Materials for propylene and propane spherical tanks, design temperature
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Propylene and propane belong to the C3 category; they are stored under pressure at room temperature, with a pressure of around 20 kilograms. Similar to liquid ammonia storage tanks, ordinary carbon steel such as Q345R or Q370R should be sufficient for use in these tanks. However, I’ve seen that the design temperatures for many propylene and propane storage tanks are set at -45 degrees and -35 degrees – which certainly isn’t the ambient temperature. Therefore, low-temperature steel such as 07MnNiMoDR is used for these tanks. The question is: what is the basis for choosing design temperatures of -45 degrees and -35 degrees?
Low temperature and low pressure can be considered, along with using a thicker Q245R material.
Improper discharge of the liquid stream causes the high-pressure liquid to experience a rapid and sharp drop in pressure, which results in its instantaneous boiling and vaporization under adiabatic conditions. This leads to a sharp decrease in the temperature of the gas; in extreme cases, the temperature can drop to levels close to its boiling point at normal pressure.
Liquefied gases have relatively low temperatures after being liquefied, which results in cold conditions.