BSPP Parallel Whitworth Pipe Thread (GB)

The BSPP thread is a British cylindrical pipe thread, also frequently used in Germany. BSPP stands for British Standard Pipe Parallel. It is standardized according to DIN ISO 228. The parallel Whitworth pipe thread creates a purely mechanical connection without sealing properties. It involves the combination of a cylindrical external thread with a cylindrical internal thread. Additional sealing material is required for a sealing connection.

The parallel Whitworth pipe thread is an inch thread, with the pitch specified in threads per inch. The flank angle is 55°. The thread designation for the parallel Whitworth pipe thread consists of the abbreviation G combined with a numerical value in inches. As with all pipe thread types, it is important to note that the numerical value does not correspond to the external thread. This is evident in the G 1″ thread, whose actual external diameter is 1.309 inches or 33.249 mm. This discrepancy between thread designation and thread dimensions arises because the typical dimensions of pipes have changed since the introduction of pipe thread standards, yet this change has not been reflected in the thread designation.

The thread table for the parallel Whitworth pipe thread lists the correct values for the external thread in inches and mm. The pitch is also given both in mm and in threads per inch. There is little variance in the pitch for the parallel Whitworth pipe thread. From the G 1″ thread upwards, the number of threads per inch is consistently 11. The thread table also lists the core hole diameter needed when working with the parallel Whitworth pipe thread. Links in the table will direct you to the respective dies and taps in our shop.