G/R/RP - Withworth thread (BSPP/BSPT)

The most common types of Whitworth thread are:

• BSPP (G) – British Standard Pipe Parallel
• BSPT (R/Rp) – British Standard Tapered Pipe, for pipes and tapered thread

An appropriate sealing compound can be used in the thread to ensure a leakproof joint.

If you have any questions please contact us or check out our fittings with BSPP/ BSPT (G) thread.

BSPP (G)
Female and male thread are both parallel.

∅	Drill ∅B	∅	TPI
G 1/16	7,723	6,561	28
G 1/8	9,728	8,566	28
G 1/4	13,157	11,445	19
G 3/8	16,662	14,950	19
G 1/2	20,955	18,631	14
G 3/4	26,441	24,117	14
G 1	33,249	30,291	11
G 2	59,614	56,656	11

BSPT (R/Rp)
Female thread is parallel and male thread is tapered.
Female thread can also be tapered: Rc, but this is not common.

Male thread size (inch)	Female thread size (inch)	Major diameter (mm)	Minor diameter (mm)	TPI
R 1/16	Rp 1/16	7,723	6,490	28
R 1/8	Rp 1/8	9,728	8,495	28
R 1/4	Rp 1/4	13,157	11,341	19
R 3/8	Rp 3/8	16,662	14,846	19
R 1/2	Rp 1/2	20,955	18,489	14
R 3/4	Rp 3/4	26,441	23,975	14
R 1	Rp 1	33,249	30,111	11
G 2	Rp 2	59,614	56,476	11