(1) The scale of seamless steel pipe wall thickness masking is relatively wide, which can achieve small diameter and large wall thickness, but in general, the length is limited (only a small number of manufacturers can produce ultra long pipes); The wall thickness of stainless steel welded pipes can be relatively thin, which can achieve large diameter and small wall thickness and small diameter and small wall thickness. In theory, the length of long coils determines the production capacity of welded pipes. Overall, the thicker the material, the more suitable it is to use seamless pipes, while the thinner the material, the more suitable it is to use welded pipes.
(2) In terms of uniformity and concentricity of wall thickness, stainless steel welded pipes are better than stainless steel seamless pipes. Because the thickness tolerance of the cold rolled sheet is relatively uniform, the deformation is even during the forming process. But the weld seam has protrusions, and different companies and specifications have different welding height requirements. In special cases, welding can be done first, followed by cold drawing or cold rolling; During the rolling process of seamless pipes, there are issues of uneven thickness and concentricity due to factors such as equipment accuracy and material function, but roundness is better than that of welded pipes.
(3) Functionally, stainless steel welded pipes have better uniformity and surface quality. The expansion tube has better function. The uniformity of the function of cold rolled sheet is superior to that of pipe material, and welded pipe generally uses online solid solution, uniform heat treatment, and more stable function. But now there is no heat treatment process for medium to low-end stainless steel welded pipes in the market, so the quality varies greatly. Stainless steel seamless pipes are sampled from different directions on the same pipe, with different functions and some may have significant differences. During heat treatment of seamless pipes, there is uneven heating and inconsistent cooling rate during bundled heat pipe treatment.
(4) Suitable for corrosion resistance function. The weld seam has undergone heat treatment and now meets the material requirements. If stainless steel welded pipes have not undergone heat treatment, their corrosion resistance is greatly reduced compared to stainless steel seamless pipes.
(5) The production cost of welded pipes is lower and more environmentally friendly. A good welding pipe factory can achieve a suitable environment for the electronic factory building; The seamless pipe factory is filled with oil and lubricants, and the pickling environment is even worse.
(6) Being under pressure is different. Under the same specification conditions, stainless steel seamless pipes bear higher pressure than welded pipes.
(7) The prices are different. Overall, stainless steel seamless pipes are more expensive than welded pipes. But there are also several characteristics: seamless pipes are suitable for thick walled pipes, and welded pipes are suitable for thin-walled pipes.
(8) Due to different delivery cycles, stainless steel welded pipes are rolled from stainless steel plates and have relatively simple processing, resulting in shorter delivery times. Stainless steel seamless pipes need to start from round steel, undergo multiple passes of cold drawing/cold rolling after perforation, and then undergo solution annealing and acid pickling to produce products, resulting in a longer production cycle.