Information about BSPT Adapters

BSPT threads are tapered, inch-based threads. They originate from the British gas industry; with this type, the outer diameter at the end of the gas pipe is threaded to make the connection. This form of thread has a flank angle of 55° and the thread pitch usually differs from NPT threads. Therefore, the two types are not compatible. Today, the BSPT thread is used in the pneumatics industry; its use in hydraulic systems is limited. In most cases, a stud fitting is screwed into a BSPP inch-parallel port thread. And precisely in this process, the thread engagement is limited, which in turn results in a lower retention force compared to the corresponding NPT variations.

An appropriate sealant is always required for sealing BSPT threads, as the sealing function is achieved on the flanks. BSPT fittings offer only limited adjustability with elbow or tee adapters; they can easily be overtightened, thereby damaging the port thread, the stud fitting, or both. Reusability is therefore limited. The use of BSPT threads should therefore be limited to low-pressure applications with moderate dynamic stresses. For this reason, Parker Hannifin does not include BSPT threads in its "Dry Technology" program.