BSPT

BSPT stands for British Standard Pipe Taper, a standardized form of screw thread used to join pipes and fittings in hydraulic, pneumatic, and plumbing systems. It is one of the two main BSP thread types, the other being BSPP (British Standard Pipe Parallel). BSPT threads are designed to seal by wedging together as the threads tighten.

Key characteristics of BSPT include a tapered profile and a 55-degree thread angle. The taper is typically 1:16, meaning the diameter changes by one unit for every sixteen units of length. This taper creates a seal as the male and female threads engage. The sizes are specified by nominal pipe size (NPS) in inches, with pitches and tolerances varying by size and standard.

sealing methods: In practice, the seal is achieved through the wedging action of the taper, often aided by jointing compounds or PTFE thread seal tape suitable for metal threads. Proper torque and alignment are important to avoid leaks.

Standards and usage: BSPT threads have historical roots in the British standard BS 21 and have been harmonized in many regions with ISO 7-1, which covers general purpose pipe threads and both tapered (BSPT) and parallel (BSPP) forms. Although BSPT and NPT (the American tapered thread) may appear similar, they are not interchangeable due to differences in thread angle (55° vs 60°), pitch, and tolerance. Adapters exist but must be chosen with attention to pressure, medium, and connection style.

Applications: BSPT is widely used in plumbing, hydraulics, and industrial machinery in the UK, Europe, and many Commonwealth countries, particularly where imperial thread sizes are common. Fittings must be matched to the correct BSPT size and the appropriate sealing method to ensure a reliable, leak-free connection.