On Sunday, December 18, 2016 at 10:23:44 AM UTC-5, wrote:
I am in Brazil now and here they use cooper pipe for gas lines in buildings, if to repair a leak, how to do a repair, i hearded you need to run nitrogen gas before solder or brazing because the gas fumes.

You run nitrogen to prevent the copper from oxidizing from the heat and forming
crud inside the pipes. It's a much bigger problem when brazing because of the
higher temps.