First, Procurement Methods for Straight Seam Steel Pipes:
1. Understanding the Types of Steel Pipes
1) By Type: Straight seam steel pipes, seamless steel pipes, spiral steel pipes, etc.
2) Classification of Straight Seam Steel Pipes by Cross-Sectional Shape: Square pipes, rectangular pipes, elliptical pipes, flat elliptical pipes, semi-circular pipes, etc.
2. Points to Note: In the early days of the steel pipe industry, there were many deceptive tricks. However, now people are more knowledgeable in this industry, so these methods can be identified with the naked eye.
1) Using a gate to make the pipe wall thickness appear thicker by using a hammer to shield the end of the pipe. However, measurement with instruments will reveal the truth.
2) Using straight seam steel pipes to pass them off as seamless steel pipes. Straight seam steel pipes have fewer welds, only one longitudinal weld. The entire pipe is ground down by machine, commonly known as polishing, to make it appear seamless.
3) A more sophisticated method now is to create seamless steel pipes, also known as hot-expanded steel pipes. After expansion, there is lead powder inside, and there are also burn marks on the outside. The weld is not visible. Many large steel pipes are sold as seamless pipes to seek large profits.
4) Circumferentially welded straight seam steel pipes are disguised as straight seam steel pipes by polishing.
Second, processing methods of straight seam steel pipes:
(1) Forging steel: A pressure processing method that uses the reciprocating impact force of a forging hammer or the pressure of a press to change the billet into the required shape and size.
(2) Extrusion: A processing method in which steel is placed in a closed extrusion cylinder, and pressure is applied to one end to force the metal to be extruded from a specified die to obtain a finished product with the same shape and size. It is mostly used in the production of non-ferrous metals and steel.
(3) Rolling: A pressure processing method in which steel billets are passed through the gap between a pair of rotating rollers (of various shapes). Due to the compression of the rollers, the cross-section of the material is reduced, and the length is increased.
(4) Drawing steel: This is a processing method in which rolled metal billets (shaped, tube, products, etc.) are drawn through a die to reduce the cross-section and increase the length. It is mostly used for cold working.
Post time: Dec-04-2025