Regular draining of tank level columns will help prevent clogging caused by sludge accumulation and consequent overflowing. In a recent incident, the contents of a fuel oil settling tank overflowed, causing oil to spill onto the lower decks.
The incident was covered by the latest Mars Reports compiled by The Nautical Institute. A transcript of the incident:
During routine rounds while in port, the deck watch officer noticed oil on the poop deck. The alarm was raised and cleanup activities begun, as did the search for the oil source. It was found that the contents of a fuel oil settling tank had overflowed from the vent pipe located in the funnel. The overflowing oil then spilled on to the lower decks through the drain pipes and scuppers.
Company Investigation Findings
- The company investigation into the factors contributing to the incident discovered that the settling tank was fitted with a float-type liquid level indicator. This had, among other features, a high-level alarm and an auto-stop function to assist in the automatic transfer of fuel to the settling tank. The tank level gauge became stuck while the transfer pump was running in auto mode. This caused first the auto-stop function and then the high-level alarm to remain inactive even as the tank filled to overflowing. It was also found that a final safety barrier had been disabled by crew during the last voyage. The settling tank overflow line to another fuel tank had been blanked off to mitigate the risk of contaminating low-sulphur fuel.
Lessons Learned
- Vessels are fitted with numerous automatic systems. These are usually equipped with safety barriers that must not be disabled, otherwise negative consequences can arise.
- Notwithstanding automatic processes, crew members should conduct regular inspection rounds to maintain safety.
- Not carrying our regular draining of tank level columns may in this instance have been a contributory factor in the gauge becoming stuck.
Mars Reports
This is one of the May Mars Reports, originally published as Mars 201937, that are part of Report Number 320. A selection of this Report has also been published in SWZ|Maritime’s July/August issue.
Submit a Mars Report
More reports are needed to keep the scheme interesting and informative. All reports are read only by the Mars coordinator and are treated in the strictest confidence. To submit a report, please use the Mars report form and send it to mars@nautinst.org.
