What are the differences between Q345B seamless steel pipe and 20G seamless steel pipe in performance and application?

Q345B seamless steel pipe belongs to low alloy steel pipe, used to be called 16Mn. Main characteristics of Q345B seamless steel pipe: good comprehensive mechanical properties, weldability, cold, hot working performance and corrosion resistance, good low temperature toughness.

However, the pressure resistance of Q345B seamless steel pipe is not as good as 20G seamless steel pipe. Q345B seamless steel pipe can only be used for general boilers or general pressure vessels, and more widely used for ships, bridges, power station equipment, hoisting and transportation machinery and other high load welding structures.

20G seamless steel pipe is a typical high pressure boiler pipe, which is in accordance with GB 5310 seamless steel pipe for high pressure boiler. 20G seamless steel pipe is used as the heating surface pipe fittings, and the maximum wall temperature for long-term use is ≤ 450 ℃. When it is used as header and steam pipe, the long-term use temperature should be ≤ 425 ℃.

The yield strength of 20G seamless steel pipe is far lower than Q345B seamless steel pipe, but the mechanical properties of pressure and high temperature resistance are better than Q345B seamless steel pipe. 20G seamless steel pipe is mainly used in high pressure boiler or pressure vessel.