3.1.1 Membrane In a membrane system, the LNG is stored at a temperature of -163°C for a cargo density of 0.470 to 0.500 tonnes per cubic metre and in atmospheric conditions. It is common for the system’s pressure to be increased to 0.7 bar when the unit is an FSRU. Most of the known membrane containment systems are provided by Gaztransport & Technigaz (GTT), with their various versions of the NO and MARK family products applied on FSUs. Of special attention for membrane LNG carriers and floating units is the assessment for sloshing and the ways in which partial filling can be achieved (even at the typical barred levels of LNG carriers) through ascertaining the sloshing intensity and a combination of strengthening the containment system and/or reducing the operational (sloshing) loads. In recent years, Korean shipbuilders and KOGAS have developed their own membrane cargo containment systems, with KC-1 chosen for LNG carrier application. The table below summarises these different containment system technologies (as approved by LR status to date) and our views on the floating units’ applications. Containment system
Design approval status
Notes on FS(R)U application
GTT NO88
Project application
Applied on two storage unit conversions.
GTT NO96
Project application
Applied on 12 FSRUs, either built or converted.
GTT NO96 L03
GApp on March 2014
Can apply on floating units when increased strength and better boil-off rate (BOR) performance is required.
GTT NO96 L03+
AiP on July 2015
Further reductions in BOR. Application on floating units as per GTT NO96 L03.
GTT MARK III
Project application
Applied on 11 FSRUs, either built or converted. Gazprom FSRU to LR Class under construction. SHELL FLNG to LR Class.
GTT MARK III Flex
GApp on November 2013 and project application
Applied on the construction of two FSRUs.
GTT MARK III Flex HD Foam
AiP on September 2011
Enhanced performance on sloshing impact loads. Suitable for units with large LNG tanks.
GTT MARK V
GApp on October 2015
The latest MARK version of GTT. Can apply on floating units due to enhanced BOR and enhanced secondary barrier characteristics.
KOGAS KC-1
AiP on August 2007
Applied on two LNG carriers under construction.
HHI HC-07
GApp on May 2009
No application yet on LNG carriers and/or floating units.
SHI KCS
AiP in March 2013 (previously called ‘SCAWS’ – design evolved to now be called ‘KC-S’)
No known application. Can be considered on new units.
DSME DCS16
GApp on March 2016
No known application. Can be considered on new units.
DSME SOLIDUS
AiP on October 2015
No known application. Can be considered on new units.
GApp September 2016 (expected)
Table 1: Status of membrane cargo containment systems
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