Low carbon steel pipes and rad valves

[Samneil11]

Hi all hope all is well with everyone.
Im a plumbing and heating engineer and I have worked only on domestic systems but am currently crossing over to commercial plumbing.
I havent ever really done any steel pipework hence my question to you . .
How or what is the procedure to changing a rad valve on lcs pipework? I can see that they are wound onto pipe what I don't get is bearing in mind steel doesnt wiggle about like copper how can you wind the valve off without catching on the rad tail?
I hope that makes sense

 

[ShaunCorbs]

Normally union faces so you don’t need much clearance but you can spring the iron to the left or right a bit to give you a bit extra

 

[Samneil11]

Oh i didnt realise that thanks mate