Cable Tool

One of two principal methods of drilling for gas and oil; the other is rotary. Cable tool, the older method, consists of raising and dropping a heavy drill bit, suspended from the end of a cable, so that it pounds and pulverizes its way through the subsurface structures. Water in the hole keeps the cuttings in suspension for removal at intervals by bailing.

Calculated Bill (Also Interim Bill or Estimated Bill)

A bill for service not based on meter readings for the period being billed but based on calculations of how much gas a customer used during a particular period of time utilizing the gas consumption history of that customer and temperatures during the period.

Calculated Depreciation Reserve



To ascertain, usually by comparison with a standard, the locations at which scale or chart graduations should be placed to correspond to a series of values of the quantity which the instrument is to measure, receive or transmit. Also, to adjust the output of a device, to bring it to a desired value, within a specified tolerance for a particular value of the input. Also, to ascertain the error in the output of a device by checking it against a standard.


An apparatus for measuring the amount of heat released by the combustion of a compound or mixture.


A cup-shaped fitting placed on the end of a pipe to seal the pipe, usually threaded on the inside and screwed over the end of the pipe. Also, the act of placing a cap on a pipe. Also, to close off a gas or oil well.

Capacity Allocation


Capacity Assignment/Brokering

The sale or assignment of a specific right to firm transportation (or storage) on an interstate natural gas pipeline to another entity. In some instances, transportation capacity rights may be rebrokered. The Commission's general policy is to require the initial assignor or broker to remain obligated to the pipeline for scheduling and payment of charges.

Capacity Factor

The ratio of the actual sales during any specified period to the maximum amount of sales the system is capable of delivering during that time.

Capacity Release

A mechanism by which holders of firm interstate transportation capacity can relinquish their rights to utilize the firm capacity to other parties that are interested in obtaining the right to use that capacity for a specific price, for a given period of time and under a specifically identified set of conditions. The firm transportation rights may include transmission capacity and/or storage capacity.

Capacity Rights

Refers to the level of firm transportation service to which a customer has a contractual right.

Capacity, Effective

The maximum load which a machine, apparatus, device, plant, or system is capable of carrying under existing service conditions.

Capacity, Heat


Capacity, Installed

The maximum load for which a machine, apparatus, device, plant, or system is designed or constructed, not limited by existing service conditions.

Capacity, Peaking

The capacity of facilities or equipment normally used to supply incremental gas under extreme demand conditions; generally available for a limited number of days at maximum rate.

Capital Asset Recovery

A method to determine the cost of common equity component of return using the rate of risk- free investments plus a risk premium based on the stock market and the company's market volatility.

Capital Costs

Costs incurred in acquiring capital assets. Capital costs are capitalized and recovered through yearly charges for depreciation and amortization rather than being expensed and recovered in the year incurred.

Capital Structure

The long term debt and equity of a company. In ratemaking the capital structure is projected at the end of the test period (or when new rates are expected to go into effect) and used to determine the rate of return on rate base.

Capital Structure, Hypothetical

When a subsidiary company has a parent company that provides consolidated financing and other services that affect the subsidiary's capital structure, the subsidiary typically must prepare a hypothetical capital structure for use in a rate case filing.


The impervious geological stratum that overlays the reservoir rock and retains gas or oil in a reservoir.

Captive Customers

Buyers who can purchase gas only from one pipeline or supplier and have no access to alternate fuel sources.

Carbon Black

Almost pure amorphous carbon consisting of extremely fine particles, usually produced from gaseous or liquid hydrocarbons by controlled combustion with a restricted air supply or by thermal decomposition.

Carbon Dioxide (CO2)

A gas which is a product of combustion resulting when carbon unites with sufficient oxygen to produce complete combustion; a component of many natural gases.

Carbon Monoxide (CO)

A poisonous, combustible gas formed by incomplete combustion of carbon, or reduction of carbon dioxide.

Carbon/Hydrogen Ratio

The ratio, either on a weight or on a molecular basis, of carbon-to-hydrogen in a hydrocarbon material. Materials with a high carbon/hydrogen ratio (e.g., coal) are solid. The ratio is useful as a preliminary indication of the hydrogen quantity needed to convert the hydrocarbon to a gas and/or liquid.

Carbonaceous Material

A material which contains carbon.


A heat-treating process in which carbon is introduced into a solid iron-base alloy by heating above the transformation temperature range while in contact with a carbonaceous material which may be a solid, liquid, or gas. Carburizing is frequently followed by quenching to produce a hardened case.


A feature in some curtailment plans that allows volumes not used in one period to be used in the following period or periods.

Cascade Cycle

A liquefaction process in which a series of refrigerants are used to obtain successively lower temperatures.


The position of the company, of staff, or of intervenors in a rate or other proceeding prepared in the event of a hearing. The rate case filing is typically the company's Case-in-Chief if the rate case goes to hearing.

Cash Incentive

An incentive in the form of a rebate or cash payment that is used to induce customers to participate in a DSM program.

Cashout Provisions

To the extent a shipper violates balancing provisions, any difference between receipts and deliveries will be "cashed out", with the pipeline purchasing excess receipts at below-market prices and selling receipt shortages at above-market prices.


A length of pipe used for encasing a smaller diameter carrier pipe for installation in a well or under a road, etc.

