Glossary

This glossary was transcribed from the supplied ISGOTT Sixth Edition scan. The text is editable and searchable; spelling, punctuation and technical abbreviations were checked against the scanned pages.

Jump to: A · B · C · D · E · F · G · H · I · L · M · N · O · P · Q · R · S · T · U · V · W

A

Adjacent spaces

Spaces bordering another space.

Administration

As used in international conventions, the government of the State whose flag the ship is flying.

Anti-static additive

A substance added to a petroleum product to raise its electrical conductivity to a safe level, above 50 picoSiemens/metre (pS/m), to prevent accumulation of static electricity.

Approved equipment

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 or dangerous area.

Auto-ignition

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.

B

Ballast

Water ballast carried in ships' tanks designated for this purpose.

Barge

Barges can be self-propelled, towed or pushed, and may be used to carry or store liquid hydrocarbons, chemicals or liquefied gases in bulk. They may be employed in inland waterways or at sea outside port limits.

Berthing

Bringing a ship to her berth until the ship is made fast. A berth could be any facility where a ship moors alongside or anchors, including a quay, jetty, offshore buoy or facility.

Best practice

A method of working, or procedure, to aspire to as part of continuous improvement.

Bonding

The connecting together of metal parts to ensure electrical continuity.

Burst pressure

The actual pressure at which a prototype hose fails.

C

Cargo transfer

Operation when crude oil, Liquefied Petroleum Gas (LPG) or other hydrocarbon products are moved from either a ship to another ship, a ship to a terminal or a terminal to a ship, by means of pumping.

Cathodic protection

The prevention of corrosion by electrochemical, impressed current or cathodic protection techniques. On tankers, it may be applied either externally to the hull or internally to the surfaces of tanks. At terminals, it is frequently applied to steel piles and fender panels.

Charterers

An organisation/a company entered into a contract with owners for the use of a ship. May take the form of a demise or bareboat charter under which the charterer has the use of the ship and engages their own crew, or where the ship is let out to the charterer for either a defined period of time (time charter) or a specific voyage (voyage charter).

Clingage

Oil remaining on the walls of a pipe or on the internal surfaces of tanks after the bulk of the oil has been removed.

Closed operations

Ballasting, loading of discharging operations carried out without recourse to opening ullage and sighting ports.

Cold work

Work that cannot create a source of ignition.

Combination carrier (also referred to as Oil/Bulk/Ore (OBO), Oil/Ore (O/O))

A ship that is designed to carry either a petroleum cargo or a dry bulk cargo on separate voyages.

Combustible (also referred to as 'Flammable')

Capable of being easily ignited and of burning. For the purposes of this guide, the terms 'combustible' and 'flammable' are synonymous.

Combustible gas detector (also referred to as 'Explosimeter')

An instrument for measuring the composition of hydrocarbon gas/air mixtures, usually giving the result as a percentage of the Lower Flammable Limit (LFL).

Company

The owner of the ship or any other organisation or person such as the manager, or the bareboat charterer, who has assumed the responsibility for operation of the ship from the shipowner and who, on assuming such responsibility, has agreed to take over all the duties and responsibility imposed by theInternational Safety Management (ISM) Code.

Competent Person

A person who has adequate training and experience to undertake the tasks they are required to perform within their job description. For personnel in the shipping industry, they should be able to demonstrate this competence by the production of certificates recognised by the ship's administration.

Conventional tanker

An oil tanker equipped for regular trading and not specially designed or adapted for loading at offshore terminals requiring specialised mooring or bow loading equipment.

Crude oil

A liquid, occurring naturally in the earth and composed mainly of mixtures of chemical compounds of carbon and hydrogen.

Crude Oil Washing (COW)

A system whereby the tanks of a crude oil tanker are cleaned with processed crude oil.

Cryogenic

Cryogenic liquids are liquefied gases that are kept in their liquid state at very low temperatures.

D

Dangerous area

An area on a tanker which, for the purposes of the installation and use of electrical equipment, is regarded as dangerous due to the likelihood for an explosive atmosphere to be present, (For terminal, see 'Hazardous area'.)

