About 6 months ago I used epoxy on two joints where a torch would have been
awkward, yet a leak wouldn't have done much damage. It was easy to apply
and has held up so far, though my maximum pressure is only 40psi so it might
not be a definitive test.
I haven't any idea about compression fittings on type L, but then again I
haven't used a compression fitting except where it came as a component.