Metal fatigue can also cause breakage. Each system should have a systematic inspection of its fittings and piping to determine if all the parts are satisfactorily supported and sufficiently strong. In some instances, nipples may be connected to relatively heavy parts, such as valves and strainers, which are free to vibrate. Since vibration contributes materially to the fatigue of nipples, rigid bracing should be installed. When practicable, bracing should be secured to the unit itself, instead of to the hull or other equipment.
Breakage can also cause leakage in the high-pressure lines of a fuel system.
The breakage usually occurs on either of the two end fittings of a line and is caused by lack of proper supports or by excessive nozzle opening pressure. Supports are usually supplied with an engine and should not be discarded. A faulty nozzle usually requires removal, inspection, and repair plus the use of a nozzle tester. Leakage from fuel lines may also be caused by improper replacement or repairs. When a replacement is necessary, always use a line of the same length and diameter as the one you remove.