An LNG terminal that was being restarted following a one-week shutdown began leaking at around 6:00 a.m. after a high-pressure pump was turned on. A technician gave the alert and the pump was shut off manually. The pump was restarted. However, gas once again began leaking at around 6:20 a.m. and formed a cloud of flammable gas. The facilities were shut down and their power supplies were cut off. The operator believed that a pocket of gas in a low-pressure circuit of liquefied gas caused excess pressure and opened the valves. The circuit was purged and another attempt to restart the terminal was made. Another leak formed at 8:40 a.m. The operator implemented its internal emergency plan and alerted neighbouring companies via its telephone warning system. An investigation is being conducted to find the cause of the excess pressure (opening of the valves on the low-pressure network).

Mechanical malfunction of a valve

An analysis found that a discharge valve on a pump had remained open, causing gas to migrate to the low-pressure network and creating the excess pressure.

None of the valves at the terminal were serviced or tested. 

Communication issues during implementation of the internal emergency plan

An error, caused either by a computer glitch or human failing, occurred when the telephone warning system was used to send the alert message to neighbouring sites. In addition, walkie-talkie communication channels used to manage the event were overloaded.

Action taken by the inspection authorities for classified facilities

The inspection authorities for classified facilities asked the operator for an analysis of the accident to identify the event’s causes and consequences. A model of the dispersion of the gas cloud in the environment will also have to be developed. The inspection authorities drew the operator’s attention to the fact that the repetition of incidents in 2017 point to the need for a comprehensive look at the safety of its facilities and more particularly its safety management system (SMS).

Measures taken by the operator

After the event, the operator implemented the following actions:

• leak testing of the discharge valves on the other high-pressure (HP) pumps;
• the test results are recorded in a software program (CMMS);
• pumps may not be restarted if leaks are detected on two valves;
• the automatic control system has been modified to check for the absence of excess pressure if the various valves (lineup) are opened/closed;
• telephone lines have been added to reduce the time required to send alert messages via the telephone warning system;
• the technician has received training in operating the remote alarm system.