Regarding design pressure
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For pressure vessels containing liquefied gases with a critical temperature below 50°C, and for those without empirical data or insulation facilities, the maximum pressure shall not be lower than the pressure of the gas at 50°C when the vessel is filled to its specified maximum capacity. May I ask, for liquefied gases with a critical temperature below 50°C, are they still in liquid form at 50°C inside the container? If it’s not a liquid, is the gas pressure now the pressure at which all the liquefied gas in the container turns into gas? Is it many times larger than when it’s in a liquefied state?
Saturated vapor pressure corresponding to 50 degrees
Liquefied gases generally have a corresponding saturated vapor pressure; if there is no liquid phase at the temperature present in the container, the pressure is normally less than or equal to the saturated vapor pressure at 50 degrees. To cause the liquefied gas to vaporize, it is necessary to increase the temperature or decrease the pressure. When the temperature remains constant, the pressure in a storage tank with 10% liquid level is the same as that with 75% liquid level. Unless there are impurities inside, resulting in a mixed gas, the pressure will be high