PETROCHEMICAL, OIL & GAS DICTIONARY (T-Z)

DIFFERENT TERMS & ABBREVIATIONS USED IN OIL & GAS INDUSTRY (REFINERIES) & IN PETROCHEMICAL INDUSTRY INCLUDING MOST COMMONLY USED CHEMICAL INDUSTRY TERMS.

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

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

2. 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.

a) 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.

b) 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.

 

Z

NOTHING FOUND FOR “Z”.