Casing, Well

Steel pipe inserted (and sometimes cemented) into a gas or oil well, intermittently as the well is drilled, to line the well as is found necessary to eliminate ground caving and water infiltration, and to prevent gas and/ or oil from escaping or leaking from the native reservoir into other formations.

Casinghead Gas

Unprocessed natural gas containing natural gasoline and other liquid hydrocarbon vapors produced from an oil well. Frequently called WET GAS, ASSOCIATED GAS (but not all wet gas or associated gas is casinghead gas), and in the past, BRADENHEAD GAS. Technically, the term should apply only to gas produced from the casing of an oil well, and not from the tubing, but it is often applied to any gas produced in association with oil.

Cast Iron Pipe

Pipe made of pouring molten iron into molds.

Catalyst (Catalyzer)

A material that brings about a chemical reaction without being permanently changed itself in the process.

Catalytic Cracking

The decomposition or breaking down of oil or hydrocarbons through the action of a catalyst and heat.

Catalytic Rich Gas (CRG)

An SNG process developed in England by the British Gas Council. See SNG.

Catenary Support

A steel cable or cables strung between two supports and sagged to the point of minimum tension for a given evenly distributed load. Used to support a heavy electrical cable, gas main or other load which is not designed to be self-supporting and is too heavy to be carried by a normal messenger wire strung with minimum sag.


Negative electrode in an electrolytic system. See ANODE.

Cathodic Protection

A technique to prevent the corrosion of a metal surface by making that surface the cathode of an electrochemical cell.


Abbreviation for CONTRACT DEMAND.

CD Conversions

The conversion of a portion or all of a firm sales customer's contract demand to firm transportation. Part 284 of the regulations requires an open access interstate pipeline to offer its firm sales customers a yearly option of converting a specified portion of its sales entitlements under any ELIGIBLE FIRM SALES SERVICE AGREEMENT to transportation.

Ceiling Panel Heating

A system using ceiling panels as heating surfaces. Such panels can be heated by embedding hot-water pipes, warm air ducts, or electric resistance units in the panels.

Ceiling Price

The maximum lawful price which may be charged for regulated gas.

Cellulose Acetate Butyrate Plastics (CAB)

Plastics made by compounding a cellulose, acetate, butyrate ester with plasticizers and other ingredients. Cellulose acetate butyrate ester is a derivative of cellulose (obtained from cotton and/or wood pulp) made by converting some of the hydroxyl groups in cellulose to acetate and butyrate groups with chemicals.

Celsius Scale

Favored name for centigrade scale, with freezing points and boiling points of water at 0 degrees and 100 degrees, respectively.

Ceramic Radiants

Baked clay devices which become incandescent and radiate heat released to them by a gas flame.

Certificate Condition

A condition imposed by the FPC or FERC when granting a Certificate of Public Convenience and Necessity.

Certificate of Necessity (for Amortization)

A certificate issued by a Federal authority certifying that certain facilities are necessary in the interest of national defense, which permits accelerated amortization of the cost of the facilities or a certain specified percentage thereof, for income tax purposes, over a 60-month period.

Certificate of Public Convenience and Necessity

A special permit (which supplements the franchise), commonly issued by a state commission, which authorizes a utility to engage in business, construct facilities, or perform some other service. Also, a permit issued by the Federal Energy Regulatory Commission to engage in the transportation or sale for resale of natural gas in interstate commerce or to construct or acquire and operate any facilities necessary therefore, to which certificate the Commission may attach such reasonable terms and conditions as the public convenience and necessity may require.

Certified Capacity

The total certified capacity of a pipeline is the sum of the increments authorized in various certificates by the FERC. If a particular construction program will change the transmission or storage capacity of the pipeline, the certificate filing must explain the change.


In refrigeration, the quantity of refrigerant in a system; also, to put in the refrigerant charge.

Charles' Law


Check Meter

A device for measuring utility service consumption within individual dwelling units where the utility service is supplied through a master meter.

Check Valve


Chemical Resistance

(1) The effect of specific chemicals on the properties of plastic piping with respect to concentration, temperature and time of exposure. (2) The ability of a specific plastic pipe to render service for a useful period in the transport of a specific chemical at a specified concentration and temperature. (3) The ability to resist chemical attack.

Chill Factor

The temperature (at zero wind velocity) which would produce the same chilling effect as a particular combination of temperature and wind velocity. See also WIND CHILL FACTOR.

Chimney Connector

The pipe which connects a fuel burning appliance to a chimney.

Chimney Effect

The tendency of air or gas in a duct, vertical passage, or building to rise when heated due to its lower density compared to the surrounding air or gas.

China Walls

An expression that refers to the complete separation of operations for affiliated companies within a corporation to prevent undue business advantages. Pipeline companies, for example, are expected to have "china walls" separating their transportation departments from marketing affiliates to ensure that all customers moving gas on the pipeline get equal treatment.

Choke (Nipple)

An adjustable or removable bored steel fitting designed to reduce pressure and/or control production from a gas well or an oil well.

Christmas Tree

The valve assembly at the top of tubing strings and casing of a gas well or an oil well to provide primary pressure reduction, production rate control, and shut-in service.


An instrument used to analyze the make-up of various substances, and often used to determine the Btu content of natural gas.

Circulated Gas-Oil Ratio

The number of cubic feet of gas introduced into the well for gas-lift operations, per barrel of oil lifted.



City Gate (Town Border Station)


City Gate Rate

The rate charged a distribution company by its supplier(s). It refers to the cost of the gas at the point at which the distribution utility takes title to the gas.

