This paper has an aim to study the effect of PWHT and its conditions(peak temperature and holding time) on the tensile properties and impact toughness of FCAW weld metal in relation to microstructure. Impact toughness was evaluated to apply the cargo tank of liquified gas carriers under the various PWHT condition of each class societies. On the basis of these study, it was found that PWHT conditions within all class societies affect charpy absorbed energy of weld metal little or no, all PWHT weld metals kept similar level of charpy absorbed energy as as-weld weld metal down-to $-60^{circ}C$ and finally indicated lower energy value than that of as-weld weld metal at $-75^{circ}C$. It is because the precipitation of 2nd phase was controlled from welding consumable and the grain size was grown by PWHT.