Thermal Stress Analysis of Process piping System installed on LNG Vessel subject to hull design

초록

This paper discusses the strength assessment procedure of the piping system installed on the deck of LNG ships. In particular, the procedure to reflect not only the load due to the temperature and self-weight of the piping installed on the deck but also the wave loading and hull motion acceleration of the ship, and the deformation due to the thermal expansion and contraction experienced by the hull during operation are presented. In order to reflect various operating conditions and load conditions of the piping system, stress analyses are performed by combining the various condition of sustained, occasional and expansion loads. The stress is evaluated by using finite element analysis based on the beam element representing the behavior of pipes. Components of the piping system such as valves, expansion joints, supports, etc. are reflected in the finite element model. CAESAR-II is used in the finite element analysis, and a component modeling, a load assignment, and a load combination are presented for evaluating piping stress subject to various load conditions. An evaluation model is selected from the piping layout of the LNG ship and the evaluated stress is compared with the allowable stress defined by ASME.