Hex coupling nut dimensions sizes table according to ASME B18.2.2. All dimensions are given in inches.
Note 1: Nuts shall be furnished without a hole, unless specially ordered by the purchaser. In some applications it may be desirable to assure that the threaded parts joined by a coupling nut are each engaged to approximately one-half nut thickness. As a visual inspection aid, a hole drilled through one side of the nut is recommended. The hole should be located at mid-nut thickness, and have a diameter of 0.2 to 0.4 times nominal nut size for sizes 2 1⁄2 in. and smaller, and 1 in. for sizes 2 3⁄4 in. and larger.