Operators Dictionary

 

ABSOLUTE PRESSURE

Pressure measured with respect to zero pressure, as distinct from pressure measured with respect to some standard pressure such as atmospheric pressure. Thus, 2 Bar gauge (i.e. atmospheric) is equivalent to 3 Bar absolute.  (Atmospheric pressure being 1 bar absolute).

ABSOLUTE TEMPERATURE

A temperature at which zero is a condition absolutely free of heat and equivalent to -459oF or –273oC.  To convert temperature on Fahrenheit or centigrade scales to degrees absolute, add 459 or 273 respectively.

ABSORPTION PROCESS

A separation process, a weak chemical reaction, by which certain components of a gas are condensed in an absorption liquid (lean oil) with which the gas is brought into contact.  The absorption liquid with the absorbed components is called fat oil.  The fat oil leaves the bottom of the absorber and is separated from the absorbed components in a following fractionator (Regenerator) whence the fresh lean oil is returned to the absorber.  For example, Adip and Sulfinol Processes for H2S + CO2 removal.

ACCELERATOR

A substance that hastens a reaction, usually by acting as a catalyst, as in the vulcanization of rubber.

Any of several automobile attachments for increasing the speed at will, especially a foot-operated throttle.

ACCUMULATOR

A vessel for the temporary storage of a gas or liquid; usually used for collecting sufficient material for a continuous charge to some refining process.

ACETYLENE C2H2

A highly unsaturated hydrocarbon gas usually made by the action of water on calcium carbide and by pyrolysis of natural gas.  It is largely used in industry for cutting and welding metals.  Several important intermediates have been synthesised from acetylene but a cheaper route via ethylene has now been developed for many of them.

ACID

A member of an important and fundamental category of chemical substances characterised by having an available reactive hydrogen and requiring an alkali to neutralise them.  Acid solutions usually have a sour, biting and tart taste, like vinegar.

ADDITIVE

A substance added to a product in order to improve its properties.

ADIP

Shell trade name for aqueous DIPA solution.

 ADIP TREATING

A process for removal of hydrogen sulphide from hydrocarbon gases and LPG by a specific regenerable solvent.

Carbon dioxide and, to a certain extent, carbonyl sulphide can be removed at the same time.  The solvent employed is an aqueous DIPA solution.

ADSORPTION PROCESS

A fractionation process based on the fact that certain highly porous materials preferentially adsorb certain types of molecules on their surface, e.g. PSA units.

AEROBIC

Existing in the presence of oxygen.

AEROMETER

An instrument for ascertaining the weight or density of air or other gases.

AGGREGATE

As applied to non-bituminous materials, the inert material, such as sand, gravel, or broken stone, with which cementing material is mixed to form a mortar or concrete.

AIR-BLOWN ASPHALT

Asphalt produced by blowing air through residual oils or similar mineral oil products at moderately elevated temperatures.

AIR HEAT EXCHANGER

A heat exchanger in which air is used as the cooling medium.

AIR SWEETENING

In this process sour gasoline fractions are sweetened by dissolving air in the hydrocarbon phase followed by contacting with a strong NaOH aqueous solution. The reaction products formed are disulphides which dissolve in the sweetened gasoline and water remaining in the aqueous phase.

ALCOHOLS

A class of organic compounds containing oxygen (as a hydroxyl), of which ethyl alcohol (the alcohol of potable spirits and wines) is the best known.  They can react with acids to form esters.  They are largely used as solvents.

ALGAE

Plants of the group comprising practically all seaweed’s and allied freshwater or nonaquatic forms, such as pond scum’s, stoneworts, etc.

ALIPHATIC HYDROCARBONS

Hydrocarbons in which the carbon atoms are arranged in open chains, which may be branched.  The term includes paraffins and olefins and provides a distinction from aromatics and naphthenes which have at least some of their carbon atoms arranged in closed rings.

 ALKALI

In chemistry, any substance having marked basic properties.  In its restricted and common sense, the term is applied only to hydroxides of ammonium, lithium, potassium, and sodium.  They are soluble in water, they have the power of neutralising acids and forming salts with them and of turning red litmus blue.  In a more general sense, the term is also applied to the hydroxides of the so-called alkaline earth metals - barium, calcium, and strontium.

ALKALI TEST

A test to determine the presence or absence of free alkali in finished oils after chemical purification.

ALKALINE

Having the properties of an alkali; opposite to acidic.

ALKALINITY

The amount of free alkali in any substance.

ALKYLATION

A reaction in which a straight-chain or branched-chain hydrocarbons group, which is called an alkyl group or radical, is united with either an aromatic molecule or a branched-chain hydrocarbon. Used for detergent or petroleum manufacture.  Usually catalysed by Hydrofluoric or Sulphuric acid.

ALLOY

A substance composed of two or more metals, or of a metal and a nonmetal, intimately united, usually by being fused together and dissolved in each other when molten.

AMERICAN PETROLEUM INSTITUTE

An association incorporated in the United States, having as its object the study of the arts and sciences connected with the petroleum industry in all its branches and the fostering of foreign and domestic trade in American petroleum products.

AMERICAN SOCIETY FOR TESTING MATERIALS

An association incorporated in the United States for promoting knowledge of the properties of engineering materials and for standardising specifications and methods of testing.

AMINE

Hydrocarbon with attached Ammonia group having absorbent properties, making it useful in treatment processes (ADIP, SULFINOL).

AMMONIA NH3

Ammonia is manufactured by the direct combination of hydrogen and nitrogen under pressure over a catalyst.  Anhydrous ammonia is mainly used for the manufacture of nitrogenous fertilisers, but is used at NZRC for pH control in various processes.  A colourless, gaseous compound, NH3 is of extremely pungent smell and taste and is very soluble in water.

ANAEROBIC

Existing in an oxygen free condition.

ANALYSIS

The process of determining the composition of a substance by chemical or physical methods.

ANHYDROUS

Free of water.

ANILINE POINT

The minimum temperature for complete miscibility of equal volumes of the chemical aniline and a petroleum product.  In conjunction with API gravity the aniline point may be used to calculate the net heat of combustion of aviation fuels or the diesel index of diesel fuels.  The lower temperature at which an oil product is completely miscible with aniline in a 1:1 volumetric ratio.

ANNEALING

Heating and slowly cooling to increase the ductility or remove internal stresses, as of metal or glass.

ANTIFOAM AGENT

An additive used for controlling foam.  Antifoam agents are used in some lubricating oils.  At NZRC, used as additives in ADIP, Sulphinol and BDU Units.

ANTI‑KNOCK

An adjective signifying resistance to detonation (pinking) in spark‑ignited internal combustion engines.  Anti‑knock value is measured in terms of octane number of gasoline engines and of cetane number for diesel fuels.

ANTI‑KNOCK AGENT

A chemical compound such as tetramethyl‑lead which, when added in small amounts to the fuel charge of an internal‑combustion engine, tends to lessen knocking.

ANTIOXIDANT

A chemical added to gasoline, lubricating oil, etc. to inhibit oxidation.

ANTI‑STATIC ADDITIVE

An additive for reducing static properties, notably in Kerosene.

API GRAVITY

In the USA an arbitrary scale known as the API degree is used for reporting the gravity of a petroleum product.  The degree API is related to the specific gravity scale (15°C/15°C) by the formula:

141.5           

Degree API =                Sp. Gr. 15°C/15°C               ‑ 131.5

AROMATIC BLEND

A mixture made by the addition of a component or stock essentially aromatic in nature to impart to the mixture some property of the aromatic.

AROMATICS

A group of hydrocarbons characterised by their having at least one ring structure of six carbon atoms, each of the latter having one valency outside the ring.  If these valencies are occupied by hydrogen atoms, hydrocarbon radicals, or inorganic groups one speaks of condensed aromatics.  These hydrocarbons are called aromatics because many of their derivatives have an aromatic odour.  They are of relatively high specific gravity and possess good solvent properties.  Certain aromatics have valuable anti‑knock characteristics.  Typical aromatics are: benzene, toluene, xylene, phenol (all mono‑aromatics) and naphthalene (a di‑aromatic).  Aromatics can cause smoke and freeze point problems in Kerosene.

ASH

The solid residue left when combustible material is thoroughly burned.

ASH CONTENT

The percent by weight of residue left after combustion of a sample of a fuel oil or other petroleum oil.

ASPHALT

This term may have several meanings:

It refers to a mixture of bitumen and mineral aggregate, as prepared for the construction of roads or for other purposes.

In the United States it refers to the product which is known as bitumen elsewhere.  Black to dark‑brown solid or semisolid cementitious material which gradually liquefies when heated and in which the predominating constituents are bitumens.  These occur in the solid or semisolid form in nature: are obtainable by refining petroleum; or are combinations with one another or with petroleum or derivatives thereof.

At NZRC ‑ very heavy fuel oil produced as bottom product from BDU (short residue with DAO removed).

ASPHALTENES

Polyaromatic constituents of asphaltic bitumen characterised by being insoluble in aromatic‑free low‑boiling petroleum spirit, but soluble in carbon disulphide.

ASPHALTIC BASE CRUDE OILS

Crude oils which contain little or no paraffin wax but usually contain asphaltic matter.  Now often referred to as naphthene base crude oils.

ASPHALTIC BITUMEN

The full name for bitumen adopted by the Permanent International Association of Road Congresses.

ASPIRATOR

An apparatus which serves to create a partial vacuum through pumping a jet of water, steam, or some other fluid or gas past an orifice opening out of the chamber in which the vacuum is to be produced.

ASSOCIATED NATURAL GAS

Natural gas associated with oil accumulations by being dissolved in the oil under the reservoir temperatures and pressures (solution gas) and often also be forming a gas cap of free gas above the oil (gas cap gas).

ASTM DISTILLATION

Any distillation made in accordance with an ASTM distillation procedure; and, especially, a distillation test made on such products as gasoline and kerosene to determine the initial and final boiling points and the boiling range.

ASTM GUM TEST

An analytical method for determining the amount of existing gum in a gasoline by evaporating a sample from a glass dish on an elevated temperature bath with the aid of circulating air.

Any gum test carried out in accordance with an ASTM gum test procedure.

ASTM MELTING POINT

The temperature at which wax first shows a minimum rate of temperature change, also known as the English melting point.

ATMOSPHERIC PRESSURE

The pressure of air.

More specifically, the pressure of the air at sea level.

As a standard, the pressure at which the mercury barometer stands at 760mm, or 30in. (equivalent to approx. 14.7 psi).

ATOM

The smallest complete particle of an element which can be obtained, yet retain all physical and chemical properties of the element.  According to present theory, the atom consists of a nucleus of neutrons and positively charged protons, surrounded by negatively charged particles called electrons.

ATOMISE\

To divide a liquid into extremely minute droplets, either by impact with a jet of steam or compressed air, or by passing through some mechanical device.

ATTEMPERATOR\

See Desuperheater.

ATTRITION\

The act of wearing out by rubbing or grinding, or the state of being so worn or ground.  Granular catalysts or absorbents may suffer such attrition as a result of movement.

AUTO IGNITION POINT

The temperature at which the vapour given off by a sample will ignite in air without any ignition source.

AVERAGE BOILING POINT

Unless otherwise indicated, the sum of the ASTM distillation temperatures in steps of 10°C from the 10‑percent point to the 90‑percent point, inclusive, divided by 9.  Sometimes half the initial and half the maximum distillation temperatures are also added, and the sum then divided by 10.

AVGAS

High octane aviation gasoline for piston type engine.  Not made by NZRC.

AVIATION GASOLINE

Any of the special grades of gasoline suitable for use in certain aeroplane engines.  Not made by NZRC.

AVTAG

Wide range aviation turbine fuel, gasoline type, about identical to the JP 4 type fuel.  Not made by NZRC.

AVTUR

Kerosene type aviation turbine fuel, (Jet A1).

AZEOTROPE

Two (or more) components are said to form an azeotrope if there is a mixture of those components which has no boiling range but whose boiling point and dew point are the same.

AZEOTROPIC DISTILLATION

A distillation process characterised by the fact that the relative position of the components boiling points is influenced by the addition of a compound which selectively forms an azeotrope with one or a group of the components.  The added compound is called the azeotrope former.  E.g. furfural, used in the extraction of aromatics, forms an azeotrope with water.

B

BACK PRESSURE

The pressure on the outlet or downstream side of a flowing system.

In an engine, the pressure which acts adversely against the piston, causing loss of power.

BAFFLE

A partial restriction, generally a plate, located so as to change direction, guide the flow, or promote mixing within the equipment in which it is installed.

BALANCED DRAUGHT

A method of furnace air control using both forced and induced draught fans.

BAR OVER

To manually or mechanically rotate a compressor or turbine to ensure free movement or enable even heating/cooling.

BAROMETER

An instrument employed to determine atmospheric pressure.

BAROMETRIC CONDENSER

A device for condensing steam by direct contact with water.  It produces a partial vacuum in refinery equipment such as a vacuum distillation unit.

BAROMETRIC LEG

Water filled tube for sealing vacuum systems.  (See also Liquid Seal).

BARREL

A standard measure of crude oil quantities; equivalent to 35 imperial gallons, 42 US gallons or 159 litres.

BASIC SEDIMENT AND WATER

The heavy material which collects in the bottom of storage tanks, usually composed of oil, water, and foreign matter.  Also called bottoms, bottom settlings, etc.  It is measured in all incoming feedstocks.

BATCH

Any quantity of material handled or considered as a unit in processing.

BATCH PROCESS

Any process in which a quantity of material is handled or considered as a unit.  Such processes involve intermittent, as contrasted to continuous operation. 

BATTERY

A series of individual items of refinery equipment operated as a unit.

BATTERY LIMITS

A term used when a unit or a battery is to be built in a refinery by an outside contractor or construction company.  It specifies the area within which the contractor shall supply all services, and defines the limits beyond which this shall be done by the refinery.  Also defines plant interface limits.

BEARING

A support for holding a shaft in its correct position.  Examples: journal bearings to confine radial motion, thrust bearings to control axial movement, and "rolling element" bearings which are used in both services.

BENZENE C₆H₆

The parent compound of the aromatic hydrocarbon series.  It is used in the manufacture of a large number of chemicals including phenol, styrene, detergent alkylate and insecticides and is a major component of platformate.

BIOCHEMICAL OXYGEN DEMAND (BOD)

Important water test that shows the amount of bio-degradable matter in the water.  Amount of oxygen required by aerobic organisms for breakdown of organic matter in water over a 5 day period.

BIODEGRADATION

Degradation of solid materials by bacterial consumption.

BIOTREATER

Process for biological degradation of effluent water.

BITUMEN

A non‑crystalline solid or semi‑solid cementitious material derived from petroleum, consisting essential of compounds composed predominantly of hydrogen and carbon with some oxygen and sulphur, it gradually softens when heated.  Bitumen’s are black or brown in colour.  They may occur naturally or may be made as end products from the distillation of, or as extracts from, selected petroleum oils.

BLACK PRODUCTS

Fuel oils, bitumen’s and residues.

BLANK ‑ See Spade

BLEEDING

Divert or release a small portion of the material contained in a line or vessel, usually by opening a valve slightly.

BLEND

Any mixture prepared for a special purpose, e.g. the products of a refinery are blended to suit market requirements.

BLENDED FUEL OIL

A mixture of residual and distillate fuel oils.

BLENDING

Mixing of the various components in the preparation of a product of required properties.

BLENDING STOCK

Any of the stocks used to make commercial gasoline.  These include: straight‑run gasoline, cracked gasoline, and synfuel among others.

BLENDING VALUE (ANTI‑KNOCK)

Some anti‑knock blending agents possess the property of apparently increasing the rated octane number of certain gasoline base stocks to a higher octane number than their own value in terms of octane numbers.  This property is known as the blending value.

BLOCK VALVE

A valve used for isolation of equipment.

BLOCKED OPERATION

The use of a single process unit alternately in more than one operation.

BLOWBACK

A system in which a liquid or a gas is continuously bled through the lead lines of an instrument meter into the main line.  This prevents the main line fluid from coming in contact with the meter body, thus eliminating vaporisation, corrosion or plugging.

BLOW‑BY

In internal‑combustion engines, the escape of combustion gases or unburned fuel from the combustion chamber past the pistons and rings into the crankcase during the power stroke or the compression stroke.

BLOWDOWN

The act of flushing or clearing a piece of pressurised equipment by blowing to a drain (or similar). Term is often used by Boilermen, continuos blowdown indicating blowdown from the Steam Drum or Scum level, and Intermittent Blowdown from the bottom header of a boiler.

BLOWER

Usually an enclosed fan used in a forced/induced/balanced draught furnace to provide the combustion air.

BLOWN BITUMEN

A type of bitumen prepared by the oxidation of short residues, normally by blowing air at an elevated temperature.

BLUE SMOKE

A blue exhaust smoke from a diesel engine, indicating that only a part of the fuel is being burned; also called cold smoke.

BOILING POINT (AT A GIVEN PRESSURE)

The temperature at which a liquid, contained in a closed vessel under a given pressure, will form a first bubble of vapour on the addition of heat.  Further heating of the liquid at its boiling point results in evaporation of part or all of the liquid.

BOILING RANGE

Petroleum products (which are mixtures of many compounds, each having a different boiling point) do not have a simple boiling point but have a boiling range instead, i.e. the temperature range from boiling point to dew point.

