Numéro : 2609 - Year : 2011
Validation studies of GTT membrane insulations for a methane carrier in arctic conditions
Brahim BENALI, GTT – Service innovation
Thomas CREMIERE, Jean-Marc QUENEZ, GTT – Service innovation
Valery M. SHAPOSHNIKOV, Krylov Shipbuilding Research Institute – Ship & Offshore Strength Laboratory
Maxim S. BOYKO, Mikhaïl A. KUTEYNIKOV, Russian Maritime Register of Shipping
Today the development of Liquefied Natural Gas Carriers (LNGC) able to operate in arctic conditions has become necessary given the potential demand of natural gas transportation from the arctic zones located in the north-west of Russia. The purpose of this document is to demonstrate that membrane insulations equipping LNGC are adapted to the navigation in such conditions, should it be the Barents Sea or more severe conditions like those of the Kara Sea or of the whole northern sea route (NSR).
In order to determine if membrane technologies developed by GTT have sufficient life duration when submitted to ice related vibrations due the navigation in such conditions, some theoretical and experimental studies have been performed.
In a first step, a concept of RMRS Arc6 LNGC of 180,000m3 was developed. Then the exciting forces under ice operations were evaluated and implemented in a finite elements mode. The ship vibrations were calculated for three loading conditions: ballast condition (tanks empty), full loading condition and minimal loading condition (all tanks empty except for tank number 4 filled at 10% of its height). This phase of the study allowed the definition of the ship vibration spectra.
The second step of the study was the development of the test program on the basis of these vibration levels. Endurance tests were conducted in displacement on full scale mock-ups representative of NO96 insulation, and endurance tests in acceleration were performed on mock-ups representative of NO96 and Mark III insulation. These tests permitted the evaluation of the fatigue strength margins of the membrane containment systems in Arc6 service conditions.