the angle changes. Spiral although yield strength and ultimate strength in different directions difference is small, showing a very slight strength anisotropy, however cvn value in different directions is a big difference, that exhibit very serious impact toughness anisotropy the consequences of this serious cvn anisotropy values generated by the fracture resistance is different in different directions: straight along the rolling direction, that is the same as the spiral weld direction, the fracture of least resistance, that is easy along cracking in this direction; perpendicular to the rolling direction of the fracture resistance of the maximum; in the axial direction, the fracture resistance in between. 2, The line, the maximum principal stress is the hoop stress, that is the biggest driver of cracking along the axial direction. In other words, just from the stress situation, genetic defects most likely to crack the axial direction. For straight seam pipe, the direction of maximum and minimum driving directions crack fracture resistance is the same, and therefore the fracture must be carried out in the axial direction. However, the spiral, the two are not the same. 3, Spiral fracture propagation direction depending on whether the spiral pipe for CVN value anisotropic size. 4, Pipe defects are rarely found in the base material, generally in the weld or heat affected zone, and defects in the weld or heat affected zone is most consistent with the trend of the weld, ie straight seam tube defects in the axial direction, the spiral ramp of the defects.

Large diameter ssaw steel pipe processing to a certain length, then bent certainly exist in the steel case and the phenomenon is often encountered. Large diameter spiral pipe due to uneven along the longitudinal direction or in the bottom of the pipe will be the occurrence of such a curved shape, commonly known as "goose head bent." Bending of the main reasons, artificial heat check, local cooling caused; straightening when adjusted properly, serious straightening roll wear generated; bending caused by lifting transport; sizing machining, assembly and improper adjustment may be possible. For the occurrence of bending large diameter spiral pipe, if the curvature is excessive, it can be secondary re-straightening, but if it is unable to straightening "goose head bent" should be given to the removal process. In addition, the large diameter spiral pipe production process, due to several rolls can not be very accurate in a straight line, so it is easy to bend, the solution is to increase the number and distance of these rolls.

Thick-walled ssaw steel pipe production control first is to improve the toughness of plastic pipe, improve the cleanliness of molten steel and reduce harmful inclusions, improve the overall quality of steel pipe. Use in the production process and reasonable cooling system to prevent internal cracks, in many ways starting to improve the quality of steel pipe. SSAW steel pipe in the production process reasonable control of the heating temperature by measuring the thermoplastic curve, select the optimal heating temperature. Note also that there is enough heating tube holding time, in order to reduce deformation resistance and improve the structure of the thick spiral plastic toughness. Program spiral pipe production process requires more, the final step is to reduce the roll speed, roll speed is a key parameter piercing process, the roll speed from low to process high variability, there is a start delamination critical roll speed. Lower roll speed, easy to form a tube bore; higher roll speed, tube and spiral steel structure is easy to form a layered defects. In order to eliminate the structural tube and spiral steel lamination defects, should reduce the roll speed to the start of the critical delamination roll speed or less.

First, in the 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.