In article ,
Harry Bloomfield writes:
After serious thinking Andy Burns wrote :
dropbox worked.

that tank doesn't look like it owes anyone anything, if you bodge a repair
it's just going to be waiting to let go ...

I agree! None of those OP suggested fixes will work, the tank will be
under some pressure at that point.

The only fix with even a slim chance of success is to remove that boss
completely and solder in a replacement. That will involve removal of
the tank and undoing the other unions - that itself will involves the
risk of the other bosses failing. As Andy said, it owes you nothing,
get a new tank fitted.

It looks as if it was leaking from behind the boss anyway.

It's an old tank (no insulation), so the copper is probably
quite thick. It will have a significant scrap value when
you replace it.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]