The sum of gauge pressure and ambient atmospheric pressure.
The section or area of the ship in which the crew quarters, cargo control
room and navigation bridge are located; also called the superstructure.
Acute toxic effect
The effect on a man of a single exposure of short duration to high concentrations
of poisonous compounds or vapours.
A person or business holding a limited agency authority from a shipowner
or master to act on behalf of the ship in arranging and facilitating
a visit to a port.
An empirical scale used for measuring the density of liquid petroleum.
The unit is called the 'degree API'. It was established by the American
Petroleum Institute in 1892 as a standard for the American petroleum
industry. The conversion from specific gravity to API gravity is: API
gravity = (141.5/specific gravity - 131.5.)
Approved by a flag state authority, government department, classification
society or other appropriate authority, such as by the Commandant of
the US Coast guard.
An articulated cargo pipe device used to connect the shore terminal
piping to a tanker's manifold flange connection for the transfer of
Containing little or no wax.
Automatic radar plotting aid - an electronic device incorporated in
or operating with a radar set to provide an automatic indication of
the tracks of approaching vessels and also their courses, speeds and
CPA's. Sometimes called a 'collision avoidance system' (CAS).
Black, solid or semi-solid bitumens which occur in nature or are obtained
as residues during petroleum refining.
American Society for Testing Materials.
Cargo tanks which are reserved to receive the final amounts of cargo
Sea water carried aboard vessels to provide adequate draft for safe
manoeuvring and seakeeping, or to adjust the trim of the vessel.
A unit of liquid measurement equal to 42 US gallons at 60 °F, or about
0.159 cubic meters.
Dark coloured petroleum liquids, including such products as fuel oils,
some diesel fuels, and some gas oils, but excluding refined lubrication
A circular flat plate bolted to the flanged end of a section of cargo
piping (as at the amidship manifold) to close off the line. Blind flange.
A small valve used for draining off air or liquid from a pipeline.
Intentional mixtures of two or more products or cargoes.
Valves in the main cargo lines used to isolate sections of the cargo
A portable fan used for cargo tank ventilation.
The temperature at which the vapour pressure of a substance is equal
to the ambient atmospheric pressure.
An electrical cable intended to ground (earth) the ship to the pier
it is moored to.
The process and procedures of loading fuel on board a vessel.
A proprietary name for Butterworth Systems Inc., manufacturers of tank
washing machines, equipment and systems.
The loading, discharging and transferring of cargo.
A method of preventing wastage or corrosion of a vessel's steel structure
using sacrificial (zinc) anodes or a system of impressed electrical
Computerised and automated vessel.
Clean ballast tank system, which uses reserved tanks for ballasting,
but employs the ship's cargo pumps and piping for filling and emptying
the ballast tanks.
Cargo control room — the control space on the ship from which cargo
operations are directed and cargo valves and cargo pumps are controlled.
Certified gas free
Indicates that a confined space has been inspected and tested by a licensed
marine chemist using calibrated equipment and approved procedures and
found to be free of toxic or explosive concentrations of petroleum vapour.
A certificate is issued indicating the type of work which can be performed
in the tank and protective equipment required for entry.
A contract for the use or employment of a vessel for a period of time
or for one or more voyages.
A summary reminder list of tasks to be completed in preparing for and
conducting an operation or procedure. The properly completed checklist
serves as a record of correct performance.
Chemical absorption indicator
An instrument used for detecting the presence of and measuring the concentration
of gasses or vapours by means of discolouration of a chemically treated
material contained in a glass tube.
Chronic toxic effect
The cumulative effect on a man of prolonged exposures to low concentrations,
or of intermittent exposures to higher concentrations, of a poisonous
compound or vapour.
Refined oils with little or no colour; also known as 'clean petroleum
products', 'white oils', or 'white products'.
A method of measuring the contents of a tank without opening the tank
or permitting the escape of tank atmosphere, by use of a fixed device,
or a portable device which can be connected to a vapour-tight fitting
at the measurement point.