BOMB

A small pressure vessel, such as used for taking samples of HP gases and LPG.

BOND

Chemically, a unit link between atoms.  In graphic chemical formulas, it is often represented by a short line or dash.

Electrically, a common grounding system e.g. Bonding wires used between fuel tanker and petrol station ground tanks or airport delivery systems and aircraft.

BOOSTER STATION

An auxiliary station consisting of suitable storage tanks, motive power and pumps for pumping oil through pipelines.

BOTTLED GAS

Ordinarily, butane or propane, or butane‑propane mixtures, liquefied and bottled under pressure for domestic use.

BOTTOMS

The bottom product from a distillation of petroleum; also the liquid layer left in a tank or similar container after draining to the level of the pump suction.

BOX‑IN

To isolate a piece of equipment,  usually by block valves.

BOX‑UP

The act of closing up a piece of refinery equipment following construction, maintenance, inspection etc.

BRAKE HORSEPOWER

That horsepower delivered by an engine to a brake or dynamometer.  It is less than the indicated horsepower by the amount lost in transmission bearings, gear teeth, belts, etc.

BREAKER POINT

The point of contact actuated by a cam to break the primary circuit in the ignition system and thereby cause a current surge in the secondary circuit which produces the spark.

BREATHING

When a storage tank containing volatile products is heated by solar radiation, some of the liquid contents evaporate.  The excess vapour thus formed is blown out to the atmosphere.  On cooling, the less volatile components of the vapour contents condense and a slight vacuum is created, causing air from outside to be sucked into the tank.  This double action is referred to as "breathing" of the tank.  The movement of gas (oil vapours or air) in and out of the vent lines of storage tanks as a result of alternate heating and cooling.

BRINE

Water which is nearly saturated with salts.

BRITISH THERMAL UNIT (BTU)

The quantity of heat required to raise the temperature of 1lb of water through 1°F.  1.000 Btu = 252 kcal.

BRITOLITE

A drying solvent used by BP.  Manufactured from hydrocracked Naphtha and Tops.

BUFFER

A vessel for temporary storage of liquid (buffer drum).

A chemical used to maintain another within set limits of (e.g.) pH.

A device to polish the floor.

An old Navel name for a person in-charge of the deck of a Ship.

BUG COUNT

Microscopic estimation of active bacteria in a sample.

BULK CRUSHING STRENGTH

Test to determine the mechanical strength of a catalyst.

BULK DENSITY

The weight of solid particles which can be held by a container of known dimensions compared to the weight of water which can be held by the same container.

BUND WALL

See Fire Wall.

BUNKER FUEL

Any fuel oil or diesel fuel taken into the bunkers of ships.

BURNING OIL

An illuminating oil, such as kerosene, mineral seal oil, etc. suitable for burning in a wick lamp.

BUTANE C₄H₁₀

Commercial butane is a mixture of two gaseous paraffins, normal butane and isobutane.  When blended into gasoline in small quantities it improves volatility and octane number.  Butane can be stored under pressure as a liquid at atmospheric temperatures ("bottled gas") and it is widely used for cooking and domestic heating.  Used at NZRC in the reformer and BDU.

BUTANE DE‑ASPHALTING

A solvent extraction process whereby a short residue is split into components having low (D.A.O.) and high (Asphalt) asphaltic content by contact with liquid butane.

BYPRODUCT

A secondary or additional product not of primary importance. (e.g. Sulphur).

C

C₁,C₂,C₃,C₄,C₅

A common way of representing fractions containing a preponderance of hydrocarbons of 1, 2, 3, 4 or 5 carbon atoms, respectively, without reference to hydrocarbon type.

CALIBRATION

The determination of fixed reference points on the scale of any instrument by comparison with a known standard and the subsequent subdivision or graduation of the scale to enable measurements in definite units to be made with it.  Also the process of measuring or calculating the volumetric contents or capacity of a receptable.

CALMING SECTION TRAYS

Fractionating trays characterised by the presence of calming sections on a tray of the grid, sieve or valve variety (hence the names: c.s. gridtray, c.s. sieve tray and c.s. valve tray).  Calming sections are actually downcomers, carefully designed and distributed over the tray area so as to ensure the best distribution of liquid.

CALORIE

The amount of heat required to raise the temperature of 1 gram of water through 1C (from 14.5 to 15.5C).  In calculations the k calorie, equal to 1,000 calories is often used.  1,000 kilocalories = 3,968 Btu.

CALORIFIC VALUE

The calorific value of a combustible material is the quantity of heat produced by complete combustion of unit weight of the material.  The units in which the calorific value is usually given are (a) calories per gram and (b) British Thermal Units per pound.  The systems may be converted by the relationship:

calorie per gram = 1.8 Btu per lb.

CANDLEPOWER

The illuminating power of a standard candle employed as a unit for determining the illuminating quality of kerosene and other illuminants.  One international candle or one American candle equals 1.11 Hefner candles.

CAPILLARITY

That physical action by which the surface of a liquid, where it is in contact with a nonhorizontal solid surface (as in vertical capillary tube), is elevated above or depressed below the level of the liquid.  Its magnitude is determined by the interfacial tensions involved.

CARBON

A nonmetallic element existing in diamonds, graphite, and numerous amorphous forms; combined as carbon dioxide, carbonates, and in all living things.  Carbon is unique in forming an almost infinite number of compounds (it is present in all organic compounds).

CARBON (FIXED CARBON)

In the case of coal, coke, and bituminous materials, the solid residue other than ash contained by destructive distillation.

CARBON DEPOSIT

Engine deposits containing soot from over‑rich fuel mixtures and the carbon residue and tars from decomposed lubricating oil.  Road dust, metal particles, gum and tarry substances also form a part of such deposits.

CARBON DIOXIDE

A heavy, colourless gas, CO₂, which will not support combustion.  Dissolved in water, it forms carbonic acid.  It is exhaled by lung‑possessing animals as a waste gas, but is inhaled by certain plants which absorb its carbon and release its oxygen as a waste gas.

CARBON MONOXIDE

A colourless, odourless gas, CO; a product resulting from the incomplete combustion of carbon.  It is very poisonous.

CARBURETTOR

A device for metering the correct mixture of air and gasoline to an internal‑combustion engine.

CARRYOVER

Relatively nonvolatile contaminating material which is carried over by the overhead effluent from a fractionating column, absorber, or reaction vessel.  It may be carried as liquid droplets or finely divided solids suspended in a gas, a vapour, or a discrete liquid.

CASCADE TRAY

A fractionating device consisting of a series of parallel troughs arranged in stair‑step fashion.  Liquid from the tray above enters the uppermost trough.  Liquid thrown from this trough by vapour rising from the tray below impinges against a plate and a perforated baffle.  Liquid passing through the baffle enters the next lower of the troughs.

CATALYSIS

The alteration of the rate of a chemical reaction by the presence of a "foreign" substance (catalyst) that remains unchanged at the end of the reaction.

CATALYST

In technology this word means a substance added to a system of reactants which will accelerate the desired reactions, while emerging virtually unaltered from the process.  The catalyst allows the reaction to take place at a temperature at which the uncatalyzed reaction would proceed too slowly for practical purposes.  Used extensively in secondary processes.

CATALYST POISON

Generally, coverage of the catalyst surface with nonreactants.  If a large fraction of the catalyst surface is covered selectively by any one strongly adsorbed chemical, the catalytic reaction will be drastically reduced in rate.  This circumstance is called poisoning, and self‑poisoning can result when one reactant or product is much more strongly adsorbed than another reactant.  May be reversible, but can destroy entire catalyst inventory.

CATALYTIC PROCESS

Any process which employs catalysis.  Examples : Hydrocracking, Platforming and hydrotreating.

CATALYTIC REFORMING

Process of changing the molecular structure of the components of straight‑run gasoline or of a gasoline fraction by subjecting the gasoline to thermal treatment in the presence of a catalyst (for example platinum).  By this process the anti‑knock performance of the gasoline is improved.

CATHODIC PROTECTION

Method of protecting tanks, ships, pipelines and jetties against corrosion.  By reversing the electric current which flows away from a corroding metal, a corrosion process can be arrested.

CAUSTIC SODA

The name used in industry for sodium hydroxide (NaOH) on account of its property of corroding the skin.  It is strongly alkaline.  Used extensively in water treatment or pH control in process units.

CENTRIGRADE (CELSIUS) SCALE

A thermometer scale on which the interval between the freezing point and boiling point of water is divided into 100 parts or degrees centigrade, so that 0C corresponds to 32F and 100C to 212F.  Also called Celsius after Anders Celsius who first described it.

CENTIPOISE, CENTISTOKES

A Centipoise (cP) is 1/100th of a poise (P) which is the fundamental unit of dynamic viscosity in the centimetre‑gram‑second system of units.  The viscosity of water at 20C is approximately 1 cP.  The centistokes (cS) is 1/100th of a stoke (S) which is the fundamental unit of Kinematic viscosity in that system.  The two c viscosity’s are related by the density, i.e. number of centistokes = number of Centipoise divided by liquid density (in g/cm3).

CENTRIFUGAL COMPRESSOR

A machine in which pressure is built up by means of rotating fans or blades.

CENTRIFUGAL PUMP

A pump that derives its pressure increase from the centrifugal force generated when the impeller throws the liquid outwards at high speed.

CENTRIFUGE

A whirling instrument for separating liquids and solids or liquids of different specific gravity by use of centrifugal force.

CERAMIC BALLS

Balls of chemically inert ceramic, used as filler and support in reactors etc.

CETANE NUMBER

The cetane number of a diesel fuel is a number equal to the percentage by volume of cetane in a mixture with alph‑methyl‑naphthalene having the same ignition quality as the fuel under test.

CFR ENGINE

A standard single‑cylinder variable compression engine developed by the Co‑operative Fuel Research Council, to determine the anti‑knock value of motor gasoline’s or the ignition quality of diesel fuels.

CHANNELING

Non uniform flow of process fluid through (e.g.) a reactor bed.

CHARACTERISATION

Identifying a feed or product by its properties e.g. distillation,

carbon: hydrogen ration, density etc.

CHAR VALUE

In the 24 hours kerosene burning test the amount of char formed on the wick under prescribed conditions is measured and reported as mg/kg.

CHECK VALVE (NON RETURN VALVE)

An automatic valve which permits fluids to pass in one direction but closes when the fluids attempt to pass in the opposite direction.

CHEMICAL OXYGEN DEMAND (COD)

Total amount of oxygen needed for oxidation of all organic matter in water to CO₂ and H₂O.

CHLORINATION

A chemical reaction in which chlorine reacts with hydrocarbon and one or more of the hydrogen atoms are replaced by atoms of chlorine, or chlorine reacts with an unsaturated hydrocarbon and two chlorine atoms (one molecule) are added to the double bond.

CHROMOMETER ‑ See Colorimeter

CLADDING

A homogeneous bonded or resistance‑welded metallic liner applied to a base metal such as carbon steel.  Used in lines, vessels, and heat exchanger equipment to reduce corrosion and increase service life.  Also called clad lining.

CLAUS PROCESS

Process for the manufacture of sulphur from H₂S, comprising oxidation of part of the H₂S to SO₂ in a thermal reaction stage, followed by catalytic reaction of the remaining H₂S with the SO₂ formed to give sulphur.

CLEAR GASOLINE

A gasoline which is free from anti‑knock additives such as tetraethyl‑lead.  In making comparative engine tests between leaded and unleaded fuels, the clear, unleaded gasoline is sometimes referred to as straight gasoline base, base fuel, or as gasoline "neat".

CLOUD POINT

The temperature at which a fuel, when cooled, begins to congeal and present a cloudy appearance owing to the formation of minute crystals of wax.

COAGULATION

The precipitation from solution or suspension of fine particles which tend to unite in clots or curds.

COALESCER

A vessel packed with steelwool, glasswool, polypropylene wool or felt used to remove fine droplets of treating liquids or water from a petroleum product.

COASTAL TANKER Ltd‑ (CTL)

A Company responsible for coastal tanker movements in NZ

COEFFICIENT OF EXPANSION

The ratio of the increase of length, area, or volume of a body for a given rise in temperature (usually 1F) to the original length, area, or volume of the body.

COFFERDAMS

The empty spaces fore and aft in a tanker, which traverse the whole breadth of the vessel and isolate the cargo tanks from the rest of the ship (fire protection).

COKE

Hard carbon deposit, usually formed by the unintentional thermal cracking of heavy residues.

 COKE DRUM

A vessel in which coke is formed or collected and which can be cut off from the process for cleaning.

COLD FILTER PLUGGING POINT

The highest temperature at which a fuel ceases to flow through a test filter.

COLORIMETER

An instrument for determining the colour of oil product by measuring the percentage transmission of monochromatic light through the liquid.

COMBINED FEED RATIO (CFR)

The ratio of the 2nd to 1st stage feed on the Hydrocracker.

COMBUSTION

The process of burning; rapid oxidation caused by the union of the oxygen of the air with a material.

COMBUSTION CHAMBER

The space in which the process of burning takes place e.g. in a jet engine.

COMPATABILITY

Ability of additives or products to mix together without separation or reaction.

COMPOUND

A substance formed by the combination of two or more ingredients in definite proportions by weight, and possessing physical and chemical properties entirely different from those of the ingredients.  e.g. table salt, paint.

COMPRESSION

In general, the act of increasing the pressure on gas or vapour.  It is usually attended by a reduction in volume.

COMPRESSION IGNITION

The combustion which takes place when fuels are injected in a fine spray into the hot compressed air (500C) in the cylinder of a diesel (compression ignition) engine.  The heating of the air is due to its rapid compression by the piston.

COMPRESSION RATIO

The ratio of the cylinder volume when the piston of an engine is at the crank end of the cylinder, to the volume when the piston is at the head end.

COMPRESSOR

A device which draws in air or other gases, compresses it and discharges it at a high pressure.

CONDENSATE

Liquid hydrocarbons which are sometimes produced together with natural gas.  In general: the liquid that is formed when a vapour cools.

CONDENSATION (PHYSICAL)

The transfer of a material from the vapour phase into the liquid phase, for example by the withdrawal of heat.

CONDENSER

A special type of heat exchanger for the removal of heat from e.g. the top of a fractionating column.

CONDENSER BOX

A large box‑shaped structure in which the condenser, which may consist of coils or tubes, is submerged in a heat‑absorbing medium, usually water.

CONDUCTIVITY

A materials ability to conduct an electrical charge.  Important in water treatment (as an indication of impurities) and some hydrocarbons (static risk).

CONGEAL

To change from a liquid to a semi‑solid or solid state.

CONTINUOUS CATALYST REGENERATOR

see Fluid bed operation.

 CONTINUOUS DISTILLATION

An operation in which the steps of charging, heating, vapourisation, fractionation, and collection of products are performed continuously rather than in a batchwise manner.  The unit employed is known as a continuous still.

CONTROL LOOP

Combination of control signal, feedback signal and instrumental response that characterises an automatic control system.

CONTROLLER

The actual control instrument is the controller.  However, the word is often used in reference to the control valve that acts on the process.

CONVECTION

The flow of heat through liquid or gas by actual mixing of the fluids (physical turbulence).

CONVECTION SECTION

That portion of the furnace in which tubes receive heat by convection from the flue gases (contrast with radiant section).

CONVENTIONAL PRODUCTS

Petroleum products which are manufactured from crude oil by physical separation processes. (See primary processes).

CONVERSION PROCESSES

Manufacturing processes which involve a change in the structure of the hydrocarbons (See secondary processes).

COOLER

A heat exchanger whose primary purpose is to reduce the temperature of one of the passing fluids.

COOLING TOWER

A unit or structure, for the purpose of cooling by evaporation.

COPPER STRIP CORROSION

A qualitative method of determining the corrosivity of a product by its effect on a small strip of polished copper suspended or placed in the product.  One of the kerosene quality tests.

CORRECTED ENERGY & LOSS (CEL)

Yardstick used for monitoring refinery efficiencies.

CORROSION

The gradual eating away of metallic surfaces as the result of chemical action such as oxidation.  It is caused by corrosive agents such as acids.

COUNTERCURRENT FLOW

A system in which one fluid flows in one direction and another fluid flows in the opposite direction e.g. in a heat exchanger, in which the direction of flow of the cold oil is opposite to that of the hot oil.

CRACKING

Process whereby the large molecules of the heavier oils are converted into smaller molecules of the gasoline type.  When this is brought about by heat alone, the process is known as thermal cracking.  If a catalyst is also used the process is referred to as catalytic cracking (in speech generally abbreviated to cat. cracking) or Hydrocracking if the process is conducted over special catalysts in a hydrogen atmosphere ‑ other processes include visbreaking and hycon.

CREDITORS

Accounts payable.

CREEP

Change in the micro structure of a metal.  The continuous stretching which occurs when metal is under stress or pressure, especially apparent when at high temperatures.

CRITERIA REFERENCED INSTRUCTION

Method of instruction based on meeting specific criteria.

CRITICAL PRESSURE

The pressure necessary to condense a gas at the critical temperature.

CRITICAL TEMPERATURE

The maximum temperature at which a gas can be liquefied by pressure (critical pressure); above this temperature the gas cannot be liquefied, no matter what pressure is applied.

CRITICAL VELOCITY

The rate of flow in a pipe at which streamline flow changes into turbulent flow.

