To identify BSP Threads also known as British Standard Pipe, they come in two different variants
- Parallel which is a female thread
- Tapered which is a male thread
Both BSP thread variants have the same pitch, angle and shape (rounded peaks and valleys). The BSP thread size can be determined by the outside diameter (male thread) or inside diameter (female thread) and thread pitch. The pitch is the distance from the crest of one thread to the next. Once you have the thread size, you can then determine the number of threads per inch to verify that it is a BSP fitting. This can be done by counting the number of thread crests over a 1.4″ length. Then multiply by 4 to get the number of threads per inch.