Threaded Hot Water tank connector - HELP!

[pls1]

I'm replacing my hot water cylinder and everything went to plan & no leaks apart from the top HW outlet connector. Its a 1" thread and I've got a 22mm x 1" 90 degree elbow. No matter how tight I have it or how much PTFE I use, it still leaks.
The thread on the tank is starting to get a bit threaded now I've taken the fitting on and off several times. It will still get tight when screwing the fitting on but still leaks.
What can I do to prevent the leak, I've tried at least 10 wraps of PTFE and Boss Super Green (which is even worse)
My worse fear is the tank thread is knackered. Can they be repaired? The tank manufacturer isn't that far away so I could take it back to them.

 

[seco services]

i have soldered them in before when they have been old cylinders or the customer has stripped the thread.

 

[pls1]

is that easy enough to do with a standard torch & solder soldering a brass fitting onto copper? - whats the best way to do it?
Presumably I would have to strip off some of the insulation around the top.

 

[seco services]

brass solders just as easy as copper. same as when you solder a brass draincock into copper fittings.

clean the top of the cylinder up and the brass fitting.
plenty flux, screw fitting in with a very slight gap between the cylinder lip and brass fitting lip and the solder will run round.
i just use a wet cloth round the top of the insulation.

 

[jackthom]

I also had a problem completely stopping these sort of fittings from leaking. Fortunately they were very slow leaks and I think the slight hardness of the water here may have helped seal them off over the course of a few weeks so now I'm leaving well alone.