Assessment Procedures for Mechanical Securing Components of LNG Cargo Containment System With Potential Damages

Abstract

This research has been performed to evaluate the structural integrity of the LNG cargo containment system. The structural integrity under vibrational loading and hull deflection was evaluated for damaged and undamaged systems. The test Mock-ups had been constructed for vibrational loading tests and hull deflection tests to compare the system behaviors under the damaged and the undamaged conditions. The damaged Mock-up was constructed with particular damages at the mechanical joints of the top and the bottom boards. The damages of the joints were applied at the designated points, which were selected based on the FEM analysis that compares the stress levels for the various damaged systems. The static tests were performed when the bottom board and the top board was installed, respectively. The visual inspection had been performed to compare the structural integrity of the damaged and the undamaged system during and after the tests. The vibrational loading tests had also been performed to compare the fatigue performance of both the damaged and the undamaged system. Endurance tests were performed for both vertical and lateral directions based on the results of resonance search tests. The specimens were vibrated at the resonant frequencies determined to most seriously affect the structural integrity. Abnormality of the acceleration time history had been monitored during the endurance tests and the acceleration level at the beginning of the test was compared with the level at the end of the test. After the endurance tests, the structural integrity of both systems had been thoroughly investigated by visual inspection.