Seamless steel pipes can be divided into the following categories according to different manufacturing processes, materials and uses:

1. Classification by production process
Hot-rolled seamless steel pipe: produced by high-temperature rolling, suitable for high strength and high toughness requirements, widely used in machinery, construction, oil and gas and other fields.
Cold-drawn seamless steel pipe: produced by cold drawing or cold rolling process, with high precision and high finish, suitable for precision equipment, hydraulic systems, etc.
Extruded seamless steel pipe: the heated steel billet is passed through an extrusion die to make a high-precision seamless steel pipe, which is usually used in environments requiring extremely high quality and corrosion resistance.
2. Classification by material
Carbon steel seamless steel pipe:
Representative grades: 20#, 45#, Q235
Standard: GB/T 8162-2008 (seamless steel pipe for structure), GB/T 8163-2018 (seamless steel pipe for fluid transportation)
Use: commonly used in building structures, machinery manufacturing, general fluid transportation and other fields.
Alloy steel seamless pipe:
Representative grades: 16Mn, 12CrMoV, 10CrMo910
Standard: GB/T 5310-2017 (seamless steel pipe for high-pressure boilers), GB/T 6479-2013 (high-pressure seamless steel pipe for fertilizer equipment)
Application: Mainly used for equipment under high temperature and high pressure conditions, such as boilers, heat exchangers, fertilizer equipment, etc.
Stainless steel seamless pipe:
Representative grades: 304, 316, 321
Standard: GB/T 14976-2012 (stainless steel seamless steel pipe for fluid transportation), GB/T 13296-2013 (stainless steel seamless steel pipe for boilers and heat exchangers)
Application: Mainly used in occasions with high corrosion resistance requirements, such as food, pharmaceutical, petrochemical and other industries.
3. Classification by use
Structural seamless steel pipe:
Standard: GB/T 8162-2008
Application: Suitable for general structure and mechanical structure.
Seamless steel pipe for fluid transportation:
Standard: GB/T 8163-2018
Purpose: used to transport water, oil, natural gas and other fluids.
Seamless steel pipe for high-pressure boiler:
Standard: GB/T 5310-2017
Purpose: used to manufacture various high-temperature and high-pressure boilers and their pipelines.
Seamless steel pipe for fertilizer equipment:
Standard: GB/T 6479-2013
Purpose: used to transport high-temperature and high-pressure fluids in fertilizer equipment.

Different types of seamless steel pipes are suitable for various industrial fields according to their chemical composition and mechanical properties, meeting different requirements of strength, corrosion resistance and high temperature and high pressure conditions.