The difference between seamless steel pipes and welded steel pipes

1.In terms of appearance, there are no seams on the surface of seamless steel pipes. There are generally welding seams on the surface of welded pipes.

2. Seamless steel pipes are formed in one pass during cold rolling. Welded pipes must be welded by electric welding after production, generally including spiral welding and direct welding. Smaller diameter welded pipes mostly use straight seam welding, while larger diameter welded pipes mostly use spiral welding. The welding method for spiral welded pipes and straight seam steel pipes is the same, but straight seam welded pipes inevitably have many T-shaped welds, which greatly increases the probability of missing welds. Moreover, the weld metal at the T-shaped weld is often in a three-dimensional deformation state, increasing the possibility of cracks. Seamless steel pipes have better characteristics and higher natural prices.

3. Seamless steel pipes are generally used as fluid pipelines that require special environments such as high pressure and high temperature resistance. Welded pipes are usually used as low-pressure fluid transmission pipelines.

4.The key is that the forming and processing processes are different. Seamless steel pipes are made by piercing solid pipe blanks or steel billets and processing them through hot or cold rolling. This method can ensure the diameter and roundness of seamless steel pipes, but the wall thickness is thick and uneven.

Welded steel pipes are formed by bending and welding steel plates or strips. During production, the steel plate or strip is rolled and formed by the machine and mold, and the edges are welded together through a welding process. This process can produce welded pipes with thin wall thickness, high accuracy, and high surface brightness.