There are many types of steel pipe, use different, its different technical requirements, production methods are also different. The current production range of 0.1 ~ 4500 mm steel pipe diameter and wall thickness range of 0.01 ~ 250 mm. In order to distinguish the characteristics, usually classified according to the following method for steel pipe. 

1Classification according to production mode
Steel pipe according to the mode of production divided into two categories: seamless pipe and welded pipe, seamless steel pipe and can be divided into hot rolled tube, cold rolling tube, cold drawn tube and extruded tube, cold drawing, cold-rolled steel pipe secondary processing;Welded pipe is divided into straight seam welded pipe and spiral welded pipe, etc.

2 according to the steel tube cross section shape of the classification
Steel pipe according to the cross section shape can be divided into circular tube and special-shaped tube.Special-shaped pipe with rectangular tube, the diamond, oval tube, six eight square tube and square tube, all kinds of tube for asymmetry, etc.Abnormity tube is widely used in all kinds of parts, tools and machinery parts.Compared with the circular tube, special-shaped tube usually have large moment of inertia and section modulus, have bigger bending and torsional capacity, can greatly reduce the structure weight, save steel.
Steel pipe according to the profile shape can be divided into section tube and variable cross-section tube, etc.Variable cross-section tube has a tapered tube, stepped pipe section and cycle, etc.

3 according to the material of steel pipe
Steel pipe according to the material can be divided into ordinary carbon steel, high quality carbon structural steel, alloy structural pipe, alloy steel, bearing steel, stainless steel tube, and to save precious metals and meet the special requirements of double metal composite tube, pipe coating and coating, etc.

4 according to the pipe end shape classification
Steel pipe according to the pipe end state can be divided into light tube and wire tube (with thread steel tube).Car wire tube and can be divided into ordinary car wire tube (water, gas, such as low pressure tube, using common cylindrical or tapered pipe thread connection) and special thread tube (geology, oil drilling pipe, for important car wire tube, the use of special threaded connection), for some special tube, to compensate for the influence of the strength of pipe end of thread, often in a car wire before pipe end upset (internal upset, more external upset or inside and outside).

5 according to the outer diameter and wall thickness D S ratio (D/S) of the classification
According to the ratio of wall thickness and diameter D s of different steel tube can be divided into thick tube (D/s (10) or less, thick wall tube (D/s = 10 ~ 20), thin wall tube (D/s = 20 ~ 40) and extremely thin wall pipe (D/s of 40 or higher).

6 classification according to the use
According to use can be divided into oil well pipe (casing, tubing and drill pipe, etc.), line pipe, boiler pipe, mechanical structure, hydraulic prop, cylinder pipe, geological, chemical pipe (high pressure chemical fertilizer pipe, oil cracking pipe) and tube for ships, etc.