City Gate Station

Point at which a distribution gas company receives gas from a pipeline company. See GATE STATION.

Class Life Asset Depreciation Range System (CLS)

A depreciation system effective in the year 1971, based on broad industry class of assets which can provide faster capital cost recovery through depreciation by using shorter useful lives, more advantageous first year convention and more flexibility for changing depreciation methods as well as administrative simplification.

Class of Service

Defines the type of customer. The common classes of service applied to ultimate consumers, and considerably more completely described in the A.G.A. publication "Definitions of a Gas Customer and Classes of Service for Industry Reporting Purposes", are: 1.Residential Service: Covers service to customers for domestic purposes (single, multifamily, or mobile homes, etc.). In residential service, the number of housing units within a structure determines the customer classification. 2.Commercial Service: Covers service to customers engaged in wholesale or retail trade, agriculture, communications, finance, fisheries, forestry, government, insurance, real estate, transportation, etc., and to customers not directly involved in other classes of service. 3.Industrial Service: Covers service to customers engaged primarily in a process which either involves the extraction of raw materials from the earth or a change of raw unfinished materials into another form or product.

Classification of Costs

A two step process to take functionalized costs and (1) determine whether they are fixed or variable and then (2) determine whether the fixed costs will be recovered through the demand rate or the commodity rate.

Clause, Adjustment

A provision in a utility tariff which provides for periodic changes in charges or credits to a customer due to increases or decreases in certain costs over or under those included in base rates and incurred by the seller such as purchased gas cost, transportation costs, or advance payments made for gas.

Clause, Favored Nations


Clean Air Act of 1970 (as amended)

Mandated restrictions on sulfur dioxide and nitrogen oxide emissions from power plants.

Clear Gas

Tar free gas occurring between the carbonization and gasification zones in a coal gasification plant.

Clearing Accounts

Accounts used for the accumulation of expenses which cannot be equitably distributed at the time of the charge. These accounts are cleared by distribution to other accounts on the basis of past experience, benefits received, or on some other reasonable basis.

Closed Water Piping System



The process of burning natural gas in conjunction with another fuel.

Coal Equivalent of Fuels Burned

The quantity of coal (tons) of a stated kind and heat value which would be required to supply the Btu equivalent of all fuels burned. In determining this coal equivalent, the Btu content of other fuels is generally divided by the representative heat value per ton of coal burned.

Coal Gas

Manufactured gas made by distillation or carbonization of coal in a closed coal gas retort, coke oven, or other vessel.

Coal Gasification

A controlled process of reacting coal, steam, and oxygen under pressure and elevated temperature. The crude gas is purified and has a low heating value. Subsequent catalytic upgrading can be employed to produce high-Btu pipeline grade gas.

Coal Liquefication (Coal Hydrogenation)

The conversion of coal into liquid hydrocarbons and related compounds by hydrogenation.

Coal Rank

Classification of coal based on carbon content and fuel value.

Coal Seam Gas


Coalbed Methane

Methane derived from a coal seam.

Coated Pipe


Coefficient of Expansion

The change in length per unit length or the change in volume per unit volume, per degree change in temperature.

Coefficient of Performance

Ratio of effect produced to the energy supplied -- effect produced and energy supplied being expressed in the same thermal units.


The use of a single prime fuel source in a reciprocating engine or gas turbine to generate electrical and thermal energy in order to optimize the efficiency of the fuel used. The dominant demand for energy can be either electrical or thermal. Usually it is the latter with excess electrical energy, if any, being transmitted into the local power supply company's lines (with a reciprocal situation existing when electrical demands exceed the cogeneration plant's output). A parallel exists with total energy plants, which are typically designed for the electrical demands rather than thermal. Under the 1978 Public Utility Regulatory Policies Act (PURPA), regulated utilities are required to purchase electricity furnished by cogenerators and small power producers at rates set by regulatory bodies having jurisdiction over the utility receiving the electricity based on "full avoided cost."

Coincidence Factor

The ratio of the maximum demand of a group, class, or system as a whole to the sum of the individual maximum demands of the several components of the group, class, or system. Reciprocal of the diversity factor. Compare DIVERSITY FACTOR.

Coincident Demand

The sum of the simultaneous demands of a group of consumers.


A porous, solid residue resulting from the incomplete combustion of coal heated in a closed chamber, or oven, with a limited supply of air. Coke is largely carbon and is a desirable fuel in certain metallurgical industries.

Cold Expanded Pipe

Pipe that is formed and then expanded in the pipe mill while cold so that the circumference is permanently increased by at least 1/2 percent and tensile strength is increased.

Cold Flow

The dimensional change with time of a plastic under load, following the instantaneous elastic or rapid deformation. (Also referred to as Creep.)

Combination Utility

Utility which supplies both gas and some other utility service (electricity, water, etc.). For purposes of A.G.A. statistics, a combination utility derives at least 5 percent but less than 95 percent of its total operating revenues from gas operation.

Combined Accounts

When two or more meters are combined for billing purposes under the following conditions: Where combinations of meter readings are specifically provided for in rate schedules. Where the maintenance of adequate service and/or where a company's operating convenience shall require the installation


The utilization of waste heat from large gas turbines to generate steam for conventional steam turbines, thus

Combo Heater

A single gas appliance that provides both space heating and domestic hot water. These systems are designed primarily for use as a forced air heating system, but can also be adapted for new hydronic baseboard installations.

