Welded pipes with smaller diameters adopt straight seam welding, while large-diameter welded pipes mostly use spiral welding; they are divided into round welded pipes and special-shaped (square, rectangular, etc.) welded pipes according to the shape of the end of the steel pipe; are divided into mine fluids according to their materials and uses. Conveying welded steel pipes, galvanized welded steel pipes for low-pressure fluid transportation, electric welded steel pipes for belt conveyor rollers, etc. According to the specification and size table in the current national standard, they are sorted by outer diameter * wall thickness from small to large.

How to control the precision of welded pipes

The internal and external polishing of welded pipes is very important. Generally speaking, steel pipes with a diameter of less than 89 mm have a high surface finish after polishing. The outer surface of stainless steel welded pipes above 89 mm, especially those above 108 mm, is not very ideal. If the surface of the welded pipe requires no pitting and small holes, it generally needs to be polished and then polished, and then automatically polished.

Because the surface density of the welded pipe is relatively high, even if the outer surface is not polished, it can generally reach about 260 mesh. If the stainless steel welded pipe is polished internally and externally, its straightness will decrease. Therefore, if there are special requirements for the straightness of the steel pipe, polishing is generally not recommended. The polished surface of the stainless steel welded pipe is already very bright.

Cold-rolled stainless steel welded pipe has excellent overall performance, can withstand high pressure, and can be cold-bent, flared, and flattened without cracking or wrinkling, and can be subjected to various complex deformations and mechanical processing. After the stainless steel welded pipe is vacuum annealed, the steel pipe can be processed. Stainless steel welded pipes are generally used in the manufacture of mechanical structures, hydraulic equipment, machinery, and other production fields.

Since the size of the welded pipe can be customized according to the needs of users, and the tolerance range is well controlled, it can be directly used on mechanical equipment and then processed, which can save costs and greatly save machining hours, and improve production capacity and material utilization. Therefore, the precision of stainless steel welded pipe products will generally be controlled at about 0.02mm.