Connecting in to Galvanised pipe.

[ShaunCorbs]

Remove a fitting and buy a 3/4 threaded to 22mm or 15mm fitting. That should do it, if its water probably best using ptfe on the threads as I've had mixed luck with water and paste.

best option

 

[DAVE01]

I have used a 3\4 straight conector on 1/2 GB it held a pressure of six bar and i have also used a 1 x1/4 inch straight connector on a boiler with 1 inch GB only thing is it was all irish fittings but in the uk its 22mm but i am sure if you swap rings and nuts on fittings it will still work beets brakeing out stocks and dies or striping back to a thread hope this is of use