ASTM A194 Grade 2H heavy hex nuts are intended for use in flange bolting applications, as well as structural applications and with other high strength bolting. ASTM A194 covers carbon steel, alloy steel, and stainless steel nuts for bolts in high pressure or high temperature service. Grade markings consists of both the grade symbol "2H" and the manufacturer's identification mark. They are a common high strength nut used with many different bolting grades, including A193 Grade B7, F3125 Grades A325 and A490, as well as with F1554 Grade 105 anchor bolts and studs. 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.