Solid Theading Endmills for Internal Thread with Coolant Hole Solid Threading Endmills for Internal Thread with Coolant Hole H W 55 ° WHIT WORTH ( BSW , BSF, BSP, BSB ) BSPT 55 ° BRITISH STANDARD PIPE ap ap P P D dh6 dh6 15 *L 15 *L ^ ^ R0.137 P 90°/ R0.137P Screw 1 7 - Screw •Application: General engineering •Application: General engineering fittings and pipe couplings fittings and pipe couplings Dimension ( mm ) Dimension ( mm ) Designation TPI BSP No . of flutes Designation TPI BSP No . of flutes d D ap L d D ap L SMTB 08078 C 14 28 W 28 G1/ 8 8 7.8 14.1 64 3 SMTB 08078 C 14 28 BSPT 28 RC 1 / 8 8 7.8 14.1 64 3 1010 D 16 19 W 19 G1 / 4- 3 / 8 10 10.0 16.7 73 4 1010 D 16 19 BSPT 19 RC 1 / 4 - 3 / 8 10 10.0 16.7 73 4 1616 E 26 14 W 14 G1 / 2 - 7 / 8 16 16.0 26.3 105 5 1616 E 26 14 BSPT 14 RC 1 / 2 - 7 / 8 16 16.0 26.3 105 5 1616 D 38 11 W 11 G>1 16 16.0 38.1 105 4 1616 D 28 11 BSPT 11 RC 1 - 2 16 16.0 28.9 105 4 2020 E47 11 W 11 G >1 20 20.0 47.3 105 5 NPT 60 ° NATIOANL PIPE ap 105 p 106 E ^ A m D dh6 ^ 15 L • Application: Steam , gas and water pipes Dimension ( mm ) Designation TPI NPT No . of flutes d D ap L SMTB 08076 C 10 27 NPT 27 1/8 8 7.6 10.8 64 3 1010 D 16 18 NPT 18 1/ 4 - 3 / 8 10 10.0 16.2 73 4 16155 D 22 14 NPT 14 1 / 2-3 / 4 16 15.5 22.7 105 4 2020 D 29 11.5 NPT 11.5 1- 2 20 20.0 29.8 105 4 2020 D 39 8 NPT 8 >2 1 / 2 20 20.0 39.7 105 4 Ai ri