Processing Technology of Seamless Steel Pipe

The time of issue:2014-2-24 9:30:43       Author:

Generally, there are two kinds of processing technology in producing the seamless steel pipe—cold rolling and hot rolling. The process of cold rolling is more complicated than hot rolling in general. First of all, the pipe billet should be rolled by three rollers in row and then after the rolling, the sizing test should be done. If there's no flaw in the surface of the pipe, then the round pipe need to be cut by the cutting machine into semi-finished products in about 1 meter's length. The next step is annealing during which the pipes need to be scoured by acid liquid. Here we need to pay attention to the surface of the pipe. If there are a large amount of bubbles in the pipe surface, it means the pipe is not up to the quality standard. The cold rolling steel pipe is shorter than the hot rolling ones in appearance but is thicker in wall thickness. With less coarseness on surface and less rag on caliber, the cold rolling steel pipe seems much lighter than the pipe with thick wall.

As to the hot rolling seamless steel pipe, it should be selected manually after quality check. The surface should be anointed after quality check, and then a series of cold test. It should also go through the perforation test after hot rolling and if the pipe diameter expansion is too large, it needs to be set into straightening correction. After that, the pipe will be delivered by transport unit to the defectoscope to practice the flaw detection test. After all these series are done, the hot rolling steel pipe can be arranged by specifications and stored in the storehouse. Normally, the procedure of the hot rolling is inspection and preparation of pipe billet, heating of the pipe billet, punching the hole, rolling the pipe, reheating the pipe, sizing, heat treatment, finished pipe straightening, finely processing, testing (undamaged, physicochemical) and storage. But cold rolling procedure seems much simpler compared to the hot rolling process. It can be come down to as the following, preparation of the semi-finished products, scouring and lubricating, cold rolling, heat treatment, straightening, refining and testing.

In addition to the general usage as plain steel pipes, the seamless hot rolling steel pipe are mainly used as low/middle/high pressure boiler pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe and geology steel pipe. While as for the cold rolling steel pipe, in addition to the usage as low/middle/high pressure boiler pipe, alloy steel pipe, stainless steel pipe and petroleum cracking pipe, it can also be utilized as carbon thin wall steel pipe, alloy thin wall pipe, stainless thin wall pipe and shaped steel pipe. The external diameter of the seamless hot rolling steel pipe is usually greater than 32mm with the thickness of wall varying from 2.5mm to 200mm. But the external diameter of the cold rolling one can be minimized to 6mm, and the wall thickness 0.25mm. The external diameter of the thin wall pipe can even be minimized to 5mm with the thickness of wall smaller than 0.25mm. From these, we may easily know that cold rolling procedure has a higher accuracy than the hot rolling technology.

The slight difference we discussed above about the processing technology is just a drop in the bucket in terms of the black steel pipe and seamless steel pipe, to know more about it, you need a much further research.

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