A pipeline containing water vapour at 300°C under 25 bar of pressure burst at 3:10 pm at a chemical site; 4 m of pipe were torn. A loud whistling noise could be heard outside the plant boundary.

A nearby damaged ethylene line started to leak slightly. The internal emergency plan was activated and the in-house response team had the ethylene leak plugged by 11:45 pm. In order to stop the water vapour leak, the plant was forced to suspend all activities. This extremely rare occurrence gave rise to extensive “flaring”; tremendous releases of non-toxic smoke could be observed, though without any other noteworthy impact on the environment. All companies on the same chemical platform also shut down their activities. The leak isolation steps lasted until 7th September. The operator issued a press release, which insisted that the incident was not due to any maintenance problem since this part of the facility was being inspected on a regular basis. Industrial activity on the site resumed bit by bit over the course of the week; the steam cracker started back up on 16th September.

This break was caused by a violent “water hammer” effect when vapour was sent to the ethylene oxide unit of one of the firms on the chemical platform that had been down for over a month. The employees of this firm had adjusted the pipeline bypass valves in order to reheat the line prior to vaporization without first notifying the site’s main operator. The water hammer occurred right at this time. The condensed water most likely vaporized inside the pipe, which should have been bled before vaporization.

Subsequent to this incident, the classified facilities inspectorate noted the absence of adapted procedures relative to utility lines at the main operator’s business and with the ethylene oxide producer, as well as the inadequate implementation of daily procedures and the lack of communication among the platform’s various stakeholders. The inspectorate requested the Prefect to order a safety audit of the site.