CRUDE NAPHTHA

Light distillate made in the fractionation of crude oil.

CRUDE OIL TYPES

See appropriate sub‑heading for description.

Paraffin‑base crude oils

Asphaltic‑base crude oils

Mixed‑base crude oils

CRUDE WAX

Crude wax, also called petroleum wax or slack wax, is an unrefined mixture of high‑melting hydrocarbons, mainly of the normal straight‑chain type, still containing a fairly high percentage of oil.  It is obtained by filtration (as such, or after addition of a solvent) from high boiling distillates or residual oils.  Slack wax is primarily obtained as by‑product in the manufacture of lubricating oils.  The crude wax made from distillate oils is refined to make a range of microcrystalline waxes.

CRYSTALISATION

A fractionation process based on the difference in freezing point of the various constituents of the mixture to be fractionated. The process is, for example, used in the separation of paraffins from lube oil (de‑waxing).

CUSTODY TRANSFER TANKS

Tanks which receive products from external sources or deliver products to external sources

CURRENT RATE

Current Assets    

Current Liabilities

CUT

Refinery term for a fraction obtained direct from a fractionation unit.  Several cuts can be blended for the manufacture of a certain product.

CUT POINT

(Between two process streams).  The boiling point at atmospheric pressure of the component distributed in equal percentage in both process streams.

CYCLISATION

A reaction, for example, platinum‑catalysed, by which a straight‑chain paraffin hydrocarbon is converted into a naphthene and then into an aromatic: i.e. The process of changing an open‑chain hydrocarbon structure to a closed ring, e.g. hexane to benzene.  Accompanied by production of Hydrogen.

CYCLONE SEPARATOR

A conical vessel provided with a tangential inlet for a gas stream containing finely divided solids or liquid droplets, normally designed with a centrally located overhead gas withdrawal line.  Powdered solids or coagulated liquids are separated by centrifugal force and pass downward along the incline (conical) to a centrally located outlet.  In catalytic cracking, a pipe, known as a dip leg, is connected to this bottom outlet and serves to convey the solids back to the catalyst bed.

D

DAMPER

Usually a flap or shutter to control air flow in a furnace (may be in the supply and/or the flue ducting).

DEACTIVATION

Reduction in catalyst activity by poisoning or coating of catalyst particles by contaminants, or by a change in the physical structure of the catalyst particles.

DEADWEIGHT

The amount of cargo, stores and fuel which a vessel carries when loaded to the appropriate draught allowed by law.  The difference between deadweight and displacement is the actual weight of the vessel.

DEARATOR

Device for the steam stripping of 0₂ and other gases from boiler feed water.

DEBTORS

Accounts receivable.

DECOMPOSITION

The breaking up of compounds into smaller chemical forms through the application of heat, change in other physical conditions, or introduction of other chemical bodies.

DEFERRED TAXATION

Provision for tax payable in the future, but deferred in the current year because of timing differences between the Company's accounts and the accounts required by the Inland Revenue Department.

DEHYDRATION

The removal of water from crude oil, from gas produced in association with oil, or from gas from gas‑condensate wells.

DEHYDROCYCLISATION

Any process involving both dehydrogenation and cyclisation reactions.

DEHYDROGENATION

A reaction process in which hydrogen atoms are eliminated from a molecule.

DEIONIZED WATER

Water that has had all the free ions removed by ion‑exchange, also called demineralised water.

DEISOLATION

The opposite of isolation i.e. To energise a piece of equipment.

DEMISTER

Any device used to stop passage of liquid droplets e.g. a demister section in a vacuum column is to stop the asphaltenes from the residue getting into the waxy distillate.

DEMULSIFIER

An additive used to prevent the formation of an emulsion ‑ applicable in crude/water emulsions in desalter.

DEMURRAGE

Amount payable to ship owner for failure to load or discharge ship within time allowed.

DENITRIFICATION

Removal of nitrogen compounds on feedstock by hydrogenation.  N₂ + 3H₂ = 2NH₃.

 DENSE BED LOADING

Catalyst loading system of "raining" the catalyst onto the bed which achieves a higher loaded density than "sock" loading.

DEOXYGENATION

Removal of oxygen on feedstock by hydrogenation.  0₂ + 2H₂ = 2H₂0.

DESALTING

A process to remove inorganic salts and other impurities from crude oil by mixing with water followed by settling in an electrostatic field.

DESULPHURISATION ‑ See Hydrodesulphurisation

The removal of sulphur or sulphur compounds from a charge stock.

DESUPERHEATER

Equipment used to reduce the temperature of superheated steam.

DETERGENCY

The ability of a substance to clean and to wash away undesirable substance.  Detergents may be either oil‑soluble or water‑soluble.  Soap and synthetic detergents help to wet, disperse, and de-flocculate solid particles.  Oil‑soluble detergents are used in motor oils to disperse, loosen, and remove carbon, dirt, etc. from interior surfaces of internal‑combustion engines.

DETERGENT OIL

A lubricating oil possessing special sludge‑dispersing properties for use in internal‑combustion engines.  These properties are usually conferred on the oil by the incorporation of special additives.  Detergent oils hold sludge particles in suspension and thus promote engine cleanliness.

DETONATION

Detonation or knocking is the sharp metallic sound emitting from the cylinders of spark‑ignition engines under certain conditions.  It occurs when conditions in a cylinder are such that self‑ignition of an unburnt mixture of fuel and air takes place.  It reduces power output.

DEW POINT (at a given pressure)

The temperature at which a vapour, contained in a closed vessel under the given pressure, will form a first drop of liquid on the subtraction of heat.  Further cooling of the vapour at its dew point results in condensation of part or all of the vapour as liquid.  The dew point of a normal gasoline is approximately the same as the temperature at which 70% by volume distils over in the ASTM‑distillation test.  The dew point of a pure compound is the same as its boiling point.

DEWAXING

The process of removing paraffin wax from lubricating oils.

DIESEL ENGINE

As internal‑combustion engine in which air drawn in by the suction stroke is so highly compressed that the heat generated ignites the fuel, which is automatically sprayed into the cylinder under high pressure.

DIESEL FUEL

A general term covering oils used as fuel in diesel and other compression ignition engines.

DIESEL INDEX

A measure of the ignition quality of a diesel fuel; the index is calculated from a formula involving the gravity of the fuel and its aniline point (API gravity times the aniline point (determining by ASTM D611‑47T) divided by 100).

DIFLUOROETHANE

A catalyst promoter used on the Hydrocracker.

DILUENT

A liquid used to dilute or thin out another liquid.

DIPPING

A process for measuring the height of a liquid in a storage tank.  This is usually done by lowering a weighted graduated steel tape through the tank roof and noting the level at which the oil surface cuts the tape when the weight gently touches the tank bottom (see Ullage).

DISTILLATE

The liquid obtained by condensing the vapour given off by a boiling liquid.  Also the top product taken off a fractionating column; and in its broadest sense: any fraction other than the bottom product of the fractionator.

DISTILLATION (fractional)

A fractionation process based on the difference in boiling point of the various constituents of the mixture to be fractionated.  It is carried out by evaporation and condensation in contact with reflux.  When applied to the separation of gasoline, kerosene, etc., from a crude oil, to leave a residual fuel oil or asphaltic bitumen, the process is frequently called topping.  Distillation is normally carried out in such a way as to avoid decomposition (cracking); in the case of the higher boiling distillates, such as long residue, this is accomplished by carrying out the distillation under vacuum (which requires a lower temperature).

DISTILLATION CURVE

Curve made by plotting the percentage of gasoline (or other petroleum product) distilled versus the temperature.

DISTILLATION LOSS

The difference, in a laboratory distillation, between the volume of liquid originally introduced into the distilling flask and the sum of the residue and the condensate recovered.

DISTRIBUTOR (LIQUID/GAS)

A device for distributing a 2 phase flow correctly within a vessel, i.e. encouraging separation.

DISULPHIDE

A compound containing a ‑S‑S‑ linkage.  Such compounds are colourless liquids completely miscible with hydrocarbons and insoluble in water.  The lower members, when pure, possess a nauseating sweet odour which is particularly clinging and penetrating.  Although disulphides are normal constituents of the lighter distillates, they are also formed as a result of the oxidation of mercaptans.  Sour distillates become sweetened in this way.

DIVIDEND COVER

Net profit after tax and before extraordinary items

Dividend for year

DIVIDEND YIELD

Market Price of Shares (cents)

Dividend Paid (cents)

DOCTOR SOLUTION

A solution (sodium plumbite) made from lead oxide and sodium hydroxide, used to treat gasoline or other light petroleum distillates to remove mercaptan sulphur.  The "doctor test" is used for the detection of sulphur compounds in light petroleum distillates which react with sodium plumbite.

DOCTOR TREATMENT

A process of sweetening sour gasoline’s ‑ by conversion of the mercaptans ‑ by means of a solution of lead oxide in caustic soda, together with sulphur.         Not used at NZRC.

DOLPHIN

Separate pile in jetty system ‑ used for mooring.

DOWNCOMER

A means of conveying liquid from one tray to the next below in a trayed column.

DOWNSTREAM

Towards the later end of the process e.g. final blending, product tankage.  In the business sense ‑ Marketing of finished products, filling stations etc.

DRAW OFF

A connection which allows liquid to flow from the bottom of a vessel or to remove the contents from a draw off tray.

DRY GAS

Natural gas which does not contain liquid hydrocarbons at storage pressure.  Also often used for a petroleum gas consisting of no other compounds than inert gases (e.g. hydrogen, nitrogen, etc) and the light hydrocarbons methane, ethane, ethene, propane, propene (sometimes also: hydrogen sulphide).

DUAL PURPOSE KEROSENE

An export grade Kero that meets both premium and Avtur specifications.

E

EARNINGS PER SHARE (CENTS)

Net profit after tax and before extraordinary items

Number of shares.

ECONOMISER

Equipment for preheating boiler feed water by use of low grade flue gas.

EJECTOR

A device that uses the venturi effect to pull a partial vacuum.  Usually driven by steam and associated with condensing plant.

ELASTOMER

A synthetic polymer with rubber‑like characteristics.  Examples of commercial products are styrene‑butadiene rubbers, butyl rubber, chloroprene rubber, nitrile rubber, polyurethane rubber and silicone rubber.

ELECTRICAL ISOLATION CERTIFICATE

Permit required to isolate or de‑isolate any electrical equipment.

ELECTROLYSIS

Chemical decomposition by the action of an electric current.

EMULSIFIER

A substance used to promote or aid the emulsification of two liquids and to enhance the stability of the emulsion.

EMULSION

A dispersion of fine droplets of a liquid (the disperse phase) in the bulk of another liquid (the continuous phase) with which it is immiscible.  A third substance, the emusifier, is sometimes necessary to keep the droplets dispersed as a stable emulsion.

END POINT

The point indicating the end of some operation or at which a certain definite change is observed.  In titration, this change is frequently a change in colour of an indicator which has been added to the solution, or the disappearance or excess of one of the reactants which is coloured.  In the distillation of liquids, such as gasoline, the end point is the maximum temperature which occurs during the test (F.B.P).

ENDOTHERMIC

Relating to or designating a reaction which occurs with the absorption of heat, so that the temperature of the reacting bodies is lowered (i.e. heating is required).

ENGINE OIL

A term applied to oils used for the bearing lubrication of all types of engines, machines, and shafting, and for cylinder lubrication in other than steam engines.

ENGLER DISTILLATION

A standard test for determining the volatility characteristics of a gasoline by measuring the percent distilled at various specified temperatures.

ENTRAINMENT

See CARRYOVER

EROSION

To gradually wear away e.g. Catalyst circulation causes erosion.

ETHANE C₂H₆

A colourless, odourless gas of the methane series.  Along with methane one of the main constituents of natural gas.

ETHENE

The normalised name for ethylene.  A hydrocarbon gas and first member of the olefin series.

EVACUATION

Act of pulling a vacuum on a vessel at atmospheric pressure ‑ thus evacuating the air/gas present.

EVAPORATION

The conversion of a liquid into vapour, usually by means of heat.

EVAPORATOR

A vessel which receives the hot discharge from a heating coil, and by a reduction in pressure, flashes off overhead the light products and allows the heavy residue to collect in the bottom.

EX SITU REGEN

Where catalyst is removed from a reactor and regenerated elsewhere (usually at a catalyst specialists own plant).

EXOTHERMIC

Relating to or designating a reaction which occurs with the evolution of heat, so that the temperature of the reacting bodies is raised (i.e. cooling is required).

EXPANSION JOINT

A joint or coupling designed so as to permit an endwise movement of its parts to compensate for expansion or contraction.

EXTRACT

The portion of an unrefined petroleum product (often a kerosene or a lubricating oil) resulting from a solvent extraction process and consisting mainly of those components which are best soluble in the solvent.  Generally the extract, after removal of the solvent consists largely of aromatic hydrocarbons.

EXTRACTION

A fractionation process based upon the difference in solubility, in a given solvent, of the various constituents of the mixture to be fractionated.  The process is, for example, used in the separation of de‑asphalted oil from short residue (see butane de‑asphalting).

EXTRACTION DEPTH

Depth to which DAO may be extracted from short residue on BDU unit ‑ the greater the extraction depth, the higher the DAO yield, although too deep an extraction may affect DAO specification.

EXTRACTOR

Column in which an extraction process (e.g. BDU) is carried out.

EXTRAORDINARY ITEMS

Items of expenses or income that are not related to the main activities/operations of the company.

EXTREME PRESSURE LUBRICANTS

A term applied to lubricating oils or greases which contain a substance or substances specifically introduced to prevent metal‑to‑metal contact in the operation of highly loaded gears and bearings.  In some cases this is accomplished by the substances reacting with the metal to form a protective film.

F

FAECAL COLIFORM (F. COLI.)

Bacteria found in intestines of humans and animals. Indicative of sewage contamination.

FATIGUE

The tendency of a metal to become brittle and fracture under conditions of repeated cyclic stressing at stress levels below its tensile strength.

FEED PREPARATION UNIT

High vacuum unit to split a long residue into a short residue and waxy distillate fraction with a low metal content; the latter fraction is used as Hydrocracker feed.

FEEDSTOCK

Stock from which material is taken to be fed (charged) into a process unit.

FILTER

A porous material on which solid particles are largely caught and retained when a mixture of liquids and solids is passed through it.

FILTRATE

The liquid which has passed through a filter; the product from a filtration process.

FIN FAN

See air heat exchanger.

FIRE WALL

An earth bank or cement wall built around an oil storage tank compound to prevent the spread of the oil in case of fire or bursting of the tank.  Height normally calculated to contain contents of largest tank within compound.

FIXED‑BED OPERATION

A type of operation in which the catalyst remains stationary in the reactor.  The catalyst may be regenerated insitu or exsitu periodically.  To be contrasted with fluid‑bed operation.

FLAME ARRESTOR

An assembly of perforated plates or screens enclosed in a case and attached to the breather vent on petroleum storage tanks, and on bitumen or sour water gas lines prior to burning the gas in a furnace.

FLAMMABLE

Capable of being easily set on fire; combustible.

FLASH

A sudden release in pressure resulting in partial or complete vapourisation.

A sudden burst of light; a momentary blaze.

FLASH DISTILLATION

The process of heating a liquid to a temperature within the boiling range of the liquid which causes the evaporation of part of the liquid.  The vapour may then be taken off and condensed.

FLASH POINT

The lowest temperature under closely specified conditions at which a combustible material will give off sufficient vapour to form an inflammable mixture with air in a standardised vessel.  Flash point tests are used to assess the volatilities of petroleum products.

FLEXIBLE VOLATILITY INDEX

A measure of the volatility of gasoline’s calculated by the formula

RVP +( 0.7 x E70 )       E70 = Evaporation at 70 ⁰C  

FLOATING HEAD

An end of a heat exchanger into which tubes are fitted, constructed to allow for the expansion and contraction of the exchanger tubes.

FLOATING ROOF

A special tank roof which floats upon the oil.  Applied to do away with the vapour space in storage tanks and thus reduce losses by breathing and hazards of explosions.

FLOC

Any small, tufted, or flake‑like mass of matter floating in a solution, e.g. as produced by precipitation.  Used in water treatment for removal of impurities.

FLOCCULATION

Process of forming and removing floc and associated impurities.

FLOODING

In a fractionating column, the filling up with a liquid.

FLUE GAS

Gas from the combustion of fuel, the heating effect of which has been substantially spent and which is, therefore, discarded to the flue or stack.  Its constituents are principally CO₂, CO, 0₂, N₂ and H₂0.

FLUID

Non rigid substance consisting of particles that move freely amongst themselves (includes particulate, liquids and gases).

FLUID BED OPERATION

Where catalyst is continually moved from the reactor to a regenerator and back again, as in the continuously regenerated platformer or cat cracker processes.

 FOAM

A preparation designed to smother oil fires.  It consists of a solution which, on mixing with water, produces a mass of foam many times the volume of the original liquids.

FOAMING

The formation of froth or foam on lubricating oils or other oils as a result of aeration or release of gas dissolved in the oil.

The formation of bubbles on the surface of boiled water.  The foam may entirely fill the steam space of the boiler or may be of minor depth; in either case, it causes appreciable entrainment of boiler water with steam.

Caused in Adip systems by presence of liquid hydrocarbons or fines affecting surface tension of solution.

FORCED DRAUGHT

Air forced into a furnace by means of a fan or blower to improve combustion (compare induced draught).

