Here is the second part of the column that was published in the May issue.
There are two types of refrigerant tubing, rigid and soft. The rigid copper type comes in long lengths and it can't be bent or swaged. To make bends and to connect segments all sorts of prefabricated joints, which must be brazed together. Insulation must be purchased and installed on some lines to prevent water from condensing and dripping, and to minimize thermal losses. Also, to prevent oxides from being created inside the tubing, which can damage the compressor and metering orifices, a gentle flow of inert nitrogen gas must be passed through the tube during the brazing process.