Caecilius wrote:
On Sat, 16 Feb 2013 18:13:33 -0000, "Nick"
wrote:
Would there be any plastic/rubber components within? Heat might damage
these.

Yes, I suspect there may be heat sensitive stuff inside, so I'm wary
of using a blowtorch.

What about cleaning thoroughly with wire brush, and a few taps around the
periphery with a toffee hammer. Then a few drops of Plus-Gas or similar at
the joint, leave to soak and repeat as seems fit. I can't imagine WD40
having much effect. A few drops isn't going to greatly contaminate the
system.

Then a well fitting ring spanner and give it a decent thump whilst
bracing adjoing pipework.

I wish I could use a proper spanner, but it's about 40mm (or one and a
half inches) across the flats, so I don't have a spanner that would
fit. And most spanners only seem to go up to about one inch anyway. So
I need to use an adjustable, which is not the best thing for these
circumstances.

If all else fails, and I hesitate to say
this.............................................. .............angle
grinder.

No, stilsons come before angle grinder surely.

Can you soak a rag in descaler (vinegar maybe) and drape it over the valve?
Maybe wrap it in cling film to stop it drying out.

Tim