Steel pipe introduction: steel with hollow section and its length is much larger than the diameter or circumference. According to the section shape, it is divided into circular, square, rectangular and special-shaped steel pipes; According to the material, it is divided into carbon structural steel pipe, low alloy structural steel pipe, alloy steel pipe and composite steel pipe; According to the purpose, it is divided into steel pipes for transmission pipeline, engineering structure, thermal equipment, petrochemical industry, machinery manufacturing, geological drilling, high-pressure equipment, etc; According to the production process, it is divided into seamless steel pipe and welded steel pipe. Seamless steel pipe is divided into hot rolling and cold rolling (drawing), and welded steel pipe is divided into straight seam welded steel pipe and spiral seam welded steel pipe.

Steel pipe is not only used for conveying fluid and powdery solids, exchanging heat energy, manufacturing mechanical parts and containers, but also an economic steel. Using steel pipe to make building structure grid, pillar and mechanical support can reduce weight, save metal by 20 ~ 40%, and realize industrialized and mechanized construction. Manufacturing Highway Bridges with steel pipes can not only save steel and simplify construction, but also greatly reduce the area of protective coating and save investment and maintenance costs. By production method

Steel pipes can be divided into two categories according to production methods: seamless steel pipes and welded steel pipes. Welded steel pipes are referred to as welded pipes for short.

1. According to the production method, seamless steel pipe can be divided into: hot rolled seamless pipe, cold drawn pipe, precision steel pipe, hot expanded pipe, cold spinning pipe and extruded pipe.

Bundles of steel pipes

Bundles of steel pipes

Seamless steel pipe is made of high-quality carbon steel or alloy steel, which can be divided into hot rolling and cold rolling (drawing).

2. Welded steel pipe is divided into furnace welded pipe, electric welding (resistance welding) pipe and automatic arc welded pipe due to different welding processes. Due to different welding forms, it is divided into straight seam welded pipe and spiral welded pipe. Due to its end shape, it is divided into circular welded pipe and special-shaped (square, flat, etc.) welded pipe.

Welded steel pipe is made of rolled steel plate welded by butt seam or spiral seam. In terms of manufacturing method, it is also divided into welded steel pipe for low-pressure fluid transmission, spiral seam welded steel pipe, direct rolled welded steel pipe, welded steel pipe, etc. Seamless steel pipe can be used for liquid and gas pipelines in various industries. Welded pipes can be used for water pipelines, gas pipelines, heating pipelines, electrical pipelines, etc.

Material classification

Steel pipe can be divided into carbon pipe, alloy pipe and stainless steel pipe according to the pipe material (i.e. steel grade).

Carbon pipe can be divided into ordinary carbon steel pipe and high-quality carbon structural pipe.

Alloy pipe can be divided into: low alloy pipe, alloy structure pipe, high alloy pipe and high strength pipe. Bearing pipe, heat and acid resistant stainless pipe, precision alloy (such as kovar alloy) pipe and superalloy pipe, etc.

Connection mode classification

According to the connection mode of pipe end, steel pipe can be divided into: smooth pipe (pipe end without thread) and threading pipe (pipe end with thread).

The threading pipe is divided into ordinary threading pipe and thickened threading pipe at the pipe end.

Thickened threading pipes can also be divided into: externally thickened (with external thread), internally thickened (with internal thread) and internally and externally thickened (with internal and external thread).

According to the thread type, the threading pipe can also be divided into ordinary cylindrical or conical thread and special thread.

In addition, according to the needs of users, the threading pipes are generally delivered with pipe joints.

Classification of plating characteristics

According to the characteristics of surface plating, steel pipes can be divided into black pipes (without plating) and coated pipes.

Coated pipes include galvanized pipes, aluminum plated pipes, chromium plated pipes, aluminized pipes and steel pipes with other alloy layers.

Coated pipes include outer coated pipes, inner coated pipes and inner and outer coated pipes. The commonly used coatings include plastic, epoxy resin, coal tar epoxy resin and various glass type anti-corrosion coating materials.

Galvanized pipe is divided into KBG pipe, JDG pipe, threaded pipe, etc.

Classification purpose classification

1. Pipe for pipeline. Such as seamless pipes for water, gas and steam pipelines, oil transmission pipes and pipes for oil and gas trunk lines. Faucet with pipe for agricultural irrigation and pipe for sprinkler irrigation, etc.

2. Pipes for thermal equipment. Such as boiling water pipes and superheated steam pipes for general boilers, superheated pipes, large smoke pipes, small smoke pipes, arch brick pipes and high-temperature and high-pressure boiler pipes for locomotive boilers.

3. Pipe for mechanical industry. Such as aviation structural pipe (round pipe, oval pipe, flat oval pipe), automobile half axle pipe, axle pipe, automobile tractor structural pipe, tractor oil cooler pipe, agricultural machinery square pipe and rectangular pipe, transformer pipe and bearing pipe, etc.

4. Pipes for petroleum geological drilling. Such as: oil drilling pipe, oil drill pipe (Kelly and hexagonal drill pipe), drilling tappet, oil tubing, oil casing and various pipe joints, geological drilling pipe (core pipe, casing, active drill pipe, drilling tappet, hoop and pin joint, etc.).

5. Pipes for chemical industry. Such as: petroleum cracking pipe, pipe for heat exchanger and pipeline of chemical equipment, stainless acid resistant pipe, high-pressure pipe for chemical fertilizer and pipe for conveying chemical medium, etc.

6. Pipes for other departments. For example: tubes for containers (tubes for high-pressure gas cylinders and general containers), tubes for instruments, tubes for watch cases, injection needles and tubes for medical devices, etc.

Section shape classification

Steel pipe products have a wide variety of steel types and specifications, and their performance requirements are also various. All these should be distinguished according to the changes of user requirements or working conditions. Generally, steel pipe products are classified according to section shape, production method, pipe material, connection mode, plating characteristics and application.

Steel pipes can be divided into round steel pipes and special-shaped steel pipes according to the cross-sectional shape.

Special shaped steel pipe refers to all kinds of steel pipes with non-circular annular section.

They mainly include: square tube, rectangular tube, elliptical tube, flat elliptical tube, semicircular tube, hexagonal tube, hexagonal inner tube, unequal hexagonal tube, equilateral triangle tube, pentagonal quincunx tube, octagonal tube, convex tube, double convex tube, double concave tube, multi concave tube, melon seed tube, flat tube, rhombic tube, star tube, parallelogram tube, ribbed tube, drop tube, inner fin tube, twist tube, B-TUBE D-tube and multilayer tube, etc.