Combuster Basket, Can or Chamber

That part of a gas turbine into which fuel is injected and burned.

Combustible Constituents

The components of a fuel that will burn. In natural gas, this is mostly methane.

Combustible Limits


Combustible Material

Combustible material, as pertaining to material adjacent to or in contact with heat producing appliances, chimney connectors and vent connectors, steam and hot water pipes, and warm air ducts, means material made of or surfaced with wood, compressed paper, plant fibers, or other material that will ignite and burn. Such material shall be considered as combustible even though flameproofed, fire retardant treated, or plastered.


Rapid chemical reaction of oxygen with fuel accompanied by the production of heat, or heat and light.

Combustion Analysis

The determination of combustion characteristics, such as exhaust gas composition and temperature, air-fuel ratio, the relation of these to perfect combustion.

Combustion Control

A device which manually or automatically proportions combustion air to fuel over the whole operating range of the burner or burners.

Combustion Tests

The sampling of combustion products to determine the percentage of constituents and their temperature.

Combustion, Products of

Constituents resulting from the combustion of a fuel with the oxygen of the air including the inerts but excluding excess air. (Not to be confused with flue gases). Compare GAS, FLUE.

Commercial Paper

Short-term promissory notes issued and sold by utilities and other companies usually through dealers in such paper.

Commercial Service


Commingled Gas

A homogeneous mix of gas obtained from various physical and contractual supply sources.


Federal Energy Regulatory Commission (FERC), or local public utility regulatory commission (PUC).

Commodity Charge

A charge per unit volume or heat content (i.e., therm) of gas delivered to the buyer. Compare DEMAND CHARGE.

Commodity Costs (Rate)

That part of the total cost of service which must be recovered through use of a commodity rate; i.e., a rate for each Mcf of gas sold. Revenue from a commodity rate varies with throughput.

Common Capital Stock or Common Stock

Shares of stock issued and stated at par value, stated value, or the cash value of the consideration received for such no par stock; none of which is limited nor preferred as to distribution of earnings or assets.

Common Carriage

The obligation to carry, for a fee, gas that belongs to another party. Also called MANDATORY CARRIAGE.

Common Costs


Common Plant

Utility plant used by a combination utility company (i.e., one which renders more than one utility service, such as gas and electric) to such extent and in such manner as to render segregation impractical, as would be the case of a garage housing gas utility and electric utility trucks.

Common Stock Dividends

Payment declared on common stock and charged to unappropriated retained earnings during a stated period.

Common Stock Equity

The funds (including retained earnings) invested in the business by the residual owners whose claims to income and assets are subordinate to all other claims.

Common Stock Equivalent

A security which is not, in form, a common stock but which usually contains provisions to enable its holder to become a common stockholder and which, because of its terms and circumstances under which it was issued, is in substance equivalent to a common stock. Convertible debt, convertible preferred stock, stock options and stock warrants meeting certain criteria are considered common stock equivalents.

Common Trench

A trench containing two or more utilities.

Communities (Served)

A community is a contiguous built-up area, incorporated or unincorporated, commonly recognized as a separate entity. Any incorporated area and its adjacent built-up unincorporated area may be counted as one community.

Company Storage

Natural gas storage facilities owned and controlled by the LDC.

Company Used Gas

The quantity of gas consumed by a gas distribution or gas transmission company or the gas department of a combination company for the use of the gas company or gas department in its gas operations such as fuel for

Comparability of Service

Refers to the comparability of quantity and quality of firm transportation service offered to the pipeline's firm bundled sales service. Aspects of comparability include access to storage and production area facilities, flexibility of receipt and delivery points, balancing requirements and other terms and conditions of service. There must be sufficient comparability of service, as well as DIVERTIBLE GAS SUPPLIES, in order to determine that a pipeline's market is competitive as firm transportation cannot be a viable alternative to the pipeline's sales service if transportation service is not comparable. The Commission has found that one way of enhancing comparability is for customers to convert all of their sales entitlements to firm transportation and for the point of sale from the pipeline to be moved upstream to the wellhead or to a HEADSTATION. In this way, all gas on the mainline is transportation gas.

Comparable Earnings


Comparison Group

A selected group of customers that do not participate in a DSM program, but otherwise have the same characteristics as the participating group. The comparison group is used to isolate program effects from other factors that affect demand. Also known as CONTROL GROUP.


A condition wherein components of a piping system and/or different specific materials can be joined together to form satisfactory joints.

Composite Book Depreciation

A method of determining an allowance for depreciation to be included as an element of cost in a cost of service study. The method looks to the service life of the total plant investment for determining depreciation rates, rather than the individual plant components. Under a composite method, an item of plant is not considered fully depreciated until that item is retired from service.

Compressed Natural Gas (CNG)

Natural gas in high-pressure surface containers that is highly compressed (though not to the point of liquefaction). CNG is used extensively as a trans-portation fuel for automobiles, trucks and buses in some parts of Italy, New Zealand, and in Western Canada, and has recently begun to penetrate some regions of the United States. Small amounts of natural gas are also transported overland in high-pressure containers.


The property of a material which permits it to decrease in volume when subjected to an increase in pressure. In gas-measurement usage, the compressibility factor "Z" is the deviation from the ideal Boyle and Charles' law behavior. See SUPERCOMPRESSIBILITY FACTOR.

