If you are not comfortable wit soldering definitely get a quote,
But, Let’s get some facts in order
50/50 solder melts at 350f, 95/5 melts at 464, that’s the range we are in here.
Propane torch is 3600f, mapp is 3700f, oxy/ acetylene 6000f, any of the 3 will solder, oxy/ac will be my last choice to solder.
Soldering is defined as below 840f, brazing is above 840f. All 3 will braze, it just takes Longer with lower heat…
Heating the parts, brushing flux on, melting solder on it and wiping it off to leave a bonded layer is referred to as “pretinning”, a good practice for both parts for this application.
I would expect that pretinning both parts and then putting a puddle on the tank to set the heated bung on to melt in would be the method of choice. Heat/ torch control is everything and not burning the flux or parts (will contaminate the joint). The tank being thin sheet metal will heat and blacken very quickly, no so for the bung. (If the tank was stainless that is a whole different level and I don’t think you should even try solder, different flux etc, I would probably weld on a SS bung)
Choice of solder and flux is yours, Nokorode flux is old school tried and true, 50/50 solder (lead-tin)is softest and bridges gaps best, 95/5 (tin-antimony) is strongest but harder to bridge gaps, and you are closer to the burn temp of the flux. There are choices in between, I used a lot of Bridgit lead free because it was at hand, 50/50 is not weak and common in the tin shops, but I am out of trades for a while.
Last edited by Hanks custodian; 01/06/2024 1:26 AM.