FRACTION

A portion of petroleum separated from other portions in the fractionation of petroleum products.  It is often characterised by a particular boiling range.

FRACTIONAL CONDENSATION

A separation of the components of vapourised oil coming off during distillation by condensing the vapours in stages (partial condensation).  The oil of highest boiling point will condense first and may be removed in the liquid stage, allowing the portion still in the vapour state to pass on to the next stage condenser.

FRACTIONATING COLUMN

An apparatus in which fractionation is carried out.  It consists of a vertical cylindrical metal vessel, containing equipment for the proper contacting of flashed liquid and vapour.  heat is often supplied at the bottom of the column in a reboiler, whereas heat is withdrawn at the top in a condenser.  Heat can also be supplied or withdrawn at intermediate heights of the column, if beneficial to the process (inter‑heaters or inter‑coolers).  The oil to be fractionated is fed into the column at one or more predetermined locations throughout the height of the column.  The contacting equipment is formed by fractionating trays in the oil and chemical industry in general, although for some applications various packing materials are used.

FRACTIONATING TRAYS

Equipment aimed at promoting contact between vapour and liquid for fractionation.  The flow can be of a single type (i.e. vapour and liquid are arranged to use separate aperatures) or of the dual type (i.e. vapour and liquid may use the same aperature).  The former type is promoted by the provision of downcomers for the liquid.  Various arrangements of downcomers lead to various systems of trays.  Analogously there may be different provisions for the vapour passage, again leading to various possibilities of trays.  For further information see bubble cap trays, calming section trays, grid trays, sieve trays and valve trays.

FRACTIONATION

The general name for a physical process of separating a mixture into its constituents, or into groups of these constituents, called fractions.  Examples are:  absorption, azeotropic distillation, crystallisation, decanting, distillation, extraction, extractive distillation and flotation.

FREE ON BOARD (FOB)

The unit price at the loading port.

FREE WATER

Water which is not dissolved (ie not chemically bound in solution) in a fuel or feedstock.

FREEZE POINT

An important characteristic of aviation fuels.  The test for Jet A1 is to cool until solid then reheat, the temperature at which the solid MELTS is called freeze point.

FREEZING POINT

The temperature at which crystals first appear when a liquid is cooled under specified conditions. 

FRESH GAS

In the HYDROCRACKER, Fresh H₂ from the reformer to replace H₂ used up in the process.  Otherwise any imported gas as distinct from recycle gas.

FRICTION

Resistance to the motion of one surface against another.

FUEL AIR RATIO

The ratio of the weights of fuel to air supplied to an engine, furnace or boiler at any time.

FUEL CELL

An electrochemical device to convert chemical energy directly into electricity.  It is similar in some respects to a storage battery or a dry cell.  Like a battery, the fuel cell produces electricity by a chemical reaction.  Unlike a storage battery, however, the fuel cell continues to produce electricity as long as fuel is added.  In a fuel cell chemical energy is directly converted to electrical energy by a process that is the reverse of electrolysis.  A fuel gas is fed into one or two hollow porous electrodes in a liquid electrolyte whilst oxygen or air is supplied to the other electrode.

FUEL GAS

Any gas used for heating by combustion.

FUEL OIL

Any liquid or liquefiable petroleum product burned for the generation of heat in a furnace or firebox, or for the generation of power in an engine, exclusive of oils with a flash point below 100^oF.

FUNCTIONAL LOGIC SCHEME

Diagrams used to show the interaction of plant trips, both cause and effect.

FUNCTIONAL LOGIC SYSTEM

System of plant protection whereby loss of a signal indicates a failure or trip of part of the unit.  This trip will then shutdown all or part of the unit.

FURNACE

That section of the refinery process in which the combustion of fuel and air takes place.

FURNACE PASS

For more even heat transfer, the product to be heated is usually split into 4 or more individual pipes (passes) and then recombined at the furnace exit.

G

GAP

In adjacent fractions, the temperature difference between the initial boiling point of the higher boiling fraction and the end point of the lower boiling fraction.  Specifically, the term 'gap' is only used when this difference is positive (c.f. overlap).

The mid‑position where a pair of gap‑acting split range controllers are both closed.

GAS HOLDER

A tank for the storage of gas.  It usually floats on a liquid seal, buoyed up by the pressure of the stored gas.

GAS OIL

Another common name for diesel fuel (A.G.O.)

GAS/OIL RATIO

The volume of gas at atmospheric pressure produced per unit volume of oil produced (from oil wells).

GASOLINE

Light petroleum fraction, with a boiling range between the approximate limits of 30 and 200^oC.

GAS TURBINE

An engine in which gas (as distinct from steam) is directed, under pressure, against a series of turbine blades.  The energy contained in the rapidly expanding gas is converted into rotary motion.

GATHERING STATION

Oilfield installation which receives the production from several wells in its vicinity.  It provides facilities to separate the gas and the water, to gauge the production of oil, gas and water, and to transport the oil to the main storage tanks.

GEAR OIL

A lubricating oil for use in standard transmissions, most types of differential gears, and gears contained in gear cases.

GLAND

The outer portion of a stuffing box, consisting of a tubular projection which embraces the rod and extends into the bore of the box, thus bearing against the packing.

GOVERNOR

A device used to control the speed of a turbine, the best known example being the Woodward Governor.

GRAVITOMETER

Instrument used for measuring changes in the specific gravity of oil flowing in a pipeline.

GRID TRAYS

Fractionating trays consisting of parallel bars of flat or round section.  The flow is essentially of the dual type, but this character may be reduced by the provision of downcomers (see Fractionating trays).

GUM

Oxidation of gasoline's may produce a sticky substance known as "gum".  When unstable gasoline’s are stored for long periods, the gum content may increase.  Gum forming is retarded or prevented by using certain inhibitors, e.g. Topanol.

H

HAMER LINE BLIND

A spectacle blind‑type blanking device which has only 3 retaining bolts, these are a type of wing not.

HEADER

A common manifold in which a number of pipelines are united.  Also used in reference to the U‑bend connection between two consecutive tubes in a coil.

HEAT CAPACITY

Amount of heat per kg per ^oC change in temperature.

HEAT EXCHANGER

An apparatus for transferring heat from one fluid to another.  Specifically, a piece of equipment having a tubular piping arrangements which affects the transfer of heat from a hot to a relatively cool material by conduction through the tube walls.

HEAT OF COMBUSTION

The heat created when a substance is burned in oxygen.  The calorific, thermal, or heating value of a fuel is the total amount of heat developed by the complete combustion of a unit quantity of fuel; it is reported as calories per gram or Btu per pound.

HEATER

The furnace‑and‑tube arrangement which normally furnishes the principal heating element in a processing unit.

HI‑FI TRAYS

Similar to calming section trays, except there is a greater downcomer area.

HIGH VACUUM UNIT

A unit for the production of vacuum gas oil and waxy distillate from long residue, by means of distillation at very low pressures, i.e. high vacuum.

HORSEPOWER

A unit of rate of operation; one mechanical horsepower equals 33,000 ft‑lb per minute, or 550 ft‑lb per second. This is just one form of Horse Power there are more.

HORTON SPHERE

A spherical tank used to store volatile liquids under high pressure, e.g. butane.

HOT OIL

Any oil used for the transfer of heat, as in the 700 Unit.

HOT SPOT

A finite area in the combustion zone of an engine which remains at a temperature higher than that of the immediate surrounding, thus aggravating detonation or pre ignition.

An area on the wall of a vessel or line which is appreciably above normal operating temperature.  Often as a result of the deterioration of an internal insulating liner which exposes the line or vessel shell to the temperature of its contents.

HUMIDITY

A measure of the moisture contained in the atmosphere.

HYDRATE

A compound formed by the chemical union of water with a molecule of some other substance such as gypsum, from which water may be separated by a simple readjustment of the molecular structure.  Gas hydrates, formed from water and, for example methane, may cause plugging of the tubing and flow lines of gas wells.

HYDRATION

The addition of water to a double bond, no breakdown of the molecular structure being involved.

HYDRAULIC FLUIDS

Fluids used in the hydraulic systems of aircraft and industrial equipment etc.

HYDROCARBON

A compound containing only hydrogen and carbon.  The simplest hydrocarbons are gases at ordinary temperatures; but with increasing molecular weight, they change to the liquid form and, finally, to the solid state.  They form the principal constituents of petroleum.

HYDROCHLORIC ACID

A strong mineral acid, HCL.  It is also called muriatic acid.

HYDROCRACKING

A process in which hydrocarbons are converted under hydrogen pressure into products of lower molecular weight, in the presence of an acidic catalyst.

HYDRODEALKYLATION

A process to remove side‑chains on aromatic molecules, either thermally or catalytically, under hydrogen pressure.

HYDRODESULPHURIZATION

The elimination of sulphur containing molecules in crude’s or distillates by the action of hydrogen under pressure over a catalyst.

HYDROGEN

The lightest of all gases, occurring chiefly in combination with oxygen in water, also in acids, bases, alcohol’s, petroleum and other hydrocarbons.

HYDROGEN BLISTERING

A form of corrosion.  Blistering of steel is caused by trapped molecular hydrogen formed as atomic hydrogen during attack of steel by hydrogen sulphide.

HYDROGEN SULPHIDE

A compound of hydrogen and sulphur, specifically the monosulphide; a colourless, flammable, poisonous gas, H₂S, having a disagreeable odour; also called sulphureted hydrogen.

HYDROGENATION

The filling of the "free" places in unsaturated structures by hydrogen atoms.  The chemical addition of hydrogen to a material.  In non‑destructive hydrogenation, hydrogen is added to a molecule only if, and where, unsaturation with respect to hydrogen exists.  In destructive hydrogenation, the operation is carried out under conditions which result in rupture of some of the hydrocarbon chains (cracking); hydrogen is added where the chain breaks have occurred.  This process is known as hydrocracking.

HYDROLYSIS

The decomposition of a molecular structure by the action of water.  A chemical decomposition in which a compound is broken up and resolved into other compounds by reaction with water.  In many cases, it is induced by the presence of a small amount of dilute acid.

HYDROMETER

A graduated instrument for determining the gravity of liquids, usually made of hollow glass and weighted at one end so as to float upright.  On immersion, the lighter the liquid, the lower the instrument sinks because the buoyancy force is less.  Some hydrometers are marked to read percentage of constituent, or some other property related to gravity.  The instruments used in measuring petroleum products usually read degress API or specific gravity directly.

HYDROSTATIC HEAD

The pressure exerted by a column of fluid, equalling the height of the column times the fluid density times the acceleration of gravity.  An expression of the pressure existing at a certain point, in terms of weight of a superimposed column of fluid.

HYDROSTATIC TEST

A pressure test using water to check the reliability of equipment prior to being bought into service.

HYDROTREATING

A vapour phase process used to treat petroleum fractions boiling up to approximately 250C.  The process involves passage over a fixed bed of catalyst (usually prepared by depositing the metals COBALT and MOLYBDENUM on an alumina base) in a hydrogen atmosphere.  The process achieves:

Hydrogenation of the sulphurous contaminants in the feedstock to hydrogen sulphide.

Saturation of unsaturated component compounds such as olefins.

I

IGNITION POINT

The point or temperature at which a substance takes fire.

IGNITION QUALITY

A measure of the ignition delay of a fuel in a diesel engine.

IMMISCIBLE

Not capable of mixing; tending to form two layers, e.g. oil and water.

INCOMPATIBLE

Applied to a substance which, for chemical, physical, or physiological reasons, cannot be mixed with another without changing its nature or affect.

INDIGENOUS FEEDSTOCK

Local (i.e. NZ) crude’s or condensates e.g. Maui, Kapuni etc.

INDUCED DRAUGHT

Air drawn into a furnace by means of a fan to improve combustion (compare forced draught).

INERT ENTRY

Specialised entry into a vessel under N₂ atmosphere, by use of B.A. and special safety precautions.  Used e.g. in hydrocracker catalyst change operation.

INERT GAS

Nitrogen on the refinery, scrubbed flue gas on the tankers.  Used for air (oxygen) exclusion to reduce fire/explosion risk.

INERT FILLER

Non reactive packing/support material, e.g. ceramics, stainless steel etc.

INFLAMMABLE

Very flammable ‑ not to be confused with non‑flammable.

INHIBITOR

A substance, the presence of which in small amounts in a product prevents or retards undesirable changes in the quality of the product, or in the condition of the equipment in which the product is used.  In general, the essential function of inhibitors is to prevent or retard oxidation.  Examples of uses include the delaying of gum formation in stored gasoline’s and of colour change in lubricating oils; also the prevention of corrosion, e.g. rust prevention by inhibitors in turbine oils and fuels.

INITIAL BOILING POINT

According to ASTM Method D 86 the recorded temperature when the first drop of liquid falls from the end of the condenser.

INJECTOR

A mechanism which may be used in different forms for spraying fuel oil into the combustion chamber, or for feeding water into steam boilers.

IN‑LINE BLENDING

A system in which all components are pumped simultaneously into a common discharge pipe (header) at rates of flow corresponding to the required proportions, the rates of flow being controlled.  Blending takes place in the lines between the header and the storage tank into which the blend is discharged.

INORGANIC

Pertaining to substances not organic, nonliving, i.e. which are not carbon compounds, with the possible exception of the oxides and sulphides of carbon.

INSITU REGEN

Catalyst regeneration carried out within the reactor.  Carbon is burned off under controlled conditions of heat/air.  Less effective, but cheaper and usually quicker than ex‑situ.

INSTITUTE OF PETROLEUM

The organisation in Great Britain primarily responsible for the advancement of the study of petroleum and its allied products in all their aspects.  It is the recognised British standardisation authority for methods of testing petroleum products.

INTERCEPTOR

Equipment to remove oil from water either for process separation or pollution control.  Weir, parallel and tilted plate types are used.

INTERNAL‑COMBUSTION ENGINE

An engine which operates by means of combustion of a fuel within its cylinder.

ION EXCHANGE RESINS

Preparation used in water softening ‑ Anion and Cation resins are used.

ISOLATE

Any means of positive separation from a risk source:‑

To electrically disconnect.

To valve/spade isolate a piece of linework/equipment.

ISOMER

Two substances composed of equal amounts of the same elements but differing in properties owing to variation in structure are called isomers.

ISOMERISATION

The conversion of a compound into its isomer.  For example, butane may be converted into isobutane.  A reaction which alters the fundamental arrangement of the atoms in the molecule without adding or removing anything from the original compound.  In the petroleum industry, straight‑chain hydrocarbons are converted catalytically to branched‑chain hydrocarbons of substantially higher octane number by isomerisation.

ISO‑OCTANE C8H18 (2,2,4‑TRIMETHYLPENTANE)

A colourless liquid used with n‑heptane to prepare standard mixtures to determine anti‑knock properties of gasoline.

ISOTOPE

Any one of a number of atomic species differing in atomic weight but having the same atomic number.

Used in some Refinery instruments and for radiography.

J

JET A1

See Avtur.

JET ENGINE (see also Gas Turbine)

An engine which converts fuel and air into a fast‑moving stream of hot gases which effect propulsion of the device of which the engine is a part.

JET FUEL

Fuel meeting the required properties for use in jet engines and aircraft turbine engines.  It is subject to intense testing and quality control as laid down in DERD and AFQRJOS documents internationally.

JETTY HOSE

Large bore counterbalanced heavy rubber hose used for loading/unloading ships.

K

KELVIN

The unit used as the Absolute temperature scale, i.e. zero Kelvin is absolute zero, 273K is 0^oC.  The Kelvin degree has the same dimensions as the Celsius degree. The ^o symbol is not used on the Kelvin scale.

KEROSENE

Any petroleum product with a boiling range between the approximate limits of 140 ^oC and 270^oC which satisfies certain quality requirements (for lamp oil or jet fuel).

KETTLE REBOILER

A reboiler with facilities for separation of liquid and vapour.

KNOCK

Related to internal combustion engines the noise associated with detonation of a portion of the fuel‑air mixture in a cylinder ahead of the advancing flame front.

KNOCKOUT (DRUM OR VESSEL)

A vessel, constructed with baffles, through which a mixture of gas and liquid is passed to disengage one from the other.  As the mixture comes in contact with the baffles, the impact frees the gases and allows them to pass overhead; the heavier substance falls to the bottom of the drum.  

L

LAGGING

A covering to retain heat, such as mineral wool wrapped on steam pipes.

LASER ALIGNMENT

Method of aligning rotating equipment shafts using a laser beam.

LATENT HEAT

Heat required for a change of state without a change of temperature.

The latent heat of fusion, or the amount of heat necessary to change a unit mass of solid into a liquid without change of temperature.

The latent heat of vaporisation, or the amount of heat necessary to change a unit mass of liquid into vapour without change of temperature.

The latent heat of condensation.  Effectively the opposite of 2 (above).

LEAD

Industry parlance for the motor fuel anti‑knock additive compounds tetraethyl‑lead, tetramethyl‑lead, or for other organometallic lead anti‑knock compounds. Not used in NZ.

LEAD ACETATE TEST

A method of detecting the presence of hydrogen sulphide in a sample using lead acetate paper, which will change from white to brown upon detection.

LEAD SUSCEPTIBILITY

Ability of gasoline’s to respond to the addition of tetramethyl‑lead, or other organometallic lead anti‑knock compounds, as reflected in the increase of anti‑knock quality (octane number) with increase in lead content.

