What are the differences between 20G, 20g, 20R, and 20 steel, and how should they be chosen for use in chemical pipelines?

20G--refers to 20# boiler steel pipe； 20g refers to 20# boiler steel plate ； 20R represents steel for 20# pressure vessels ； 20# denotes high-quality carbon steel with a carbon content of around 0.2%. Several types of steel have similar physical properties; only 20G, 20g, and 20R contain less impurities. The welding properties and physical and chemical properties are better. Several types of steel can be used for pressure-bearing pipes; however, the operating temperature for 20# steel is lower.

What is the difference between Q 20G and 20R? The four steel grades 20, 20G, 20g’, and 20Zhu are all carbon structural steels with a carbon content of 0.20%. But there are significant differences between them, and the price differences are quite substantial. If the right selection is not made during design and use, it can lead to catastrophic accidents in severe cases, or it can affect the product’s service life in less serious cases. It may also result in the misuse of high-quality materials. The differences among these four steel grades, as well as the points to note in their design and use, are described below. I. The applicable standards and uses are different. 1.1 20 steel is used for ordinary steel pipes, and there are three standards for it. Standard GB8162 applies to seamless steel tubes for structural use ； Standard GB8163 applies to general seamless steel pipes for fluid transportation ； Standard GB3087 applies to seamless steel tubes for low- and medium-pressure boilers. It covers hot-rolled and cold-drawn (rolled) seamless steel tubes made of high-quality carbon structural steel, which are used for manufacturing superheater tubes, feedwater tubes in various types of low- and medium-pressure boilers, as well as superheater tubes, large flue tubes, small flue tubes, and arch brick tubes for locomotive boilers. 1.2 20G is a high-quality carbon structural steel used for manufacturing steam boilers, pipes, and other components that require high pressures or higher. It is widely used to manufacture economizers, superheaters, water walls, feedwater pipes, main steam pipes, etc., for media temperatures ≤ 430°C. Standard GB5310 applies to seamless steel tubes for high-pressure boilers. 1.3 20g is used to manufacture carbon steel plates with a thickness of 60–120 ram for various pressure-bearing components in boilers. Standard GB713 applies to carbon steel and low-alloy steel for boilers; alloy steel is also covered by this standard. 1.4 20R is suitable for carbon steel with a thickness of 6–10 mm for pressure-bearing components in medium- and high-temperature pressure vessels. Standard GB6654 applies to steel plates for pressure vessels.

Reply to 3# qiangyou*u: The operating temperature for carbon steel should not exceed 370°C; otherwise, the formation of spheroidized pearlite can occur, leading to a deterioration in the quality of the material.