1. Concentricity
The manufacturing process of seamless pipe makes a hole punched in the stainless steel billet at 2200 ° F. At this high temperature, the tool steel becomes soft and spirally formed from the air after stamping and drawing. In this way, the wall thickness of the pipe is uneven and the degree of migraine is high. Therefore, astm agreed that the wall thickness difference of seamless welded pipe is larger than that of welded pipe. Seamed pipes are made from accurate cold rolled sheets (4-5 feet in width per roll). Generally, the maximum wall thickness difference of these cold rolled sheets is 0.002 inches. The steel plate is cut into π d width, and d is the outer diameter of the pipe. The public service with the wall thickness of the slit pipe is very small, and the wall thickness of the whole circumference is very uniform.
2. Welding function
Generally, there are certain differences between the chemical composition of the welded pipe and the seamless pipe. The steel composition of seamless pipe production is only the basic requirement to reach astm. The steel produced with welded pipes contains a kind of weld melt that is suitable for heat transfer during the welding process, so that the whole weld can be fully welded. The square tube machine with less than chemical composition, such as seamless tube, will have various unstable factors during the welding process, and it is not easy to weld firmly and completely.