LEADED GASOLINE

Refers to gasoline containing tetramethyl‑lead or other organometallic lead anti‑knock compounds. Not used in NZ.

LEAN ADIP

Adip that has been regenerated and had H₂S removed.

LICHEN

Simple plant that is sensitive to SO₂ and can thus be used as an indication of SO₂ (i.e. stack emission) pollution.

LIGHT DISTILLATE

A term applied to distillates the final boiling point of which does not exceed 300^oC.

LIGHT ENDS

The lower‑boiling components of a mixture of hydrocarbons.

LIGHT TOPS

The lower‑boiling components of Naphtha.

LINEAR PROGRAMME (LP)

A mathematical representation of an operation which can be optimised according to a set of economic criteria.

LIQUEFIED NATURAL GAS (LNG)

Natural Gas can be liquefied, e.g. at atmospheric pressure by cooling to about ‑ 160^C (‑256^oF).

LIQUEFIED PETROLEUM GAS (LPG)

of the gaseous hydrocarbons, propane and the butanes can be liquefied under relatively low pressure and at ambient temperature and are then known as liquefied petroleum gas.  Light hydrocarbon material, gaseous at atmospheric temperature and pressure, held in the liquid state by pressure to facilitate storage, transport and handling.  Commercial liquefied gas consists essentially of propane, butane, or mixtures thereof.

LIQUID PHASE

The term describing a product or substance when in the form of a liquid.

LIQUID SEAL

A quantity of liquid used to prevent the emission of a gas through an orifice.  To be completely effective the hydrostatic head exerted by the liquid must be greater than the pressure of the gas and the gas must be insoluble in the liquid.

LITRE

The primary standard of capacity in the metric system, equal to the volume of one kilogram of pure water at maximum density, at approximately 4C, and under normal atmospheric pressure.

LIVE STEAM

As contrasted to exhaust steam, steam coming directly from a boiler before being utilised for power or heat.

LOAD‑ON‑TOP SYSTEM

System of cleaning the tanks of a crude oil tanker by collecting washings from each tank in one tank, allowing the water to separate from the oil, then discharging the water overboard, leaving the oil residues in the tank.  The next crude oil cargo is loaded on top of the residues.

LOADING RACK

A structure built alongside railroad tracks or at road depots for the purpose of loading tank cars or road tankers with products.

LOGIC

See functional logic.

LONG RESIDUE

The residue resulting from the atmospheric distillation of crude oil.

LOST TIME ACCIDENT (LTI)

Any work injury that results in the worker being unable to recommence work on the day after the injury.

LOW VISCOSITY INDEX

See Viscosity index.

LOWER EXPLOSIVE LIMIT

Leanest mixture that will explode.  A greater air: hydrocarbon ratio will not ignite.

LUBOIL

Lubricating oil

LUBRICANT

A substance, especially oil, grease, or a solid such as graphite, which may be interposed between moving parts of machinery, thus reducing friction by preventing contact between the bearing surfaces.  The lubricant has an important function in removing heat and dirt from the region of the bearing surfaces.

LUBRICATING OIL

A fluid lubricant used to reduce friction between bearing surfaces.  Petroleum lubricating oils may be produced either from distillates or residues; amounts of other substances, known as additives, may be added to impart or improve certain required properties.

LUBRICATION

The state of being lubricated, or the act of applying lubricating substances which are capable of reducing friction between and removing heat from moving mechanical parts.

M

M CAP DECK

A de‑entrainment draw off tray used on HVUII.

MANIFOLD

A piping arrangement which allows one stream of liquid or gas to be divided into two or more streams, or which allows several streams to be collected into one.

MANOMETER

An instrument for measuring the expansion or the expansive power of gases or vapours; a pressure gauge or vacuum gauge.

MASS SPECTROMETER

A device for analysing a substance in terms of the mass‑to‑charge ratios of its constituents.  It is so designed that the beam constituents of a given‑mass‑to‑charge ratio are focused on an electrode and detected or measured electrically.  The mass spectrum shows the distribution in mass or the mass‑to‑charge ratio of ionised atoms, molecules, or molecular fragments.

MELTING POINT

Temperature at which a solid substance melts or fuses.  For asphalt, the melting point is defined as the temperature at which the asphalt is soft enough to permit a steel ball to drop through a disk of asphalt supported in a ring suspended in water (ring‑and‑ball method).  The grease melting point is determined by placing a small amount of the grease on the bulb of a thermometer and heating in hot air until the grease begins to run off.

MERCAPTANS

Mercaptans or alkyl‑hydrosulphides are organic compounds of carbon, hydrogen and sulphur.  They have a bad odour and frequently occur in unrefined gasoline.  Mercaptans must be removed from gasoline or converted to the unobjectionable disulphides by suitable refining (e.g. by sweetening).

METHANATOR

Part of the reformer process that converts unwanted carbon oxides to methane which is more acceptable to the hydrocracker.

METHANE CH4

A light, odourless inflammable gas.  It is the chief constituent of natural gas.  It is also often produced by a partial decay of plants in swamps (marsh gas), so that its occurrence  is commonly misinterpreted by the layman as an indication of the presence of petroleum.

METHANE SERIES

A homologous series of open‑chain saturated hydrocarbons of the general formula CnH2n+2 of which methane (CH₄) is the first member of the type; generally called the paraffins.

METHANOL

Methylalcohol, CH3OH.  The first member of the class of organic compounds known as alcohols.  It is a liquid boiling at 66C.  Methanol is inflammable and poisonous.  It is used in the production of synthetic gasoline ‑ see synfuel.

METHYL CHLOROFORM

Used as a catalyst promotor in the platformer.

METHYL TERTIARY BUTYL ETHER (MTBE)

An oxygenated compound which can be used as a blending compound in gasoline to boost octane.

METRIC SYSTEM

A system of weights and measures derived from the metre.  The system includes: measures of length, wherein the metre is the unit, measures of surface, wherein the square metre is the unit, measures of capacity, wherein the litre is the unit, and weights, wherein the gram is the unit.

MICROCRYSTALLINE WAXES

Waxes having a very fine crystal structure, and consisting mainly of iso‑ and cycloparaffins with some aromatics.  They are produced mainly from heavy lubricating oil residues and have melting points from 60‑90C.

MIDDLE DISTILLATE

One of the distillates obtained between kerosine and lubricating oil fractions in the refining processes.  These include light fuel oils and diesel fuel.

MINERAL OIL

Generally speaking, this term refers to a wide range of products derived from mineral substances.

MINIMUM STOP

A setting used to restrict the closure of a control valve.  There are two ways of achieving this:‑

Mechanical, by use of a collar or nut on the spindle, diaphragm.

Pneumatically, by restricting the minimum air signal from the control instrument.

MISCIBLE

Capable of being mixed (stability and uniformity throughout the mixture are usually inferred).

MIXED BASE CRUDE

A crude oil which is a mixture of paraffin ‑ and naphthene‑base crude.

MIXER

Device used for mixing partially im-miscible liquids in process plant or to prevent layering in tanks ‑ a propeller or jet mixture may be used.

MIXING VALVE

A valve which creates turbulence within a pipe to effect mixing of the materials flowing through the pipe.

MIXTURE

The intermingling of two or more substances, each retaining its original properties.

MOLE PERCENT

An expression of the percent composition of a mixture in terms of moles.  The relative numbers of moles are computed by dividing the numbers of units of weight of the individual constituents by their respective molecular weights.

MOLECULAR WEIGHT

The sum of the atomic weights of the atoms composing a molecule.

MOLECULE

The smallest portion of an element or a compound which retains chemical identify with the same particular substance en masse, e.g. unit of water.

MOTOR GASOLINE

A complex mixture of relatively volatile hydrocarbons, with or without small quantities of additives, which have been blended to form a fuel suitable for use in automotive internal‑combustion engines.

MOTOR OCTANE NUMBER (MON)

The Octane number of a Motor Gasoline determined in a special laboratory test engine under high "engine‑severity" conditions, giving a rough measure of the high‑speed knock properties of the gasoline.

MOTORISED VALVE

A valve incorporated in automatic control systems to regulate the rate of flow of material through a section of pipe.  It is actuated either hydraulically, electrically, from a control instrument.

MULTIGRADE OIL

One of the multi‑viscosity number oils in which one oil combines three SAE viscosity number grades.  For example, multigrade SAE 10W‑30 grade may be used where SAE 10W, SAE 20‑20W, or SAE 30 grades specified.  Multi‑grade oils are usually made to meet the requirements of API Services MS, DG, and DM.  They have been made possible by improved refining processes and the use of improved additives.

MULTISTAGE PUMP

Pump with more than one impeller.  Generally used in high pressure/medium flow applications.

N

NAPHTHA

Naphtha’s are straight‑run gasoline fractions boiling below kerosene.  Being generally unsuitable as a blending component for premium gasoline’s, they are used as a feedstock for Platforming.  Other important outlets for naphtha’s are their use as chemical feedstock (e.g. ethylene manufacture) and as feedstock for town gas manufacture.

NAPHTHENE

A class of saturated cyclic hydrocarbons of the general formula CnH2N.  One of a group of cyclic hydrocarbons, also termed cycloparaffins or cycloalkanes.  Polycyclic members are found in the higher boiling fractions of crude oil.

NAPHTHENIC ACID

Naturally occurring acidic compounds commonly found in Naphthenic crude’s.

NAPHTHENIC CRUDE

Crude oil containing a relatively large percentage of naphthene.   An oil obtained from a Naphthenic crude is said to be a naphthene base oil.  Lubricating oils made from such crude’s are normally distinguished from similar oils made from paraffinic crude’s (both oils equally well refined) by lower gravity, lower carbon content and pour point, and lower rating viscosity index.

NATURAL DRAUGHT

A flow of air into the combustion chamber of a heater which is neither induced nor forced but derives solely from the fact that the pressure inside the heater is lower than that of the ambient atmosphere (due to effect of stack).

NATURAL GAS

Naturally occurring mixtures of hydrocarbon gases and vapours, the more important of which are methane, ethane, propane, butane, pentane, and hexane.  The gas which occurs naturally with crude oils, but also in reservoirs which contain only a few heavier constituents.  It consists mainly of the lighter paraffin hydrocarbons.  Natural gas is usually classified as wet or dry, depending on whether the proportions of gasoline constituents which it contains are large or small.  Most gas reaches the surface through the tubing, but in some pumping wells it is taken off at the top of the casing (casinghead gas).

NATURAL GASOLINE

Gasoline extracted from wet natural gas, consisting of butane, pentane and heavier hydrocarbons.  After stabilisation ‑ the removal of the lighter components ‑ the gasoline is suitable for blending into motor gasoline.

NET ASSET BACKING/SHARE

Shareholders' Investment

Number of shares

NET PROFIT AFTER TAX

Income from all sources less operating costs, depreciation and tax.

NET PROFIT BEFORE TAX

Income from all sources less operating costs and depreciation.

NEUTRAL

Neither acid nor alkaline.

NEUTRON

An uncharged particle having the mass of the proton.  Generally, together with the protons, neutrons make up the nucleus of atoms.

NITROGEN

Element of atomic number 7, in group V of the periodic system; colourless, odourless, tasteless diatomic gas constituting approximately four‑fifths of the air; chemically rather inert; soluble in water.  Derived from liquid air by fractional distillation.  Used extensively in refineries for inerting process plants (air exclusion).

NITROGEN BASE

A compound, such as amine, which may be considered a substitution product of ammonia; a compound containing trivalent nitrogen, capable, like ammonia, of combining with acids in the formation of salts containing pentavalent nitrogen.

NON‑ASSOCIATED NATURAL GAS

Gas accumulations which exist independently of any oil accumulation.

NON CUSTODY TRANSFER TANKS

Tanks which receive products from internal sources or deliver products to internal sources.

NORMALISE

Correction made to a calculated figure (e.g. WABT) to allow for the effect of other variables.

O

OCTANE

The octane number of a fuel is a number equal to the percentage by volume of iso‑octane in a mixture of iso‑octane and normal heptane having the same resistance to detonation as the fuel under consideration in a special test engine.  It is a measure of anti‑knock value of a gasoline and, in the case of the special test engine, the higher the octane number the higher the anti‑knock quality of the gasoline.

OIL RING

A loose ring, the inner surface of which rides a shaft or journal causing the ring to rotate.  The ring dips into a reservoir of lubricant, from which it carries the lubricant to the top of the shaft for distribution to a bearing.  Also the ring on an internal‑combustion engine piston which controls the lubrication of the piston and cylinder walls, as contrasted to the compression rings.

OIL SHALE

A compacted sedimentary rock consisting mainly of consolidated muds and clays and containing organic matter which yields oil when destructively distilled but not appreciably when extracted with the ordinary solvents for petroleum.

OLEFINS

A class of unsaturated, non‑cyclic, aliphatic hydrocarbons of the general formula CnH2n (mono‑olefins).  Ethene is the parent member of the group.  Not very abundant in crude oils.

ONCE‑THROUGH

An adjective describing:

A condition or operation in which no portion of the product is recycled.

The products from such an operation.

ON STREAM

The length of time a unit is in actual production.

ORGANIC

Designation for a branch of chemistry; treating, in general, of the compounds produced in plants and animals, or of carbon‑hydrogen compounds of synthetic origin; contrasted with inorganic.

ORIFICE METER

An instrument which measures the flow through a pipe by use of the difference in pressure on the upstream and downstream sides of an orifice plate.

ORIFICE PLATE

A device for restricting the flow through a pipe.

OSMOSIS

Migration of ions or species from an area of high concentration to one of lower concentration.

OUTPUT

The pneumatic or electronic control signal sent from the control instrument to the valve.

OVERHEADS

In a distilling operation, that portion of the charge which is vapourised and removed as the total stream from the top of the column.

OVERLAP

In adjacent fractions, the temperature difference between the initial boiling point of the higher boiling fraction and the end point of the lower boiling fraction.  Specifically the term 'overlap' is only used when this difference is negative (cf. GAP).

OXIDATION

The reaction of oxygen with a molecule that may or may not already contain oxygen.  Oxidation may be partial, resulting in the incorporation of oxygen into the molecule or in the elimination of hydrogen from it, or it may be complete, forming carbon dioxide and water (combustion) ‑ contrast with reduction.

OXIDIZING FLAME

Term applied to a flame in which there is an excess of air or oxygen.

P

PACKED TOWER

A fractionating or absorber tower which is filled with small objects (packing) to effect an intimate contact between rising vapour and falling liquid.

PACKING

Typically PALL or RASCHIG rings of stainless steel or ceramic as used in a packed tower. May be DUMPED or STRUCTURED ‑ The latter being assembled rather than tipped in which results in lower p.d. and increased vapour/liquid contact thus greater efficiency.

Any material used to pack, as a layer of material put between the surfaces of a flange or used in a stuffing box to prevent leakage.

PALL RINGS

Usually of stainless steel, similar to Rashing rings, but with internal vanes (to increase surface area).

PARAFFIN‑BASE CRUDE

Crude oils which contain paraffin wax but little or no asphaltic matter.

PARAFFINS

Straight(N) or branched (ISO) open chain saturated hydrocarbons.

PARAFFIN WAX

Wax of solid consistency having a relatively pronounced crystalline structure, extracted from certain distillates of petroleum, shale oil etc.  Refined paraffin wax has a very low oil content; it is white with some degree of translucency, almost tasteless and odourless and slightly greasy to the touch.

PARTIAL CONDENSER

A heat exchanger, which condenses part of a vapour stream.  For example, partial condensers are used to condense the reflux liquid stream and liquid top product from the overhead vapours of a fractionation column.

PARTIAL PRESSURE

Partial pressure of a component of a mixture in vapour‑liquid equilibrium is that part of the pressure which is contributed by that component.

PENETRATION

Consistency, expressed as the distance that a standard needle or cone penetrates vertically into a sample of the material under known conditions of loading, time and temperature.  A measure of the hardness and consistency of asphaltic bitumen by which a weighted special cone or needle will penetrate the sample in five seconds, the temperature, unless otherwise stated, being 25C (77F).

PERMIT TO WORK

A permit raised for any job that is carried out in the “restricted area”

PETROIL MIXTURE (2 STROKE MIX)

A lubricating system for small two‑stroke gasoline engines, in which the lubricant is mixed in suitable proportions with a gasoline to make a petrol oil mixture.  During its passage through the engine some of the heavier and un-evaporated petrol oil fractions are deposited on bearing surfaces and so provide lubrication.

PETROL

Term commonly used for motor spirit or gasoline.

PETROLEUM

A material occurring naturally in the earth, predominantly composed of mixtures of chemical compounds of carbon and hydrogen with or without other nonmetallic elements such as sulphur, oxygen, nitrogen, etc.  Petroleum may contain, or be composed of, such compounds in the gaseous, liquid, and/or solid state, depending on the nature of these compounds and the existing conditions of temperature and pressure.

PETROLEUM NAPHTHA

A generic term applied to refined, partly refined, or unrefined petroleum products and liquid products of natural gas, not less than 10 percent of which distill below 347F (175C), and not less than 95 percent of which distill below 464F (249C) when subjected to distillation in accordance with ASTM method D86.

PETROLEUM SPIRITS

Refined petroleum distillates with volatility, flash point, and other properties making them suitable as thinners and solvents in paints, varnishes, and similar products.

