The ASTM A537 specification is the Standard Specification for Pressure Vessel Plates, Heat-Treated, Carbon-Manganese-Silicon Steel used in the applications of fusion welded pressure vessels and structures. ASTM A537 steel is a kind of low alloy steel that covers 3 grades (Class 1, Class 2, Class 3) , ASTM A537 steel plates are used when yield and tensile strength of ASTM A516 can not meet the requirements of pressure services like boiler and pressure vessels in oil, gas, petroleum industries. A537 Class 1 steel is available as Normalized. A537 Class 2 steel and A537 Class 3 steel are available as Quenched & Tempered plates.