How to Measure BSPT Threads?

BSPT stands for British Standard Pipe Tapered, and the BSPT male connector is like an American NPTF, but the thread pitches are different in most sizes. The thread form and diameters are close, but not identical. Sealing is accomplished by distorting the threads. A properly chamfered BSPT male will also seal with a BSPP female swivel.

To measure ORFS fittings start with the thread diameter with an I.D./O.D. caliper. When comparing your measurements with the dimensions shown in this guide, remember threads can become worn and distorted from use. Your measurements may not match exactly to the figures shown in our tables. Use a thread pitch gauge to determine the number of threads per inch or the distance between threads. Place the gauge on the threads until the fitting is snug. Match your measurements with the tables in this guide.

Important to note: British Standard Pipe Threads, are sometimes referred to a “G” (for parallel threads) and “R” (for tapered threads) followed by a fraction. For example, ½-14 BSPT may be expressed as R ½