This specification deals with carbon and alloy steel forgings (including gas bottles) for use in thin-walled pressure vessels. Covered here are the following grades of steel forgings: Grade A; Grade B; Grade C; Grade D; Grade E, Classes 55, 65, and 70; Grade F, Classes 55, 65, and 70; Grade G, Classes 55, 65, and 70; Grade H, Classes 55, 65, and 70; Grade J, Classes 55, 65, and 70; Grade K; Grade L; Grade J, Class 110; and Grade M, Classes 85 and 100. Materials shall be manufactured by melting procedures, and optionally heat treated by normalization, normalization and tempering, or liquid-quenching and tempering. Heat and product analyses shall be performed wherein steel specimens shall conform to required chemical compositions of carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, and vanadium. Steel materials shall also undergo bending, flattening and hardness tests and shall conform to required values of tensile strength, yield strength, elongation, and hardness. Forgings shall be subjected to magnetic particle examination as well.

1.1 This specification2 covers relatively thin-walled forgings (including gas bottles) for pressure vessel use. Three types of carbon steel and six types of alloy steel are included. Provision is made for integrally forging the ends of vessel bodies made from seamless pipe or tubing.

Note 1: When working to the chemical and tensile requirements of this specification, the influence of wall thickness and cooling rate will necessarily eliminate certain forging sizes in each class.

Note 2: Designations have been changed as follows:

Current

Formerly

Grade A

Type I

Grade B

Type II

Grade C

Type III

Grade D

Type IV

Grade E Class 55

Type V Grade 1 Class 55

Grade E Class 65

Type V Grade 1 Class 65

Grade E Class 70

Type V Grade 1 Class 70

Grade F Class 55

Type V Grade 2 Class 55

Grade F Class 65

Type V Grade 2 Class 65

Grade F Class 70

Type V Grade 2 Class 70

Grade G Class 55

Type V Grade 3 Class 55

Grade G Class 65

Type V Grade 3 Class 65

Grade G Class 70

Type V Grade 3 Class 70

Grade H Class 55

Type V Grade 4 Class 55

Grade H Class 65

Type V Grade 4 Class 65

Grade H Class 70

Type V Grade 4 Class 70

Grade J Class 55

Type V Grade 5 Class 55

Grade J Class 65

Type V Grade 5 Class 65

Grade J Class 70

Type V Grade 5 Class 70

Grade K

Type VI

Grade L

Type VII

Grade J Class 110

Type VIII

Grade M Class 85

Type IX Class A

Grade M Class 100

Type IX Class B

1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.

1.3 Unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished to inch-pound units.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.