The Deethaniser overhead line of a Saturated Gas Plant (SGP) suffered a catastrophic failure at an elbow immediately downstream of a washwater injection point. The release caused a huge vapour cloud which ignited after 20 – 30 seconds, resulting in a massive explosion and fire. The pressure wave from the blast caused widespread damage to houses and businesses within a 1 km radius of the site. Debris from the explosion was spread over a wide area including on an adjacent public highway. Some 10 – 15 minutes later, a second release occurred which also ignited and caused the fire to increase in size and intensity. Several other pressurised piping systems in the fire zone overheated and ruptured. The fire was brought under control within 70 minutes and was extinguished 5 hours and 40 minutes later. The damage to the SGP caused the refinery to be shut down for several weeks, followed by a phased startup. Fortunately, the incident occurred on a public holiday when there were only 185 people on site rather than the normal weekday workforce of around 800 staff and contractors. Only a few people were outside when the explosion occurred because most were inside preparing for shift handover.

Basic Cause:
Erosion-corrosion of an elbow at a point downstream and close to a water injection point that was not part of the original design.