23/4 - 16 16-UN : Basic Thread Dimensions (Pitch, minor & major diameters, depth, lead), Tolerance range for all applicable classes and much more * Permisable values for thread Class 2B # Description Value (Inch) VValue (mm) D 1: Minor Diameter: 2.682 - 2.696: 68.123 - 68.478: D 2: (UNC/UNF/UNEF) National Pipe (NPT) Dryseal Pipe (BPTF 21/4" - 4 1/2. 2 3/4" - 4. 3 1/2" - 4. 3 3/4" - 4. General Note: All dimensions expressed in inches. Thread calculators and charts. ASME UN screw thread calculator. ASME B1.1-2003, Unified Inch Screw Threads (UN and UNR Thread Form) Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . INTERNALTHREADS – CLASS 2B Nominal Size & Threads / Inch & Series Designation Allowance Minor Diameter Pitch Diameter Major Dia-meter Min. Max. Min. Max. Tolerance Min. 1/4-28 UNF 0.0010 0.2110 0.2200 0.2268 0.2311 0.0043 0.2500 5/16-18 UNC 0.0012 0.2520 0.2650 0.2764 0.2817 0.0053 0.3125 5/16-24 UNF 0.0011 0.2670 0.2770 0.2854 Metric60° Cone. DIN 7631. The male connector has a 60° recessed cone and a straight thread; the female has a straight thread as well, and a globeseal seat. The seal forms between the recessed cone on the male and the tapered nose of the female. The threads of both halves mesh to form a strong mechanical bond. UNFRECOMMENDED TAP FOR CLASS OF THREAD PITCH DIAMETER LIMITS FOR CLASS OF THREAD Class 2 Class Class 3 2B 3B (Basic) Min. All Classes Max. 3/4 10 — GH5 GH3 GH5 GH5 .6850 .6914 .6895 .6927 .6907 3/4 — GH316 GH2 GH5 GH3 .7094 .7139 .7126 .7159 .7143 7/8 9 — GH6 GH4 .8028 .8098 .8077 .8110 .8089 11/4 - 16 16-UN : Basic Thread Dimensions (Pitch, minor & major diameters, depth, lead), Tolerance range for all applicable classes and much more 1 1/4 - 16 16-UN 2B (Internal) * Permisable values for thread Class 2B # Description Value (Inch) (UNC/UNF/UNEF) National Pipe (NPT) Dryseal Pipe (BPTF) British Pipe (BSP) ACME; Threading Nominalthread sizes from 0-80 UNF to ¼-56 UNS Nominal thread sizes from 2 7/8-6 UN to 4-16 UN External Thread / Internal Thread : Nominal Size, TPI, Series: Class: Allowance: Max a Major 2B : 1.8500: 1.8200 : 1.9028: 1.8917: 2.0000: Ext. 2-6 UN: 3A: 0.0000: 2.0000: : 1.8853: 1.8016: 1External Thread Dimensions for unified UNF Screw Threads Diameter Threads Thread Major Diameter Pitch Diameter Minor Diameter Stress Per Fit Class ( ) ( ) ( ) Area Inch Max Min Max Min Max in . (TPI). No 0 80 2A No 1 72 2A No 2 64 2A No 3 56 2A No 4 48 2A No 5 44 2A No 6 40 2A No 8 36 2A No 10 32 2A No 12 28 2A 1/4 28 2A 5/16 24 2A 3/8 24 2A TMxlUS.