Copper tubing

Copper tubing is most often used for supply of hot and cold water, and as refrigerant line in HVAC systems. There are two basic types of copper tubing, soft copper and rigid copper. Copper tubing is joined using flare connection, compression connection, or sweat (solder). Copper offers a high level of resistance to corrosion, but is becoming very costly.Soft (or ductile) copper tubing can be bent easily to travel around obstacles in the path of the tubing.
It can be joined by any of the three methods, and it is the only type of copper tubing suitable for flare connections. Soft copper is the most popular choice for refrigerant lines in split-system air conditioners and heat pumps.Flare connections require that the end of a tubing section be spread outward in a bell shape using a flare tool.
A flare nut then compresses this bell-shaped end onto a male fitting. Flare connections are the most labor intensive of the three options, but are quite reliable over the course of many years.Sweat fitting. These are smooth, and easily slip onto the end of a tubing section. The joint is then heated using a torch, and solder is melted into the connection.
When the solder cools, it forms a very strong bond which can last for decades. Sweat connected rigid copper is the most popular choice for water supply lines in modern buildings. In situations where many connections must be made at once, (such as plumbing of a new building) sweat offers much quicker joinery than compression or flare.