Tanker operations glossary

Question 1

Approved Equipment

Answer 1

Equipment of a design that has been tested and approved by an appropriate authority such as a government department or classification society. The authority should have certified the equipment as safe for use in a specified hazardous atmosphere.

Question 2

Auto Ignition

Answer 2

The ignition of a combustible material, without initiation by a spark or flame, when the material has been raised to a temperature at which self-sustaining combustion occurs.

Question 3

Ballast

Answer 3

Seawater introduced into cargo or clean ballast tanks for the return leg of a voyage to the next loading port. It is the additional weight necessary to bring the vessel to a suitable draft and trim and to reduce stresses and improve stability.

Question 4

Barrel

Answer 4

Standard unit of volume commonly used in trading oil and on US ships, equivalent to 42 gallons.

Question 5

Block valve

Answer 5

There are different types of block valves which, when closed, may stop the oil from flowing in either direction. Types include remote gate valves and manual gate valves.

Question 6

Bonding

Answer 6

The connecting together of metal parts to ensure electrical continuity.

Question 7

Butterworth

Answer 7

A brand name of tank cleaning equipment, commonly applied to all portable tank cleaning equipment. Butterworth plates are plates flush with the deck that are opened to admit portable tank cleaning machines into the top of a tank.

Question 8

Cavitation

Answer 8

A condition in the operation of a pump that occurs when the pressure in the suction line falls below the vapour pressure of the cargo.

Question 9

CCR

Answer 9

Cargo Control Room

Question 10

Check valves

Answer 10

These valves are designed to operate one-way and stop oil from reversing flow. Flowing oil holds this type of valve open, and they close by themselves when oil isn’t flowing or changes flow direction.

Question 11

Chicksan (boom)

Answer 11

A mechanical steel arm or boom to connect the shore pipes with the ship’s manifold, while allowing large movement up and down and some movement sideways.

Question 12

Cofferdam

Answer 12

A void space used to physically separate the cargo area from non-cargo areas.

Question 13

Combustible (also referred to as ‘Flammable’)

Answer 13

Capable of being ignited and of burning.

Question 14

Combustible gas indicator

Answer 14

An instrument for measuring the composition of hydrocarbon gas/air mixtures, usually giving the result as a percentage of the lower flammable limit.

Question 15

COW

Answer 15

Crude Oil Washing. This uses recycled crude oil cargo to wash down tanks that are in the process of emptying or have just been emptied.

Question 16

Discharge pressure

Answer 16

The oil pressure as it leaves a pump

Question 17

Earthing (also referred to as ‘Grounding’)

Answer 17

The electrical connecting of equipment to the main body of the earth to ensure that it is at earth potential. On board ship the connection is made to the main metallic structure of the ship which is at earth potential because of the conductivity of the sea.

Question 18

Fire wire

Answer 18

Emergency towing wire affixed to the ship at bow and stern on the offshore side while in port. The eye is lightly fastened just above the waterline. This fastening is broken by a towing-off vessel, allowing the wire to run out to a suitable length.

Question 19

Flammable range (also referred to as ‘Explosive range’)

Answer 19

The range of hydrocarbon gas concentrations in air between the lower and upper flammable (explosive) limits. Mixtures within this range are capable of being ignited and of burning.

Question 20

Flash point

Answer 20

The lowest temperature at which a liquid gives off sufficient gas to form a flammable gas mixture near the surface of the liquid. It is measured in the laboratory in standard apparatus using a prescribed procedure.

Question 21

Gas free

Answer 21

A tank, compartment or container is gas free when sufficient fresh air has been introduced into it to lower the levels of any flammable, toxic or inert gases to those required for a specified purpose, e.g. hot work, entry etc.

Question 22

Gas free certificate

Answer 22

A certificate issued by an authorized person confirming that at the time of testing a tank, compartment or container it was gas free for a specific purpose.

Question 23

Gauze Screen (also referred to a ‘Flame screen’)

Answer 23

A portable or fitted device incorporating one or more corrosion resistant wire woven fabrics of very small mesh used for preventing sparks from entering a tank or vent opening or, for a short time, preventing the passage of flame.

Question 24

Hot work

Answer 24

Work involving sources of ignition or temperatures sufficiently high to cause the ignition of a flammable gas mixture. This includes any work requiring the use of welding, burning or soldering equipment, blow torches, some power driven tools, portable electrical equipment which is not intrinsically safe or contained within an approved explosion proof housing, sand blasting, or internal combustion engines.

Question 25

Hot work permit

Answer 25

A document issued by an authorized person permitting specific hot work to be done during a specific time interval in a defined area.

Question 26

Inert Condition

Answer 26

A tank is in an inert condition when the oxygen content of the atmosphere throughout the tank has been reduced to 8% by volume by the addition of inert gas.

Question 27

Inert gas

Answer 27

A gas, such as nitrogen or carbon dioxide, or a mixture of gases, such as flue gas, containing insufficient oxygen to support the combustion of hydrocarbons.

Question 28

Insulating flange

Answer 28

A flanged joint incorporating an insulating gasket and washers to prevent electrical continuity between pipelines, hose strings or loading arms.

Question 29

Intrinsically safe

Answer 29

An electrical circuit or part of a circuit is intrinsically safe if any spark or thermal effect produced normally (that is, by breaking or closing the circuit) or accidentally (for example, by short circuit or earth fault) is incapable, under prescribed test conditions, of igniting a prescribed gas mixture.

Question 30

Lower flammable limit (LFL)

Answer 30

The concentration of a hydrocarbon gas in air below which there is insufficient hydrocarbon to support and propagate combustion. Sometimes referred to as lower explosive limit (LEL).

Question 31

Manual gate valve

Answer 31

As the term implies, these are manually operated block valves.

Question 32

Non-volatile-petroleum

Answer 32

Petroleum having a flash point of 60°C (140°F) or above as determined by the closed cup method of test.

Question 33

Off-spec (specification)

Answer 33

A cargo that is unacceptable to the receiving installation. This may be because it has been contaminated in some way with water, rust, or previous cargo residues, or because it has been carried in the wrong way e.g. at the wrong temperature or with the wrong atmosphere.