The temperature at which wax crystals begin to precipitate out from
suspension in a paraffinic oil.
A narrow empty space between two bulkheads, intended to prevent leakage
between adjacent compartments, as between a cargo tank and the engine
A US acronym for the international rules for the prevention of collisions
A ship designed to carry either petroleum or dry bulk cargo.
Combustible gas indicator
An instrument used for detecting a combustible gas/air mixture. The
measurement is usually presented as a percentage of the lower explosive
The intentional mixture of two oil cargoes with the intention of forming
one homogeneous mixture.
The degree to which petroleum cargoes can be mixed without detriment
to the quality of either component. Compatible cargoes can tolerate
mixtures with small quantities of the other cargo without affecting
A light crude oil obtained from the condensation of heavy vapours from
a natural gas well.
Permanent and temporary arrangements intended to prevent the spread
or flow of cargo overflows or spills if they should occur.
Clean or segregated ballast containing free oil or dissolved oil in
concentrations above an acceptable level.
Unintentional mixture of two petroleum cargoes with the result that
one of the cargoes no longer has the required quality or cannot be used
for its intended purpose.
A prepared program of actions, personnel duty assignments and important
information prepared in advance of an incident and implemented to contain
or reduce its effects.
Crude oil washing.
Cargo pipe sections and associated valves which connect two adjacent
cargo piping systems.
The 'closest point of approach' of another vessel passing one's own
vessel. A full PA description includes time, bearing and distance off
of the closest point while passing.
A naturally occurring petroleum liquid, consisting principally of different
types of hydrocarbons and containing varying proportions of other substances.
To carefully remove the bottom water layer from a slop tank or cargo
A type of centrifugal pump, installed at the bottom of a cargo tank
in a large diameter vertical pipe ('deep well') which permits its removal
for service or replacement.
To remove part of the water vapour from air by mechanical means.
The process of removing a petroleum cargo from a tanker to a shore terminal
using the ship's pumping equipment.
Replacing the contents of a pipeline by pumping through it an amount
of cargo equal to (or nearly equal to), the total internal volume of
The depth of the lowest part of the ship below the surface of the water;
or the depth of the ship at a particular point along its length.
Lowering a portable tank washing machine from one washing level to the
next washing level in a cargo tank.
A cargo pipe extending from above the main deck downward to the bottom
of the ship, connecting the ship's deck cargo piping to the cargo piping
in the ship's tanks, used while loading to avoid flowing cargo through
Deadweight tonnage; the maximum amount of tonnage which can be safely
carried aboard a ship at the governing loadline. DWT includes fuel,
crew, water, stores and cargo.
The electric connection of equipment to the main body of the earth to
ensure that it is at earth electrical potential. On board ship, the
connection is made to the main metallic structure of the ship; also
Electronic chart display and information system.
Engine control room.
Emergency diesel generator.
A device which uses Bernoulli's principle to create a suction for tank
stripping by means of a stream of drive fluid (usually supplied by the
cargo pump discharge stream).
A mechanical mixture of two liquids which do not naturally mix, such
as an oil-in-water emulsion. An emulsion has an internal (smaller fraction)
phase and an external (larger fraction) phase. 'Mousse' which often
forms as a result of a crude oil spill is an oil-in-water emulsion.
Emergency shut down - a system or process by which cargo transfer can
be stopped suddenly without hazard or detriment to the vessel or terminal.
An average ratio of the volume of cargo on board a ship compared to
the volume of cargo received from/by the corresponding shore terminal
for cargoes which meet certain agreed criteria. Also known as vessel
experience factor or 'VEF'.
See 'Combustible gas indicator'.
Electrical equipment or fixtures which are enclosed in a case which
is capable of withstanding an explosion of a flammable hydrocarbon vapour/air
mixture occurring within it and of preventing the ignition of an explosive
vapour surrounding the fixture by sparks, flashes, external heating
or explosions from the vapour within.
