Use of nitrogen while brazing

I have watch a number of different services braze the copper lines on A.C. condensers and up to now, none of them used nitrogen to control copper oxide in the joints.

I can on attribute not doing it to the following reasons. If I am off base in my reasoning, I would appreciate any correction and information on just how important brazing with nitrogen might be or not be.

1. From experience, those that do not do it have found it not to be as necessary as others claim it to be.
2. It takes more time and another step in the job as well as extra costs involved that lead to less profit for the job.
3. If the oxide does create a problem in the system, it probably will not show up immediately leading to another service call.

 

It is customary to flow nitrogen at a slow rate thru the copper pipes while brazing to reduce the oxides that build up on the inside of the pipe during high heat.