At 11:20 am in an chemical facility located at a port industrial zone, fire broke out on a C4 refinery output pipeline undergoing maintenance. Employees of the subcontracted maintenance company fled the danger zone. Safety personnel attempted to control the blaze using extinguishers. The port’s control post notified local fire-fighters. At 11:30, as the emergency intervention began, the adjacent ethylene pipe exploded. A 30-m piece of the line broke loose from its anchorage and was blasted towards the dock, where fire-fighters had established their position. The fire spread to other flammable gas pipelines, as well as to a boat moored at the dock. Due to the thermal effect, several pipes exploded in turn. The 160 on-site responders fought the outbreak using foam. A controlled flammable gas combustion was initiated. The chemical plant’s two steam cracker units were shut down, as was a portion of its production units. The delivery of raw materials to the facility was halted. The local population was advised to remain indoors. Across the site, air quality was continuously measured. The plant operator issued reports on the accident via the company website and social media. The situation was brought under control by 9:30 pm.

Consequences and follow-up actions

The human toll was very high: 4 deaths (3 in-house fire-fighters, plus a sailor whose boat was docked at the port), 7 seriously injured, and 22 more minor injuries. Property damage was tremendous (pipelines, pipe racks, a tanker boat, light-duty vehicles, lorries and fire-fighting vehicles destroyed).

The substances that ignited during the fire were: ethylene, propylene, 2-ethyl-hexane-1-ol, pyrolysis gasoline, methanol, and a C4 refinery output. The results of measurements recorded both on-site and in the vicinity revealed the absence of any abnormally high concentrations of hazardous substances in the air, aside from the immediate environment of the accident zone.

The fire extinction water was channelled to the site’s wastewater treatment plant.

Clean-up efforts and the search for an unaccounted individual only started two days later once all risks to responders, due to gas leaks, had been eliminated. During searches conducted in the harbour basin, the sailor’s body was found.

A few days after the accident, the site’s steam crackers were restarted. The other units were gradually brought back online over the following weeks.

Analysis of accident causes

The subcontractor had returned to the site to repair a propylene pipeline, with work permits being procured ahead of time. The line had been drained, rinsed and inerted with nitrogen before works commenced on 14 October 2016. Cut-outs and welds were required at several places along the pipeline (removal of parts and replacement). On the day of the accident, a subcontractor’s supervisor was present at the scene prior to initiating works. It was verified that the pipeline needing repair had actually been drained by perforating a 3-mm hole with a handheld auger. Measurements performed using a portable gas detector confirmed the absence of all hydrocarbon residue and no explosive atmosphere. Several cut-outs were made and a number of pipe pieces removed. Equipped with an angle grinder, the subcontractor may have inadvertently cut into the wrong pipeline. Instead of applying his tool on the drained and prepared propylene pipe, he actually hit a C4 refinery output line. The gas exited via the notch left in the line and then ignited upon making contact with sparks. Presumably the flame heated an adjacent cross country ethylene pipeline (88 bar, approximately 250 mm diameter) until it burst by fast decomposition, causing additional explosions and a mass fire. The operator had been working with this subcontractor for 25 years. The worker had already completed assignments at this facility.

Following the accident, the press disclosed that some plant employees shared their concerns over the poor condition of site installations. Citing a cost savings plan, the company had apparently scaled back on the number of modernisation projects and upgrades. Given these criticisms, the operator responded that the pipelines implicated in the accident had been inspected in September 2012.

Experience feedback

The site had not experienced such a serious accident for several decades (the last one of this magnitude dating back to 1948, with 207 deaths and nearly 3,800 injured). Nonetheless, the company had been experiencing several incidents every year.

In 1998, another accident at this site involved confusion during a maintenance operation (ARIA 13414). In 2014, an accident involving a gas pipeline explosion on the chemical platform (of another operator), resulting in 2 deaths (ARIA 45867). In 2008, an accident at a chemical plant in Cologne had involved the fast ignition of an ethylene pipeline subsequent to maintenance works (ARIA 35672), prompting Germany’s North Rhine-Westphalia State to implement prescriptions regarding the minimum distance between flammable gas pipelines and Seveso-rated facilities.