The limits of the explosive (flammable) range of a hydrocarbon vapour
and air mixture. The range between the maximum and minimum concentrations
of hydrocarbon vapour in air which form explosive flammable mixtures.
The limits are usually abbreviated LEL for lower explosive limit, and
UEL for upper explosive limit.
A determination of the navigational position of a vessel by electronic,
visual or celestial means.
The national authority under whose jurisdiction a vessel is registered
and which issues its certificate of inspection.
Any device or assembly of a cellular, tubular, pressure or other type
used for permitting the passage of a gas while preventing the passage
of flames into an enclosed space.
A fitted screen of corrosion resistant wire of at least 30-by-30 (wires
per inch) mesh, or two screens of 20-by-20 mesh spaced 1/2 to 3/2 inches
apart, installed to permit the passage of gas but to prevent the passage
of a flame into a space. 'Gauze screen'.
Capable of being ignited and of burning in air. A 'flammable liquid'
is any liquid which gives off flammable vapours at or below a temperature
of 80 °F.
The range of conditions between the minimum and maximum concentrations
of vapour in air which form explosive or burnable mixtures. The limits
are usraally defined as LFL (lower flammable limit) and UFL (upper flammable
limit). See 'explosive limits'.
The face plate of the end of a pipe or hose to which another hose or
pipe flange can be bolted.
A battery operated hand lamp; a 'torch'.
The lowest temperature at which an oil gives off sufficient vapour to
form a mixture which will ignite under standard conditions.
Cleaning a cargo or ballast pipeline of its previous contents by pumping
through it an amount of fluid several times the volume of the pipeline.
The aerated solution of chemicals and water which is used for fire prevention
and fire fighting.
The uninhibited, open fall of liquid into a tank.
Hydrocarbon and other vapours from petroleum; see also 'inert gas'.
A term used to cover all vapour/air mixtures.
The condition of a confined space which has been tested using an appropriate
gas indicator and found to be sufficiently free, at the time of the
test, of toxic or explosive gases for a specified purpose such as manned
entry, cold work, hot work, etc.
A fuel oil intermediate between the light distillates and heavy diesel
The process of replacing a hazardous tank atmosphere with air.
A volatile petroleum liquid principally used as a fuel in internal combustion
engines with spark ignition.
A valve with a sliding disc mounted perpendicular to the direction of
flow in the pipeline. Gate valves provide full, unobstructed flow when
Global marine distress and safety system.
The natural flow of oil or water from one tank to another by the force
of gravity alone.
A fixed (not portable) tank washing machine.
A halogenated hydrocarbon used in fire fighting; acts by inhibiting
An area in which vapour may be present continuously or intermittently
in sufficient concentrations to create a dangerous (flammable and/or
A system of small-diameter piping in the bottom of a cargo tank through
which steam is admitted to heat the cargo.
A small amount of liquid intentionally left in a tank, to reduce measurement
errors due to tank bottom shape, or to maintain certain tank conditions
(such as the temperature of an LNG tank).
A loaded condition of a ship in which there is an excess of weight over
buoyancy at the ends and an excess of buoyancy over weight at the middle.
The ship is slightly arched, with the main deck under tension and the
keel under compression. The normal condition of a tanker in ballast.
Work involving flames or temperatures likely to be sufficiently high
to cause ignition of flammable gas. Includes welding, burning, soldering,
grinding and use of internal combustion engines, electrically driven
tools or non-explosion proof electrical equipment.
Hot work permit
A document used to control a hot work activity. It approves specified
work which could produce a source of ignition at a specific location
and time under controlled conditions.
A gas mixture composed entirely of hydrocarbons.
An instrument for determining the specific gravity of a liquid at observed
International Chamber of Shipping, London.
Releasing a liquid or vapour under pressure in the form of a spray or
stream which is directed against a surface.
International Maritime Organisation, 4 Albert Embankment, London SE1
A spark of sufficient temperatui ; and energy to ignite a flammable
An event which causes, or which may have caused but for the timely intervention
of the crew or good fortune, injury to the crew, vessel, or cargo, or
a financial loss to the owner. Also called a 'near miss'.
