29 August 2007

Partial Flare Line Blockage

Safety Incident Topic: Partial Flare Line Blockage
Location of Incident: Bulwer Island, Brisbane Australia
Date of Incident: 9 May, 2007

Brief Account of Incident
A back pressure observed at the Vacuum Tower was investigated by Operations and Technical personnel who found that the flare line was behaving as if it was partially blocked. Following a risk assessment, work was commenced to flush the line with steam and high temperature diesel. A relief valve in Crude Residue service was found to be passing. The relief valve and associated equipment was isolated and taken out of service. Flushing, steaming and external heating of the flare line was carried out until the line was cleared.

Potential Outcome
In the event of a large flare loading through unplanned shutdown of major process units, if the flare line had not been cleared, a back pressure in the flare system may have resulted in hydrocarbon venting to atmosphere through Vacuum Tower atmospheric relief valves.

Likely Causes
Currently is under investigation.

Action Taken
Risk assessment had undertaken to establish the basis of continued operation. An exclusion zone was established in affected areas. Line clearing was commenced. Monitoring of progress and for completion was undertaken.

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