Leak of pressurised flammable gas within a petrochemical complex - issue 258

Issue Number: 258


A leak of liquefied flammable gas occurred at a petrochemical facility on 17 October 2015, lasting for 21 minutes. Technicians were eventually able to stop the leak before any fire or explosion ensued. The internal emergency plan was not activated.
The leak was caused by ejection of the hatch on one of the check valves on a compressor. Although the compressor had showed no signs of operating anomalies prior to this incident, further investigation revealed poor clamping of the compressor studs and degradation of the compressor dowel. In addition, the relatively long duration of the leak was due to the operator being unaware that it was necessary to effect the valve closure remotely from the control room by actuating the emergency stop button.
As a result of the leak, the compressor was completely refurbished before it was placed back into service and a revised maintenance task list was shared with the subcontractor assigned to maintain the compressor. A review and update of task lists on the other compressors at the facility was also undertaken.
Organisational modifications were introduced as well. The criteria for activating the internal emergency plan was simplified — once the second threshold was breached on two gas detectors, the internal emergency operations plan would be activated, which would trigger the site’s general alarm, suspend all traffic on the site and inform the local authorities.

IChemE is a registered charity in England & Wales (214379), and a charity registered in Scotland (SC 039661).