Threads on compression fittings - help please

[Butchersdog]

I have a 1/2" copper feed into a valve through a compression fitting and I need to replace the valve and subsequent copper. The nut at the entry to the valve is very close to a bulkead and while access to the nut is just possible it would be virtually impossible to cut back and change the nut and olive.
Is the thread on a new 15mm valve likely to match the one on the end of my 1/2" pipe?
If not it is likely to be hammer and chisel time, lots of work, dust, bad language and eventual making good, so I'm really hoping for some good news fellas....;o)
Thanks,
John

 

[polesapart]

The odds are in your favour.

You can check compatibility by screwing the nut of the new fitting onto the old valve.

 

[Nige F]

Unless you really do have 1/2 inch copper and it has a VERY old Prestex fitting on it - with a very fine thread-

 

[Butchersdog]

Thanks folks, it looks like I'm in with a fair chance. I just needed a bit of reassurance before I dived in and started tearing things apart...
If it does all go wrong for some reason I'll come back with the story so someone els might benefit.
Many thanks