1.1 This specification covers quenched-and-tempered alloy steel and high-strength low-alloy steel plates for piping components and welded pressure vessels. 1.2 Two types are covered, which provide two different chemical This specification covers quenched and tempered alloy steel and high strength low alloy steel plates for piping components and welded pressure vessels. The steel materials shall be killed and shall conform to the fine austenitic grain size requirement.