ASTM A 266/A 266M

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 Formerly Grade 1 Class 1 Grade 2 Class 2 Grade 3 Class 3 Grade 4 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 SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.4 Unless the order specifies the applicable " M " specification designation, the material shall be furnished to the inch-pound units.