ASTM A508/A508M-95(1999)

1.1 This specification covers quenched and tempered vacuum treated carbon and alloy steel forgings for pressure vessels such as those used in reactor systems. Specifically, it covers forgings for vessel closures, shells, flanges, tube sheets, rings, heads, and similar parts.

1.2 All grades are considered weldable under proper conditions. Welding technique is of fundamental importance, and it is presupposed that welding procedure and inspection will be in accordance with approved methods for the grade of material used.

1.3 The values stated in either inch-pound units or SI (metric) units are to be regarded separately as standards. Within the text and the tables, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independent 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.

Note 1-Grades 1 and 1A are composed of different chemistries but have the same mechanical requirements. Note 2-Designations have been changed as follows: Current Grade 1 Grade 1A Grade 2 Class 1 Grade 2 Class 2 Grade 3 Class 1 Grade 3 Class 2 Grade 4N Class 1 Grade 4N Class 2 Grade 4N Class 3 Grade 5 Class 1 Grade 5 Class 2 Grade 22 Class 3 Grade 3V Formerly Class 1 Class 1A Class 2 Class 2A Class 3 Class 3A Class 4 Class 4A Class 4B Class 5 Class 5A Class 22B Class 3V