What thread is this?

[RF Lighting]

I have a water butt which comes with a plastic tap. I'd like to replace it with a better tap, but I'm not sure what thread it is.

I've found a nut which fits it in my box of plumbing bits, so I think it's a standard thread.

Here's the tap.

It measures about 26mm across the thread

If anyone could tell me what thread it is, I'd be most greatful.

 

[JohnD]

likely 1" BSP

If you look at a brass garden tap, you will probably has a thread like that which screws onto a brass wallplate, though from memory I think it is 1/2 BSP

 

[seco services]

If it's 26mm across thread it'll be 3/4" bsp thread.

 

[RF Lighting]

Thanks chaps. 3/4" it is.

 

[JohnD]

I suppose it must be based on the internal diameter of a steel pipe.

 

[RF Lighting]

I'm not sure. I managed to find a 3/4" nut which fits it perfectly.

Us electricians are simple folk with pipe and thread sizes working on outside diameter