BSPP Tap HSS (High Speed Steel) 55 degree Whitworth Thread Form. Whitworth Pipe Threads are used almost exclusively by countries which are otherwise on the metric system. "G" Series British Standard Pipe - Parallel ( Straight ) BSP or BSPF Also referred to as British Gas, British Pipe Parallel or Parallel Fastening thread. Various Symbols: BSP, BSPP, BSSPI, BSPF, BSPG, PS, R, G. We have the largest selection in stock. Taps are a bottoming style. Please contact us for special sizes Suggested tap drill sizes for BSPP taps Nominal Size (inches) T P I Major Diameter (inches) Tapping Drill Size BSPP 1/16 28 0.304 6.6 mm Letter drill G 1/8 28 0.383 8.8 mm 11/32 inch 1/4 19 0.518 11.8 mm 29/64" 3/8 19 0.656 15.25 mm 19/32" 1/2 14 0.825 19.00 mm 3/4" 5/8 14 0.902 21 mm 53/64" 3/4 14 1.041 24.5 mm 31/32" 7/8 14 1.189 28.25 mm 1-7/64" 1 inch 11 1.309 30.75 mm 1-13/64" 1-1/4" 11 1.650 39.50 mm 1-35/64" 1-1/2" 11 1.882 45.5 mm 1-25/32" 1-3/4" 11 2.116 51.00 mm 2" 2" 11 2.347 57 mm 2-1/4"
