20# and 20G steel pipe steel grades are both carbon structural steels with a carbon content of 0.20%.
1. 20 steel is used for general steel pipes, and there are three standards.
Standard GB8162 is applicable to seamless steel pipes for structures;
Standard GB8163 is applicable to general seamless steel pipes for conveying fluids;
Standard GB3087 is applicable to seamless steel pipes for low and medium pressure boilers. This standard is applicable to the manufacture of high-quality carbon structural steel hot-rolled and cold-drawn (rolled) seamless steel pipes for superheated steam pipes, boiling water pipes, and locomotive boilers for various structures.
2. 20G is usually called No. 20 boiler steel. Its material is better than ordinary No. 20 steel. 20G steel pipe is a high-quality carbon structural steel for manufacturing steam boilers and pipelines with high pressure and above. For example, it is widely used to manufacture economizers, superheaters, water-cooled walls, feed water, main steam pipes, etc. with medium temperatures ≤430℃.
Standard GB5310 is applicable to seamless steel pipes for high-pressure boilers.

3. 20g also refers to No. 20 boiler steel, 20G means pipe, and 20g means plate, which is made by rolling and welding steel plates, and is used to manufacture high-quality carbon steel plates for various boiler pressure components.

Standard GB713 is applicable to carbon cable steel and low alloy steel plates for boilers. .