TUBE OD UN / UNF S L D PART NO. mm Inch N mm mm mm 6 1/4 7/16 -20 11 22.6 4.4 4F-T 8 5/16 1/2 -20 13 24.1 6 5F-T 10 3/8 9/16 -18 14 26.9 7.5 6F-T 12 1/2 3/4 -16 19 31.8 9.9 8F-T 14/15/16 5/8 7/8 -14 22 36.8 12.3 10F-T 18/20 3/4 1 1/16 -12 27 42.2 15.5 12F-T 25 1 1 5/16 -12 33 46 21.5 16F-T 28/30/32 1 1/4 1 5/8 -12 41 52.3 27.5 20F-T 35/38 1 1/2 1 7/8 -12 48 59.2 33 24F-T