1.1This specification2 covers requirements for quenched and tempered carbon and alloy steel forgings for pressure vessel components.
1.2All 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.
Note 1:Grades 1 and 1A have different chemistries but the same mechanical requirements.
Note 2:Designations have been changed as follows:
Current |
Formerly |
Grade 1 |
Class 1 |
Grade 1A |
Class 1A |
Grade 1C |
Class 4 |
Grade 2 Class 1 |
Class 2 |
Grade 2 Class 2 |
Class 2A |
Grade 3 Class 1 |
Class 3 |
Grade 3 Class 2 |
Class 3A |
Grade 4N Class 1 |
Class 7 |
Grade 4N Class 2 |
Class 7A |
Grade 4N Class 3 |
Class 7B |
Grade 5 Class 1 |
Class 8 |
Grade 5 Class 2 |
Class 8A |
Grade 11 Class 4 |
Class 11C |
Grade 22 Class 3 |
Class 22B |
Grade 22 Class 4 |
Class 22C |
Grade 22 Class 5 |
Class 22D |
Grade 22V |
Class 22V |
Grade 3V |
Class 3V |
1.3The 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.
1.4Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch-pound units.