TERMS & DEFINITIONS

DWT = total amount of cargo plus crew, fuel, water & stores that a vessel can carry when fully loaded expressed in long tons (2,240 lbs).

Light Ship = weight in long tons minus cargo, crew, fuel, stores and ballast; meaning the ship is totally empty.

Lightening = discharging or throwing overboard some of the cargoes to lighten the weight of the ship.

Lightering = STST of cargoes between two ocean going vessels.

Thieving = measuring the volume of water underneath of the oil by lowering a metal rod or tape smeared with litmus paste which changes color when contacted by the water but is not affected by the oil.

Ullage = depth of free space from the overhaed to the surface of the cargo/liquid.

Innage = the volume of cargo/liquid inside the tank.

Hogging = a ship is loaded heavily at her ends causing the middle to bend upward and Sagging is too much load in the middle causing the ship to bend downward.

Combustible Gas Indicator (Explosimeter) = an instrument used in measuring the composition of hydrocarbons mixed with air in percentage of the lower flammable range/limit. Not effective when O2 is very low.

Bonding = connecting together of metal parts to insure electrical continuity.

Stripping = final operation in pumping bulk liquid from a tank or pipeline during discharge operations.

Torch (Flashlight) = a battery operated hand lamp approved by competent authority for use in a flammable atmosphere.

Flashpoint = The lowest temperature in which a liquid gives off sufficient gas to form a flammable gas mixture near the surface of the liquid. When a spark or heat is introduced it will burn/flash but only across the surface of the liquid.

Gas Free = A tank, compartment or container is gas free when sufficient fresh air has been introduced to lower down the level of any toxic, flammable ot inert gas to a specific purpose like hot works or entry.

Inert Gas = a gas or a mixture of gases such as flue gas containing insufficient oxygen to support combustion.

Venting = gas/gases being released from the cargo tanks or enclosed spaces.

Ventillation = air entering into the tanks or enclosed spaces.

Interface Detector = an electrical instrument used in detecting the boundary between oil and water.

Loading Overall = loading of cargo or ballast "over the top" through an open ended pipe or hose entering a tank through a hatch or other deck openings resulting in the free fall of the liquid.

Pour Point = the lowest temperature at which a petroleum oil will remain liquid/fluid.

Topping Off = operations of completing the loading to a required ullage.

Topping Up = (Purging) = putting additional inert gas into a tank which is already in an inert condition to lower down further the oxygen or increases the pressure to prevent the entry of air into the tanks.