It is divided into ordinary carbon steel pipe, high quality carbon structure steel pipe, alloy structure pipe, alloy steel pipe, bearing steel pipe, stainless steel pipe and bimetallic composite pipe, coating and coating pipe to save precious metals and meet special requirements. There are many kinds of stainless steel tubes, different uses, different technical requirements, production methods are also different.

 The current production of steel pipe outside diameter range 0.1 — 4500mm, wall thickness range 0.01 ~ 250mm. In order to distinguish their characteristics, steel pipes are usually classified as follows.

 2. Classification by production mode

 Stainless steel pipe according to the production method is divided into seamless pipe and welded pipe two categories, seamless steel pipe can also be divided into hot rolled pipe, cold rolled pipe, cold drawn pipe and extrusion pipe, cold drawing, cold rolling is the secondary processing of steel pipe; Welded pipe is divided into straight seam welded pipe and spiral welded pipe.

 3. Classification by section shape

 Stainless steel pipe according to the cross section shape can be divided into round pipe and special-shaped pipe. Special-shaped tube has rectangular tube, diamond tube, elliptic tube, hexagonal tube, eight party tube and a variety of cross-section asymmetric tube. Profiled tubes are widely used in various structural parts, tools and mechanical parts.

 Compared with the round tube, the shaped tube generally has a larger moment of inertia and section modulus, has a larger bending and torsional resistance, can greatly reduce the weight of the structure, save steel.

 Stainless steel pipe according to the profile shape can be divided into equal section pipe and variable section pipe. The variable section pipe has conical pipe, stepped pipe and periodic section pipe.

 4. Classification by pipe end shape

 Stainless steel pipe can be divided into light pipe and wire pipe (with spiral steel pipe) according to the state of the pipe end. Wire pipe can also be divided into ordinary wire pipe (conveying water, gas and other low pressure pipe, using ordinary cylindrical or conical pipe thread connection) and special thread pipe (petroleum, geological drilling pipe, for important wire pipe, using special thread connection), for some special pipe, in order to make up for the influence of thread on the strength of the pipe end, Tube end thickening (internal thickening, external thickening or internal and external thickening) is usually carried out before wire drawing.

 5 Categorize by use

 According to its use, it can be divided into oil well pipe (casing, tubing and drill pipe, etc.), pipeline pipe, boiler pipe, mechanical structure pipe, hydraulic prop pipe, gas cylinder pipe, geological pipe, chemical pipe (high-pressure fertilizer pipe, oil cracking pipe) and ship pipe.