On Fri, 4 Oct 2019 14:43:14 +0100, David wrote:

"Chris Green" wrote in message ...

I need to mend a small piece of stainless steel, it's essentially a
small length of tube (125mm dia or so) with a flange that needs to be
re-affixed to a then plate. The original welds (not mine!) were
absolute rubbish and have come apart.

I don't have TIG (only MIG and stick) so I think brazing is probably
the best option. I have a gas torch which can get it hot enough, so
what's the best sort of brazing material to use?

The stainless is probably one or two mm thick and the joint needs to
be reasonably strong as it's holding chimney cowl to a chimney.

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Silver Solder - Easyflo is you still have some or the non-cadmium equivalent
such as Silverflo 55

Flux - you will need a flux such as Tenacity 5 which will still be active
with prolonged heating.

At work I used oxy-propane for silver soldering and brazing. The fitters
couldn't dp st. st. (it was an electronics factory - not much use for such
tings). I tried some sort of 'ordinary' flux (ICR which - 30 years...) and
of course it didn't work.
Tried cleaning the pieces, applying a paste of the flux, leaving for about
an hour and it worked! I never did tell them how I did it, so had to do all
the odd bits that came along.
I made a cage for a a 1.5 li bottle for my touring bike; it's still intact
after tens of thousands of miles use. The frame did have 3 bosses on it -
wouldn't have loaded 2 bosses like that, especially on 531.
--
Peter.
The gods will stay away
whilst religions hold sway