A gas or mixture of gasses incapable of supporting combustion of hydrocarbons
or otherwise react with the cargo.
A tank is in an inert condition when the oxygen content of the atmosphere
throughout the tank does not exceed 8% by volume.
The depth of a liquid in a tank.
An electrical insulating device or method of connection placed between
the metallic flanges of a hose or cargo arm assembly to prevent passage
of electrical current through the hose string or cargo arm.
An electrical device or circuit which is incapable of producing a spark
or thermal effect (during normal operation or by accident) with sufficient
energy to ignite a prescribed gas or vapour under test conditions.
International safety guide for oil tankers and terminals, as
published by the ICS and OCIMF.
A short length of small diameter natural fibre line tied between a manual
valve handwhecl and the valve body or support to indicate that the valve
Offloading cargo from a deeply laden vessel to a barge or ship to permit
the vessel to enter harbour, go alongside a berth, or assist removal
May refer either to cargo pipelines, or to vessel mooring lines, depending
on the usage.
The tilt or inclination of a vessel to port or starboard, measured in
degrees from the vertical.
Receiving cargo on board a tanker from a shore terminal, at a SPM or
from another vessel.
Loading through hatches or deck openings by means of portable, open
ended pipes or hoses, resulting in a free fall of liquid into the tank.
Load on top procedures employed for the reduction of oceanic pollution
by loading crude oil cargoes on top of the residues of the previous
Lower explosive limit
The minimum concentration of vapour in air which forms a flammable or
explosive mixture. (LEL).
Main suction valve
Large valves located in each cargo tank used to admit cargo from the
tank into the bottom cargo lines (or from the lines into the tank whe
The cargo piping arrangement at each side of a tanker's main deck, where
the inlet/outlet ends of the cargo piping, fuelling lines, and other
piping are placed for connection to the shore terminal or lightering
vessel piping by means of hoses or articulated arms.
The cargo piping valve immediately inboard of the flange at the amidship
manifold connection point.
The planning and assignment of the correct number and qualificatioi
of personnel to perform a task or procedure.
The International Convention for the Prevention of Pollution from Ships,
1973, as modified by the protocol of 1978 adopted by the International
Conference on Tanker Safety and Pollution Prevention (TSPP Conference).
A small-diameter pipeline used to discharge the final cargo residues
from ship's tanks and pipelines into the shore pipeline.
Main cargo pump - large centrifugal pumps used to discharge the major
part of the cargo.
Marine sanitation device - a ship's sewage treatment plant.
Marine safety data sheet - an information sheet for chemicals used on
Mean time between failures.
Open flames or fires, exposed incandescent material or other unconfined
sources of ignition.
Notice of readiness.
Net positive suction head.
An ore-bulk-oil vessel.
Cargo on board a tanker before loading begins.
Oil Companies International Marine Forum, London.
Oil discharge monitor.
The condition of a petroleum product which does not meet its quality
requirements, possibly through improper refining or contamination.
Petroleum,in crude or refined liquid form.
Rivetted, caulked, gasketed or welded connections or seams which prevent
any leakage of oil.
A system which does nothing to minimise or prevent the escape of vapour
from cargo tanks while the contents are being measured.
A through-hull piping connection, located above the waterline of the
ship, used to discharge dirty ballast or slop water under controlled
The accidental escape of oil cargo from a cargo tank onto the deck of
Crude oils containing significant quantities of wax in suspension.
Person in charge
The crew member (or shore terminal employee) designated by the master
(or terminal executive) as the person responsible for the safe and non-polluting
conduct of oil transfer operations; also called the 'responsible officer'.
Crude oil and liquid hydrocarbon products derived from it.
Personal flotation device, or 'life preserver'.
Protection and Indemnity; a mutual insurance organisation.
Personal protective equipment.
The national authority of the port in which a tanker finds itself.
Water suitable for crew consumption.
The lowest temperature at which an oil will flow or can be poured under
specified test conditions.
