1.1 This specification covers high-strength quenched and tempered low-alloy steel forged parts for pressure vessels. The maximum thickness of forgings under this specification shall be 1½ in. [38 mm] for ASTM A592/A592M-04 covers the standard specification for high-strength quenched and tempered low-alloy steel forged fittings and parts used for pressure vessels. The steel shall be made by a melting process and shall be fully killed and fine grained. A