Figure 5-17.—Correct and incorrect methods of installing flared fittings.

threaded ports in pumps, valves, and other components. Several of these thread combinations are shown in figure 5-16. Tubing used with flare connectors must be flared prior to assembly. The nut fits over the sleeve and when tightened, it draws the sleeve and tubing flare tightly against the male fitting to form a seal. The male fitting has a cone-shaped surface with the same angle as the inside of the flare. The sleeve supports the tube so vibration does not concentrate at the edge of the flare, and distributes the shearing action over a wider area for added strength. Tube flaring is covered in Tools and Their Uses, NAVEDTRA 10085 (series), and other applicable training manuals. Correct and incorrect methods of installing flared-tube connectors are illustrated in figure 5-17. Tubing nuts should be tightened with a torque wrench to the value specified in applicable technical publications. If an aluminum alloy flared connector leaks after being tightened to the required torque, it must not be tightened further. Overtightening may severely damage or completely cut off the tubing flare or may result in damage to the sleeve or nut. The leaking connection must be disassembled and the fault corrected. If a steel tube connection leaks, it may be tightened 1/6 turn beyond the specified torque in an attempt to stop the leakage; then if it still leaks, it must be disassembled and repaired. Undertightening of connections may be serious, as this can allow the tubing to leak at the connector bemuse of insufficient grip on the flare by the sleeve. The use of a torque wrench will prevent undertightening. CAUTION A nut should never be tightened when there is pressure in the line, as this will tend to damage the connection without adding any appreciable torque to the connection. Figure 5-17.—Correct and incorrect methods of installing flared fittings. 5-14