To physically remove air or vapour from a pump, replacing it with liquid,
so that the pump will operate properly.
A Note of Protest as a formal, written notification of disagreement,
prepared by the master, regarding an action or situation affecting a
Pressure measured in the English (imperial) units of pounds per square
A compartment or space in the ship where cargo pumps and other cargo
transfer machinery is located.
The removal of a tank atmosphere containing hydrocarbon vapours by use
of mechanical blowers and normally by replacement with inert gas.
Pressure/vacuum relief valve - a dual purpose valve incorporated in
the cargo tank venting system which automatically prevents excessive
pressure or vacuum in the tank or tanks to which it is connected.
A short section of tapered pipe with a large diameter opening and flange
face on one end and a smaller diameter opening and flange face on the
The bottoms product from the distillation of petroleum; 'resid'.
A vertical cargo pipe extending from the bottom to the pumproom to the
Cargo 'remaining on board' when a tanker has finished discharging.
Reid vapour pressure - the vapour pressure of a liquid determined by
laboratory testing in a standard manner in the Reid apparatus at a standard
temperature of 38 °C.
Surface air breathing apparatus.
A piece of metal, usually an alloy of zinc or aluminum, installed on
the interior surface of a cargo or ballast tank, or on the exterior
surface of the hull, for the purpose of reducing corrosion of the ship
structure. See 'cathodic protection'.
A condition of loading in which the middle portion of the ship is lower
then the ends due to excess of weight over buoyancy amidship. The standard
condition of a tanker when fully loaded. When a tanker is sagged, the
main deck is in compression and the keel is under tension.
The density of the water in which the ship is floating compared to the
density of fresh water.
Segregated ballast tanks - a system of ballast tanks, piping and pumps
which is independent of (segregated from) the cargo systems of a tanker.
Securing a closed valve or other cargo control device with a numbered
seal as a means of proving at a later time or date that the valve or
device has not been opened or operated.
The connection or valve in a cargo or piping system which is connected
to the sea chest. Used for transferring sea water into the ship (ballasting
or tank washing) or for pumping clean ballast out of the ship.
Solid or semi-solid material which settles out from water or petroleum
and accumulates in the bottoms of the cargo or ballast tanks.
Physical separation of different cargoes or products within a tanker
by using separate piping systems or by maintaining designated valves
A group of cargo tanks loaded or discharged simultaneously.
The immediate stop of cargo transfer operations due to malfunction,
incident or uncertainty.
Residual oil which has been transferred to a collecting tank (slop tank),
usually mixed with other recovered oils and/or water.
A tank designated to store oily waste for subsequent ecologically approved
Deposits in the bottom of a cargo tank which may include sediment, petroleum
waxes, rust scale, sand and other foreign material.
Crude oil containing at least 0.05 cubic feet of dissolved hydrogen
sulphide (H2S), per 100 gallons of crude
oil; capable of producing dangerously toxic vapours.
(International convention for the) Safety of Life at Sea, 1974 and its
1978 Protocol, and the 1981 and 1983 amendments.
The ratio of the weight of a given volume of material at a standard
temperature to the weight of an equal volume of distilled water at the
standard temperature (usually 4 °C).
An accidental, uncontrolled discharge of oil from a tanker into the
surrounding water due to a cargo overflow, hull leak, pipeline failure,
or improper procedure.
Single point mooring - an offshore mooring buoy used for loading or
discharging deep-draft vessels.
Ignition of a combustible material by means of accumulated heat generated
by a chemical reaction within the material.
A short section of pipe of constant diameter with a flange face fitted
to each end.
A small group of crew members selected and trained for a particular
emergency or incident task.
The increase in draft of a ship in proportion to its speed through the
water and the depth of the water it is in.
The notice time (normally 10 to 20 minutes) given by a person in charge
prior to requiring stoppage of an oil transfer operation.
