ABS, Newbuild and Converted Offshore LNG

Monday, June 01, 2009

ABS is currently involved with the review of or being considered for the selected class society for several Floating LNG (FLNG) and Floating Storage and Re-gasification Unit (FSRU) concepts. “We’ve been approached by leading energy operators to help them evolve gas technology that has typically been developed for land-based facilities,” said Ken Richardson, ABS Vice President Energy Project Development. “The projects range from the conversion of smaller, older LNG carriers to serve in a new role to technically novel concepts for newbuildings that can handle both LNG and LPG.”

Richardson pointed out that the recent increases in the size of LNG carriers may create commercial challenges for the continued flexible operation of some of the existing LNG carriers. “LNG carriers are some of the best maintained vessels that can be found,” Richardson pointed out. “Strict maintenance regimes mean these ships may have many years of serviceable life ahead of them. We can provide a life extension assessment of the vessel’s structure that can help the operator clarify his options.”

An example of the second life that can await these vessels was the recent announcement by Teekay Corporation that it is pursuing the possibility of converting the 1993 built, 87,500 m3, ABS-classed Arctic Spirit to become a floating LNG export terminal to be located in the Western Canadian port of Kitimat. The vessel has the independent IHI SPB containment system which is viewed as being a competitive alternative for floating terminal applications at locations where high sloshing loads can be expected.

Other projects include approval in principle of Teekay’s newbuild design for a floating gas liquefaction unit with dual LNG and liquefied petroleum gas (LPG) capabilities. Another ABS reviewed FLNG, the SBM/Linde LNG FPSO is also nearing finalization.

The principal applications for these vessels, whether newly built or conversions are as FSRUs, as floating production units with an annual capacity in the range of 0.5 to one million tons, or as floating export or receiving terminals as envisioned by Teekay for the Kitimat project or Petrobras for gas reception.

ABS’ evaluation of a floating gas project is based upon the application of prescriptive requirements, sea-keeping studies, structural and fatigue analysis, assessment of the containment system, including sloshing analyses and an evaluation of the station keeping systems. As applicable, particularly for novel elements within a new floating LNG project, ABS will also review the topsides, the gas processing and liquefaction plants or the re-gasification modules and use advanced risk analysis to verify that accepted safety standards are attained.. A number of ABS Guides and Guidance Notes are referred to when establishing compliance for a floating gas facility including the ABS Guide for Building and Classing Offshore LNG Terminals as well as international standards such as the International Maritime Organization’s (IMO) Gas Code as applicable.

ABS is also able to draw on its previous experience as the first society to class a floating LPG storage and offloading (FSO) vessel, the Escravos, and the first floating production, storage and offloading (FPSO) LPG vessel, the Sanha.

Additional specialized analysis and technical studies that may also be applied include: mooring analysis, containment system sloshing analysis, gas dispersion and heat radiation analysis; a cryogenic liquid spillage and structural protection study; vibration studies to analyze the impact of the top side processing facilities on the hull; as well as other detailed process and marine systems studies.