By production method
Steel pipes can be divided into two categories according to production methods: seamless steel pipes and welded steel pipes, and welded steel pipes are abbreviated as welded pipes.

1. Seamless steel pipes can be divided into hot rolled seamless pipes, cold drawn pipes, precision steel pipes, hot expanded pipes, cold spun pipes, and extruded pipes according to production methods.
   Seamless steel pipes are made of high-quality carbon steel or alloy steel, which can be hot-rolled or cold-rolled (drawn).
2. Welded steel pipes are divided into furnace welded pipes, electric welding (resistance welding) pipes and automatic arc welded pipes due to their different welding processes. They are divided into straight seam welded pipes and spiral welded pipes due to their different welding forms. Because of their end shapes, they are also divided into circular welded pipes and special-shaped (square, flat, etc.) welded pipes.
   Welded steel pipes are made of rolled steel plates welded with butt or spiral seams. In terms of manufacturing methods, they are further divided into welded steel pipes for low-pressure fluid transportation, spiral welded steel pipes, directly rolled welded steel pipes, welded pipes, etc. Seamless steel pipes can be used in various industries such as liquid pressure pipelines and gas pipelines. Welded pipelines can be used for water pipelines, gas pipelines, heating pipelines, electrical pipelines, etc.
   Material classification
   Steel pipes can be divided into carbon pipes, alloy pipes, stainless steel pipes, etc. according to their material (i.e. steel grade).
   Carbon pipes can also be divided into ordinary carbon steel pipes and high-quality carbon structural pipes.
   Alloy pipes can also be divided into: low alloy pipes, alloy structural pipes, high alloy pipes, and high-strength pipes. Bearing pipes, heat and acid resistant stainless pipes, precision alloy (such as Kovar alloy) pipes, and high-temperature alloy pipes.
   Classification of connection methods
   Steel pipes can be divided into smooth pipes (without threads at the pipe end) and threaded pipes (with threads at the pipe end) according to the pipe end connection method.
   The threading tube is further divided into ordinary threading tube and thickened threading tube at the end of the tube.
   Thickened thread pipes can also be divided into: externally thickened (with external threads), internally thickened (with internal threads), and internally thickened (with internal and external threads).
   Threading pipes can also be divided into ordinary cylindrical or conical threads and special threads according to the thread type.
   In addition, according to user needs, wire pipes are generally delivered with pipe joints.
   Classification of coating characteristics
   Steel pipes can be divided into black pipes (non coated) and coated pipes according to their surface coating characteristics.
   Coated pipes include galvanized pipes, aluminum pipes, chrome pipes, aluminized pipes, and other alloy coated steel pipes.
   Coated pipes include outer coated pipes, inner coated pipes, and inner and outer coated pipes. The coatings commonly used are plastic, epoxy resin, coal tar epoxy resin and various glass based anti-corrosion coating materials.
   Galvanized pipes are further divided into KBG pipes, JDG pipes, threaded pipes, etc.
   Classification purposes classification
3. Pipes for pipelines. For example, seamless pipes for water, gas, and steam pipelines, oil transmission pipes, and pipes for oil and natural gas pipelines. Agricultural irrigation faucets with pipes and sprinkler irrigation pipes, etc.
4. 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.
5. Mechanical industry pipes. For example, aviation structural pipes (round pipes, elliptical pipes, flat elliptical pipes), automotive half axle pipes, axle pipes, automotive tractor structural pipes, oil cooler pipes for tractors, square and rectangular pipes for agricultural machinery, transformer pipes, and bearing pipes.
6. Pipes for petroleum geological drilling. For example, petroleum drilling pipes, petroleum drill pipes (square and hexagonal drill pipes), drilling rods, petroleum oil pipes, petroleum casings and various pipe joints, geological drilling pipes (core pipes, casings, active drill pipes, drilling rods, clamps and pin joints, etc.).
7. Chemical industry pipes. For example, petroleum cracking pipes, pipes for chemical equipment heat exchangers and pipelines, stainless acid resistant pipes, high-pressure pipes for fertilizers, and pipes for transporting chemical media.
8. Management for other departments. For example, container tubes (high-pressure gas cylinder tubes and general container tubes), instrument tubes, watch case tubes, injection needles and medical device tubes, etc.
   Classification of cross-sectional shapes
   The steel types and specifications of steel pipe products are extremely diverse, and their performance requirements are also various. All of these should be distinguished according to changes in user requirements or working conditions. Usually, steel pipe products are classified based on cross-sectional shape, production method, pipe material, connection method, coating characteristics, and usage.
   Steel pipes can be divided into round steel pipes and irregular steel pipes according to their cross-sectional shape.
   Deformed steel pipes refer to various non circular circular cross-section steel pipes.
   Among them, square tube, rectangular tube, elliptical tube, flat elliptical tube, semicircular tube, hexagonal tube, hexagonal inner tube, unequal hexagonal tube, equilateral triangle tube, pentagonal plum 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, twisted tube, B-type tube D-shaped pipes and multi-layer pipes, etc.
   Steel pipes are further divided into equal section steel pipes and variable section steel pipes according to their longitudinal shape. Variable cross-section (or variable cross-section) steel pipes refer to steel pipes that undergo periodic or non periodic changes in the shape, inner and outer diameters, and wall thickness of the cross-section along the rectangular direction of the pipe. It mainly includes: outer conical tube, inner conical tube, outer stepped tube, inner stepped tube, periodic section tube, corrugated tube, spiral tube, steel pipe with heat dissipation fins, and gun barrel with double lines.