Designing for an LNG Loading Arm Failure

Over the last few decades, LNG has vaulted onto the world stage as a viable candidate for future energy needs. Scores of studies have been done to illustrate the potential consequences of an accidental release of LNG. Some excellent studies have been reported, but uncertainties still exist because of randomness of events, unconfirmed extrapolation, and other factors that could affect an actual outcome One area where an accidental release of significant magnitude could pose serious problems is during the loading operations of large LNG carriers in service today. With loading rates exceeding 12,000 cubic meters per hour, a failure in the loading delivery system could cause embrittlement of a ship, supporting loading structures, possible RPTs, potentially large vapor dispersion zones, and/or a confined vapor cloud explosion.

Typically, and in the codes, 10 minutes is considered a “worst case scenario” for duration of an event. By any account, a loading arm failure represents a potentially catastrophic event.

The author will describe a system that can detect a spill or fire, activate shutdowns, and mitigation systems to stop the accidental release in less than one minute and minimize the potential effects of such an event.

Issues such as reliability/availability, code compliance, hydraulic transient analysis, and actual design considerations will be discussed.