Steel pipe fitting without thread.

[Last Plumber]

It looks like 3/8" or 1/2" to me going off the brick joints but it also looks a bit thin walled to be medium steel. Could be light though, it is difficult to tell off a photo.
I wouldn't attempt it without being able to hold back rigid and take it down gradually. You will need to take out the surrounding brickwork. It is possible you will upset the thread or threads along the way. It may even convert to copper at the other end (have you looked behind the fire)? The amount of torque on those machines is enough to break a joint. It needs a bit of skill, experience etc. It needs testing properly too afterwards.

 

[Rob Foster]

wouldnt say its gas advice more how to fix the issue

Its also a case of a keen apprentice trying to help his buddy and he asked here on UKPF well done ShaunCorbs

 

[Harvest Fields]

But then everyone would say that they are an apprentice?

 

[Riley]

Agreed although threading is a skill I think the average diyer would struggle with

 

[Harvest Fields]

So what if the pipe is gas?

 

[Riley]

Should we close this

 

[Last Plumber]

Where is the line drawn?

 

[Harvest Fields]

I thought I had.

 

[Last Plumber]

Say If you are and I will stop typing and wasting my time.

 

[Last Plumber]

What's the craic?

 

[Harvest Fields]

I closed it once. I’m not doing it again.

 

[Riley]

Ok done