This specification covers standard requirements for high-strength quenched and tempered alloy steel plates intended for use in fusion welded boilers and other pressure vessels. The steel shall be killed and shall conform to the fine austenitic grain size requirement. Heat and product analyses shall be conducted wherein the material shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, boron, vanadium, titanium, zirconium, copper, and columbium. Tensile properties of the steel plate shall meet the specified values for tensile strength, yield strength, and elongation. The material shall undergo mechanical tests such as tension test and transverse Charpy V-notch impact test.