BSP (British Standard Pipe) Thread and NPT (National Pipe Thread) thread are two common pipe thread standards, and there 

are some differences between them:

Regional and national standards:

BSP thread is a British standard, developed and managed by the British Standards Institute (BSI). BSP threads are divided into 

three types, namely BSPP (British Standard Pipe Parallel, British cylindrical Pipe thread), BSPT (British Standard Pipe Taper, 

British taper pipe thread) and BSPF (British fine pipe thread). BSPT tooth Angle is 55 degrees, with 1:16 taper, mostly used 

in Europe and Commonwealth countries, often used in the water and gas pipe industry; BSPP has only internal threads, 

equivalent to the domestic 55 degree cylinder.

NPT thread is an American standard, developed and regulated by the American Standards Institute (ANSI/ASME). It is a 60 

degree taper pipe thread of American standard. NPT thread is divided into general sealed cylindrical pipe thread and general 

sealed taper pipe thread, wherein cylindrical internal thread and taper external thread form a "column/cone" match, and the 

taper internal thread and taper external thread form a "cone/cone" match. NPT threads are characterized by good sealing 

properties and are often used to transport liquids, gases, steam and hydraulic fluids.

Taper:

BSP threads have parallel taper, also known as Whitworth threads. They have a fixed number of threads per inch.

NPT thread with taper, Angle of 60 degrees. This design helps seal because when threaded together, the seal is better as 

the tightness of the threads increases.

Sealing method:

BSP threads use washers or sealants to provide a seal.

NPT threads are designed for metal-to-metal sealing, so no additional sealant is usually required.

Unit of measurement:

BSP thread sizes are usually expressed in metric units, such as millimeters or inches.

NPT thread size is usually expressed in inches, such as 1/8 inch, 1/4 inch, etc.

Application field:

BSP thread is usually used in the United Kingdom, Australia, New Zealand and other countries and regions.

NPT threads are more common in the United States and related markets.

In general, NPT thread belongs to the United States standard, its tooth Angle is 60 degrees, often used in North America or

the use of ANSI specifications;

The BSP thread belongs to the British standard, and its tooth Angle is 55 degrees, which is usually used in European and 

Commonwealth countries.