Female & Male BSPP / Metric Bulkheads, Made by AIGNEP, These a Nickel plated Brass Bulkhead Connector. 
(A) Is the Female inside thread, (B) Is the Male outside Thread. (Female Bulkhead)

BSP (A)

(B)

1/8”

M16 x 1.5

1/4”

M20 x 1.5

3/8”

M26 x 1.5

1/2”

M28 x 1.5



Check your pipe threads before you order!

In Great Britain BSP British Standard Pipe threads are commonly used. These are either parallel (BSPP) which normally seal on a washer or 'O' ring seal, or tapered (BSPT) which taper along their length and normally seal by two mating threads and/ or tape.

How to measure your thread:

Use a tape rule or (vernier gauge) to measure across the outside of the male thread. Note that a thread that measures 0.5" is not 1/2" BSP thread!

Using the table below we can see that 0.5" is actually 1/4" BSP thread. Similarly, a thread that measures 1.0" is actually 3/4" BSP thread.

BSP SizeMax. diametermin. diameterThread pitch
 mminchmminch(mm)        TPI
1/16"7.7230.3046.5610.25828
1/8"9.7280.3838.5650.33728
1/4"13.1570.51811.4450.45119
3/8"16.6620.65614.950.58919
1/2"20.9550.82518.6330.73414
5/8"22.9110.90220.5890.81114
3/4"26.4411.04124.120.9514
1"33.2491.30930.2921.19311
1 1/4"41.911.6538.9531.53411
1 1/2"47.8031.88244.8461.76611
2"59.6142.34756.6572.23111
2 1/2"75.1842.9672.2272.84411
3"87.8843.4684.9273.34411
4"113.034.45110.0734.33411
5"138.435.45135.4725.33411
6"163.836.45160.8726.33411