scope:

1.1 This specification covers four grades of carbon steel forgings for boilers, pressure vessels, and associated equipment.

Note 1-Designations have been changed as follows: Current: Grade 1, Grade 2, Grade 3, Grade 4. Formerly: Class 1, Class 2, Class 3, Class 4.

1.2 Supplementary requirements are provided for use when additional testing or inspection is desired. These shall apply only when specified individually by the purchaser in the order.

1.3 The values stated in either inch-pound units or SI (metric) units are to be regarded separately as the standard. Within the text and tables, 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.

1.4 Unless the order specifies the applicable "M" specification designation, the material shall be furnished to the inch-pound units.