Finned tube assemblies for heat exchangers

A finned tube brazing preassembly for heat processing in a brazing furnace comprising:

• a bare steel tube having an exposed outer surface;
• a set of aluminum fins;
• a fluoride based flux and oil based carrier mixture disposed between the bare steel tube and the set of aluminum fins;
• and
• a brazing filler metal comprising aluminum, the brazing filler being disposed proximate to the set of aluminum fins and the flux and oil based carrier mixture;
• wherein the brazing filler metal forms a brazed bond between the bare steel tube and set of aluminum fins when heat processed in the brazing furnace.

A method for forming a tube assembly for an air cooled condenser, the method comprising:

• providing a bare steel tube having an exposed exterior surface of steel;
• providing an aluminum fin;
• applying a flux and oil based carrier mixture onto the exposed exterior surface of the steel tube;
• providing a brazing filler metal;
• bringing into mutual contact the bare steel tube, aluminum fin, flux and oil based carrier mixture, and brazing filler metal, wherein the bare steel tube, aluminum fin, flux and oil based carrier mixture, and brazing filler metal collectively define a finned tube brazing preassembly;
• loading the finned tube brazing preassembly into a brazing furnace;
• and
• heating he finned tube brazing preassembly to a ten erasure sufficient to melt the brazing filler metal and bond the aluminum tin directly onto the bare steel tube.