Development of Requirements for Safer Operations of FLNG Units

Abstract

Abstract Floating Liquefaction Natural Gas units, or FLNGs, have matured as a technology in recent years with Petronas, Golar, Shell and Exmar units coming on-line. Additional units from Petronas and ENI are under construction. The challenge with integrating elements of onshore LNG production plants, LNG shipping and offshore floating production and offloading (FPSOs), into one floater with limited space and load bearing capacity, was significant, necessitating the development of design guidelines. The traditional approach to mitigating the impact of fire and explosion risk in an onshore LNG plant is to use physical separation between the various elements of the plant. In addition to potentially reducing fire ignition and escalation potential, this can facilitate personnel egress and allow for additional leak containment to be incorporated. With production, liquefaction and storage integrated in one unit, there is very limited opportunities for using space segregation as a safety measure within the unit. Also, when the cryogenic fluids offload to an LNGC in a side by side configuration with the FLNG there is also no opportunity to segregate the loading carrier from either LNG storage, production or liquefaction. With this background, regulatory regimes and class societies have leaned heavily on the guides and rules for FPSOs and integrated significant elements from LNG shipping, particularly when it comes to LNG cargo containment and offloading. Every potential FLNG location with corresponding metocean and meteorological data as well as fluid flows and compositions will be different, so it is very difficult to create prescriptive rules for separation distances etc. As a result, it is typical to quantify and mitigate risk through analysis and studies and use the ALARP (As Low As Reasonably Practical) principle when reviewing risk mitigation efforts. This paper will show how the different standards and rule sets are brought together as a comprehensive regulatory approach. Standards and class rules are utilized to bring together an approach that results in a design and construction that satisfies the needs of flag, class, coastal state and owner. To this date floating LNG facilities have been able to safely carry out commissioning and start up and produce and deliver cargos without major incidents. The track record to date also highlights how the technology can be used in harsher climates and seas and hence can unlock more gas reserves.