Fuel Oil Purifier Vibration with Limited Spares
At 18:40, No.2 fuel oil purifier on a 35,000 dwt bulk carrier trips on high vibration while the ship is burning HFO 380 cSt. No.1 purifier is already isolated awaiting a spare bowl disc. The engine room has 14 m³ of HFO in the settling tank and 6 m³ in the service tank; ETA Hong Kong is 62 hours, and boiler plus auxiliary engine consumption is 2.8 m³/day. The fuel test report shows water 0.35% and density 991 kg/m³. The tripped purifier shows vibration alarm, sludge discharge every 15 minutes, and normal bowl speed of 5,800 rpm; feeder pump pressure is 3.1 bar. The second engineer proposes bypassing the vibration trip to run it at reduced throughput. No spare complete bowl assembly is on board; the company can send parts to Hong Kong. Weather is moderate. The chief engineer must decide before the next watch and before the service tank level drops below 24 hours of consumption.
1. How do you diagnose the purifier problem and what immediate actions do you take?
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Diagnosis. Normal bowl speed with high vibration and frequent sludge discharge suggests bowl imbalance from heavy sludge/water accumulation, a damaged or incorrectly fitted bowl disc, worn bowl bearings, or a gravity-disc/throughput mismatch for the dense, wet fuel. The high water content and density 991 kg/m³ increase sludge load and make separation sensitive to temperature and gravity-disc selection.
Immediate actions. Do not bypass the vibration trip. Stop the purifier, isolate and lock off the motor, and allow the bowl to stop completely. Inspect the bowl for sludge and water, check the bowl disc and bearings, verify correct assembly and gravity disc, and confirm fuel temperature. Clean and reassemble only if no damage is found; otherwise keep it isolated. Meanwhile protect the service tank: drain water from settling and service tanks, verify fuel temperature, and use the remaining service fuel conservatively. Inform the master and company, and request the Hong Kong spare package.
2. How do you manage fuel and auxiliary machinery to reach Hong Kong safely?
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Total HFO is 20 m³, and 62 hours at 2.8 m³/day requires about 7.2 m³, so quantity is not the immediate limit; fuel quality and purification capacity are. If one purifier can be restored, run it at a stable reduced throughput and monitor vibration, sludge discharge, and water content. If neither purifier is serviceable, do not burn unpurified HFO in the auxiliary engine or boiler without confirming water and solids are acceptable. Switch the auxiliary engine and boiler to MDO/MGO if available, retaining enough HFO for main engine use only if the main engine fuel system can tolerate it. Keep at least 24 hours of service fuel, drain settled water regularly, and test before use. Set a decision point: if no purification is available and fuel quality cannot be assured, reduce auxiliary load and arrange MDO in Hong Kong.
3. What safety controls, notifications, and records apply to this decision?
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Use a permit-to-work and lockout/tagout for purifier work, a toolbox talk, and a risk assessment covering rotating machinery, hot fuel, and manual handling. Record the vibration alarm, bowl speed, sludge frequency, fuel test results, isolation, inspection findings, and the decision not to bypass the trip. Notify the company technical superintendent, the master, and the port agent/agent for spares; if fuel switching affects the sulphur record, update the relevant log and changeover record. Log the defect in the planned-maintenance system and raise a near-miss if the bypass proposal was seriously considered. The safety principle is that a protective trip is not an inconvenience to be defeated; it is evidence that the machine or process is outside safe limits.