‘Nuts’ is a general term for all types of fasteners with a threaded hole for attachment to a bolt. Nuts are usually used and included with studbolts and hexagon bolts. If they are included, they are delivered with a 3.1 certificate and are ‘marked’ with a quality indication and a manufacturer’s logo.
Standard: ANSI B18.2.2
In addition to many different diameters, there are also many different qualities and types available. The quality options are usually those specified in ASTM A194. Another distinction can also made between the use of carbon steels or various alloys to manufacture the nuts.