• Mar 22, 2026 British Standard Pipe Taper Bspt Threads Size Chart e inches External Diameter mm Threads per Inch TPI Approximate 2 Internal Diameter mm 116 476 28 279 18 635 28 406 14 953 19 635 38 127 19 874 12 1588 14 1225 34 1905 14 152 1 254 11 214 1 14 3175 11 2692 1 12 381 11 3302 2 508 11 4445 Visualizing BSPT Threads Imagine a cone with threads cut into BY George Jerde