PETROLEUM WAX

See crude wax.

PHENOL

Hydroxyl derivative of aromatic hydrocarbons.  Found in effluent water ‑ occurs from contact with certain crude’s.

PHOSPHATE

A salt of phosphoric acid.

At NZRC ‑ generally used to refer to TRISODIUM PHOSPHATE, an alkaline water treatment chemical. Na₃Po₄

 pH VALUE

The logarithm of the reciprocal of the hydrogen ion concentration.  This indicates the acid or alkaline condition of a substance, pure water and neutral solutions having a pH of 7.  Acid solutions have a pH less than 7; alkaline solutions, a pH greater than 7.

PIG      

Device sent down pipelines for various purposes.  Types include Polypigs, swabs, brush pigs, go‑devils and linelogs.

PILOT PLANT

A small version of the full‑scale plant in which a laboratory pursues development work, after bench‑scale investigation of a new process has shown promise.

PIPELINE

A line of pipe with pumping machinery and apparatus for conveying a liquid or gas.

PISTON

In engines and pumps, a reciprocating device in a cylinder or tube which receives pressure from, or delivers pressure to, a fluid.

PISTON RING

A ring used to maintain a gas tight seal between the piston and the cylinder and to control cylinder wall lubrication.

PITTING

Irregular corrosion in metalwork.

PLASTICIZERS

Non‑volatile liquids or low‑melting solids which, when added to another material change certain physical and chemical properties of that material, mainly imparting greater toughness, improved stability and increased flexibility.

PLATFORMING

A reforming process which makes use of a catalyst containing platinum and excess of hydrogen.  Catalytic reforming of straight‑run heavy gasoline (Naphtha) produces a product which is richer in aromatics and branched‑chain paraffins and poorer in naphthenes and straight chain paraffins.  The hydrogen produced in this process is used for hydrodesulphurisation and hydrocracking.

POLYELECTROLYTE

Substance used to encourage flocculation in water treatment units.

POLYMER

A substance produced from another by polymerisation, i.e. the combination of a number of identical molecules to form a larger one.

POUR POINT

The lowest temperature at which an oil will flow in a laboratory test, measured under specified conditions.

POWER RECOVERY TURBINE

Equipment designed to utilise the energy given up where a process drops from a high to a lower pressure.

PREDILUTON (RATIO)

Butane added to short residue to aid dispersal before entering the extractor in the B.D.U. 

Ratio of predilution butane to short residue.

PREHEAT

To heat, previous to some treatment; as an oil to be subsequently distilled, or as a body of gas or oil to be used as fuel.

PREHEATER

Any form of apparatus in which heat is applied to a material prior to its introduction into the main heating apparatus.  The application of heat is usually accomplished by means of hot streams which have to be cooled and whose heat would otherwise be wasted.  (See also HEAT EXCHANGER).

PRESSURE

The force or thrust exerted on a surface, normally expressed as force per unit area.  Pressure is exerted in all directions in a system.  Common examples; air pressure in a tyre, or water pressure at some depth in the ocean.

PRESSURE DROP

The decrease in pressure due to friction, which occurs when a liquid or gas passes through a pipe, vessel, or other piece of equipment.

PRESULPHIDE

To add sulphur (as DMDS or CS2) in order to initially activate a catalyst by changing the oxide sites to sulphides.

PRIMARY

A term used to describe the structure of certain classes of organic compounds, such as alcohol’s and amines.  For example, a primary compound is one in which one hydrogen atom in the carbinol or amino groups is replaced by a univalent hydrocarbon radical.

PRIMARY AIR

The air required for combustion in a furnace which is mixed with the fuel (gas, oil, pulverised coal, etc.) in and through the burner (c.f. Secondary Air).

PRIMARY PROCESS

A process based on physical separation, e.g. Fractionation, gravity separation.

PRIME MOVER

Any machine capable of producing power to do work.

PROCESS INTEGRATION

A term denoting the selection and arrangement of refinery processes and the optimum use of the heat contents of the various plant streams.

PROMOTER

A substance which may considerably increase the activity of a catalyst.  For example the catalytic action of iron is greatly increased when the catalyst contains a small amount of oxides of aluminium or silicon etc., e.g. C1‑ on Platformer and F‑ on hydrocracking catalysts. 

PROPANE C3H8

A hydrocarbon of the paraffin series used for heating, welding and metal cutting.  At ambient temperature it can be stored under pressure as a liquid.

PROPYLENE C3H6

A hydrocarbon of the olefin series.  Important base material for the chemical industry.  Propylene is used to make iso‑propanol, polypropylenes, plasticisers and glycol’s.

PROSS

Shell computer system for process control and optimisation. This has passed into history in 1999

PUKING

The foaming and rising of oil to the extent that part of the liquid is driven out of the vessel through the vapour line.  (See also SURGE).

PURGING

The removal of one fluid from a vessel or plant by introduction and subsequent evacuation of a second fluid.  A common usage of this operation is in the removal of hydrocarbon vapours or air from a plant by flushing with nitrogen.

PYROPHORIC

Takes fire spontaneously upon contact with air.  Certain forms of iron sulphide exhibit this tendency.  (Pyrophoric iron).

Q

QUENCH

To suddenly cool hot material discharging e.g. into a vacuum column, by injecting cool oil into the base; its purpose is to check the cracking reaction quickly to avoid coking.

QUENCH GAS

Cool gas injected between the hydrocracker reactor beds used to control reaction temperature.

QUENCHING OILS

Specially refined high‑flash mineral oils used for hardening alloy steels.

R

RADIANT ENERGY

Energy sent out or emitted by rays or waves.

RADIANT SECTION

Section of a furnace exposed to the actual combustion of the fuel.

RADIATION

The act of emitting energy, particularly rays of light or heat.

RADICAL

In chemistry, a group of atoms whose affinity for one another is so strong that, in chemical reactions, the group acts as a single atom, and is replaced or introduced into a new compound without rearrangement of the atoms bound together in the radical.  It can never exist alone as a separate compound.

RAFFINATE

The product resulting from a solvent extraction process and consisting mainly of those components that are least soluble in the solvent.

RASCHIG RING

Tower packing consisting of a small, hollow cylinder with length equal to its diameter; may be made of metal, ceramic, plastic or other material.

REACTION

Any chemical change; the transformation of one or more molecules into other molecules.

REACTION TIME

The interval during which the material being processed experiences chemical change.

REACTOR

Term applied to the part of a plant where a chemical reaction takes place.

REBOILER

A special type of heat exchanger for the supply of heat to the bottom of fractionating columns.

RECIPROCATING COMPRESSOR

A displacement compressor relying on forward and backward piston movement.

RECIPROCATING PUMP

A positive displacement pump consisting of a plunger or a piston moving back and forth within a cylinder(s).  With each stroke of the plunger or piston, a definite volume of liquid is drawn in through the suction valve(s) and subsequently pushed out through the discharge valves(s).

RECLAIMER

Part of the reformer process used to reclaim valuable Sulfinol solution that would otherwise be lost as condensate.  Also removes impurities (notably DIPA Oxazolidone) from reclaimed Sulfinol.

RECONTACTING

Process of splitting a stream into separate gas/liquid stream and then recontacting them under pressure.  This improves the quality of both streams (i.e. makes the gas lighter and the liquid denser).  Mainly used for maximising C5 (Pentane) retention as a Mogas blending component.

RECYCLE GAS

Gas fed back from a later stage of process (usually from the separators) to the early stage.  Usually impure and heavy.

RECYCLE OIL

Oil recycled from a later stage of the process to an earlier one.  HCU second stage feed is recycled from the HCU fractionator and consists of insufficiently cracked material (i.e. heavier than gas oil).

RECYCLE RATIO

The quantity of recycle stock relative to the quantity of fresh feed.  The units of quantity in this relationship vary with the plant concerned.  See also combined feed ratio.

RECYCLING

The maintenance of reservoir pressure through re‑injection into the reservoir of the produced gas, after extraction of the condensate in a gas plant.

Continuously feeding back part of a substance obtained or used in a process for further processing or use.

REDUCED CRUDE

A residual product remaining after the removal, by distillation or other means, of an appreciable quantity of the more volatile components of crude oil.

REDUCTION

The removal of oxygen ‑ or addition of Hydrogen to a compound.  Effectively the opposite of oxidation.

REFINERS MARGIN ‑ GROSS

The difference in value between the product value ex refinery and landed value of feedstock and blendstock.

REFINERS MARGIN ‑ NET

The gross refiners margin less fixed and variable cost of refining.

REFINERY

A plant, with all its included equipment, for manufacturing finished or semi‑finished products from crude oil.

REFINERY FUEL AND LOSS

The difference in intake and output due to the amount used as fuel and lost through tank breathing etc.

REFINING

The separation of crude oil into its component parts, and the manufacture therefrom of products needed for the market.  Important processes in refining are distillation, cracking, chemical treating, and solvent extraction.

REFLUX

A part (if the top product is in the liquid state) or all (if the top product is the vapour phase) of the condensed top vapour of a fractionating column, which is returned to the top of the column.  The purpose is to create an extra downward flow of liquid; if properly applied this liquid acts as an absorbing agent for the relatively heavy components which are thus rejected from the top product.

REFLUX CONDENSER

A condenser which constantly condenses vapours and returns liquid to the original distilling unit or to lower levels of a fractionating tower.

REFLUX RATIO

The quantity of reflux per unit quantity of distillate removed from the process as a product (forward flow).

For design purposes, the ratio of liquid reflux to vapour at any given point in a fractionating column.  Values may range from zero to unity.

REFORMING

See catalytic reforming, Platforming.

Process for the manufacture of hydrogen from steam and light hydrocarbons.

REFRACTORY

Any material not easily affected by heat, such as firebrick.

Difficult to decompose, for example, in cracking gas oil to produce gasoline.

REFRACTORY BRICK

A brick which is used as a lining for the interior of fireboxes in furnaces and boilers.  Refractory brick is constructed so that it can withstand very high temperatures, but it is not a very good insulator.

REGENERATION

The process of restoring a material to its original strength or properties.

In a catalytic process, the reactivation of the catalyst, usually done by burning off the coke deposits under carefully controlled conditions of temperature and oxygen content of the regeneration gas stream.  May be done in situ or ex situ.

REGENERATOR

Term applied to the part of a catalytic cracking unit or continuously regenerable platformer (CCR) where the spent catalyst is regenerated by burning off the coke.

REID VAPOUR PRESSURE (RVP)

The pressure caused by the vapourised part of a liquid and the enclosed air and water vapour, as measured under standardised conditions in standardised apparatus: the result is given in Kilo pascals at 37.8^oC, although normally reported simply as "RVP in kPa".  There is no simple relation between the RVP and the true vapour pressure of the liquid.  RVP gives some indication of the volatility of a liquid, e.g. gasoline. Lower in summer & higher in winter.

RELIEF VALVE

A spring loaded valve fitted on any piece of equipment or plant where normal operating pressures are above atmospheric.  This type of valve automatically opens, thus relieving internal pressure when the latter exceeds the maximum permissible level.

RERUNNING

The distillation of an oil which has already been distilled.  Necessary when a finished batch has been put off grade for any reason.

RESEARCH OCTANE NUMBER (RON)

The octane number of a motor gasoline determined in a special laboratory test engine, under mild engine severity conditions, giving a rough measure of the low speed knock properties of the gasoline.

RESIDENCE TIME

The average length of time a quantity of reactant spends in contact with catalyst, or within a particular part of the process.

RESIDUAL FUEL OIL

Fuel oil consisting mainly of long, short or cracked residue (in contrast to distillate fuel oil).

RESIDUE

The heavy residual liquid from the atmospheric distillation of crude oil is called long residue.  If such residue if further distilled under vacuum a still heavier residual liquid results, which is called short residue.

RESIN

Organic compounds produced by polymerisation.

Water treatment resins are used for water softening. With a very large surface area, liken to a sponge.

Epoxy and polyester resins of various types are used as fillers, adhesives and coatings.

RETAINED EARNINGS

Accumulated profits not distributed to shareholders.

RETURN BEND

A U shaped pipe fitting, used to connect parallel pipes so that fluid flowing into one will return in the opposite direction through the other.

RICH ADIP

Adip containing dissolved H₂S.

RING COMPOUNDS

Organic compounds in which the atoms of a molecule are arranged so as to form at least one closed ring, for example, naphthenes and aromatics.  Also called cyclic compounds.

RISER

That portion of the bubble plate assembly which channels the vapour and causes it to flow upward to escape through the liquid.

Fixed vertical line used to get fire water to high levels.

ROCKET FUEL

Propellant consisting of two components, oxidiser and fuel, which react to give gaeous products and release energy.  Rocket fuels are compared on the basis of specific impulse, which means the pounds of thrust produced per pound of fuel burned per second.  Rocket fuels may be liquids or solids.  In the latter case, the two components must be intimately premixed.  In some instances the liquid system may be a single liquid, in which case it is called a mono‑propellant.

ROTAMETER

Simple flow gauge utilising a ball or float in a tapered graduated tube.  The greater the flow, the more it raises the ball up the tube.

ROTARY PUMP

A positive displacement pump used mainly to pump liquids which are either too viscous or too difficult to obtain suction with a centrifugal pump.  There are many types of rotary pump designs.  One of the most common is the gear type, in which two gears mesh and rotate toward each other within a very close‑fitting casing.  The liquid is trapped between the gear teeth and the casing and is carried around to the discharge side of the pump.  The meshing gear teeth prevent the liquid from returning to the suction side.

RUNDOWN TANK

One of the tanks in which are received the condensates from the stills, agitators, or other refinery equipment, and from which the distillates are pumped to larger tanks known as work tanks or storage tanks.  Rundown tanks are also known as "pans" or receiving tanks.  If the condensates were received directly into the large storage tanks, possible puking of a still could unnecessarily contaminate a large quantity of distillate.

S

SAE CLASSIFICATION

The SAE devised a system for the classification of motor oils and transmission oils.  It is based on the viscosity at 0 or 100^oC.  Motor oils are on the scale 5W ‑ 50 and transmission oils are 80‑250.

SAFEGUARDING

Total procedure for safety proofing plant.  Includes relief systems, functional logic and emergency procedures.

SALT

A compound in which a metal or other positive ion exists in place of the hydrogen of an acid (e.g. sodium chloride, in which sodium replaces the hydrogen of hydrochloric acid), formed:‑

By direct replacement of the acid hydrogen with a metal;

By neutralisation of the acid with an appropriate alkali; or

By double decomposition.

SAMPLE

Sample of a process flow, tank etc. taken for laboratory analysis.

SATURATED HYDROCARBON

A hydrocarbon of such molecular structure that all adjacent carbon atoms are connected by not more than one valence or bond; or, diagrammatically as follows:  C‑C.  Each valence not taken up by adjacent carbon atoms connects with a hydrogen atom.

SATURATION TEMPERATURE

Of steam ‑ the temperature at a given pressure, at which steam exists in conjunction with water e.g. 100^oC at atmospheric pressure.

SCAVENGERS

Chemical additives which remove or inactivate impurities or undesired materials in a mixture or process, e.g. hydrazine is an oxygen scavenger used in water treatment.

SCHEDULING

The day to day planning of refinery operations to meet long term programmes.

SCHOEPENTOETER

Dutch for vane trumpet ‑ an internal distribution device, may be sideways or downwards pointing.

SEAL

A device used to seal the contents of a pump/compressor from the atmosphere.  Occasionally more explosive and complex then the pump itself.

SECONDARY AIR

The air which provides the oxygen necessary for the complete combustion of fuel (gas, oil, powdered coal, etc.) and which was not provided by the burner in the form of primary air.

SECONDARY PROCESS

A process based on a chemical change, e.g. Hydrocracking, Platforming, usually catalysed.

SEIZE

To stick or fail to function, as in engine bearings, because of expansion, caused by heat, friction, or scoring.  Also called "freeze".

SENSIBLE HEAT

The heat added to, or taken from, a body when its temperature is changed.  Note that no change in stage of the body (e.g. solid to liquid) is involved, c.f. latent Heat.

SEPARATOR

An apparatus in which heavy liquid impurities are separated from oil.

The part of a distilling apparatus in which a partial separation of the vapours is effected by means of contact with cooling surfaces.

SEPARATION INDEX

A measure of the degree of separation between components in a distillation column

SEPARATION PROCESSES

Manufacturing processes based on differences in the physical properties of the components of a mixture.   See Fractionation, Primary Process.

SETTLER

A separator, a tub, pan, vat, or tank in which the partial separation of a mixture is made due to difference in density.  The operation may be continuous or batch.  The separation may be solids from liquid or gas; liquid from gas.

SETTLING POINT

Laboratory test determining the temperature at which solidification of a molten wax begins.

SETTLING TANK

A tank employed for separating two liquids which are not miscible.  If the liquids do not form an emulsion they separate into layers according to their specific gravities, and these layers can be drawn off from different levels in the tank.

SHAREHOLDERS INVESTMENT

Retained Earnings plus Capital Reserves plus Original Equity = total investment made in the Company by Shareholders.

SHIFT REACTION

Conversion of CO to CO₂ by addition of water, following general reaction CO + H₂O ‑‑> CO₂ + H₂.  Both Hi and low temperature shift reactions are used.

SHORT RESIDUE

The residue resulting from vacuum distillation of long residue.  (Removal of vacuum gas oil and waxy distillate).

