Firstly that's good advice from Simon.

Secondly that good friend should not try to fix each leak in isolation. The whole area needs to be taken up to temperature. This will avoid any thermal stress caused by localized expansion. You have got three poor joints. It is possible that there are other weak joints caused by poor alloy penetration into the joints. This stress could quite easily cause other joints to fail and you end up on a merry-go-round chasing the next leak.!

You may need to use two torches. One, a propane torch to get the background heat in and oxy/something for the final lift to brazing temperature and create the necessary heat pattern to promote the capillary flow of filler to where you want it. The leaks at the firebox end may require the use of a cyclone propane that will stay lit in the confined spaces.

A ceramic blanket will help to get, and keep, heat n.

Yes use 455 alloy with 55% silver.

Use also HT5 flux to give you a good flux life and use plenty of it to clean the joints and protect the others.

Almost forgot ……. then allow to cool naturally

Regards

Keith

PS It's my guess that the boiler was originally put together with oxy/acetylene only and the basic principles of the brazing process not followed

Edited By CuP Alloys 1 on 19/04/2017 13:35:57