A Study on Welding-induced Temperature Distribution and Deformation of IMO Type C LNG Fuel Tank Support Structures

Abstract

The burden on ship owners and shipping companies has increased due to the International Maritime Organization’s (IMO's) environmental regulations. The countermeasures against these regulations involve using low sulfur oil, installing scrubbers, and using liquefied natural gas (LNG) fuel. Among them, the demand for LNG propulsion ships is currently the highest. The most widely used storage device for LNG fuel is the IMO type C tank. The structure of the IMO type C tank is divided into a container part (pressure vessel) and a support part (saddles). In general, epoxy resin for load-bearing and wooden blocks are applied between the pressure vessel and saddles. When the saddles of the saddle-tank integrated fuel tank are welded to a hull, melting of the resin or burn-damage on the wooden blocks may occur due to the welding heat. Therefore, in this study, the temperature distribution of the saddle is checked, and the appropriate minimum height of the saddle is proposed to prevent the functional loss of the resin and wooden blocks during the installation of the saddle-tank integrated fuel tank. In addition, the initial deformation of the saddle according to the welding direction and sequence is evaluated to identify the effect of the welding on the installation of the saddle-tank separated fuel tank.