Plugging the gap in maintenance

Lloyd?s Register has alerted ship owners to the problem of neglecting plugs on fuel delivery systems. In the worst cases, the neglect can result in machinery space fires. The classification society says that the loosening of threaded plugs has resulted in fuel spraying onto hot surfaces, such as an exhaust manifold or turbocharger casing, and igniting. The classification society says two types of plug are susceptible to problems: Erosion plugs on fuel injection pump bodies and plugs in low-pressure lines from the booster pump. Hardened erosion plugs are used on fuel injection pump bodies because they are better able to resist the erosion forces, caused by the impact of fuel jets during operation, than the cast steel body of the fuel pump. However the force of the fuel jet means the plugs still erode and therefore still need replacing at set intervals (usually determined by the engine builder). Plugs in low-pressure lines are used, most commonly, for bleeding and venting the system. They are also used to fill holes required for instrumentation and manufacturing. Peter Koller, classification manager at Lloyds? Register, says particular attention should be paid to the tightening torque, through regular checks, in order to prevent the plugs workings loose. He recommends securing the plugs with locking wire, or an equivalent device, to prevent them working loose during service.