214 BS21 Thread 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Size Number of Threads in 25.4 mm Pitch Depth of Thread Basic Diameters at Gauge Plane Gauge Length (See Note1) Minimum Length of Useful Thread on Pipe End (See Note1) Fitting Allowance (See Note1) Wrenching Allowance (See Note1) Tolerance on Position of Gauge Plane Relative to Face of Internally Threaded Parts (See Note1) Diametral Tolerance on Parallel Internal Threads R/Rc Major (Gauge Diameter) Pitch Minor Basic Tolerance Maximum Minimum Basic Gauge Length Max Gauge Length Minimum Gauge Length inch mm P h d d2 d1 T1/2(+/-) T1/2(+/-) (+/-) 1/4 19 1.337 0.856 13.157 12.301 11.445 6.0 1.3 7.3 4.7 9.7 11.0 8.4 3.7 2.0 1.7 0.104 3/8 13 19 1.337 0.856 16.662 15.806 14.950 6.4 1.3 7.7 5.1 10.1 11.4 8.8 3.7 2.0 1.7 0.104 1/2 15 14 1.814 1.162 20.955 19.793 18.631 8.2 1.8 10.0 6.4 13.2 15.0 11.4 5.0 2.7 2.3 0.142 3/4 20 14 1.814 1.162 26.441 25.279 24.117 9.5 1.8 11.3 7.7 14.5 16.3 12.7 5.0 2.7 2.3 0.142 1 25 11 2.309 1.479 33.249 31.770 30.291 10.4 2.3 12.7 8.1 16.8 19.1 14.5 6.4 3.5 2.9 0.180 1-1/4 32 11 2.309 1.479 41.910 40.431 38.952 12.7 2.3 15.0 10.4 19.1 21.4 16.8 6.4 3.5 2.9 0.180 1-1/2 40 11 2.309 1.479 47.803 46.324 44.845 12.7 2.3 15.0 10.4 19.1 21.4 16.8 6.4 3.5 2.9 0.180 2 50 11 2.309 1.479 59.614 58.135 56.656 15.9 2.3 18.2 13.6 23.4 25.7 21.1 7.5 4.6 2.9 0.180 2-1/2 65 11 2.309 1.479 75.184 73.705 72.226 17.5 3.5 21.0 14.0 26.7 30.2 23.2 9.2 5.8 3.5 0.216 3 80 11 2.309 1.479 87.884 86.405 84.926 20.6 3.5 24.1 17.1 29.8 33.3 26.3 9.2 5.8 3.5 0.216 4 100 11 2.309 1.479 113.030 111.551 110.072 25.4 3.5 28.9 21.9 35.8 39.3 32.3 10.4 6.9 3.5 0.216 Note.1; Basic gauge length and limits of size are expressed in turns of threads. Liner equivalents are given in parentheses and are rounded to 0.1mm. Tolerance and fitting allowance are expressed in number of turns of thread and in millimeters. Unit: mm Comparison of JIS Threads and BS Threads JIS B 0203 Thread 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Size Number of Threads in 25.4 mm Pitch Hight of Thread Radius of Rounded Crests and Roots Gauge Diameter Gauge Plane Tolerance of Parallel Internal Threads Minimum Length of Useful Thread R/Rc Basic Major Diameter Basic Pitch Diameter Basic Minor Diameter Gauge Length (Male Thread) Tolerance (Male Thread) Tolerance (Female Thread) Fitting Allowance (Male Thread) Incomplete Taper Thread Length (Female Thread) Incomplete Parallel Thread Length (Female Thread) Complete Parallel and Taper Thread Length (Female Thread) inch mm n P h r or r' d or D d2 or D2 d1 or D1 a b (+/-) c (+/-) (+/-) f ｌ I' t 1/4 19 1.337 0.856 0.18 13.157 12.301 11.445 6.01 1.34 1.67 0.104 3.7 9.4 11.0 6.7 3/8 13 19 1.337 0.856 0.18 16.662 15.806 14.950 6.35 1.34 1.67 0.104 3.7 9.7 11.4 7.0 1/2 15 14 1.814 1.162 0.25 20.955 19.793 18.631 8.16 1.81 2.27 0.142 5.0 12.7 15.0 9.1 3/4 20 14 1.814 1.162 0.32 26.441 25.279 24.117 9.53 1.81 2.27 0.142 5.0 14.1 16.3 10.2 1 25 11 2.309 1.479 0.32 33.249 31,770 30.291 10.39 2.31 2.89 0.181 6.4 16.2 19.1 11.6 1-1/4 32 11 2.309 1.479 0.32 41.910 40.431 38.952 12.70 2.31 2.89 0.181 6.4 18.5 21.4 13.4 1-1/2 40 11 2.309 1.479 0.32 47.803 46.324 44.845 12.70 2.31 2.89 0.181 6.4 18.5 21.4 13.4 2 50 11 2.309 1.479 0.32 59.614 58.135 56.656 15.88 2.31 2.89 0.181 7.5 22.8 25.7 16.9 2-1/2 65 11 2.309 1.479 0.32 75.184 73.705 72.226 17.46 3.46 3.46 0.216 9.2 26.7 30.1 18.6 3 80 11 2.309 1.479 0.32 87.884 86.405 84.926 20.64 3.46 3.46 0.216 9.2 29.8 33.3 21.1 4 100 11 2.309 1.479 0.32 113.030 111.551 110.072 25.40 3.46 3.46 0.216 10.4 35.8 39.3 25.9 Note; Pursuant to ISO 7-1: 1994, Pipe threads where pressure tight joints are made on the threads - Part1: Dimensions, Tolerance and Designation. Unit: mm