Technical features and scope of the ASTM A320 / A320M (ASME SA 320 / SA 320M) standard
The international standard ASTM A320 (and its ASME SA 320 code equivalent) establishes rigorous requirements for the production of high-strength bolts, studs, and other threaded fasteners intended for service at cryogenic temperatures. These products, supplied by EV Group China, are indispensable for the installation of high-pressure equipment: flanged joints, valves, piping systems, and vessels operating in extremely cold climatic zones.
The manufacturing process for A320 specification fasteners involves hot deformation followed by precision machining, such as centerless grinding or cold drawing, to ensure required tolerances. Austenitic stainless steel grades undergo heat treatment (annealing or solution quenching) to achieve an optimal microstructure. When ordering products made of strain-hardened austenitic steels, EV Group China engineers recommend considering the specific provisions of Appendix X1 to ensure material property stability.
The standard classifies materials into ferritic and austenitic groups (markings such as L7, B8, etc.). The choice of specific steel is based on design loads, temperature range, and material impact toughness. EV Group China engineers conduct incoming quality control, ensuring that the steel grade meets design mechanical characteristics before machining begins. For example, to ensure high impact toughness at temperatures down to -101 °C (Grade L43), steels with high melt purity are used (minimum sulfur and phosphorus content in AISI 4340 composition).
Testing and delivery requirements
Control procedures and general delivery requirements for fasteners are regulated by the ASTM A962/A962M specification. Special attention is paid to nuts, which must also undergo mandatory impact toughness testing to meet the operating conditions of low-temperature equipment.
EV Group China offers additional fastener testing capabilities upon individual customer request. Delivery terms (units of measurement — imperial or SI) are recorded in the contract. Please note that values in different measurement systems are not direct mathematical equivalents; therefore, using data from different standards simultaneously is not permitted to avoid non-compliance with design specifications.