Kawasaki Heavy Industries, Ltd. carried out a stress measurement of Moss type spherical LNG tank of their first LNG carrier which was also the first LNG ship in Japan. The measurement was carried out on No.3 LNG tank during interaction test and hydro-pneumatic test. The test conditions were as follows : (1) Interaction test A longitudinal vertical bending moment of 500,000 T-M was introduced to the hull. This moment is about half of the maximum design bending moment (M_s+M_w of Q=10^<-8>). (2) Hydro-pneumatic test Fresh water of 70 % volume and air pressure of 1.25 kg/cm^2 G were applied to the tank. The weight of the fresh water corresponds to the weight of 100% LNG with the maximum vertical acceleration due to wave induced ship motion. The measured stresses were compared with the calculated ones. The agreement was found very good. The interaction stresses were negligibly small and the stresses due to 70% fresh water and 1.25 kg/cm^2G air pressure were all moderate as designed. This stress measurement proved the reliability of the design of the spherical LNG tank system.
