The British Standard of Hydraulic Adapters

The idea of all foreign threads are metric is a misunderstanding. Actually, there are two common forms of thread - metric threads and Whitworth standard threads (BSP). British standard straight pipe (BSP) thread, also known as Whitworth standard thread. It can be straight thread (BSPP), and also be tapered thread (BSPT), both have inverted cone.

Its flange is similar with the flange of SAE61 or SAE62 type (except -10 *). Port connections typically use BSPP threads, and adopt soft metal seal ring to seal. BSPP (straight) male thread can match with BSPP (straight) female thread or female thread port.

BSPP male thread and female thread are straight thread with 30 ° cone seat. Female port is straight thread with seal faces. Sealing at the port is formed by O-rings or soft metal washer on the male thread adapter.

BSPP (straight thread) joints are similar but not interchangeable with NPSM fittings. Most of them are different in thread pitches, and thread profile angle is 55 °, but the profile angle of NPSM thread is 60 ° (-10 are non-SAE standard flanges).