MEASURING CARGO - PART 5

Code No: 505

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This is part of a series of five videos that uses computer graphic techniques with animated sequences to produce concise, visually effective and informative training material. A full voice commentary describes and reinforces the highly detailed visual images.

The videos take as an example a 170,000 dwt segregated ballast tanker (no double bottom) with 7 cargo tanks, 2 slop tanks and 3 cargo pumps. The capacity of the cargo pumps is 4000 m3/hour.

Part 5 - During discharge it becomes very important to measure the quantity of cargo in the tanks. Remote measurement is shown using, in this example, an SAAB level transmitter to measure ullage, but manual ullage measurement is usually also needed; this is shown using an MMC ullage tape used through an ullage plug fitted with a vapour control valve. Ullage readings are then used to enter the ullage tables to determine tank contents. Interpolation due to trim and list is usually necessary, this is shown in detail. As cargo volume varies with temperature it must be converted to standard temperature using ASTM tables. Probing for free water is necessary for final evaluation of cargo volume. Preferred units of volume, weight and temperature can vary so it is necessary to be able to handle different systems; this is also explained in detail using ASTM tables. Finally, measurement of cargo remaining on board (R.O.B.) is explained. Consideration is given to the measurement of cargo in the slop tank.