How to Distinguish the Thread Type: NPT, BSPP, or BSPT?

The difference between NPT, BSPP and BSPT

NPT, BSPP, and BSPT are three different pipe thread standards. Their main differences are thread types and uses.

    NPT (National Pipe Thread) is an American pipe thread standard, which is characterized by tapered pipe threads for sealing joints. NPT threads have a profile angle of 60°, are tapered, and are commonly used in the United States and some other regions.

    BSPP (British Standard Pipe Parallel Thread) is the British parallel pipe thread standard, with only internal threads. The tooth profile angle of BSPP is 55°, which is used for sealing joints and fits with the external thread of BSPT. It is equivalent to the domestic 55-degree cylindrical pipe thread.

BSPT (British Standard Pipe Taper Thread) is also a British pipe thread standard, but it is a tapered pipe thread and is used for sealing joints. The profile angle of BSPT is also 55°, with a taper of 1:16, and it belongs to the Whitworth thread family. BSPT is mostly used in European and Commonwealth countries, and is commonly used in the water and gas pipe industries.

In summary, the main differences between NPT, BSPP and BSPT are their thread type (tapered or parallel), profile angle (60° or 55°), and their application areas and industries.