Oxy-Acetaline Gas weldling a Muffler is fine whether it be braze or Mild Steel filler rod, it is very Important to clean the area well that is to be welded. braze or mild steel filler rod does not like to stick to Rust, corrosion or grease. If you are using a Mild steel filler rod to save a few buck's on the cost of material's an old metal coat hanger work's really well. I have used them for year's and they work as well as boughten mild steel filler rods. When gas welding temperature is crucial so get your torch to a neutral flame and have the Two Pieces of steel to be welded close together. You can use a meall clamp or vice grip's to hold them together that works well. When the metal being welded heat's up enough, it will begin to Pool itself this is when you add the metal filler rod or if it is a Thicker metal you can fusion weld the two Pieces together. Keep moving with the gas torch and filler rod as you see a semi half circle of weld Puddle up. If it is Thin metal I would suggest that you start the welding process from the end of the metal so as to Not Burn a hole through it as if you were welding it going outward toward's the end of the Piece of Metal. If done Properly gas welding can leave behind a nice attractive welding bead that is as strong as the Two Pieces of metal being just one. I hope This helps, Hammerdown
Edited by Hammerdown, June 21, 2014 - 12:43 PM.