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. API steel pipe, with a hollow-section, has been usually applied to fluid transportation, for example, petroleum, water, coal gas as well as natural gas transportation. Meanwhile, ring-shaped spare parts made with steel pipe can make the utilization ratio of material higher, the process of manufacturing simpler and the time of processing shorter. Rolling bearing ring and things like that are often manufactured with the steel pipe nowadays. API is the contraction of American Petroleum Institute, one of whose main activities is the API standard design and revises. Almost all fields are involved by the standard which is highly comprehensive, systematic, excellent and authoritative. A leading role is played by this institute for a long time in the standardization field of petroleum industry, widely used over the world.