Compressibility Factor



The action on a material which decreases its volume as the pressure to which it is subjected increases.

Compression Cycles

Adiabatic (isentropic) compression takes place when there is not heat added to or removed from the system. Compression follows the formula p1V1k=p2V2k, where exponent k is the ratio of the specific heat capacities. Although an adiabatic cycle is never totally obtained in practice, it is approached typically with most positive-displacement machines and is generally the base to which they are referred. Isothermal compression takes place when the temperature is kept constant as the pressure increases, requiring continuous removal of heat generated during compression. Compression follows the formula p1V1=p2V2. However, in practice it is never possible to remove the heat of compression as rapidly as it is generated. Polytropic compression is a compromise between the two basic processes, the adiabatic and the isothermal. It is primarily applicable to dynamic continuous-flow machines such as centrifugal or axial compressors. Compression follows the formula p1V1n=p2V2n, where exponent n is experimentally determined for a particular type of machine. It may be lower or higher than the exponent k used in adiabatic cycle calculations.

Compression Efficiency

The ratio of the theoretical work requirement (using a stated process) to the actual work required to compress a given quantity of gas. It accounts for the gas friction losses, internal leakage and other variations from the idealized thermodynamic process.

Compression Ratio

The relationship of absolute outlet pressure at a compressor to absolute inlet pressure.

Compressive Strength

The ratio of crushing load at failure to area of minimum original cross section of a specimen.


A mechanical device for increasing the pressure of a gas.

Compressor Fuel

Natural gas consumed by the engines in a compressor station, reported as a percentage of the gas transported through the station. Thus, a transporter whose gas passes through one or more compressor stations will be entitled to take delivery of less than 100 percent of the gas introduced into the pipeline network.

Compressor Station

Any permanent combination of facilities which supplies the energy to move gas at increased pressure from fields, in transmission lines, or into storage.

Compressor Stations

Locations along the interstate pipeline at which large (thousands of horsepower) natural gas-powered engines increase the pressure of the market natural gas stream flowing through the station by compression.


A number expressing the percent of the specified constituent in a mixture to the total quantity of the mixture, as pounds of salt per pound of brine.


The liquid resulting when a vapor is subjected to cooling or application of pressure. Also, liquid hydrocarbons condensed from gas and oil wells. Compare LIQUIDS, NATURAL GAS.


A heat exchanger which removes heat from vapor causing it to condense into a liquid.

Conditional Demand Analysis

A method that is used to estimate equipment-specific energy consumption, without requiring end-use metered data for the appliances. Instead, it relies on the statistical analysis of consumption data, appliance saturation data, and other data such as demographic, household, weather, economic and market data.

Conditionally Effective Rates

Rates that have been allowed by FERC subject to refund pending final disposition of the rate hearing.

Conduction, Thermal

Process of heat transfer through a material medium in which kinetic energy is transmitted by the particles of the material from particle to particle without gross displacement of the particles.

Conductivity, Thermal

Time rate of heat flow through a unit area and unit thickness of a homogeneous material under steady conditions when a unit temperature gradient is maintained in the direction perpendicular to area, expressed in Btu per hour per square foot of surface, per foot or inch of thickness, per degree Fahrenheit temperature difference across the thickness. Materials are considered homogeneous when the value of the thermal conductivity is not affected by variation in thickness or the size of the sample within the range normally used in construction.

Conductor, Thermal

A material which readily transmits heat by means of conduction.

Confined Space

Any space not intended for continuous employee occupancy, having a limited means of egress.

Confirmed Nomination

An agreement by a seller to deliver/cause delivery or a transporter to receive and deliver a specific quantity of gas for a specified period at various points under a Sales or Transportation Agreement or for all contracts at one specific point. The confirmed nomination is in response to a purchaser's or shipper's nomination. See NOMINATION.

Confiscatory Rates

Approved rates which yield a rate of return insufficient to attract new capital.

Conjunctive Billing

Tariff provisions which permit the grouping of delivery points for billing purposes. These provisions permit customers having multiple delivery points to fill up the "valleys" in gas takes at some points by taking in excess of contract demand at other points for resale industrial loads without paying additional demand charges for such excess volumes.

Consenting Party

A party (the company, staff, a customer, or other interested party) that supports a stipulation and agreement or settlement in a rate or other proceeding. See STIPULATION & AGREEMENT, CONTESTING PARTY.

Conservation Program

A utility-sponsored program that attempts to reduce a customer's energy consumption, over most, or all hours of the day.

Conservation Supply Curve

A graph showing the quantity of energy savings of individual efficiency measures on the x-axis and the total cost per unit of energy saved on the y-axis.


Means of reducing the energy resources required to do a task such as heating a house, transporting freight between two points, or producing steel.

Construction Expenditures

Cost of construction, including work-in-progress (CWIP), overhead or contributions in aid of construction and allowances for funds used during construction (AFUDC), for additions to, renewals and replacements of plant facilities, but excluding the purchase cost of an acquired operating unit or system of utility plant, accounting transfers and adjustments to utility plant, and cost to remove plant facilities from service.

Construction Work in Progress (CWIP)

Balances of work orders for utility plant in the process of being constructed but not yet placed in service. Most of the items shown as CWIP are eventually closed to utility plant in service.

Consumer, Gas

The ultimate user of gas, as contrasted to a "customer" who may purchase gas for resale.


The quantity of natural gas used by ultimate consumers.