Deadweight

Deadweight is the difference between the displacement and the mass of the empty ship (lightweight). It may be defined for any load waterline from the ship's tables, but is normally referenced for ship comparative purposes to the summer deadweight.

Designated area

An area or space that has been identified and dedicated for a specific purpose.

Displacement

The mass of water in tonnes displaced by a ship at a given draught.

Dry chemical powder

A flame inhibiting powder used in firefighting.

E

Earthing (also referred to as 'Grounding')

The electrical connection 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.

Elasticity

The elastic (non-permanent) elongation of a unit length of an element caused by a unit load. May refer to a material or a composite structure such as a mooring line.

Emergency Release System (ERS)

A system for quickly and safely disconnecting the cargo transfer connection (e.g. loading arm or hose) from a ship with minimal product spillage. It consists of an emergency release coupler between two interlocked block valves.

Enclosed space

A space that has limited openings for entry and exit, unfavourable natural ventilation, and where it is foreseeable that a risk of death or serious injury may exist making it unsuitable for continuous worker occupancy. It is not possible to include a comprehensive list but includes cargo spaces, double bottoms, fuel tanks, ballast tanks, pumprooms, cofferdams, void spaces, duct keels, inter-barrier spaces, engine crankcases and sewage tanks.

Entry permit

A document issued by a Responsible Person on completion of all required preparation and testing allowing entry into a space or compartment during a specific time interval.

Explosimeter

See 'Combustible gas detector'.

Explosion-proof (also referred to as 'Flame-proof')

Electrical equipment is defined and certified as explosion-proof when it is enclosed in a case that is capable of withstanding the explosion within it of a hydrocarbon gas/air mixture or other specified flammable gas mixture. It must also prevent the ignition of such a mixture outside the case either by spark or flame from the internal explosion or as a result of the temperature rise of the case following the internal explosion. The equipment must operate at such an external temperature that a surrounding flammable atmosphere will not be ignited.

F

Fatigue

A state of physical and/or mental impairment resulting from factors such as inadequate sleep, extended wakefulness, work/rest requirements out of sync with circadian rhythms and physical, mental or emotional exertion that can impair alertness and the ability to safely operate a ship or perform safety related duties.

Fibre

A long, fine, very flexible structure that may be woven, braided, stranded or twisted into a variety of fabrics, twine, cordage or rope.

Flame arrester (also referred to as a 'flame trap')

A permeable matrix of metal, ceramic or other heat-resisting materials that allow gas to pass through but stop the propagation of flame through cooling of the combustion products to below the temperature required for the ignition of the flammable gas on the other side of the arrester.

Flame-proof

See 'Explosion-proof'.

Flame screen

A portable or fitted device incorporating one or more corrosion resistant wire-woven fabrics of very small mesh, which is used for preventing sparks from entering a tank or vent opening or, for a short time, preventing the passage of flame. (Not to be confused with 'Flame arrester'.)

Flammable (also referred to as 'Combustible')

Capable of being ignited and of burning. For the purposes of this guide, the terms 'flammable' and 'combustible' are synonymous.

Flammable atmosphere

An atmosphere that contains 10% or more of the Lower Flammable Limit (LFL) of a substance that is capable of ignition and burning.

Flammable range

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.

Flashlight

See 'Torch'.

Flashpoint

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

Flow rate

The linear velocity of flow of liquid in a pipeline, usually measured in metres per second (m/sec). The determination of the flow rates at locations within cargo pipeline systems is essential when handling static accumulator cargoes.

Foam (also referred to as 'Froth')

An aerated solution that is used for fire prevention and firefighting.

Foam concentrate (also referred to as 'Foam compound')

The full strength liquid received from the supplier, which is diluted and processed to produce foam.

Foam solution

The mixture produced by diluting foam concentrate with water before processing to make foam.

Free fall

An unrestricted fall.

Freeboard

The vertical distance between the ship's deck and the waterline at the amidships location. On ships with manifolds not amidships, it may also be provided separately for the manifold location.

From the top (or overall)

See 'Loading over the top'.

G

Gas free

A tank, compartment or container is gas free when it has been adequately cleaned and sufficient fresh air has been introduced into it to lower the level of any flammable, toxic or inert gas to that required for a specific purpose, e.g. hot work, entry etc.

