b. Clean. All filler alloy must be cleaned from debrazed joints before reassembly. Heat each piece of the joint until
the filler is melted and then wipe it away with a wire brush. Be sure no filler alloy or other debris is left inside any
tubing, fitting, or component. Use abrasive cloth as necessary to clean joints.
(1) Protect wiring harnesses and other components with appropriate heat shields.
All joints, except those provided with flare fittings, are made by brazing in
accordance with MIL-B-7883, except that radiographic examination is not required.
Grade IV or VI brazing alloy (50% silver) and Type-B flux, as specified in MIL-B-
7883, must be used for all copper to brass joints. Grade III (15% silver) brazing
alloy may be substituted for Grade IV or VI for copper to copper joints, flux is not
required for copper to copper joints.
(2) If brazing a joint on a valve, disassemble the valve to the extent possible and wrap all but the joint with a
wet rag to act as a heat sink.
If interconnecting tubing was removed with a component, braze tubing to the new
components before installation.
(3) Position component or assembly into place.
Never use a heating torch on any part that contains refrigerant. Heat may cause
the refrigerant to decompose and release irritating, toxic, and corrosive gases. All
refrigerant must be removed and recovered from the system and the entire system
must be purged with dry nitrogen before beginning any brazing operation.
If heat is applied slowly, or only on one side, the entire component or length of
tubing will be heated and filler alloy in adjacent joints may also be melted.
Brazing a joint without nitrogen flowing through the tubing, will cause deposits to
form on the inside of the tube and may cause obstructions in the refrigeration
system or equipment damage.
(4) Check that the system is being purged per paragraph 5.5 and apply sufficient heat uniformly around the
joint to quickly melt the filler alloy. Remove heat and stop purging as soon as brazing is completed.