Content of Fuel

The heat value per unit of fuel expressed in Btu as determined from tests of fuel samples. Examples: Btu per pound of coal, per gallon of oil, per cubic foot of gas.

Contesting Party

A party (staff, a customer, or other interested party) that does not support a stipulation and agreement or settlement in a rate or other proceeding, and prefers to take the case to hearing. The filing company can not be a contesting party; in that case there is no settlement. See STIPULATION & AGREEMENT, CONSENTING PARTY.

Continuing Property Record (CPR) Unit

A Continuing Property Record Unit is the minimum division of plant selected to be continuously associated with its cost in the plant records.

Contract Area

For the purpose of FERC Form 15, the area encompassed by one or more fields under a single purchase contract but not larger than the area covered by a single supply source.

Contract Assignment

A mutual agreement to release or ascribe a contractual obligation from the original contractor to another party.

Contract Balancing

A process of managing the difference between the quantities received and delivered at various points under a contract during a defined period of time (i.e., hourly, daily, monthly, etc.).

Contract Carriage

Transportation, by a company, of gas quantities belonging to another party, for which the company charges a fee.

Contract Carrier

A transporter that voluntarily provides its services on a contractual basis for other parties.

Contract Demand (CD)

The amount of the system's capacity to deliver gas which a natural gas pipeline or distributor agrees to reserve for a particular customer and for which the customer agrees to pay a demand charge as specified in the applicable tariff. Also, the daily quantity of gas which a supplier agrees to furnish and for which the buyer agrees to pay, under a specific contract.

Contract Imbalance Quantity

The cumulative difference between all quantities of gas received and quantities of gas delivered for a contract from inception through the most current billing period.

Contract Pressure

The maximum or minimum required operating pressure at a receipt or delivery point as specified in the Service Agreement.

Contract Quantity Method

A method to allocate demand costs by function to customer classes based on the customer classes' contract quantity or a company's obligation to serve the customer class.

Contract Request

A customer request for transportation or sales service.

Contract Storage

Storage facilities, or a portion of storage facilities, which are leased to others for the purposes of storing gas. The portion of storage facilities which has been made available to others may not be used by the pipeline for system supply. See SYSTEM STORAGE.

Contract Storage Service

A service provided by a pipeline, or other owner of storage facilities, whereby storage customers may lease a portion of the facilities for the purposes of storing customer-owned gas. Contract storage service generally involves the injection of customer-owned gas into the facility during the off-peak period, the holding of the accumulated inventory for the customer, and the withdrawal of gas during the peak heating season.

Contracted Reserves

Natural gas reserves dedicated to the fulfillment of gas purchase contracts.

Contributions in Aid of Construction (Non-Refundab

The contributions or donations in cash, property, or services from companies, states, municipalities, other governmental agencies, individuals, and others for construction purposes, now carried as a plant item. Compare ADVANCES FOR CONSTRUCTION.


A device designed to regulate the gas, air, water, and/or electrical supply to a gas-consuming or any other device.

Control Gas

That part of the main gas flow which is separated and used to actuate the automatic valve through a moving member such as the diaphragm in a diaphragm valve.

Control Group


Control, Limit

An automatic safety control responsive to changes in level, pressure, or temperature and normally set beyond the operating range for limiting the operation of the controlled equipment.

Control, Operating

A control other than a safety control or interlock, to start or regulate burner firing according to load demand and to stop or regulate fire on satisfaction of demand or upon reaching normal temperature or pressure in the device being fired. Operating controls may also actuate auxiliary equipment.

Control, Primary Safety, Combustion Safeguard

A control responsive directly to flame properties, sensing the presence of flame and, in event of ignition failure or unintentional flame extinguishment, causing safety shutdown.

Control, Safety

Automatic controls and interlocks, including relays, switches, and other auxiliary equipment used in conjunction therewith to form a safety control system, which is intended to prevent unsafe operation of the controlled equipment.


Internal procedures to monitor the components of cost of service based on updated actual costs.


Heat transfer by the movement of fluid.


An agency of convection. In heat transfer, a surface designed to transfer its heat to a surrounding fluid largely or wholly by convection. The heated fluid may be moved mechanically or by gravity (gravity convector). Such a surface may or may not be enclosed or concealed.

Conversion Burner


Conversion to Natural Gas

Changing the gas service to ultimate customers from a fuel other than natural gas to natural gas, including adjustment of consumers' appliances to perform satisfactorily with natural gas. Natural gas does not necessarily mean straight natural gas; stabilizing the heat content of the sendout gas by diluent gases or enriching gases is not considered to change the basic character of natural gas. For the purpose of uniform reporting, a company should be considered a natural gas company when 95 percent of the system has been converted.

Conversion Unit

A unit consisting of a burner together with associated thermostat and safety controls, which can be used to convert heating equipment from one fuel to another.

Convertible Securities

Securities which are convertible into other classes of securities (usually common stock) of the same corporation at the option of the security holder, but only in accordance with prescribed conditions.

Cooling Coil

A coil of pipe or tubing used as a heat exchanger to cool material inside or outside the coil by means of colder material passing over or through the coil respectively.

Cooling Degree Day


Cooling Tower


Copper Insert

Insertion of a copper liner into a steel service line.

Core Customers

Residential and small commercial customers who must rely on the traditional distributor bundled service of sales and transportation. Compare NON-CORE CUSTOMERS.

