1.1 This specification covers high-strength quenched and tempered alloy steel plates intended for use in fusion welded pressure vessels.

1.2 Plates furnished under this specification are available in three classes having different strength levels as follows:

1.3 The thickness of plates under this specification is limited to a maximum of 2 in. [50 mm].

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 is to be used independently of the other without combining values from the two systems.