ASME SA516 refers to a specific material used in the manufacture of pressure vessel shells. In pressure vessels, the shell refers to the main plate material forming the cylindrical or spherical portion of the vessel.

SA516 Gr.70 and Gr.485 are essentially the same material; their chemical composition, mechanical properties, and processing characteristics are considered completely equivalent in the ASME standard, and they are the most commonly used carbon steel plates for manufacturing cryogenic pressure vessel shells.

The core difference lies in their naming system: Gr.70 uses imperial units, where "70" represents a minimum tensile strength of 70,000 psi; while Gr.485 uses metric units, where "485" represents a minimum yield strength of 485 MPa.

This naming difference stems from the different unit systems used in the project. Gr.70 is commonly used in North America, while Gr.485 is more common in Europe and China. Therefore, in actual engineering, they can meet the same design requirements, but they must be procured and manufactured strictly according to the grades specified in the design documents and cannot be substituted.