(1) Tank nozzle information to be provided by basic engineering.

Underground vessels (41☌) LPG Storage Tank Nozzles.

Vessels over 4.5 m 3 in capacity (46☌).

The NFPA specifies the equilibrium pressure at a design temperature of 41, 46, and 54° C, respectively, to be a design pressure, for each type of vessel as given below. Design temperature determination standards are closely connected with design pressures. Where the country’s regulations or the client’s design standards do not specify design temperatures, NFPA shall be applied. Major oil companies may have their own design standard for temperature selection. Generally, design temperatures are specified per country based on the ambient air conditions of the district where the plant facilities are to be constructed. (1) Design Temperature: A design temperature shall be determined based on the assumed highest temperature, with consideration given to input heat generated by solar radiation. Where the mole fraction of contents of the liquid in the tank fluctuates, the most severe case in normal operation shall be considered. (2) Operating Pressure: An operating pressure shall be an equilibrium pressure at operating temperature.

The temperature of products when they are received from a tanker.

Ambient air temperature (annual mean or annual highest mean temperature).

The temperature of rundown from process units.

Net Working capacity- Volume between HLL and LLL or HHLL and LLLL.

This volume varies depending on the operating temperature.

Storage capacity- The volume from the tank bottom to the maximum design level.

Geometrical capacity- Volume inside a vessel which is called “a water volume” in NFPA.This capacity is usually used as a tank name.

Nominal capacity- All this capacity can be used, defined as below in Fig.LPG Storage Capacity Definition of Capacity Where the tank is installed underground, the horizontal type shall be selected, even if the vessel capacity exceeds 100 m3.

The type of this capacity range will be decided by the total weight. Both types will be applicable for volumes ranging from 100 to 500 m 3. The horizontal cylindrical type is usually used for sizes smaller than 100 m3. The spherical type is usually employed for sizes greater than 500 m 3. A tank type will usually be selected considering the cost or the size of transportation.

Storage tank design calculations xls