Stainless steel pipe can be divided into round pipe and special-shaped pipe according to the cross-section shape. Special-shaped tube has rectangular tube, lozenge tube, elliptic tube, hexagonal tube, eight direction tube and all sorts of section asymmetry tube to wait. Special-shaped tubes are widely used in various structural parts, tools and machinery parts. Compared with the round tube, the special-shaped tube generally has a larger moment of inertia and section modulus, has a larger bending, torsion resistance, can greatly reduce the weight of the structure, save steel. Stainless steel pipe can be divided into equal section pipe and variable section pipe according to the longitudinal section shape. Variable section pipe has conical pipe, ladder pipe and periodic section pipe, etc. Stainless steel pipe can be divided into light pipe and wire pipe according to the state of the pipe end (with threaded steel pipe). Turning wire pipe can be divided into ordinary turning wire pipe (water, gas and other low-pressure pipe, using ordinary cylindrical or conical pipe thread connection) and special thread pipe (oil, geological drilling pipe, for important turning wire pipe, using special thread connection), for some special pipe, in order to make up for the influence of thread on the pipe end strength, The pipe end is usually thickened (inside, outside or inside) before the wire is spun. It can be divided into oil well pipe (casing, tubing and drill pipe), pipeline pipe, boiler pipe, mechanical structure pipe, hydraulic prop pipe, gas cylinder pipe, geological pipe, chemical pipe (high-pressure fertilizer pipe, petroleum cracking pipe) and ship pipe. Raw material - swatch - welding pipe - end - polishing - inspection (printing) - packaging - shipment (warehousing) (decoration welded pipe). Raw material - article points - welding pipe, heat treatment, correct, straightening, fix the end, pickling, water pressure test, inspection (spurts India) - packaging - shipment (transport) (tube) for piping weld pipe industry.