Gas free certificate

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

Grounding

See 'Earthing'.

Guidance

Provision of advice or information by OCIMF/ICS/IAPH.

H

Halon

A halogenated hydrocarbon used in firefighting that inhibits flame propagation.

Hazard

Any event/object that could cause harm.

Hazardous area

Any place in which a sufficiently explosive atmosphere may occur to require special precautions to protect the safety of workers (for ships, see 'Dangerous area').

Hazardous situation

A situation that may directly cause an accident that causes harm to people or the environment.

Hazardous task

A task other than hot work that presents a hazard to the ship, terminal or personnel, the performance of which needs to be controlled by a risk assessment process such as a permit to work system or a controlled procedure.

Hazardous zone

A hazardous zone is a classification designation found within a hazardous area and is determined by an assessment based upon the frequency of the occurrence and duration that an explosive gas atmosphere may be present.

High Modulus Synthetic Fibre (HMSF)

Manmade, continuous filament synthetic fibre with modulus in the range of 50-150Pa.

Hot work

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 that is not intrinsically safe or contained within an approved explosion-proof housing and internal combustion engines.

Hot work permit

A document issued by a Responsible Person on completion of all required preparation and testing that permits specific hot work to be done during a particular time interval in a defined area.

Hydrocarbon gas

An organic chemical gas compound composed entirely of hydrogen and carbon atoms.

I

Incident

Any unplanned event, including accidents or near-misses, that may result in injury or ill health of people, damage or loss to property, plant, materials or the environment.

Inert condition

A condition in which the oxygen content throughout the atmosphere of a tank has been reduced to 8% or less by volume by the addition of inert gas.

Inert Gas (IG)

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

Inert gas plant

All equipment fitted to supply, cool, clean, pressurise, monitor and control the delivery of inert gas to the cargo tank systems.

Inert gas system

An inert gas plant and inert gas distribution system together with means for preventing backflow of cargo gases to the machinery spaces, fixed and portable measuring instruments and control devices.

Inerting

The process of introducing inert gas into a tank with the object of attaining the inert condition.

Insulating flange

A flanged joint incorporating an insulating gasket, sleeves and washers to prevent electrical continuity between pipelines, hose strings and Marine Loading Arms (MLAs).

Interface detector

An electrical instrument for detecting the boundary between oil and water.

International Safety Management (ISM) Code

The International Management Code for the Safe Operation of Ships and for Pollution Prevention.

Intrinsically safe

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

L

Loading over the top (or loading overall)

The loading of cargo or ballast through an open-ended pipe or by means of an open-ended hose entering a tank through a hatch or deck opening, resulting in the free fall of liquid.

Loading rate

The volumetric measure of liquid loaded within a given period, usually expressed as cubic metres per hour (m³/hr) or barrels per hour (bbls/hr).

Lower Flammable Limit (LFL)

(LFL) 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).

M

Manifold

The flanged pipe assembly mounted on board ship to which the presentation flange of the Marine Loading Arm (MLA) or spool piece connects.

Marine terminal (or terminal)

For the purposes of this publication, a marine terminal is defined as a place where ships are berthed or moored for loading or discharging cargoes that include crude oil and products, chemicals and liquefied gases.

Marine terminal manager

The person, or management team, having overall responsibility for the safe and efficient operation of a marine terminal.

Master

The Master is responsible for the safe and efficient operation of the ship (including its seaworthiness, safety and security, cargo operations, navigation, crew management, and legal compliance) and for the persons and cargo on board.

Material Safety Data Sheet (MSDS)

A document identifying a substance, and all its constituents, and occupational health and safety information. It provides the recipient with all necessary information to manage the substance safely. The format and content of an MSDS for International Convention for the Prevention of Pollution from Ships (MARPOL) Annex I Cargoes and Marine Fuel Oils are prescribed by the IMO and follow the Globally Harmonized System (GHS).

Mercaptans

A group of naturally occurring organic chemicals containing sulphur. They are present in some crude oils and in pentane plus cargoes. They have a strong odour.

Metacentric height

The vertical distance between the centre of gravity (the point through which the force of gravity is considered to act vertically downwards) and the metacentre (the point at which the force of buoyancy will cut the centreline at a given angle of heel).

