ASME B18.2.1 B18.2.2 Full UNC UN UNF Threaded ASTM A320 L7M Hex Bolt And Nuts
The A320 Gr L7 stud material will undergo the following parametric tests – Impact Test, Tensile Test and Hardness Test according to the mechanical specification of A320 Grade L7 Bolts. The specification of A320 Gr L7 Hdg covers several grades of stainless steel including austenitic and ferritic stainless steels.
A320 bolts will use A194 heavy hex nuts. There are multiple grades within the A194 specification. The appropriate grade of A194 nut will be determined by the chemistry and strength of the fastener grade. Machining ASTM A320 Hex Head Bolts requires low speeds and constant feeds to reduce its tendency to work harden. The low carbon in ASTM A320 Hex Head Nuts provides resistance to sensitization during welding and other thermal processes. ASTM A320 Grade L7M is a standard material specification for alloy steel bolting materials for pressure vessels, valves, flanges, and fittings for low temperature services. ASTM A320 Grade L7M is heat treated chromium molybdenum alloy steel (AISI 4140/AISI 4140H) with notch toughness properties. Please find chemical composition, mechanical properties, impact test requirement, and reference standards for product dimensions, threads, coatings and recommended nuts and washers. Carbon steel nuts can undergo an impact test and will need to marked with an “L” to show it has been tested. However, impact testing is not required if the bar stock or nut is smaller than 5/8″ diameter.