BSW (British Standard Whitworth)
A coarse thread devised and standardised at Manchester in 1841
by British Engineer Sir Joseph Whitworth (1803 - 87). It is
used in many types of engineering throughout the world,
although in Britain its use is now being superseded by the
ISO metric system.
Angle of Thread = 55 Degrees
Sizes range from 1/16" to 2-1/2"
BSP = British Standard Pipe, or BSPP = British Standard
Parallel Pipe, or BSPF = British Standard Parallel Fixed.
This thread needs a gasket or seal to be gas/liquid tight.
Angle of thread = 55o degrees
NPT - National Pipe Thread Taper
Characteristics of NPT (also known as ANSI/ASME B1.20.1 Pipe
Threads, General Purpose):
· tapered thread 1o 47'
· truncation of roots and crests are flat
· 60o thread angle
· pitch is measured in threads per inch
· Parallel ('straight') threads, BSPP (British Standard Pipe
Parallel Thread), which have a constant diameter; denoted by
the letter G.
· Taper threads, BSPT (British Standard Pipe Taper Thread),
whose diameter increases or decreases along the length of
the thread; denoted by the letter R.