1. In terms of appearance, the difference between seamless steel pipes and welded pipes is that the welded steel pipes have welding bars in the inner cavity, but the seamless ones do not.
2. The working pressure of seamless steel pipes is higher, and that of welded steel pipes is generally around 10 MPa. Nowadays, welded steel pipes are being seamlessly spliced.
3. Seamless steel pipes are formed in one step during cold rolling. Welded pipes must be welded by electric welding after production. Generally, there are spiral welding and direct welding. Smaller diameter welded pipes mostly use straight seam welding, while large diameter welded pipes mostly use spiral welding. The welding methods of spiral welded pipes and straight seam steel pipes are the same, but straight seam welded pipes inevitably have many T-shaped welds, so there are welding defects. The probability of cracking is also greatly increased, and the weld metal at the T-shaped weld is often in a three-way deformation state, increasing the possibility of cracks. In terms of properties, seamless steel pipes are better, and naturally the price is higher.
4. Seamless steel pipe is a hollow strip-shaped stainless steel plate, which is often used as a pipeline for transporting fluids, such as crude oil, natural gas, water, liquefied gas, steam, etc. In addition, when the bending and torsional strength are the same , light weight, so it is also widely used to produce mechanical parts and engineering structures. It is also commonly used in the manufacture of various strategic weapons, barrel rifling, bullets, etc.
