Libiti tsa 321 li koahela molao oa ho ts'oaroa ka mokhoa o sa sebetseng oa tšepe bakeng sa khatello ea lisebelisoa tsa poping. Lintho tsa bohlokoa tsa li-pipi li tla kenyelletsa lijo, mekoallo, lipolanete kapa lipompo tse sa sebetseng. Forging or forming operations shall be performed by hammering, pressing, piercing, extruding, upsetting, rolling, bending, fusion welding, machining, or a combination of two or more of these operations. Lisebelisoa tsohle li lokela ho ba mocheso.