Mooring buoy

A floating cylinder or drum, anchored to the seabed, to which mooring lines are attached. The mooring buoy may serve only as a float with the anchor chain passing through the buoy directly to the mooring hook, in which case none of the tension loads are transferred to the buoy. Alternatively, the buoy may be used as a tension member whereby loads are transferred from the mooring lines via the buoy to the anchor system. In this case, the mooring buoy is a structural member of the mooring system.

Mooring hook

A device for connecting a ship's mooring line to a quay, jetty, offshore buoy or facility, which is often fitted with a quick release system.

Mooring Master

A suitably qualified marine representative placed on board ships to advise the Master during navigation of the ship to/from the facility. The Mooring Master may also assist with, or undertake, ship handling, hose handling, cargo operations and documentation duties.

Multi Buoy Mooring (MBM)

A facility where a tanker is usually moored by an array of mooring buoys, typically between three and seven, positioned at some distance from the tanker, or a combination of mooring buoys and one or more ship's anchors, to moor the ship on a fixed heading.

N

Naked lights

Open flames or fires, lighted cigarettes, cigars, pipes or similar smoking materials, any other unconfined sources of ignition, electrical and other equipment liable to cause sparking while in use. This also includes unprotected light bulbs or any surface with a temperature that is equal to or higher than the auto-ignition temperature of the products handled in the operation.

Non-volatile petroleum

Petroleum having a flashpoint of 60°C or above, as determined by the closed cup method of test.

O

Odour threshold

The lowest concentration of vapour in air that can be detected by the human sense of smell.

Oil/Bulk/Ore (OBO)

See 'Combination carrier'.

Oxygen analyser (or oxygen meter)

An instrument for determining the percentage of oxygen in a sample of the atmosphere drawn from a tank, pipe or compartment.

P

Packaged cargo

Petroleum or other cargo in drums, packages or other containers. Depending on the nature of the goods the relevant provisions of theInternational Maritime Dangerous Goods (IMDG) Code and MARPOL may apply.

Permit to work

A document issued by a Responsible Person on completion of all required preparation and testing, which allows work to be performed in compliance with the ship's Safety Management System (SMS).

Permit to work system

A documented system for controlling activities that expose the ship, the terminal, personnel or the environment to hazard. The system will use risk assessment techniques and apply them to the varying levels of risk that may be experienced. The system should conform to a recognised industry guideline.

Petroleum

Crude oil and liquid hydrocarbon products derived from it.

Petroleum gas

A gas evolved from petroleum. The main constituents of petroleum gases are hydrocarbons, but they may also contain other substances, such as hydrogen sulphide or lead alkyls, as minor constituents.

Phase of oil

Oil is considered to have three phases in which it can exist depending on the grade of oil and its temperature. The three phases are the solid phase, the liquid phase and the vapour phase. The phases do not exist in isolation and operators must manage the carriage of oil with an understanding of the combinations of the phases of oil in the cargo being carried.

Pigging

A form of line clearance where a cylindrical object (known as a 'pig') is propelled along a line by liquid or compressed gas. Pigging may also be undertaken during line maintenance functions, such as line integrity checks, using a so-called 'intelligent pig' to measure the thickness of the pipeline wall.

Port authority

The organisation that is responsible for the safe and efficient operation and management of a specific port.

Portable tank

A tank used for the storage and transportation of liquids, including liquefied gases, that can be moved. Also known as UN portable tanks, ISO tank containers, bulk or intermodal tanks.

Pour point

The lowest temperature at which a petroleum oil will flow under standard conditions.

Presentation flange

Loading arm flange for connection to either the ship's manifold or spool piece.

Pressure surge

A sudden increase in the pressure of the liquid in a pipeline brought about by an abrupt change in flow rate.

Pressure/Vacuum relief valve (P/V valve)

A device that enables a tank to 'breathe', keeping a tank over pressure or under pressure within approved limits by providing for the flow of the small volumes of vapour, air or inert gas mixtures caused by thermal variations in a cargo tank.

Product

Any substance that flows through a Marine Loading Arm (MLA). This includes, but is not limited to, crude oil, refined and chemical products, liquefied gases, vapour and ballast water.

