Double thickness flares are formed with tools made for this purpose. Fig. 2-14 illustrates a cross-section through a simple block-and-punch type of tool used to make

a double flare. The appearance of the double flare is shown in the final operation in this figure. Some flaring tools are fitted with adapters which makes it possible to form either single or double flares with the same tool. Fig. 2-15 shows such a tool.

Fig. 2-16 shows the step-by-step procedure in making a double flare.

Double thickness flares are recommended, for only the larger size tubing

(5/16 in. and over) and are not easily formed on smaller tubing. The double flare makes a stronger joint than a single flare.