This specification covers chromium-molybdenum-tungsten alloy steel plates intended primarily for welded boilers and pressure vessels designed for elevated temperature service. The plates shall be available in three grades, namely Grades 23, 911, and 122, having different alloy contents. The maximum thickness of plates is limited only by the capacity of the composition to meet the specified mechanical requirements. The steel shall be killed and the plates shall undergo heat treatment. In order to determine mechanical properties such as yield strength and elongation, the plates shall be subjected to tension and hardness tests.

1.1 This specification covers Chromium-Molybdenum-Tungsten alloy steel plates intended primarily for welded boilers and pressure vessels designed for elevated temperature service.

1.2 Plates are available under this specification in three grades having different alloy contents as follows:

1.3 The maximum thickness of plates is limited only by the capacity of the composition to meet the specified mechanical property requirements.

1.4 The specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable "M" specification designation (SI units), the material shall be furnished to inch-pound units.

1.5 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.