Public Relations Officer

Person who relays information to the public, other port users and all involved groups.

Purging

The introduction of inert gas into a tank already in the inert condition with the object of further reducing the existing oxygen content and/or reducing the existing hydrocarbon gas content to a level below which combustion cannot be supported if air is subsequently introduced into the tank.

Pyrophoric iron sulphide

iron sulphide capable of a rapid exothermic oxidation causing incandescence when exposed to air and potential ignition of flammable hydrocarbon gas/air mixtures.

Q

Quick Connect/Disconnect Coupling (QC/DC)

The manual or hydraulic mechanical device used to clamp the presentation flange to the ship's manifold without the use of bolts.

R

Recommendations

OCIMF/ICS/IAPH support and endorse a particular method of working or procedure.

Reid Vapour Pressure (RVP)

A common measure of volatility and defined as the absolute vapour pressure exerted by the vapour of a hydrocarbon liquid and any dissolved gases at 37.8°C under specified conditions. See "True Vapour Pressure'.

Relaxation time

The time taken for an electrostatic charge to relax or dissipate from a liquid. This time is typically half a minute for static accumulator liquids. Not to be confused with 'Settling time' - see definition.

Responsible Officer (or Person)

A person appointed by the company or the Master of the ship and empowered to take all decisions relating to a specific task and having the necessary knowledge and experience for that purpose.

Resuscitator

A device using positive pressure to assist or restore the breathing of a person overcome by gas or lack of oxygen.

Risk

The exposure to a hazard.

Risk assessment

The process that collects information and assigns values to risks for informing priorities, developing or comparing courses of action, and informing decision making.

S

Safety Management System (SMS)

A formal, documented system or framework designed to manage safety in the workplace on shore or on a ship. An SMS will include policies, objectives, plans and procedures, as well as organisational responsibilities for those involved in ensuring the system is effectively implemented. For ship activities, an SMS is a requirement of the ISM Code.

Safety of Life at Sea (SOLAS)

The International Convention for the Safety of Life at Sea 1974, as amended.

Sea chest

Underwater opening within the shell plating through which sea water is drawn in or discharged, for example, for cooling of machinery systems.

Self-stowing mooring winch

A mooring winch fitted with a drum on which a mooring wire or rope is made fast and automatically stowed. They may be split drum (where the wire or rope is stored separately to the working/tension drum) or a single undivided drum.

Settling time

The time it takes for tank contents to stop moving once filling has stopped, and therefore the cessation of further static electricity generation. Typically, this time is 30 minutes. Not to be confused with 'Relaxation time' - see definition.

Ship

Any vessel, including barges, that is designed to carry oil, liquefied gases or chemicals in bulk.

Single Point Mooring (SPM)

An integrated mooring arrangement for bow mooring a conventional tanker. An SPM includes Catenary Anchor Leg Mooring (CALM) buoy, Single Anchor Leg Mooring (SALM), Single Buoy Mooring (SBM), Floating Production Storage and Offloading Unit (FPSO) and a turret type mooring to a spar or similar structure.

Sounding pipe

A pipe extending from the top of the tank to the bottom through which the contents of the tank can be measured. The pipe is usually perforated to ensure the level of liquid in the pipe is the same as the level of liquid in the body of the tank and to prevent the possibility of spillages. The pipe should be electrically bonded to the ship's structure at the deck and at its lower end.

Sour crude oil or products

A crude oil or product containing appreciable amounts of hydrogen sulphide and/or mercaptans. They will often be associated with a strong pungent odour.

Spiked crude oil

A crude oil blended with a liquefied gas or condensate.

Spontaneous combustion

The ignition of material brought about by a heat producing (exothermic) chemical reaction within the material itself without exposure to an external source of ignition.

Spread loading

The practice of loading a number of tanks simultaneously to reduce the flow rate of oil or product into a tank to reduce static electricity generation when loading static accumulator cargoes.

Stakeholders

Individuals, groups or organisations that have an interest in or are affected by the activity of a business.

Static accumulator oil

An oil with an electrical conductivity of less than 50 picoSiemens/metre (pS/m), capable of retaining a significant electrostatic charge.

