1.1 This specification 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 ve 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;