Safety Evaluation of LNG Bunkering in Ship-to-Ship Configuration Using a Flexible Metal Hose

Abstract

In recent years, under the tightening of environmental regulations by the International Maritime Organization (IMO), attention has been focused on the superiority of LNG fuel and LNG fueled ships that can reduce CO₂ emissions in addition to SOX. Over 129 LNG fueled ships are already in service worldwide, and the movement for introducing LNG fueled ships is gradually increasing in Japan.

One of the authors previously demonstrated a method of safety evaluation for LNG bunkering in Ship-to-Ship configuration using a LNG transfer hose, and examined based on the proposed method the limit of environmental conditions in LNG transfer operation. The use of a cryogenic composite hose is typical to transfer LNG fuel in Ship-to-Ship bunkering for LNG fueled ships. However, there is a problem of icing around the composite hose because of LNG transfer at extremely low temperatures. Another problem is that contact occurs between the hose and the ship hull or the hose and the sea surface during bunkering operation.

In this study, we investigated the use of a flexible metal hose provided with a heat insulation layer and an outer sheath in order to avoid these problems during Ship-to-Ship bunkering. We compared results of calculation with those of actual test using a newly manufactured 1/3 scale LNG transfer hose, and verified the accuracy of the calculation in terms of the end load of the hose and the minimum bending radius. In addition, we evaluated the safety of LNG bunkering in Ship-to-Ship configuration using the validated simulation model. Necessary requirements for applying the flexible metal hose to Ship-to-Ship bunkering were also investigated in this paper.