Correct size iron coupler for steel pipe.

[chainsaw_masochist]

I need to use a coupler to join an existing steel pipe to copper. I have measured the diameter of the steel pipe to one and one sixteenth inch. This is confusing because the sizes of the male iron couplers that I have seen are either 22mm x 1; 28mm x 1 or 28mm x 1 1/4?

Am I missing something here? Thanks for any advice.

 

[ChrisR]

That'll be wots known as 3/4" because it's measured on the inside. So its thread will be 3/4 male and the normal size equiv is 22mm.
If there's no thread you can get a big expensive fitting which compresses onto the iron.

 

[chainsaw_masochist]

Ah…that does make sense. Right, I have learnt something today, then! Thanks, Chris. There is a thread actually – it goes into a steel coupler which I will be removing – and I will connect the coupler to this. Just out of interest though, what is the device that you mention should a thread not be available? Is it called a Firmafit or something similar?

 

[chainsaw_masochist]

If there's no thread you can get a big expensive fitting which compresses onto the iron.

Looks like I am going to require one of these after all. Any idea what they are called? Is it a Primofit? I have checked the George Fischer website but the references seem to be more relevant to gas than water.

 

[noonespecial]

It is not a galvanised steel fitting is it? - not a good idea at all to connect galvanised to copper

 

[chrishutt]

What happened to the thread on the end of the pipe?

 

[chainsaw_masochist]

It is not a galvanised steel fitting is it? - not a good idea at all to connect galvanised to copper

No, it's not galvanised. It's an original steelpipe fitted in a local authority property.

 

[noonespecial]

ok that is fine

 

[chainsaw_masochist]

What happened to the thread on the end of the pipe?

Looking at the pipe in question again I now think it would be better to cut the pipe and then connect a self-tapping adaptor - this gives more scope for positioning than if I unscrew the existing coupler and use a threaded adaptor. Obviously with cutting the pipe like this there will be no thread on to which I could screw an adaptor. It is the type of self-tapping adaptor required that I am unsure. Thanks.