BSP Stainless Steel Cast Fittings

British Standard Pipe (BSP) is a standardized system for screw threads used in plumbing and pipe fittings throughout Commonwealth countries such as the United Kingdom, South Africa, and Australia. (The American equivalent is NPT – National Pipe Thread). BSP ensures that pipes and fittings mate correctly, providing reliable connections between male (external) and female (internal) threads.

BSP Thread Measurements

BSP threads are based on trade size rather than the actual diameter. This can be confusing when measuring ports, so it’s important to know exactly what you are measuring.

There are two types of BSP threads:

Parallel (BSPP) – also known as G or Rp threads
Tapered (BSPT) – also called R or Rc threads

Both types share the same thread shape (rounded peaks and valleys), angle (55°), and pitch, but serve different applications.

Types of BSP Joints

BSP threads are commonly used for two main joint types:

1. Joining Threads – Creates a pressure-tight joint by mating threads. The male thread is always tapered, while the female thread may be parallel or tapered.

2. Longscrew Threads – Parallel threads that achieve a tight-pressure seal using a soft material, such as a washer or O-ring, compressed between the male thread face and a nipple or socket with a backnut.

Important: BSP and NPT threads must never be interchanged for high-pressure applications. They differ in thread pitch and form: