On Aug 25, 10:13*am, Stephen
wrote:
Hello,

Is the thread on a 15mm compression fitting 1/2 inch BSP?

IME almost always yes.

And on a
22mm fitting 3/4 inch?

No unfortunately, would be handy it it was.

I ask because Screwfix sell male compression couples that have a 15mm
nut on one side and a 1/2 inch male thread on the other. I wondered
whether this is just a straight 15mm couple with one nut removed or
are they different?

A 15mm compression to 1/2 BSP male will have a flat on the threaded
end to seal against a washer.

In a pinch where needing the above, I've used a 15mm compression
coupler and sanded a flat on one side with medium/fine wet'n'dry
paper.

cheers,
Pete.