wrote in message
oups.com...
I have an old plumbing elbow, female both ends, it looks like half inch
bsp to me but is there a way to double check please. Just for info it
will thread on to a 15mm compression joint thread.
Thanks

PS The inside diameter is about three quarters inch

Hi Tec.
The OD of 1/2" BSP is just over 21mm.
Baz