It is important to use flare fittings when you are dealing with a lot of water pressure going through a pipe or are dealing with high gas distribution.
Flare fittings on the end of copper tubing should provide a strong connection to a fixed point with a threaded nipple.
Used for fuel, oil, air, propane, liquid petroleum (LP) and natural gas lines connections
These fittings contain lead and are not allowed by federal law to be installed for potable water use in the U.S.A. and its territories.