1. Purchasing needs to understand the types of steel pipes:
A. Divided by type: straight seam steel pipe, seamless steel pipe, spiral steel pipe, etc.
B. Classification of cross-section shapes of straight seam steel pipes: square pipe, rectangular pipe, elliptical pipe, flat ellipse pipe, semicircular pipe, etc.

2. Points to note:
A. The wall thickness of the steel pipe is not sufficient. Using the gate means, the mouth end of the steel pipe looks thicker with a hammer shield, but the original shape will be unveiled by measuring with an instrument.
B. Use straight seams as seamless steel pipes. The number of straight seam welds is less than one longitudinal weld. The sturdy steel pipe is polished with a machine, commonly known as polishing. It seems like there is no gap to be seamless.
C. Now there is still a more sophisticated method is seamless steel pipe, which is also thermally expanded steel pipe. After the expansion, there is lead powder on the inside, and there are burn marks on the outside. The welds are equally invisible. Many relatively large steel pipes are sold seamlessly using this kind of steel pipe to seek larger profits.
D. Circumferential welded seam steel pipes use polishing to represent seamless steel pipes and straight seam steel pipes.