Fitting Threads

vignesh · December 17, 2019, 4:58am

The Main types of Fitting Threads are NPT Threads (National Pipe Thread) and BSP Threads (British Standard Pipe).

NPT Threads (National Pipe Thread)

This is an American standard taper thread which fits into the matching taper port. Sealing is provided by a pre-coating on the thread.

Example: 1/8 NPT thread = 1/8 NPT

BSP Threads (British Standard Pipe)

There are two types of “Pipe” profile threads:

These threads fit in matching parallel ports. Sealing is provided by an O-ring gasket or a sealing washer.

These threads fit in matching parallel or taper ports. Sealing is provided by a pre-coating on the thread.

G followed by the denomination, according to standard ISO 228-1.

Example: 1/8 BSP parallel thread = G1/8

R followed by the denomination, according to standard ISO 7-1.

Example: 1/8 BSP taper (BSPP) thread = R1/8

Female threads:

BSP parallel: G followed by the designation

BSP taper: R followed by the designation

Metric Threads

These ISO-profile threads are parallel and are fit into the matching parallel port. Sealing is provided by an O-ring or a sealing washer.

Thread designation

M depending on the diameter and pitch in millimetres, separated by a multiplication sign, in accordance with standards ISO 68-1 and ISO 965-1.

Example: metric thread diameter 7 with a pitch of 1 mm = M7x1