Small Hex Nuts

Inch Hex Nut Description

Threads are standard right-hand and Unified inch coarse series (UNC, Unified National Coarse) or Unified inch fine (UNF, Unified National Fine).
Inch Hex Nut size refers to its nominal thread diameter. Typically, sizes range from 1/4" to about 2 1/2". Size is specified in inches, usually fractional rather than decimal. Table 1 lists width across flats and across corners, and thickness.
Width across flats, which is wrench size, ranges from 1.50 to 1.75 times the nominal hex nut size and thickness is 0.850 to 0.875 times the size. Nuts that are 5/8" and smaller are double (top and bottom) chamfered (beveled); larger sizes may be double chamfered or have a washer face bearing (bottom) surface and a chamfered top.
Stainless steel hex nuts and bolts/screws used together are susceptible to thread galling and seizing. While it may not be completely preventable, it can be substantially reduced. A thread lubricant is the most effective method. Alternatively, stainless steel alloys having different hardnesses—like a 316 nut and a 304 bolt—have less tendency to gall.
If you need a thinner nut, choose a jam nut. For smaller sizes—diameter, width and thickness—look to machine screw nuts. For a wider and thicker nut, consider a heavy hex nut.
Refer to ASME B18.2.2 for specifications relating to hex nuts.