GB/T 5310-2017 is the technical specification for seamless steel pipes for high-pressure boilers in the Chinese national standard. It is applicable to the manufacture of steam boilers, pipelines, and other equipment operating at high pressures and above.
This standard covers a variety of alloy steels, of which 12CrMoG and 15CrMoG are two commonly used alloy steels with extensive applications and significant advantages.
12CrMoG is a chromium-molybdenum alloy steel with excellent high-temperature resistance and oxidation resistance. It is suitable for boiler superheaters, reheaters, steam piping, and other components operating at temperatures below 540°C. Its advantages include high creep strength and endurance strength, and the ability to maintain stable mechanical properties under high-temperature and high-pressure environments. It also has good weldability and processability, making it easy to manufacture and install.

15CrMoG is another chromium-molybdenum alloy steel with superior performance to 12CrMoG. It is suitable for high-pressure boiler components operating at temperatures below 550°C. This material offers higher high-temperature strength and oxidation resistance, making it particularly suitable for manufacturing key components such as boiler headers and main steam piping. 15CrMoG also boasts excellent resistance to hydrogen corrosion, effectively preventing material degradation in high-temperature, high-pressure hydrogen environments and extending equipment life.

These two alloy steels are widely used in high-temperature, high-pressure equipment in the power, petrochemical, and chemical industries. Their advantages are primarily reflected in the following aspects: First, they exhibit excellent high-temperature mechanical properties, enabling them to withstand long-term high-temperature, high-pressure operating conditions; second, they exhibit excellent microstructural stability, making them less susceptible to structural degradation during long-term service; third, they exhibit excellent weldability and processability, facilitating fabrication and maintenance; and finally, their use significantly improves equipment safety and reliability, reduces downtime and maintenance, and lowers operating costs.

Other high-performance alloy steels are also available to meet the needs of varying temperature, pressure, and corrosive environments.

20G (Carbon Steel)
Although 20G is not an alloy steel, it is a key material listed in GB/T 5310-2017 as a high-quality carbon structural steel, primarily used in low-temperature boiler components such as economizers and low-temperature superheaters. Its advantages include low cost and excellent machining and welding properties. It is suitable for medium- and low-pressure boiler piping with operating temperatures not exceeding 450°C.
12Cr1MoVG
12Cr1MoVG is a chromium-molybdenum-vanadium alloy steel with superior high-temperature strength and oxidation resistance compared to 12CrMoG and 15CrMoG. The addition of vanadium improves the material's creep strength and endurance strength, enabling it to maintain stable performance in long-term high-temperature environments. 12Cr1MoVG is suitable for high-pressure boiler superheaters, reheaters, and main steam piping with operating temperatures below 570°C.
25MnG (Manganese Low Alloy Steel)
25MnG is a low-alloy steel with a high manganese content, offering improved strength and toughness compared to 20G. It boasts higher yield strength and tensile strength while maintaining good weldability. 25MnG is suitable for boiler components with slightly higher operating temperatures, such as superheater tubes and steam piping in medium-pressure boilers. Its operating temperature generally does not exceed 480°C. For boiler components with lower temperature requirements, 20G carbon steel is preferred due to its economical performance. When temperatures approach 450°C, 25MnG is an option. For temperatures between 450-500°C, 15MoG is recommended. For temperatures between 500-530°C, 20MoG is a more suitable choice. These non-alloy and low-alloy grades, combined with high-alloy steel, can optimize boiler manufacturing costs while maintaining performance.