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 compositions with the same tensile requirements. Both types are quenched-and-tempered to enhance mechanical properties.

1.2.1 Type A is an alloy steel intended for use at low ambient temperatures of -80°F [-60°C] and higher.

1.2.2 Type B is a high-strength low-alloy steel intended for use at ambient temperatures of -20°F [-30°C] and higher.

1.3 The maximum thickness of plates is limited only by the capacity of the chemical composition and heat treatment to meet the specified mechanical property requirements. Individual manufacturers should be consulted on thickness limitations since current industry limitations have not been ascertained to date.

1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.