A 62-year-old technician was killed when an LNG vapor cloud exploded while he offloaded liquefied natural gas (LNG) from a tanker semi-trailer. He
worked for his employer, a natural gas supplier, for about five (5) years. The technician was offloading the trailer at a temporary and mobile LNG transfer station. The trailer belonged to the technician’s employer but was being hauled by a driver from a contracted motor carrier. The driver had delivered LNG to the station at least 25 times. The facility supplied LNG vapor through a pipeline that served customers. The technician connected an 18-foot transfer hose from the trailer control cabinet to a queen storage trailer and began the LNG transfer. The driver unexpectedly turned his truck on and drove forward 17 feet while the transfer was still in progress, which yanked and disconnected the hose coupling from the queen. LNG vapor leaked from the trailer and formed a large, thick LNG Gas cloud in the work area. A co-worker, who was outside of the offloading area, saw the cloud and attempted to warn the technician. Around the same time, the driver realized what was happening and rushed from his truck cab to activate the Emergency Shutdown (ESD) at the back of the trailer to stop the vapor from being released. Just then, the vapor cloud contacted an unknown ignition source and exploded into flames.
The driver ran to a nearby field away from the fire. The co-worker called 911 and his supervisors. He found the technician badly burned but alert at a muster point west of the fire area. He then moved him to a safer place where first responders could treat him. First responders evacuated the surrounding area and took the technician and driver to the hospital. The technician died two days later from burn shock. The driver was treated for minor burns and released the next day.
CONTRIBUTING FACTORS
Following the incident, investigators found:
- The driver believed he could move his truck when a technician gave him paperwork before the transfer was complete.
- He did not exit his cab or complete a pre-trip inspection before moving the truck forward.
- The transport trailer’s wheels were not chocked before the transfer hose was coupled to the queen trailer.
- Possible sources of ignition included a spark from ungrounding when the truck moved, nearby generators, or static electricity.
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