Bolt Type A Narrow Wide Regular ASME B18.21.1 A320 L7M hex bolt alloy bolt
ASTM A320 Grade L7M bolts and studs are also made from quenched and tempered alloy steel.
Mechanical properties and requirements are lower compared to L7 bolts. L7M bolts require a 100% hardness test. Final heat treatment must be done after threading or rolling and any type of cutting. This grade is typically used for sour gas applications. ASTM A320 Grade L7 is the most common A320 bolt grade. Bolts made from this material are extremely resistant to corrosion and various environmental conditions. Steel alloyed with chromium, manganese, and molybdenum is used to make ASTM A320 Grade L7 studs. In order to achieve the necessary mechanical quality, the bolts are subjected to a heat treatment process.