Fluxing & Soldering Techniques

You need to know  the proper technique prepare the clean  joint by applying flux to the tube and  the fitting water-soluble flux that  meets the ASTMBA  standard is  recommended this wax-like compound  dissolves when heating is apply and  removes oxidation from the joint  surfaces it also protects the clean  surface from reoxidation during heating  and it promotes wetting of the surfaces  by the solder alloy stir the flux to  activate it then use a brush to apply a  thin coating to both the tube and the  fitting immediately after cleaning them.

Insert the tube into the fitting cup  making sure the to be seated against the  base of the cup a slight twisting motion  ensures even coverage by the flux wipe  excess flux from the exterior of the  joint be sure to support the tube the  joint is now ready for soldering  using an acetylene or propane gas torch  begin at the bottom of the tube the  copper will conduct the heat into the  joint next week the flame between the  fitting cup and the tube when the  assembly is hot enough point the flame  at the base of the fitting cup and touch  the solder to the joint if the solder  does not immediately melt.

When it  touches the metal remove it and continue  heating be careful not to overheat which  can burn the flux this will prevent the  solder from entering the joint properly  shift the heat to the base of the cup  when the solder begins to melt capillary  action will draw the solder into the cup  as the solder melts push it into the  joint while keeping the torch at the  base of the fitting and slightly ahead  of the solder apply solder across the  bottom of the fitting and up one side to  the top return to your starting point .

Overlapping slightly and up the  uncompleted side to the top be sure to  apply it enough solder to the top of the  joint allow the completed joint to cool  naturally shot cooling with water can  weaken the joint when it cools clean off  any remaining flux residue with a wet  rag flush completed system to remove  excess flux and debris finally test all  completed assembly for joint integrity..