SIDE STRIPPER

A fractionating column for stripping undesired volatile components from a side stream which is drawn off as a liquid from a main fractionating column.  Various fractions may be drawn off from one main column, and be stripped in as many side strippers.

SIDESTREAM

A liquid stream taken from any one of the intermediate trays of a trayed distillation column.

SIEVE TRAYS

Fractionating trays consisting of sieve‑like materials, generally perforated plate.  The flow is essentially of the dual type, but this character may be reduced by the provision of downcomers.

SIGHT GLASS

Device used to directly show the level in a vessel, boiler, etc. by means of a glass tube.

SILVER STRIP

A very strict corrosion test for AVTUR.

SLACK WAX

See Crude wax.

SLIDE VALVE

A type of valve for controlling or shutting off the flow of catalyst in a continuous regeneration unit.

SLOPS

A term loosely used to denote:

Crude oil containing excessive water contamination which must be removed by settling before pumping to the crude distiller.

All products which are off‑specification and must be reprocessed before marketing.  Such products are for example produced during the start‑up period.

SLUDGE

Acid sludge or acid tar: material formed during refining of oils with sulphuric acid.

Engine sludge: insoluble product formed from fuel combustion products and from lubricating oils in internal combustion engines and deposited on parts outside the combustion space.

Tank sludge: material collected at the bottom of oil storage tanks.

SMOKE POINT

The maximum height of flame measured in millimetres at which a kerosene will burn without smoking when tested in a standard lamp for this purpose.

SOLAR ENERGY

Energy produced by radiation from the sun.

SOLUBLE OIL

Oil which readily forms stable emulsions or colloidal suspensions in water.  Used as a cutting fluid in machine work.

SOLUTION

A homogenous mixture of two or more chemically un-reacted fluids.

SOLVENT

A substance, usually liquid, capable of dissolving another liquid, gas or solid to form a homogenous mixture.

SOLVENT EXTRACTION

See Extraction.

SOLVENT/FEED RATIO

On the BDU, the rate of the total amount of butane (predilution and normal) to short residue.

SOOTBLOWER

A device for removal of soot from furnace tubes ‑ to increase heat transfer ‑ ‑ generally using a steam blast nozzle.  However, a shot drop system (as on the HCU) does the same job and is sometimes referred to as a sootblower.

SOUR CRUDE

Crude oils containing an abnormally large amount of sulphur and sulphur compounds which break down upon refining to liberate troublesome quantities of corrosive sulphur compounds.  This is a relative term.

SOUR GAS

Gas which contains objectionable amounts of contaminants, e.g. hydrogen sulphide and other corrosive sulphur compounds.

SOUR GASOLINE

Gasoline fractions which contain a certain amount of mercaptans and therefore must be sweetened.

SOUR WATER

Water which contains objectionable amounts of dissolved contaminants, e.g. hydrogen sulphide, ammonia, phenols etc.

SPACE VELOCITY

A convenient unit for expressing the relationship between feed rate and reactor volume in a flow process.  It is defined as the volume or weight of feed (measured at standard conditions) per unit time per unit volume of reactor or per unit weight of catalyst.

SPADE

A solid plate inserted in a flanged joint to positively isolate one side of the flange from the other.  Also called blank, banjo.

SPALLING

Flaking of the surfaces of metals or refractories, leaving new surfaces exposed.

SPARGE

Spray ‑ usually with water (originally a brewers term).

SPARK ADVANCE

In an ignition‑type internal‑combustion engine, the amount measured in degrees of crankshaft rotation, that the spark plug fires before the piston reaches the point of its traverse closest to the cylinder head.

SPECIFIC GRAVITY

The ratio of the weight of a volume of a body to the weight of an equal volume of some standard substance.  In the case of liquids and solids, the standard is water, in the case of gases, the standard is hydrogen or air.

SPECIFIC HEAT

The ratio of the quantity of heat required to raise the temperature of a body by one degree to that required to raise the temperature of an equal mass of water by one degree.

SPECTACLE

Or Spec blind.  A figure of 8 shaped plate that can be either put to the open or closed position, but always stays in the line.

SPHERE ‑ SEE HORTON SPHERE

             SPLITTER

A fractionating tower with overhead and bottoms product streams only.

SPOT

Refers to prices of single cargoes traded on an open market basis.  They can vary considerably with the supply/demand situation.

STABILISATION

The process of separating light gases from petroleum or gasoline, thus leaving the liquid stable in the sense that it can be handled or stored with less liability to change in composition.

STABILISED GASOLINE

Gasoline after subjection to fractionation by which the vapour pressure has been reduced to a specified maximum.

STABILITY

Resistance of petroleum products to chemical change.  Gum stability means the resistance of a gasoline to gum forming while in storage.  Oxidation stability means that the product is stable to oxidation, i.e resists the action of oxidation which forms gums, sludges etc.

STABILISER

A fractionating column designed to make a sharp separation between very volatile components and gasoline ex crude oil, casing head gasoline or pressure distillate, thus controlling the gasoline’s Reid vapour pressure.

STADIS

An anti static additive.

STANDARD PRESSURE

Pressure under which the mercury barometer stands at 760mm, or 30in.  (Equivalent to approximately 14.7 psia).

STANDARD REFINERY FUEL (SRF)

A hypothetical refinery fuel with a gross calorific value of 10336 Kcal/kg.  Allows all refinery fuel components to be converted to an SRF equivalent based on calorific values.

STAND‑BY

A term used to designate emergency auxiliary equipment which is not used during normal operation.

STAND PIPE

Any pipe that stands proud from a base, e.g. Fireman’s stand pipe for tapping into an underground main or a vessels internal stand pipe to avoid ingress of  dirt, scale etc. from the base of the vessel.

STATIC ELECTRICITY

The electricity generated by the relative movement of unlike materials such as oil/pipeline, oil/water, plastic granules/vessel; or by the operation of equipment such as driving belts.

STEAM/AIR DECOKING

In heavy oil furnaces over the period of a process run, the differential pressure across the furnace tubes may increase until it is uneconomical to continue the run.  This high pressure drop is caused by carbon built up on the inside of the tubes.  We can burn this carbon off by steam/air decoking.

STEAM DISTILLATION

A distillation in which vaporisation of the volatile constituents is effected at a reduced temperature by introduction of steam directly into the charge.  Steam used in this manner is termed open steam.

STEAM REFORMING

As used in the reformer for manufacture of H2 ‑ follows general formula CH4 + H20  ‑‑> 3H2 + CO.

STEEL

A solid state mixture of iron and 1‑4% carbon.  Can have different structures e.g.

Austenitic  ‑ strong, ductile

Pearlitic   ‑ low mechanical strength, eventually occurs in furnace tubes when

subjected to flame impingement

Martensitic ‑ Very hard ‑ used in valve faces etc.

STONEWALL

The condition where a centrifugal compressor is delivering its maximum flow.

STRAIGHT‑RUN

A term applied to a product of petroleum made by distillation without conversion.

STRAINER

Alternative term for filter.  Used for removal of fine material.

STRAPPING

The measurement of the external diameter of a cylindrical tank by stretching a steel tape around each course of the tank's plates and recording the measurement.

STREAM DAY

Denoting 24 hours of actual operation of a refinery unit; in contrast to a calendar day, i.e. takes into account the units availability factor.

STRIPPING

Removal of the lightest fractions from a mixture.  The process is usually carried out by passing the hot liquid from a flash drum or tower into a stripping vessel or stripping section of a column, through which open steam or inert gas is passed to remove the more volatile components of the cut.  A fractionating process, closely related to distillation by which undesired volatile components are separated from a liquid mixture by fractional evaporation.  The desired fraction is thus purified from lower boiling components.  Stripping is generally effected by the introduction of steam, by the reduction of pressure, by the vapour generated in a reboiler or a combination of these.  In the laboratory nitrogen is often used as a stripping agent.

STUFFING BOX

A device affording the passage and the length wise and rotary motion of a piston rod, shaft, or some similar moving piece while maintaining a fluid‑tight seal about the moving part.

SULFINOL PROCESS

A process for removing contaminants such as carbon dioxide from gases by contacting with a regenerable solvent.  Sulfinol is a three component solvent combining the chemical properties of the ADIP solvent with physical properties of sulfolane and water.

SULFOLANE

Tetrahydro ‑ Thiophene ‑ Dioxide ‑ A component of sulfinol solution.

SULPHATE

A salt of sulphuric acid, e.g. sodium sulphate, Na2SO4, or ethylsulphate (C2H5)2SO4.

SULPHIDE

Any of the compounds resulting from the combination of sulphur ions (S==) with metallic or other positive ions, or organic radicals.

SULPHUR

At NZRC, the final product from H₂S removal.  A non‑metallic element of lemon‑yellow colour, sometimes known as brimstone.  Sold in liquid form to fertilizer works.

SULPHUR CEMENT

Hard, high melting point solid formed by the mixing of refractory brickwork and liquid sulphur.

SULPHUR DIOXIDE

A colourless gas, SO₂,  a by product of combustion of sulphurous fuels.

SULPHURIC ACID

Traditionally known as Oil of Vitrol.  A combination of sulphur trioxide with water (SO₃+H₂0=H₂SO₄).  it is a eavy, strongly oily liquid, an important water treating agent.

SUPERHEATER

Apparatus which imparts heats to a liquid above that required for vapourisation. e.g. as used for adding heat to steam above the saturation temperature.

SURFACE AREA

The sum of the outer and inner surfaces.  A porous solid may be said to have two different types of area ‑ one made up of the external, the geometric, or the outer surface of the particle; the other, called the inner, made up of the walls of capillaries, crevices, and cracks in the particle.  The sum of these is the total surface area.  The ratio of total to outer area is sometimes known as the roughness factor.

SURFACE TENSION

The force exerted by the particles of a liquid at its surface which maintains a continuous surface.  The surface tension is determined by measuring the energy required to increase the surface by the unit of area.  That property, due to molecular attractive forces and existing in the surface film of all liquids, which tends to bring the volume contained in the liquid surface film into a form having the least surface area.

SURFACRANTS

(Surface active agents) ie trace chemical species which can adversely affect the water shedding properties of fuel.

SURGE

An upheaval of fluid in a system frequently causing a carryover of liquid through the vapour lines (see also PUKING).

An undesirable condition of unstable flow occurring within centrifugal compressors when the surge parameter drops below a critical value.  A very dangerous condition for the compressor, hence the need for surge protection (anti‑surge line).

SURGE DRUM

Vessel used to even out the flow into a unit, as the unit throughput and the feed rate may vary.  See also buffer.

SURGE PARAMETER

Indication of nearness to surge condition based on process instrumentation.

SUSPENSION

A heterogeneous mixture of one or more materials ‑ distinct from a solution.  The state of a solid or liquid when its particles are mixed with and buoyed in another liquid but are not dissolved by it.  A suspension of a liquid in a liquid is called an emulsion.

SWEET GAS

Hydrocarbon gas free from sulphur compounds.

SWEETENING

The process by which petroleum products are improved in odour and colour by oxiding or removing the sulphur‑containing and unsaturated compounds.  The conversion of the mercaptans present in sour gasoline into non‑smelling disulphides.

SYNFUEL 

A fuel made by the catalytic deoxidisation of methanol using the MOBIL ZSM‑S catalyst.  It is blended by NZRC into gasoline or sold as unleaded 92 RON gasoline overseas.

SYNTHESIS

The act or process of making or building up a compound by the union of simpler compounds or of its elements.

T

TANK CAR

A cylindrical metal tank mounted on an underframe and trucks so that it can be run along a railroad.

TANK FARM

Area in which a number of storage tanks are located.

TANK VOLUME

GROSS ‑ total amount of pumpable material plus tank bottoms.

NET   ‑ total amount of pumpable material only.

TANKAGE

The capacity of a tank, or of a series of tanks, in the same field.

TANKER

A ship especially constructed for the transportation of oil.

TEMPERATURE

An arbitrary measurement of the degree of heat possessed by a body.  It should be distinguished from heat itself.  Heat is a form of energy; temperature is a measurement of its intensity.

TEMPERATURE GRADIENT

The difference in temperature between two locations, e.g. between the top and bottom of a distillation column.  Often expressed as temperature difference per unit length.

TEROMAN

A computerised maintenance management system. (Now not used in NZRC)

TETRAETHYLLEAD (TEL)

It is added to gasoline to prevent knocking (increase octane number) in internal combustion engines.  Not used at NZRC.

TETRAMETHYL LEAD (TML)

Is added to motor gasoline to prevent knocking in internal combustion engines.  It is more effective than TEL in improving the Road Octane Number of a gasoline at a certain RON level, as a result of its higher volatility.  Not used at NZRC

THERM

Unit of heat equal to 100,000 Btu.

THERMAL CRACKING

Process of breaking down the larger molecules of heavy oils into smaller ones by the action of heat.  In this way heavy oils can be converted into lighter and more valuable products.

THERMOCOUPLE.

The junction of two wires of dissimilar metals, which develops an electrical potential that is a function of the temperature.  An instrument for measuring temperature by means of the electrical potential produced at a heated junction of two dissimilar metals.

THERMOSTAT

An automatic device for regulating temperature.

TOLUENE C6H5CH3

An aromatic hydrocarbon, used in the manufacture of the explosive TNT (trinitrotoluene) and in the production of dyestuffs and pharmaceuticals.

TONNAGE (MARINE)

A marine measurement term.  Gross tonnage is the total internal volume of the hull and all superstructures, such as deck houses, etc. being expressed in tons of 100 cubic feet or approximately 2.83 cubic metres.  Deadweight tonnage (d.w.t.) is the weight of the cargo, stores, bunkers and water which the ship can lift, expressed in long tons (2,240lb or 1016 kg).

TOPANOL

An inhibitor to prevent the formation of gum during storage of petroleum products.  Gum forms as a result of the polymerisation of unsaturated hydrocarbons under the influence of peroxides.  Topanol is added to prevent peroxide formation.

TOPS

The lightest gasoline fractions obtained when distilling crude oils.  also generally: the top product of any fractionating column.

TORQUE

An engineering term defined as the product of force times the length of the lever arm.  It is a measure of the ability to produce rotation.

TOTAL ORGANIC CARBON (TOC)

Amount of organic carbon in sample, determined by oxidation to CO₂.

TOTAL SUSPENDED SOLIDS (TSS)

A water specification, undissolved solid matter greater than 1.5 microns.

TOWER

An apparatus for increasing the degree of separation obtained during the distillation of oil in a still.  Towers may be divided into two general classes:  those which secure separation by fractionation, and those which take advantage of partial condensation only.  Towers of the first class are used when accurate work is necessary, as in the production of naphthas and gasoline.   Condensation towers are used to divide roughly the vapours from a still into several liquid portions. 

TRANSFER LINE

A pipe through which material being processed flows from one piece of equipment to another.

TRANSFORMER OIL

Oil used in transformers to remove the heat generated in the core and  coils and to provide insulation between live parts.  Transformer oil as a rule is a highly refined spindle type oil.  A high degree of refining is required to give the oil good dielectrical properties.

TRAP

A device or piece of equipment for separating one phase from another, as liquid from a gas or condensate from steam.

Any geological formation that will trap hydrocarbons e.g. fault, salt dome, discontinuity

TRAYS

See fractionating trays.

TREATING PROCESSES

Supplementary refining processes in which undesirable constituents (mainly olefinic and oxygen, nitrogen and sulphur containing compounds) are removed or converted into less harmful compounds so as to meet the product specifications for further processing or for marketing.

TRIP SYSTEM

A system of fail safe partial and total shutdown mechanisms to protect the plants safety under extreme operating conditions.

TRYCOCKS

A series of valves for double checking the supposed level in a sight glass.

TURBINE

A rotating prime mover actuated by either the reaction or the impulse, or both, of a current of water, steam or gas, usually on a series of curved vanes attached to a central shaft.  (Steam turbines only used at NZRC).

TURBINE OIL

A specially refined, inhibited lubricating oil used to lubricate steam turbines.

TURBOJET ENGINE

An engine in which air is compressed by a rotating compressor, is heated by fuel combustion at compressor pressure, released through a gas turbine which drives the compressor, and finally ejected at high velocity through the rearward exhaust nozzle.

TURNAROUND

Time necessary to clean and make repairs on refining equipment after a normal run.  It is the elapsed time between drawing the fires ( shutting the unit down) and putting the unit onstream again.

TURN DOWN

Amount or percentage by which a unit or plant may be turned down from its maximum.  Typically 50% is the minimum.  (The plants are designed to run at /or close to maximum).

U

ULLAGE

The volume of space in a container unoccupied by contents.  Hence ullaging, a method of gauging the contents of a tank by measuring the height of the liquid surface from the top of the tank.  See dipping.

UNSATURATED.

A term applied to organic compounds in which some carbon atoms are held together by double or triple bonds, so that these compounds are under favourable conditions, capable of combining with other elements or compounds.

UPPER EXPLOSIVE LIMIT

The richest mixture that will explode.  A lesser air/hydrocarbon ratio will not ignite.

UPSTREAM

Towards the start of the process e.g. crude storage, feed pumps, pre‑treatment etc.

In the business sense, exploration and crude production from wells.

V

V50

A viscosity index (at 50^oC) which enables linear viscosity blending calculations.

