I need to know the best way to braze a brass fitting to a steel gas tank. Tank is brand new. What type of rod and flux would work best for this application? Would I need a special type of flux? Thanks!
I just soldered a brass fitting to a steel tank, much lower temperature and no chance of melting the brass fitting.
Ok just regular old 50/50 plumbing solder will stick? I was worried this would not provide much strength compared to a brazing rod.
I would use silver solder. You won't have to worry about twisting it off of there when you tighten the line.
You can braze it but if you're asking how, you will melt the fitting before you get your temp right, I've never tried to silver solder dissimilar metals so I don't have any advice on that one. 50/50 lead will get it done easily.
Why not weld a steel threaded pipe socket on the tank and then thread your brass into it? If you ever Buggar up the brass threads you can change it right out.
You can get silver solder that looks like flux coated brazing rod. It is thinner and the ones I have are blue flux. Yes silver solder is stronger, but regular solder would be fine on that new tank. I have a portable one gallon test tank that I have used for almost 10 years. It is made from a PPG Reducer can, and you know how flimsy those are for thickness. I drilled a hole, sanded the paint off, and placed a 1/8" NPT hose barb in the hole and used regular solder. This can has been crushed a few times by my son, and the fitting connection is the only thing that still looks good Also; Silver solder flux is very toxic, stay upwind from the smoke.
Pre heat the the brass and use silicon bronze rod, I've done it a few times on motorcycle gas tanks and haven't had any issues. Gotta be careful not to boil out the zinc in the brass though as you weld it. Never tried silver solder, I've heard the fumes can be rough and toxic so becareful. But so can melting brass due to the zinc in the alloy.
Soft solder 60/40 or 50/50 is plenty strong. Many early car and motorcycle gas tanks were put together this way. Use plumber's acid flux or paste flux will do. The metal must be clean and you should tin it first. That means coat it with solder and wipe off the excess with a damp rag. Then put the pieces together and solder them. The secret is to get enough heat so the solder flows in and seals. Dobbing half melted solder on the surface won't do anything. The solder should run in like water. Once it flows in take the heat away. A fitting properly soldered, will not crack or come out. You will twist off the brass before the solder gives way.
Why permanently install a brass fitting to a steel (or aluminum) tank of any type? The proper way to do this is as posted by 31 Vicky with a Hemi, post #9 above. The fitting you need is called a "bung". Select the compatible material and thread size you need for the brass fitting. Place the bung in position and weld (or braze). Clean up the bung threads if needed, apply your proper thread sealer and screw the fitting in. Done. PS....if the bung is a pipe thread be POSITIVE that the taper is in the correct position before welding or brazing. An upside down fitting is a hassle...ask me how I know.
If you have a brand new tank and it is coated inside to prevent corrosion, If you use too much heat or weld you will burn the coating and it could rust in that area. Ago
Excellent idea welding the bung on! I should have thought of that. I will pick up an 1/8" npt bung and mig it.
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