Wednesday, May 30, 2012

Major Step Taken in LNG Bulk Cargo Storage and Shipping

World's Largest Independent Insulated Gas Tanks Approved
Shipping News Feature

UK – WORLDWIDE - Giant prismatic tanks which will reduce ‘sloshing’ and are suitable for widespread use as LNG (Liquified Natural Gas) containers have been approved by Lloyd’s Register. The ACTIB (Aluminium Cargo Tank Independent Type B) tanks, constructed of insulated aluminium 5083, will have the world’s largest storage capacity in an independent, insulated LNG tank system. The volume capacity in the initial design will be nearly three times larger than comparable types currently in operation.

The approval in principal of the new prismatic IMO Type B independent cargo tanks follows a one year period of development and collaboration between Daewoo Shipbuilding and Marine Engineering (DSME) and Lloyd’s Register. An evaluation for the next step, that of General Approval, has also been completed by Lloyd’s Register. The initial approval is for use in a DSME-developed 210,000 cubic metres STD LNG-RV design in accordance with Lloyd’s Register’s Guidance notes for liquefied gas carriers and floating offshore installations adopting IMO Type B independent tanks primarily constructed of plane surfaces.

One of the leading benefits of ACTIB is the potential for safe and more flexible operations in part filled conditions as the structural arrangement can be designed to withstand sloshing. As the ACTIB tanks are safer and more flexible than traditional types in part filled conditions as the structural arrangement can be designed to withstand sloshing, they will be of particular interest for wider use in LNG shuttle tankers, LNG floating production storage and offloading units (FPSO’s) as well as LNG-as-fuel tanks where partial fill is a critical operational issue as well as their application in the DSME designed 210,000 m3 volume LNG carrier.

Through continued collaboration, Lloyd’s Register and DSME become aware of the importance of further technical issues requiring examination, such as sloshing and fatigue calculations, and which are dealt with in the Particular Ship Application Approval (PSApp) stage, which takes place, typically, once a newbuilding contract has been signed. Mr. Man Soo Kim, Vice President and head of hull design of DSME, commented:

“We are very pleased to continue our good relationship with Lloyd’s Register, which has enabled such an excellent achievement by good cooperation. This new IMO type B independent cargo tank with insulation system developed with our own technology for extremely low temperature LNG containment system can be immediately incorporated into very large LNG carriers and/or LNG- FPSO’s while enabling DSME to become greatly competitive in the market.”

Daewoo Shipbuilding and Marine Engineering developed the ACTIB tanks two years ago and their use means DSME no longer has to pay technology fees to the French and Japanese patent holders whose tanks they had previously used. To get an idea of the scale, one of these tanks can store sufficient gas to supply a user such as Daewoo’s native South Korea with gas for a day and a half. The Korean ship buider also plans to apply the ACTIB system to the fuel tank design of LNG-fuelled ships such as DSME’s next-generation ‘green ship’ which is powered by LNG.Luis Benito, Global Strategic Marketing Manager, Marine of Lloyd’s Register, added:

"This is a very important achievement and a significant milestone for Lloyd’s Register and DSME to drive the practical application of new technology enabling partial filling during operations; it also provides another option to the gas industry for cargo containment systems in LNG carriers, LNG FPSO’s, and the like."

Photo: Daewoo built the LNG carrier Amali last year for BGC Brunei, doubling the capacity of their existing B class ships, yet stil only two thirds the size of new STD-LNG RV vessels fitted with the new tanks.