Tail Block
The last or lowest priced block of energy in a declining block rate structure.
Tail Gas
The residue gas left after the completion of a treating process designed to remove certain liquids or liquefiable hydrocarbons.
A clause that requires a minimum quantity to be physically taken and paid for, usually gas in association with oil, or wells that will be damaged by failure to produce.
The clause in a gas supply contract which provides for a specific period a specific minimum quantity of gas must be paid for whether or not delivery is accepted by the purchaser. Some contracts contain a time period in which the buyer may take later delivery of the gas without penalty.
Take-or-Pay Credits
Credits provided by FERC Order No.500 which allow the pipeline to credit a quantity of gas it transports against its obligation to take a similar quantity of gas under a take-or-pay contract executed before June 23, 1987.
Take-or-Pay Liabilities
The liabilities incurred by many pipelines under contractual obligation to pay for volumes of gas they were unable to take because of reduced sales and lack of market demand. Some of the liability may in effect represent prepayment for gas that may be taken at a later time. Conversely, a portion of the liability may represent unrecoverable obligations due to contractual limitations or the inability of the pipeline to take the gas at a later period. See TAKE-OR-PAY CREDITS. Methods for recovery of Take-or-Pay liabilities were addressed by the Commission in Order No.500. See EQUITABLE SHARING MECHANISM.
The process of sorting liquids in a tank, the capacity of tanks, or the price paid for tank storage of liquids.
To cut threads in a round hole so that other fittings or equipment can be screwed into the hole. Also to make an opening in a vessel or pipe.
Tar Sands
Hydrocarbon bearing deposits distinguished from more conventional oil and gas reservoirs by the high viscosity of the hydrocarbon which is not recoverable in its natural state through a well by ordinary oil production methods.
A gas company schedule detailing the terms, conditions and rate information applicable to various types of natural gas service. This document is filed with and approved by FERC or a state regulatory body.
Tariff Gas
Gas purchased by gas distributors from gas pipelines. The term is usually used by natural gas distributors to distinguish gas they purchased from pipelines from gas they purchased directly from producers and had transported.
Tariff Volume
The maximum amount of natural gas which a consumer is entitled to receive during any specified time period. Usually the volume of gas that is subject to a curtailment plan. Also referred to as a contract obligations and entitlements.
Tax Life
The facility life permitted by the tax law for use in determining the tax depreciation deduction.
Technical Potential
In DSM, an estimate of energy savings based on the assumption that all existing equipment or measures will be replaced with the most efficient equipment or measure that is technically feasible, without regard to cost or market acceptance. Compare ACHIEVABLE POTENTIAL, MARKET POTENTIAL and ECONOMIC POTENTIAL.
Technically Feasible
In DSM, an option which could be implemented for which equipment has been developed and tested and is available in the current marketplace, or will be in the future.
Tee, Street
Use of an electrical apparatus transmitting data to a distant point for indicating, recording, or integrating the values of a variable quantity.
Telescoping Points
The degree of "hotness" or "coldness" as measured on a definite scale.
Temperature Limiting Device
A device which automatically interrupts the gas flow to the burner when the temperature exceeds the limit set.
Temperature Scale, Absolute (Kelvin)
A temperature scale independent of the thermometric properties of the working substance. For convenience, the absolute (Kelvin) degree is identified with the Celsius degree. The absolute zero in the Kelvin scale is minus 273.160 Celsius (C). See THERMODYNAMICS.
Temperature, Ambient
The temperature of the air, atmosphere or other fluid that completely surrounds the apparatus, equipment or the workpiece under consideration. For devices which do not generate heat, this temperature is the same as the temperature of the medium at the point of device location when the device is not present. For devices which do generate heat, this temperature is the temperature of the medium surrounding the device when the device is present and generating heat. Allowable ambient-temperature limits are based on the assumption that the device in question is not exposed to significant radiant-energy sources such as sunlight or heated surfaces.
Temperature, Critical
The temperature above which a fluid cannot exist as a liquid and hence cannot be liquefied by pressure alone.
Temperature, Dew-Point
The temperature at which a vapor begins to condense and deposit as a liquid.
Temperature, Dry Bulb
Technically, the temperature registered by the dry bulb thermometer of a psychrometer. It is identical with the temperature of the air.
Temperature, Effective
An arbitrary index which combines into a single value the effect of temperature, humidity, and air movement on the sensation of warmth or cold felt by the human body. The numerical value is that of the temperature of still, saturated air which would induce an identical sensation. See CHILL FACTOR.
Temperature, Ground
In the gas industry, the temperature of the earth at pipe depth.
Temperature, Wet Bulb
The temperature an air parcel would have if cooled adiabatically to saturation at constant pressure by evaporation of water from it, all latent heat being supplied by the parcel.
