All the two ends of the opening and hollow section, and the length and the section circumference of the larger steel, can be called steel pipe.
Steel pipe is a kind of economic steel, is an important product in the steel industry, usually accounts for the total amount of steel10About %, it has a wide range of applications in the national economy. Because of the hollow section of the steel pipe, so the most suitable for the fluid transport pipeline; At the same time, compared with the same weight round steel, steel pipe section coefficient is large, bending and torsional strength is large, and it has become an important material in various mechanical and architectural structures, especially in oil drilling, smelting and transportation needs the most, followed by drilling, chemical industry, construction industry, machinery industry, aircraft and automobile manufacturing, as well as boilers, medical instruments, furniture and bicycles, etc. You need a lot of steel pipes of all kinds. In recent years, with the development of new technologies such as atomic energy, rocket, missile and space industry, steel pipe plays an increasingly important role in national defense industry, science and technology and economic construction, and is known as the "blood vessel" of industry.
There are many kinds of steel pipes, different uses, different technical requirements, production methods are also different. At present, the outer diameter of steel pipe produced by0.1~4500Mm, wall thickness is0.01~250millimeter In order to distinguish their characteristics, steel pipes are usually classified in the following ways:
According to the production method: steel pipe is divided into seamless pipe and welded pipe two categories, seamless steel pipe can be divided into hot rolled pipe, cold rolled pipe, cold drawn pipe and extrusion pipe; Cold drawing and cold rolling are the secondary processing of steel pipe. Welded pipe is divided into straight seam welded pipe and spiral welded pipe.
According to the cross-section shape of steel pipe: according to the cross-section shape can be divided into garden pipe and shaped pipe; Special-shaped tube: rectangular tube, diamond tube, elliptic tube, hexagonal tube, eight party tube and a variety of cross-section asymmetric tube; 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.
According to the material of the steel pipe, the steel pipe is divided into ordinary carbon steel pipe, 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.
According to the shape of the pipe end: according to the state of the pipe end can be divided into light pipe and wire pipe (with spiral steel pipe). 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, using special thread connection, for important wire pipe), 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.
By outside diameter (D) and wall thickness (S) to (D/S) divide steel tubes into extra thick tubes (D/SOr less10), thick-walled tube (D/S=10~20), thin-walled tube (D/S=20~40) and ultra-thin-walled tube (D/Sp40).
Divided by use: 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), ship pipe, etc.