An oil with an electrical conductivity less than 100 picoSiemens/meter
(pSm), so that it is capable of retaining a significant electrostatic
The electric charge accumulated in a material or on the surface of a
material through rapid physical contact and separation of dissimilar
materials (ie. oil flowing in cargo piping).
(International convention on) Standards of Training, Certification and
Watchkeeping for Seafarers, 1978.
The operation which removes the last pumpable cargo from a cargo tank
or cargo pipeline; also called 'draining'.
A small capacity reciprocating (or rotary) pump used to empty or drain
cargo tanks after the main cargo pumps become ineffective.
A bell-shaped fitting on the end of a cargo suction pipe.
An unsteady fore-and-aft movement of a vessel in a seaway or at a berth.
A sudden increase in pressure in a cargo line caused by starting a pump
or by shutting off the outlet of the cargo line against flow.
A baffle plate or open bulkhead in a cargo tank designed to prevent
excessive forces from the movement of the liquid cargo.
Shore facilities where tankers load or discharge petroleum cargoes.
The amount of water under the cargo at the bottom of a cargo tank, measured
as a vertical dimension (or innage).
Thieving a tank
Measuring the amount of water innage at the bottom of a tank of petroleum
Threshold limit value - the highest concentration of a harmful substance
in air to which it is believed a person may be exposed for eight hours
per day for an indefinite period without danger to health.
A long ton of 2240 pounds avoirdupois (16 ounces per pound).
A metric tonne of 1000 kilograms.
A material which has a poisonous effect on a person who inhales or ingests
Ton(ne)s per inch of immersion - the number of ton(ne)s which must be
loaded into or removed from a ship to change the amidship draft by one
inch. This may also be expressed as TPC (tonnes per centimetre).
The operation of completing the loading of a tank to a desired ullage.
The intentional movement of cargo, ballast, or fuel from one tank to
another within a vessel.
The arithmetic difference between the forward draft and after draft
of a vessel.
The final tanks to be filled when loading a tanker; the levels in the
tanks being adjusted to achieve the desired trim at the completion of
The true vapour pressure, or absolute pressure exerted by the gas produced
by evaporation from a liquid when gas and liquid are in equilibrium
at ambient temperature.
Ultra-high frequency radio transmission.
The vertical distance from the surface of the cargo in a cargo tank
to the measurement or datum point for that cargo tank. Outage.
The space or distance between the upper surface of the cargo in a tank
and the underside of the deck, or top of the tank.
Unmanned machinery space.
A pump used to evacuate air from equipment of tanks, commonly used to
prime main cargo pumps and in oil spill recovery operations.
One or more components of petroleum when in the vapour or gaseous phase.
The force exerted when a solid or liquid is in equilibrium with its
own vapour at a stable temperature. May refer to the vapour pressure
of one component of a mix of vapours, or to the total of the vapour
pressures in a mixture at ambient temperature.
Vessel experience factor; see 'experience factor'.
The replacement of the atmosphere in a confined space by natural or
Controlled release (or intake) of gas (or air) from (into) a cargo tank
by manual or mechanical action, such as by the manual opening or automatic
action of a P/V valve.
The piping system fitted to relieve excessive pressure of vacuum conditions
in a cargo tank.
Very-high frequency radio transmission.
The property of liquids which causes them to resist instantaneous change
of shape, or instantaneous rearrangement of their parts due to internal
friction. Viscosity of oils is usually express as the number of seconds
required for a standard quantity of oil to from through a standard apparatus
at a specified temperature. Scales and ratios of measurement include
Saybolt Furol, Saybolt Universal, Engler, Redwood and Kinematic.
The tendency of a liquid to vapourise.
Vessel response plan.
Vessel traffic service.
The group of ship's personnel assigned to perform routine duties for
a specified time period. A set time period of the day during which various
crew members perform their duties. A particular duty ('gangway watch'),
to which a crew member has been assigned.
A document or form which when completed authorises a specified person
to perform defined work in a limited area under prescribed conditions
while observing required precautions. Any variation or departure from
the conditions set forth voids the permit, requiring suspension of work
and amendment of the permit.