In an LNG terminal, commissioned on 08/07/2016, liquefied natural gas (LNG) passed into the flare stack circuit at around 4 a.m., causing LNG vapours to ignite at the base of the flare stack. The site’s internal emergency services were able to extinguish the fire using mono-ammonium phosphate powder. The torch stack’s supply lines were isolated, which caused the pressure in the storage systems to increase. To prevent the safety valves from opening, the pressure inside the tanks was regulated by their vent valves. During the event, LNG at -160 °C was sent to a tank that was in the process of being cooled. The temperature of the tank dropped 37 °C in less than 2 minutes.

It was estimated that 1,000 m³ (500 t) of LNG was released, resulting in a €10 million loss.

Alarms inoperative

It was determined that the control alarm had been deactivated. The shift manager had apparently deactivated the alarms, without supervisor approval. His justification for this was that the terminal was undergoing testing and the sensors were malfunctioning. The Inspection authorities for classified facilities thus requested that the operator ensure proper supervision of alarm ‘shunting’ operations.

Measures taken

The operator reinforced the procedure for inhibiting automatic controls: a written authorisation is now required to disable an alarm. Shift/crew management is also being strengthened. Thermographic imaging cameras were also installed pending the replacement of the temperature sensors.

The Inspection authorities for classified facilities consider that the integrity of the tank may be affected due to the rapid drop in temperature. It, therefore, requested that the operator provide it with an assessment of the tank in question and its accessories, validated by a third party. Compensatory measures and in-service monitoring should be implemented, as required.