Figure 1: Rags found in the drain tank
A container ship departed its berth and was heading on the outward passage with a pilot on board. Before the ship left the pilotage area, a low level alarm for the main engine lub-oil drain tank sounded. The engineer on watch alerted the bridge and the ship’s speed was reduced while he went to investigate. The lub-oil tank contents gauge indicated that the tank was empty; approximately 10000 litres of oil had apparently ‘disappeared’. To prevent significant damage, the ship was immediately anchored and the engine was shut down. About 30 minutes later, to the surprise of the ship’s engineers the contents gauge showed the tank was full. Consequently, the main engine was re-started, but again the lub-oil tank appeared to empty. Not wishing to take any chances, the master shut down the engine and returned back alongside with tug assistance. Soon after, the contents gauge indicated that the lub-oil tank was full again.
A service engineer attended to help identify and rectify the problem. Once the engine had cooled, the contents of the lub-oil drain tank were transferred to a holding tank and the lub-oil drain tank was inspected. A number of items, such as rags, plastic tape and plastic end caps were found in the tank (Figure 1), caught on a steel mesh protecting the oil pump suction well. The tank’s contents sensor was located in the well and the debris had slowed the oil flow from the tank. Consequently, after the oil pump had drawn the lub-oil from the well, the contents gauge indicated that the tank was empty. Once the engine and lub-oil pump were stopped, the oil had seeped through the debris from the tank and filled the well. After the lub-oil tank was thoroughly cleaned and the oil replaced, the vessel resumed its schedule without further problems.
- Tanks and engine crankcases should not be left open after work has finished. Before being closed, they should also be thoroughly inspected to ensure that no detritus or tools are left behind. Ideally this should be done by someone not involved with the work being carried out.
- Prompt and appropriate responses to machinery alarms are necessary if damage to equipment is to be prevented. This requires the on-watch engineers and the bridge team to have a good understanding of the propulsion system and to be well drilled in the event of an alarm or breakdown.
- Anchoring and returning alongside following mechanical problems inevitably causes delays. However, it is better to be late than to not reach the intended destination through ‘pressing on’ until a problem is sorted. Tug assistance and engineering expertise are easier and less expensive to access in port than they are elsewhere.
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