Spiral Mill-Thread Inserts Spiral Mill-Thread Inserts W 55 ° WHIT WORTH ( BSW, BSF, BSP, BSB INTERNAL & EXTERNAL ) BSPT 55 ° BRITISH STANDARD PIPE ( INTERNAL & EXTERNAL ) P Nut P R 0.137P R0.137P Nut W 0 55 ° W 0 7.5 ° 27.5 R 0.137P / R0.137P Screw Screw 1° 7 ’ Thread Size Dimensions Thread Size Dimensions Designation TPI Designation TPI Internal External I W t Internal External I W t H 23 EI 14 W 14 >G 7 / 8" >G 1/2" 27 8.0 3.5 H 23 EI 11 BSPT 11 > 1 " BSPT > 1" BSPT 27 8.0 3.5 H 23 EI 11 W 11 > G 1" > G 1" 27 8.0 3.5 H 32 EI 11 BSPT 11 > 1 1 / 8 " BSPT > 1" BSPT 32 9.0 4.0 H 32 EI 14 W 14 >G 1 / 2 " 32 9.0 4.0 H 45 EI 11 BSPT 11 > 1 3 / 4 " BSPT > 1" BSPT 37 11.9 5.0 H 32 EI 11 W 11 >G 1 1/8" > G 1" 32 9.0 4.0 H 63 EI 11 BSPT 11 > 2 1 / 2 " BSPT > 1" BSPT 38 11.9 5.0 H 45 EI 11 W 11 >G 1 3/4" >G 1" 37 11.9 5.0 H 63 EI 11 W 11 >G 2 1/2" >G 1" 38 11.9 5.0 HELICAL LONG EDGE FINISHING INSERT 085 086 W 55 ° WHIT WORTH ( BSW , BSF, BSP, BSB INTERNAL & EXTERNAL ) -> p W >< o w 0 Dimensions Thread Size Dimensions Designation I W t Designation TPI Internal External I W t H 23 F R 0.20 27 8.0 3.5 H 23 EI 11 . 5 NPT 11.5 1 " - 2 " NPT 1 " - 2 " NPT 27 8.0 3.5 H 23 F R 0.50 27 8.0 3.5 H 32 EI 11.5 NPT 11.5 1 1 / 4 " - 2 " NPT 1 " - 2 " NPT 32 9.0 4.0 H 23 F R 1.00 27 8.0 3.5 H 45 EI 11.5 NPT 11.5 2 " NPT 1 " - 2 " NPT 37 11.9 5.0 H 32 F R 0.20 32 9.0 4.0 H 45 EI 8 NPT 8.0 2 1 / 2 " NPT- 3 " NPT 2 1 / 2 " NPT- 3 " NPT 37 11.9 5.0 H 32 F R 0.50 32 9.0 4.0 H 63 EI 11.5 NPT 11.5 1 " - 2 " NPT 38 11.9 5.0 H 32 F R 1.00 32 9.0 4.0 H 63 EI 8 NPT 8.0 2 1 / 2 " NPT- 3 " NPT 2 1 / 2 " NPT- 3 " NPT 38 11.9 5.0 H 45 F R 0.20 37 11.9 5.0