Correlative Rights

Ownership rights of multiple oil and/or gas producers within a common reservoir.


Destruction of a metal by chemical or electrochemical reaction with its environment.

Corrosion Fatigue

Reduction of fatigue durability by a corrosive environment.

Corrosion Mitigation

The reduction of metal loss or damage through use of protective methods and devices.

Corrosion Prevention

The halting or elimination of metal damage through use of protective methods and devices.

Corrugated Stainless Steel Tubing (CSST) Piping Sy

An assembly of corrugated stainless steel tubing, distribution manifold(s), tube connection fittings, and tube shielding devices, intended for field assembly and installation in residential or commercial buildings to distribute fuel gas to gas utilization equipment within the building. The piping system may also include a gas pressure regulator(s), a shutoff valve(s), and other approved devices or components.


The amount of money actually paid for property, material or services. When the consideration given is other than cash in a purchase and sale transaction, as distinguished from a transaction involving the issuance of common stock in a merger or a pooling of interest, the value of such consideration shall be determined on a cash basis.

Cost Allocation

The rate design step that allocates the demand and commodity costs of the various functions to the customer classes. See COST OF SERVICE.

Cost Based GIC


Cost of Capital

The weighted average of the cost of various sources of capital, generally consisting of outstanding securities such as mortgage debt, preferred and preference stock, common stock, etc., and retained earnings, but which may include other interest-bearing obligations or sources of capital such as short-term notes, customer security deposits; and which may also include noninterest-bearing sources such as funds generated through use of deferred taxes, i.e., accelerated amortization, accelerated depreciation, and accumulated investment tax credit (subject to tax law limitations). The weight to be used for each source of funds generally is the percentage of each fund outstanding to the total amount outstanding of all sources of funds considered; however, target or projected ratios may also be used. The cost rate assigned each source may be the average cost of all obligations outstanding or projected costs for each source or a rate specifically assigned by a commission. The summation of the product of the weight (percentage) of each source to the total source times its cost is the cost of capital.

Cost of Removal

The cost of demolishing, dismantling, tearing down or otherwise removing plant, including the cost of transportation and handling incidental thereto.

Cost of Service

A term used in public utility regulation to mean the total number of dollars required to supply any total utility service (i.e., revenue requirements); it must include all of the supplier's costs, an amount to cover operation and maintenance expenses, and other necessary costs such as taxes, including income taxes, depreciation, depletion, and amortization of the property not covered by ordinary maintenance. Included also is a fair return in order that the utility can maintain its financial integrity, attract new capital, and compensate the owners of the property for the risks involved. A "cost of service study" is made in order to assist in determining the total revenue requirements to be recovered from each of the various classes of service. The amounts to be recovered from each of the classes of service are determined by the management or a commission after study of the various factors involved in rate design. Cost analysis or cost allocation is an important factor in rate design but only one of several important factors. Cost analysis does not produce a precise inflexible "cost of service" for any individual class of service because cost analysis involves judgment in certain cost areas. Its principal value is in determining the minimum costs attributable to each class of service. Other factors that must be considered in rate design are the value of the service, the cost of competitive services, the volume and load factor of the service and their relation to system load equalization and stabilization of revenue, promotional factors and their relation to the social and economic growth of the service area, political factors such as the sizes of minimum bills, and regulatory factors.

Cost of Service Tariff

A special type of tariff which allows a gas pipeline to adjust periodically for any overage or underage in recovery of its cost of service (including per unit adjustments for loss of load). In contrast, a normal fixed-rate tariff, while specified based upon a cost of service estimate, does not provide for recovery of any previous underage or return of any overage above actual costs incurred.

Cost Zones

Geographic areas of the company's operations established for the purpose of accumulating certain costs to facilitate a fair distribution of such costs among all customer classes. Common cost zones for a long line pipeline are supply zones and market zones.

Cost, Original

The direct and indirect cost of utility property at the time it was first dedicated to public service.

Cost, Reproduction

The cost of reproducing utility property at current cost.

Cost-Effectiveness Test


Costs, Common

Those costs incurred by combination utilities which are not directly or solely identified with a specific department (e.g., gas and electric), and which are normally allocated to each department on the basis of some reasonable and factual relationship. Compare COSTS, JOINT.

Costs, Joint

Those costs (e.g., supervisory costs) not directly assignable to either construction or operation accounts which are accumulated in clearing accounts to be distributed to appropriate accounts on some reasonable basis. Compare COSTS, COMMON.

Council of Petroleum Accountants Societies (COPAS)

An organization that publishes industry guidelines for oil and gas accounting and shipping.


A sleeve-type fitting used to connect two pipes of similar or different materials, providing insulation or continuity.


Processing that breaks down and rearranges the molecular structure of hydrocarbon chains. In thermal cracking, high temperature and high pressures are applied; in catalytic cracking, temperature and pressure are applied in the presence of a catalyst. See CATALYST.

Cream Skimming

Installing only the lowest cost or easy-to- install DSM measures while ignoring other cost-effective opportunities.


The time-dependent part of strain due to a constant stress (also referred to as cold flow).

Critical Temperature and Pressure

That temperature above which a gas cannot be liquefied by pressure alone. The pressure under which a substance may exist as a gas in equilibrium with the liquid at the critical temperature is the critical pressure.

Cross Over

Piping used to connect two or more pipelines.

Cross Subsidization

Practice of charging one customer class with rates that are higher than the cost of service for that class, thus allowing another class to be charged rates that are lower than the respective cost of service for that class.

