from the product loaded if only part of a tank is drawn from and may also lead to problems in determining a density (degrees API / kg/m3) for the cargo when blending on board.
b) increase in temperature of the cargo caused by ambient conditions or heating of the cargo. c) the improper operation of the vessel’s inert gas system and the incorrect setting of P/V on the vessel.
EXAMPLE: VOLUMETRIC THEORETICAL TEMPERATURE CALCULATION VESSEL DISCHARGE
7.6.10.4 Volume Correction Factors (VCF)
d) gauge hatches left open.
VCF tables should be consistent at all measurement points throughout the voyage. If the loaded quantities were calculated using VCF tables other than the VCF tables used at the discharge port, the loaded quantities should be recalculated based on the VCF tables used at the discharge port for the purposes of comparison. When investigating measurement differences, the VCF table difference should be reviewed to confirm that it is within parameters for the tables involved and the cargo temperature. NOTE: Not all countries apply current ISO or API/EI/ASTM standards. Some continue to use the 1952 ASTM tables, and many former Soviet Union (FSU) countries use GOST tables, which calculate cargo quantities as weight in vacuum.
e) excessive agitation of cargo during loading or passage, e.g. heavy weather conditions. f) poor integrity of the cargo compartment - worn packing on tank lids.
7.6.10.2 Evaporation Losses
g) COW operation at discharge.
h) the amount of free surface area of the cargo.
evaporation is the loss of the relatively low boiling point hydrocarbon components (“light ends”) of cargoes to the atmosphere, and occurs during loading, in transit, and at discharge. The extent of this loss is influenced by the volatility of the cargo, the temperature of the cargo, and agitation of the cargo; COW; the condition of the vessel; and the design and operation of the vessel inert gas system and pressure/vacuum relief (P/V) valves. Vapour pressure can be used as an indication of the relative volatility of the cargo at a given temperature. The evaporation portion of a loss is difficult to measure. Factors that can contribute to evaporation loss include:
7.6.10.3 Density (degrees API/kg/m3)
A significant difference between shore and vessel density (degrees API/kg/m3) measurements may lead to a quantity difference. For example, in the case of long shore lines, a large proportion of the loaded quantity may not have been sampled. Although losses due to density (degrees API/kg/m3) differences are quite small when considering standard volume, many product cargoes are traded in weight, and in these situations, density (degrees API / kg/m3) differences can lead to more significant losses. Density (degrees API / kg/m3) stratification may occur with some products. This can result in composite shore tank samples showing differences
7.6.10.5 Volumetric Shrinkage
Volumetric shrinkage can occur when mixing two hydrocarbons with different molecular structures. The amount of shrinkage depends on the density (degrees API / kg/m3) difference and percentage of the components.
a) high Vapour pressure of the cargo.
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