Flaring copper tubing is spreading the end of the tube into a funnel shape with a 45° angle to match the flare fittings. A flare nut tightens over the fitting to get tight, leak-proof, metal-to-metal contact. You have to practice.
Flaring plumbing must be used for natural gas lines and other dangerous materials – refrigeration tubing connections must withstand at least 300 psi without leaking.
A flare is used for vibrating connections, like certain pumps, or the dryer.
Do not use a water compression fitting in place of the required flared connection because they are not designed for it.
The tubing is clamped in a flaring block. The copper end reaches just over the top edge (about 3/32) on the block, called the chamfer because it is beveled to help form the flare. Smooth any burrs or rough edges. Then clamp the flaring adapter onto the block, and center the yoke above the tube. As turning down the screw, the copper tubing end will spread out like a trumpet.
Remember to put the flare nut on first, else cut off the flare and start again.
Problems could develop:
– Over-tightening the flaring adapter screw while forming the flare creates a thin area weakness where the adapter meets the chamfer, and could break off sometime when the flaring nut is tightened.
– If the tubing extends too high above the chamfer, the result is a flare that is too wide.
– If the tubing is too low in the chamfer, the small flare can pull free from the flare nut.
– A proper flare will almost fill the flare nut bottom without binding or rubbing the threads.
You have to practice.