VACUUM

A space entirely devoid of matter (called specifically absolute vacuum); a space, such as the interior of a closed vessel, exhausted to some degree by a steam ejector set or other artificial means.  (Any vacuum less than absolute is a partial vacuum).

VACUUM DISTILLATION

Distillation of a liquid under reduced pressure, aimed at keeping the temperature level so low as to prevent appreciable cracking.  For example used to distill vacuum gas oil and waxy distillate feedstock from long residue, leaving the short residue as remainder, also used for manufacture of bitumen.

VALENCE

The combining power of an element, as exhibited by the number of atomic weights of hydrogen with which one atomic weight of the element will combine.  Certain atoms are capable of combining with others in different proportions; they are said to have a number of valences or are multi valent.

VALVE

Apparatus used to control the flow or supply of gases, liquids or fluidised solids.

VALVE TRAYS

Fractionating trays consisting of a plate with holes for vapour passage, characterised by the presence of valves over these holes.  These valves are aimed at preventing liquid passage (if liquid pressure should become too high) while allowing flexibility in vapour passage (depending on pressure of the vapour).  The flow is meant to be of the single type, and downcomers are generally provided.

VAPOUR

Gaseous substance which can be at least partly condensed by cooling or compression.

VAPOUR DENSITY

The weight per unit volume of gas e.g. grams per litre or pounds per cubmic foot.

VAPOUR LINE

The pipe through which vapours are led from a column to a condenser.

VAPOUR LOCK

A condition which arises when a gas or vapour is present in the fuel line or fuel pump in sufficient volume to interfere with or prevent the flow of fuel to the carburettor of an engine.

VAPOUR PHASE

The term describing a substance in the gaseous state, under conditions in which it is capable of being liquefied either by pressure or cooling or a combination of both.

VAPOUR PRESSURE (AT GIVEN TEMPERATURE)

The pressure exerted by the vapours released from any material, at a given temperature, when enclosed in a vapour‑tight container.  The lower pressure at which a liquid, contained in a closed vessel at the given temperature, can remain in the liquid state without evaporation.  Lowering the vessel pressure below the vapour pressure results in evaporation of part or all of the liquid.  A compound or fraction with a high vapour pressure requires a high pressure to be kept as a liquid, thus it is volatile.

VAPORISATION

The conversion of a liquid to its vapour, such as the changing of water into steam.

VENTURI METER

A specially designed tube for measuring the rates of flow of gases or liquids, having a constriction or throat with convergent upstream and divergent downstream walls, the angles of which are such that streamline or almost streamline flow through the tube is achieved.  The rate of flow is measured by the pressure drop across the throat.

VENTURI TUBE

A tube, inserted in a line, whose internal surface consists of two truncated cones connected at the small ends by a short cylinder (the throat).  As the velocity of flow of the fluid increases in the throat, the pressure decreases.  The tube is used to measure the quantity of fluid flowing or, by jointing a branch tube at the throat, to produce suction.

VISCOSIMETER

Instrument for measuring viscosities.

Absolute viscosity is determined by a capillary type instrument.  The time required for a sample to flow through a known length of glass capillary is registered.  Results are often given in centistokes or Centipoise.

In the petroleum industry the viscosity is generally determined in standardised instruments consisting of a container with a hole or jet in the bottom.  Various types are used, viz in the UK, the Redwood 1 and Redwood 11, in the USA the Saybolt Universal and Saybolt Furol and on the European continent the Engler viscosimeter.  Results with the Redwood and Saybolt viscosimeters are expressed in seconds, those with the Engler in Engler degrees.

VISCOSITY

The dynamic viscosity of a liquid is a measure of its resistance to flow.  It is defined as the force per unit surface required to shear a layer of unit thickness at unit velocity.  The kinetic viscosity is equal to the dynamic viscosity divided by the density of the liquid.  If no distinction is made the dynamic viscosity is usually meant.

VISCOSITY INDEX

A method of indicating the viscosity/temperature of an oil.  Oils are generally classed as high, medium and low viscosity index oils (HVI, MVI, LVI).

VOLATILE

Term applied to materials which have a sufficiently high vapour pressure at normal temperature to evaporate readily at normal atmospheric pressure and temperature.  It implies a high degree of volatility.

W

WASH OILS

petroleum fractions employed for the absorption of the relatively heavy and easily liquefiable components of a mixture of gases (to reduce gas stream density).

WASH WATER

Water injected into a process either for scrubbing a recycle gas or for corrosion protection in critical parts of the unit.

WASTE HEAT BOILER

Equipment used for generation of steam etc. from excess heat in stack gases.

WATER BOTTOM

Water accumulated at (or sometimes added to) the base of the oil in a storage tank.  In cases where the tank bottom is very uneven, the water level assists in the accurate measurement of the oil content of the tank.

WATER SOFTENING

Process of removing free ions from water ‑ see deionised water.

WAXY DISTILLATE

A fractional cut about equal to the middle section of long residue.  Hydrocracker Feedstock.

WEAR

The attrition or rubbing away of the surface of a material as a result of mechanical action.

WEATHERING

The often undesired process of slow evaporation of volatile fractions from a petroleum fraction during storage.  It is promoted by breathing.

WEIGHTED AVERAGE BED TEMPERATURE (WABT)

The sum of the individual bed temperature weighted for the amount of catalyst in each bed, divided by the total catalyst weight.

The WABT is often 'normalised', to take account of changes in feed type or reaction severity, to allow direct comparison on the same base.

WEIR

A wall or partition for maintaining a level of liquid, used in fractionator trays and kettle reboilers.

WET GAS

petroleum gas containing such quantities of the lower members of the paraffin hydrocarbon series (propane, butane etc.) that the recovery of liquid products from that gas may be economical.  A gas containing a relatively high proportion of hydrocarbons which are recoverable as liquids.

WHESSOE

Tank gauging systems used in oil movements.

WHITE OIL

Generic name applied to highly refined, colourless hydrocarbon oils.

WHITE PRODUCTS

Light petroleum products such as gasoline, white spirit and kerosene.

WHITE SPIRITS

Fractions intermediate between gasoline and kerosene with a boiling range of approximately 150‑200C.  They are used in paints and dry cleaning.  Not an NZRC product.

WIDE RANGE DISTILLATE

A distillate with a wide boiling range.  As a combination of gasoline and kerosene fractions it is used for aircraft powered by gas turbines.

WORK SAFE AUDIT

A method of assessing any job for unnecessary risk.  Can be done by another or by oneself.

X

XRAY

Otherwise known as Rontgen rays.  One of the highly penetrating radiations similar to Gamma rays; they do not come from the nucleus of the atom, but from the surrounding electrons.  They are produced by electron bombardment.  Applications; analysis (fluorescent x‑ray spectroscopy); non‑destructive testing, e.g. tube walls in furnace.

XYLENE C₆H₄ (CH) ₂

An aromatic hydrocarbon of which there are three isomers (ortho, meta and para).  An important constituent of gasoline.

Y

YARD PIPE (YP)

Any of the pipes within the Tank Farm used for rundown, transfer, shipping etc.  As distinct from the pipes within the unit battery limits.  The yard pipes are numbered.

YIELD

The amount of a desired product or products obtained in a given process, expressed as a percentage of the feedstock.  There are many yields, each of which should be specifically defined when used, e.g. Saleable yield is the volume % of feedstock turned into saleable product.

REGULARLY USED ABBREVIATIONS

A                           Absolute (Pressure or Temperature)

ABS                      Asphalt Burning System

AFQRJOS               Aviation Fuel Quality Requirements for Jointly Operated Systems

AFRA                   Average Freight Rate Assessment

AGST                   Authorised Gas Safety Tester

AGO                     Automotive Gas Oil

AIP                       Australian Institute of Petroleum

AN                        Asset North

AO                        Asset Offplot

AOC                     Accidentally Oil Contaminated Sewer

APC                      Advanced Process Control.

API                       American Petroleum Institute

ARPS                   Asset Release Permit Signatory

AS                         Asset South

ASA                      Anti‑static Additive

ASTM                  American Society for Testing Materials

ATCE                   Average Total Capital Employed

B

BA                        Breathing Apparatus

BBL                     Barrel

BBL                     Block Battery Limit

BBU                     Blown Bitumen Unit

BCW                    Boiler Circulation Water

BDU                     Butane Deasphalt Unit

BFW                     Boiler Feed Water

BHP                     Brake Horse Power

BOD                     Biochemical Oxygen Demand

BS&W                 Basic Sediment & Water

BTHU, BTU       British Thermal Unit

C

^oC                          Centigrade (or Celsius)

CAD                     Computer Aided Design

CAM                    Computer Aided Management

CASS                   Critical Activity Specification Sheet.

CASP                   Computer Aided Shutdown Planning

CD                        Crude Distiller

CEL                      Corrected Energy and Loss

CFPP                    Cold Filter Plugging Point

CFR                      Combined Feed Ratio

CFR                      Co-operative Fuel Research Council

CO                        Cooling Oil

CO                        Carbon Monoxide

CO₂                       Carbon Dioxide

COC                     Continuously Oil Contaminated Sewer

COD                     Chemical Oxygen Demand

COW                    Crude Oil Wash

CP                         Centipoise

CPA                      Critical Path Analysis

CPR                      Cardio Pulmonary Resuscitation

CPSL                    Competitive Price and Supply Level

CR                        Compression Ratio

CRI                      Criteria Referenced Instruction

CS                         centistokes

CTL                      Coastal Tankers Ltd

CW                       Cooling Water

CWD                    Combined Waxy Distillate

D

DAO                     De‑asphalted Oil

dB(A)                   Scale for measuring all levels of Noise

DCF                      Discounted Cash Flow

DEP                      Design & Engineering Practice

DERD                  Min of Defence Directorate of Engines

DERV                  Diesel Engined Road Vehicle

DFE                      Di‑Fluoro Ethylene

DIPA                    DI Iso Propanol Amine

DMDS                  Di Methyl Di Sulphide

DOL                     Department Of Labour

DRG                     Drawing

DWT                    Dead Weight Tons

E

ECC                     Employee Consultative Committee

EMPRV               Maintenance planning & Scheduling system used at NZRC.

ENCHEM               Energy & Chemical Plant (NZQA National Certificate levels 2 & 4)

EOR                     End of Run

EPC                      Enhanced Process Control.

ESO                      Emergency Shut Off

ETA(D)                Estimated Time of Arrival (Departure)

F

^oF                          Fahrenheit

FBP                      Final Boiling Point

FC                         Foecal Coliform

FIFO                     First In First Out

FMA                     Free Mineral Acidity

FO                         Flushing Oil

FOB                      Free On Board

FOR                      Flushing Oil Return

FOS                      Flushing Oil Supply

FVI                       Flexible Volatility Index

G

GLC                     Gas Liquid Chromatography

GCWR                 Gland Cooling Water Return

GCWS                  Gland Cooling Water Supply

GM                       General Manager

GRM                    Gross Refiners Margin

GSC                      Gas Solid Chromatography

GSP                      Government Selling Price

H

HCC                     Hydrocarbon Collecting System

HCU                     Hydrocracker Unit

HBFW/HHFW   HP Boiler Feed Water

HDS                     Hydrodesulphuriser

HDT                     Hydrotreater

HITLOP              High Temperature Low Pressure

HMU                    Hydrogen Manufacturing Unit

HR                        Human Resources

HSE                      Health, Safety & Environment

HTS                      High Temperature Shift

HVI                      High Viscosity Index

HVU                     High Vacuum Unit

HWD                    Heavy Waxy Distillate

H₂S                       Hydrogen Sulphide

I

IBP                       Initial Boiling Point

ICA                      Ignition Control Additive

ID                         Internal Diameter

IGS                       Inert Gas System

IP                          Institute of Petroleum

ISP                        Information Systems Planning

J

JFTOT                  Jet Fuel Thermal Oxidation Test

K

K                           Kelvin (temperature scale)

KHT                     Kerohydrotreater

KHDS                  Kerosene Hydrodesulphuriser

KSLA                   Koninklijke Shell Laboratorium Amsterdam (Shell Research Centre)

kWh                     Kilowatt Hour

L

LEL                      Lower Explosive Limit

LHSV                   Liquid Hourly Space Velocity

LIFO                    Last In First Out

LNG                     Liquefied Natural Gas

LOIT                    Local Oil Inland Trade

LP                         Linear Programme

LPG                      Liquefied Petroleum Gas

LTI                       Lost Time Injury

LTS                      Low Temperature Shift

LVI                       Low Velocity Index

LWD                    Light Waxy Distillate

M

MCF                     Methyl Chloroform

MESC                  Material and Equipment Standards and Code

MDFI                   Mid Distillate Flow Improper

MLSS                   Mixed Liquor Suspended Solids

MMI                    Man Machine Interface

MON                    Motor Octane Number

MOV                    Motor Operated Valve

MPMP                 Multi Period Multi Product

MSDS                  Material Safety data Sheets

MVI                     Medium Viscosity Index

N

NaOH                  Sodium Hydroxide (Caustic Soda)

NHDT                  Naptha Hydrotreater

NH₃                      Ammonia

NIAT                    Net Income After Tax

NIBT                    Net Income Before Tax

NNF                      Normally No Flow

NPV                      Net Present Value

NRV                     Non Return Valve

NSHP                   Net Suction Head Pressure

NZRC                  The New Zealand Refining Company Ltd

NZQA                  New Zealand Qualifications Authority

O

OEL                      Occupational Exposure Limit

OD                        Outside Diameter

OPCO                   Operating Company

OPEC                   Organisation of Petroleum Exporting Countries

OSH                     Occupational Safety & Health

P

PAG                      Project Approval Group

PCA                      Polycyclic Aromatic

PCR                      Plant Change Request

PEFS                    Process Engineering Flow Scheme

PEUFS                 Process Engineering Utilities Flow Scheme

PFS                       Process Flow Scheme

pH                        Power of Hydrogen Ion

PICW                   Person in Charge of Work

PID                       Proportional, Integral, Derivative

PITO                    Petrochemical Industry Training Organisation

PK                        Premium Kero

PLS                      Production Laboratory Standing Instructions

PM                        Pensky Martin

PM                        Planned Maintenance

PONA                   Paraffins, Olefins, Naphthenes, Aromatics

PROSS                 Process Control and Supervisory System

PRT                      Power Recovery Turbine

PPE                       Personal Protective Equipment

PPM(b)                Parts per Million (billion)

PPI                        Parallel Plate Interceptor

PPR                      Plant Project Request

PSA                      Pressure Swing Adsorption

PSFS                     Process Safeguarding Flow Scheme

PSIA(G)               Per Square Inch Absolute (gauge)

PSV                      Pressure Safety valve

PTW                     Permit to Work

PV                         Process variable

O

QMI                     Quality Measuring Instrument

R

RAP                      Refinery Auckland Pipeline

RBU                     Refinery Business Unit

RCU                     Remote Control Unit

RFB                      Regenerable Free Base

RFL                      Refinery Fuel and Loss

RFSU                   Ready For Start Up

RIF                       Report Input Form

RON                     Research Octane Number

ROV                     Remote Operated Valve

RPM                     Revolutions Per Minute

RSI                       Refinery Steering Instructions.

RTU                     Remote Terminal Unit

RUPIA                 Residue Upgrading Performance Index Actual

RV                        Relief Valve

RVP                      Reid Vapour Pressure

S

SAC                      Strong Acid Cation

SAE                      Society of Automotive Engineers

SAFETNET         Computer Database system used by NZRC to store HSE information

SBA                      Strong Base Anion

SCADA                Supervisory Control and Data Acquisition

SCBA                   Self Contained Breathing Apparatus

SCR                      Software Change Request

SD                         Shutdown

SDWT                  Short Dead Weight Tons

SG                         Specific Gravity

SI                          Standing Instruction

SIOP                     Shell International Oil Products

SMOC                  Shell Multi Verbal Optimising Control

SO                         Seal Oil

SO₂(O₃)                Sulphur Dioxide (trioxide)

SOR                      Start of Run

SP                         Set Point

SPL                       Sound Pressure Level

SRF                      Standard Refinery Fuel

SRU                      Sulphur Recovery Unit

STEL                    Short Term Exposure Limit

SSV                      Settled Sludge Volume

SU                         Start Up

SVI                       Sludge Volume Index

SWL                     Safe Working Load

SWS                     Sour Water Stripper

T

TAB                     Total Aerobic Bacteria

TBP                      True Boiling Point

TDC                     Total Distributed Control

TDS                      Total Dissolved Solids

TEL                      Tetraethyl Lead (Not used any more)

TLF                      Truck Loading Facility

TLV                      Threshold Limit Value

TML                     Tetramethyl Lead (Not used any more)

TOC                     Total Organic Carbon

TOIT                    Total Oil Inland Trade

TPI                       Tilted Plate Interceptor

T/SD                     Tonnes Per Stream Day

TSO                      Tight Shut Off (Valve)

TSS                       Total Suspended Solids

TWA                    Time Weighted Average

U

UEL                      Upper Explosive Limit

US                         Un-Serviceable

V

VGO                     Vacuum Gas Oil

VLCC                  Very Large Crude Carrier

VMLSS                Volatile Mixed Liquor Suspended Solids

W

WABT                 Weighted Average Bed Temperature

WHB                    Waste Heat Boiler

WHSV                 Weight Hourly Space Velocity

WOSL                  Wiri Oil Services Ltd

Y

YP                         Yard Pipe