The standard for 304 stainless steel pipes

The standard for 304 stainless steel pipes 

The implementation standards for 304 stainless steel pipes mainly include domestic standards and international standards.

Domestic standards

1. GB/T 14975-2002: This standard stipulates the technical requirements, test methods, inspection rules, packaging, marking, quality certificates, etc. of 304 stainless steel seamless pipes. It also makes specific requirements for the chemical composition, mechanical properties, appearance quality, and dimensional deviations of 304 steel pipes, ensuring the stability of product quality. 

2. GB/T 14976-2002: This standard is applicable to 304 stainless steel welded pipes. It specifies the technical requirements, test methods, inspection rules, packaging, marking, and quality certificates, ensuring the quality reliability of the products. 

3. GB/T 18705-2002: This standard is specifically designed for stainless steel welded pipes used for fluid transportation. It stipulates dimensions, shape, weight, technical requirements, etc., and is applicable to the application of 304 stainless steel pipes in the field of fluid transportation. 

4. GB/T 12771-2008: This standard specifies the classification, code, dimensions, appearance, quality, test methods, packaging, and marking for stainless steel welded pipelines. It is applicable to welded pipelines in fields such as food, pharmaceuticals, and papermaking. 

International standards

‌ASTM A312/A312M-2019‌: This standard is applicable to the manufacturing and inspection of 304 stainless steel seamless pipes and welded pipes, stipulating requirements in terms of chemical composition, mechanical properties, appearance quality, dimensional deviations, etc., and is widely accepted and applied.

‌EN 10217-7:2005‌: It specifies the technical requirements, test methods, inspection rules, packaging, marking, quality certificates, etc. of 304 stainless steel welded pipes, providing a basis for international trade. 

Chemical composition and mechanical properties

The chemical composition of 304 stainless steel includes elements such as chromium (Cr), nickel (Ni), carbon (C), manganese (Mn), phosphorus (P), and sulfur (S), among others. Chromium and nickel are the key elements that ensure corrosion resistance and formability. According to the national standard GB/T 20878-2007, the chromium content of 304 stainless steel should be at least 18%, and the nickel content should be at least 8%. Its mechanical properties include tensile strength, yield point, elongation, and hardness, etc. Usually, the hardness is between HRC 17 and 23. 

Operating environment and surface treatment process

304 stainless steel is suitable for use in most corrosive medium conditions, including oxidative environments and environments with acetic acid, acidic chlorides, and high-temperature conditions, etc. In certain specific environments, such as high-temperature and high-humidity environments, intergranular corrosion may occur. Surface treatment processes include hot rolling, cold rolling, wire drawing, sandblasting, polishing, etc. Different processes will affect the appearance and performance of the product.