Static electricity

The electricity produced by movement between dissimilar materials through physical contact and separation.

Static non-accumulator oil

An oil with an electrical conductivity greater than 50 picoSiemens/metre (pS/m), incapable of retaining a significant electrostatic charge.

Stripping

The final operation in draining liquid from a tank or pipeline.

Surge pressure

A sudden increase in the pressure of the liquid in a pipeline, brought about by an abrupt change in flow velocity e.g. through the starting or stopping of a pump, a rapid closure or opening of a valve or a reduction of pipeline diameter. The pressure surge may cause a rupture of the piping and an extensive oil spill.

T

Tank breathing (see also 'P/V valve')

The ability of a tank to maintain over pressure or under pressure within approved limits by providing for the flow of the small volumes of vapour, air or inert gas mixtures caused by thermal variations in a cargo tank.

Tank cleaning

The process of removing hydrocarbon vapours, liquid or residue from tanks. Usually carried out so that tanks can be entered for inspection or hot work or to avoid contamination between grades.

Tanker

A ship designed to carry liquid petroleum cargo in bulk, including a combination carrier when being used for this purpose.

Telemetry

A system of two-way radio communication that interlinks data between ship and installation. This data is often related to Emergency Shutdown (ESD) and emergency release activities, but can also include information on valve positions.

Tension winch (automated or self-tensioning mooring system)

A mooring winch designed and fitted with a device that can maintain the tension on a mooring line automatically to a certain pre-set value.

Terminal

A place where tankers are berthed or moored for the purpose of loading or discharging petroleum cargo.

Terminal Representative

A person designated by the terminal to take responsibility for an operation or duty.

Threshold Limit Value (TLV)

Airborne concentrations of substances under which it is believed that nearly all workers may be exposed day after day with no adverse effect.

Topping-off

The operation of completing the loading of a tank to a required ullage.

Topping-up

The introduction of inert gas into a tank that is already in the inert condition with the object of raising the tank pressure to ensure the minimum tank pressure is maintained and to prevent any ingress of air.

Torch (also referred to as 'Flashlight')

A battery operated hand lamp. An approved torch is one that is approved by a competent authority for use in a flammable atmosphere.

Toxicity

The degree to which a substance or mixture of substances can harm humans or animals. Acute toxicity involves harmful effects to an organism through a single short term exposure. Chronic toxicity is the ability of a substance or mixture of substances to cause harmful effects over an extended period, usually upon repeated or continuous exposure, sometimes lasting for the entire life of the exposed organism.

True Vapour Pressure (TVP)

The absolute pressure exerted by the gas produced by evaporation from a liquid when gas and liquid are in equilibrium at the prevailing temperature and the gas liquid ratio is effectively zero. See 'Reid Vapour Pressure'.

U

Ullage

The space above the liquid in a tank, conventionally measured as the distance from the calibration point to the liquid surface.

Under Keel Clearance (UKC)

The vertical distance between the ship's bottom, at its deepest point of immersion, and the seabed or any objects resting on the seabed (for example, submarine pipelines, manifolds or concrete clumps).

Upper Flammable Limit (UFL)

The concentration of a hydrocarbon gas in air above which there is insufficient oxygen to support and propagate combustion. Sometimes referred to as Upper Explosive Limit (UEL).

V

Vacuum breaker

A valve in the apex which, when opened to atmosphere, breaks the internal vacuum and expedites gravity draining of the outboard arm.

Vapour

A gas below its critical temperature.

Vapour Emission Control System (VECS)

An arrangement of piping and equipment used to control vapour emissions during tanker operations, including ship and shore vapour collection systems, monitoring and control devices and vapour processing arrangements.

Vapour lock system

Equipment fitted to a tank to enable the measuring and sampling of cargoes without release of vapour or inert gas pressure, They are frequently fitted to sounding pipes, particularly on ships not fitted with inert gas systems.

Volatile petroleum

Petroleum having a flashpoint below 60°C as determined by the closed cup method of test.

W

Water fog

A suspension in the atmosphere of very fine droplets of water, usually delivered at a high pressure through a fog nozzle for use in firefighting.

Water spray

A spray of water divided into coarse drops by delivery through a special nozzle for use in firefighting.