At 4:18 a.m., a leak of liquefied natural gas (LNG) was detected in an LNG terminal at a pier. Gas detectors triggered the alert. The automatic safety system triggered a series of actions to ensure the safety of the facilities: emergency shutdown of unloading operations, start-up of the fire-fighting pump, pressurization of the electrical substation and the control tower, and load shedding of the building and the laboratory. At 4:45 a.m., the operators closed the damaged purge valve and 35′ later opened a purge valve to degas the letdown line. The incident area was marked out. The Classified Installations Inspectorate conducted an initial non-routine inspection the day following the incident in order to take note of the circumstances and consequences of the incident.
Over 20 m² of the concrete slab of the intermediate platform had become covered over with frost (expansion of the escaping gas). An estimated 26,000 m³ of LNG (17 t at atmospheric pressure) had been released into the atmosphere. The release also created a cloud of natural gas which drifted towards the terminal.
The day before the event, an operator had forgotten to close a bleed valve on an LNG recovery line on a degasser. The release had gone undetected by the surveillance rounds and temperature sensors.
An in-depth analysis of the occurrence revealed the following:
- a variety of practices existed among the watch crews for locking out degassers on the piers,
- the lock-out method and the tracking procedure were partially described,
- the available elements do not provide the operators a precise and global explanation of the operations performed and the status of the degasser systems,
- the route and purpose of the rounds were not clearly described, leaving some room for interpretation.
The operator conducted an in-depth causal analysis of the incident and implemented the corrective actions that were identified.
The Inspectorate:
- asked that the operator identify the organisational and human factors involved in terminal operations in its analysis,
- reminded the operator to allocate appropriate resources to the safety management system.
A second inspection was conducted five months later to examine the application of the Safety Management System (SMS) with regard to “organisation, training” and “process control, operating control” concerning the incident’s circumstances. No deviations from the applicable regulations were noted on this occasion. The operator’s recognised inspection department conducted checks on the pressure equipment. Their integrity was not called into question following the incident. A specialist company conducted an assessment of the concrete structures. No damage related to the leak was identified. However, recommendations were made (core samples of the concrete slab were taken and a detailed study was conducted on the cracking observed). The operator agreed to have the necessary studies and expert assessments performed to respond to these recommendations. The studies and assessments were scheduled for late 2019.
Three events occurred at the site in 2016 (ARIA 48644, 48661) and in 2017 (ARIA 50755).
