ASTM A194 Grade 7 heavy hex nuts are manufactured from alloy steel, quenched and tempered. The ASTM A194 specification covers carbon steel, alloy steel, and stainless steel nuts for bolts in high pressure or high temperature service. They are a common high strength nut used with stud bolts for high and low temperature service, such as B16 and L7. Dimensional specifications are governed by ASME B18.2.2. Heavy hex nuts provide increased bearing surface area over finished nuts such as J995 Grade 5 nuts.