Crude Oil (Crude, Mineral Oil, Crude Oil, Petroleu

A geological liquid consisting of hydrocarbons and relatively small amounts of sulfur, nitrogen, and oxygen in the form of derivatives of hydrocarbons. Crude is formed under pressure from residual plant matter accumulated in a swamp over a period of time. It may come from the earth with varying quantities of water, gas, and other organic matter. Some crudes are very volatile and others are very viscous liquids. Crude oil may contain such impurities as sulfur and hydrocarbons. These are compounds containing a variety of combinations of carbon with hydrogen. There are a very large number of these compounds and they form the basis of a number of petroleum products. These compounds may exist as gases or liquids or solids. A number of hydrocarbons are also contained in bituminous coal, oil shale and tar sands. Crude is generally classified into three basic types: paraffin base crude oils contain a high degree of paraffin wax and little or no asphalt. Besides wax, they also yield large amounts of high-grade lubricating oil. Asphalt base crudes contain large proportions of asphaltic matter, and mixed base crudes contain quantities of both paraffin wax and asphalt. This is why crude oils do not always look alike. Some are almost colorless or pitch black. Others can be amber, brown or green. They may flow like water or creep like molasses. Some crudes, containing relatively large amounts of sulfur and other mineral impurities, are called "sour" crudes. Others, having a fairly low sulfur content, are called "sweet" crudes.


A material that is a gas at ambient conditions but can be liquefied at below-ambient temperatures. This includes all of the ambient temperature gases.


The science of producing very low temperatures such as natural gas liquefaction.


A state of molecular structure in some resins which denotes uniformity and compactness in the molecular chains forming the polymers.

Cubic Foot

The most common unit of measurement of gas volume. It is the amount of gas required to fill a volume of one cubic foot under stated conditions of temperature, pressure, and water vapor.

Cubic Foot Metered

The quantity of gas that occupies one cubic foot under pressure and temperature conditions in the meter.

Cubic Foot, Standard

That quantity of gas which under a pressure of 14.73 psia and at a temperature of 60oF occupies a volume of one cubic foot without adjustment for water vapor content.

Curb Box

A vertical tube, capped at ground level, and usually located near the street, that protects access to the underground shut-off valves on service lines to residential and small commercial customers. (Usually found in sidewalk with gas company name).

Curb Line

Street or highway map line which shows the curb location.

Curb Stop or Curb Valve

A shut-off valve in a gas service line, usually between the curb and the customer's property line.

Current Adjustment

Applicable to pipelines which have a PGA mechanism in effect. The Current Adjustment is a rate component in a pipeline's tariff used to reflect the difference between 1) the current weighted average projected purchased gas costs and 2) the weighted average projected purchased gas costs reflected in the effective period of the previous scheduled PGA.

Current and Accrued Assets

Generally consists of items realizable or to be consumed within one year from the date of the balance sheet. Includes Cash, Special Deposits, Working Funds, Temporary Cash Investments, Notes and Accounts Receivable, Materials and Supplies, (including Fossil Fuel), Prepayments, and Other Current and Accrued Assets (receivable, for interest, dividends, rents, etc.).

Current Gas


Current Reservoir Capacity



Curtailment of gas service is a method to balance a utility's natural gas requirements with its natural gas supply. Usually there is a hierarchy of customers for the curtailment plan. A customer may be required to partially cut back or totally eliminate his take of gas depending on the severity of the shortfall between gas supply and demand and the customer's position in the hierarchy.

Cushion Gas

The gas required in a reservoir, used for storage of natural gas, so that reservoir pressure is such that the storage gas may be recovered.

Custody Transfer

The legal and commercial transfer of a commodity such as natural gas, LNG, etc. from one party to another.

Custody Transfer Transaction

The Custody Transfer Transaction is the hand-off of the physical commodity from one operator to another.


An individual, firm, or organization which purchases service at one location under one rate classification, contract, or rate schedule. If service is supplied at more than one location or under more than one rate schedule, each location and rate schedule shall be counted as a separate customer unless the consumption at the several locations is combined before billing and billed on one rate schedule. See CLASS OF SERVICE.

Customer Advances for Construction


Customer Charge

A fixed amount to be paid periodically by the customer without regard to demand or energy consumption.

Customer Costs

The costs directly related to serving the customer, regardless of sales volume such as meter reading, billing, and fixed charges for the minimum investment required to serve a customer.

Customer Density

Number of customers in a given unit or area or on a given length of distribution line.

Customer Imbalance Quantity

The cumulative difference between quantities of gas received and quantities of gas delivered for all of a customer's transportation contracts from inception through the most current billing period.

Customer Nomination Method

A method to allocate a portion of demand cost to customer classes based on those classes' nominated level of service.

Customers, Average Number of

The average number of customers is determined by summing the customers for each of the periods involved and dividing by the number of periods. See CUSTOMER.


The rock fragments dislodged by the bit and brought to the surface in the drilling mud. Cuttings are analyzed by geologists to obtain information about the formations drilled through.

Cycle Billing

A billing procedure which provides for the billing of a portion of utility customers each working day so that all customers are billed within a predetermined period, such as one month, two months, etc. (In some companies, each day's billing is referred to as a "billing cycle day," "billing day," or "billing cycle." Other companies use "billing cycle" to refer to the total period which covers billing of customers within a specific period).1

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