Marine LNG/LPG Loading Arms

As natural gas exploration and production move further offshore, floating LNG (FLNG) platforms have become more popular to unlock these previously inaccessible resources.  This warranted new marine offloading technology to safely transfer LNG/LPG from FLNGs to LNG/LPG carriers under a variety of harsh environmental conditions.   To support their technology development, FMC Technologies engaged SC Solutions in the development of new LNG and LPG marine loading arms for the world’s first large scale FLNG platforms.

SC Solutions worked with FMC Technologies from proof of concept studies, to advancing the design during pre-FEED, and to final design verifications during FEED for two unique LNG/LPG offloading systems:

• OLAF – a system of friction-based swivels and bearings with counterweights to facilitate LNG/LPG transfer between a FLNG and carriers in a side-by-side configuration
• ATOL – a system of three articulated product pipes supported by a rigid gantry on the FLNG side and connected to carriers equipped with bow skid loading.  Articulation is facilitated by friction-based torsional swivels and bearings.  This tandem system allows greater separation distance between the FLNG and carriers for more challenging environments.

During this multi-year effort, SC Solutions performed time domain simulations and assessed the dynamic response of the two loading arm designs.  To support the analytical effort, SC Solutions performed the following:

• Developed analytical models of the two offloading systems.  Key features of the finite element models include articulation in the friction-based torsional swivels and bearings and the counterweight systems.
• Performed 3-hour transient analyses of the marine loading arms to simulate offshore offloading.  The suite of time domain analyses considered the worst sea states and different configurations of the loading arms, FLNG, and carriers.  The time domain analyses include application of motions independently at the FLNG and LNG/LPG carrier.
• Assessed the dynamic response of the two marine loading arms, including evaluating the critical components (swivels, bearings, manifolds, product pipes, etc.) against stringent performance criteria.

SC Solutions played an integral part in resolving many analytical issues, including: very large displacements imposed by motions at the FLNG and LNG/LPG carriers, modeling of the friction and damping in the articulation elements (swivels and bearings), and long duration time domain analysis.

SC Solutions was able to effectively automate the suite of analyses (over 100 for each phase) within the design schedule, and to provide accurate and detailed results to efficiently support the design effort from concept to final design.

ATOL Loading Arm Model