Hex nuts (dimensional data) are defined in ASME B18.2.2
Depending on a customer specification, nuts must be both sites chamfered or with on one side a washer-face.
Materials for Stud Bolts
Frequently used grades are A193 for thread rods and A194 for the nuts.
ASTM A193 covers alloy and stainless steel bolting material for pressure vessels, Valves, flanges, and fittings for high
temperature or high pressure service, or other special purpose applications.
ASTM A194 covers a variety of carbon, alloy, and martensitic and austenitic stainless steel nuts. These nuts are
intended for high-pressure or high-temperature service, or both.