Soft copper tubing is used in domestic, also in some commercial refrigeration and air conditioning work. It is annealed to make the tubing flexible and easy to bend and flare. Since this tubing is easily bent, the tubing must be supported by clamps or suitable brackets when used. Soft copper tubing is most often used in connection with flared fittings (SAE) and soft soldered fittings.
This tubing is sold in rolls of 25, 50 and 100-foot lengths. The most commonly used sizes are 3/16, 1/4, 5/16, 3/8, 7/16, 1/2, 9/16, 5/8 and 3/4 in. outside diameter (OD). The wall thickness is usually specified in thousandths of an inch,
Fig. 2-1 is a table of common copper tube diameters and thicknesses. Soft copper tubing may become hardened by repeated bending or hammering. This is called work hardening, The tubing may be softened some if it is heated to a blue surface color and allowed to cool slowly at room temperature. This treatment is called annealing.