ASTM A537 Standard Specification for Pressure Vessel Plates, Heat-Treated, Carbon-Manganese-Silicon Steel This specification covers heat-treated carbon-manganese-silicon steel plates intended for fusion welded pressure vessels and structures. Material under this specification is available in the following three classes: Class Heat Treatment Thickness Yield Strength, min, Tensile Strength, min, ksi (MPa) ksi (MPa) 1 Normalized ≤2.5in.( ≤65mm) 50…