For semi-refrigerated and semi-pressurized liquified natural gas(LNG) carrier without liquefaction systems

the temperature and pressure in the tank will gradually increase in voyage

with the density and volume of the liquid cargo will change accordingly. In this paper

a simplified method for calculating the daily variation of temperature and pressure of a 14000 m3 LNG carrier is proposed. The calculation results show that the deviation of the daily variation of temperature and pressure calculated by the simplified method is small under the condition of higher loading rate

which can meet the basic requirements of engineering calculation. The relationship between the loading rate and the maximum allowable relief valve setting and the influence of the loading rate on the temperature and pressure of the liquid cargo are also discussed and analyzed.