>
> I use this JB Weld Extreme heat combined with a hose clamp... so far so
> good it's holding well https://www.jbweld.com/product/j-b-extremeheat
>

Looks like interesting stuff.  It's based on sodium silicate aka water
glass like regular muffler paste; but with much less sodium silicate and a
heavy loading (50-75%) of powdered iron.

I'm amused that their "apply" photo on the website shows someone using it
at a jeweler's bench.

Yrs,
d