Temperature-Compensated Meters
These meters measure volume at pipeline conditions using a device which will convert volume at flowing temperature to volume at base temperature. These temperature compensators use a temperature-sensitive device to continuously vary the diaphragm-stroke to provide a temperature-compensated volume output. Meters equipped with temperature-compensators are often identified by red badges on the index face.
Temporary Certificate
Temporary authorization from the Commission allowing a jurisdictional pipeline for good cause to commence sales and service and/or construction of facilities prior to the time that the Commission issues a permanent certificate pursuant to Section 7 of the NGA of 1938.
Tensile Strength
The tensile stress necessary to cause failure in a short-time test. It is performed by pulling a specimen of specified dimension at a specified rate.
Test Period
A period of time extending nine months beyond the end of the Base Period. Adjustments to Base Period data may be made for changes expected to occur during the Test Period, as provided in the Code of Federal Regulations. See BASE PERIOD, TEST YEAR.
Test Weld
The process of cutting out a portion of a weld in a pipeline for testing as to acceptability.
Test Year
The period selected as the base for presenting data in a case or hearing before a regulatory agency upon which revenue requirements are determined. The period is generally a 12-month period, and it may or may not include adjustment to reflect known or projected changes in operating revenues, expenses, and rate base.
Test-Well Contribution
An agreement to pay the owner of an adjacent tract for a portion of the cost of drilling an exploratory well on his property.
Theoretical Air Requirements
Volume of air necessary to insure the complete combustion of unit mass or volume of a fuel.
Theoretical Depreciation Reserve
A calculated or artificial reserve, rather than actual, used as a guide in analyzing the actual reserve condition. It is not an exact measurement for determining the condition of the actual reserve.
A unit of heating value equivalent to 100,000 British thermal units (Btu).
Thermal Conductivity
Thermal Expansion (Coefficient of)
The fractional change in length (sometimes volume, specified) of a material for a unit change in temperature.
Thermal Stress Cracking (TSC)
Crazing and cracking of some thermoplastic resins which results from overexposure to elevated temperatures.
Thermally Actuated Valve
An automatic valve which utilizes the heat generated by the resistance of an electrical component in opening or closing the valve.
Two pieces of dissimilar metal welded or brazed together at one end. When the welded end is at a different temperature from the free ends, an electrical voltage is developed that can be measured across the free ends, and that is proportional to the temperature difference and can, therefore, be used to measure the temperature at the brazed end.
The science and study of the relationships between heat and mechanical work. First Law: Energy can be neither created nor destroyed, but has a mass equivalent. Second Law: Heat cannot pass from a colder to a warmer body without the expenditure of energy; all systems tend to equilibrium. Third Law: At absolute zero, the entropy of a pure substance can be taken to be zero.
A quality which allows a material to repeatedly soften when heated and harden when cooled. Typical of the thermoplastics family are the styrene polymers and copolymers, acrylics, cellulosics, polyethylenes, vinyls, nylons, and the various fluorocarbon materials.
A material that will undergo or has undergone a chemical reaction by the action of heat, catalysts, ultra-violet light, etc., leading to a relatively infusible state. Typical of the plastics in the thermosetting family are the aminos (melamine and urea), most polyesters, alkyds, epoxies, and phenolics.
An automatic device actuated by temperature changes designed to control the gas supply to the burner(s) in order to maintain temperature between predetermined limits, and in which the thermal actuating element is an integral part of the device: 1. Electric Switch Type: A device which senses changes in temperature and control electrically, by means of separate components, the flow of gas to the burner(s) to maintain selected temperature. 2. Graduating Thermostat: A thermostat in which the motion of the thermostat valve is in direct proportion to the effective motion of the thermal element induced by temperature change. 3. Quick-Acting Graduating Thermostat: A thermostat which changes from the completely closed position, or vice versa, but not with a snap. 4. Snap-Acting Thermostat: A thermostat in which the thermostatic valve travels instantly from the closed to the open position, or vice versa.
Total of transportation volumes and tariff sales; all gas volumes delivered.
Throughput Level
The combination of Sales Level and Transportation Level. See SALES LEVEL, TRANSPORTATION LEVEL.
In heating or air conditioning, the distance air will carry, measured along the axis of an air stream, from the supply opening to the position in the stream at which air motion reduces to 50 feet per minute.
Tie In
To make a connection to an existing pipeline or piping.
Tight Sands
Gas-bearing geologic strata that holds gas too tightly for conventional extraction processes to bring it to the surface at economic rates without special stimulation.
Times Fixed Charges and Preferred Dividends Earned
The ratio of (a) income before interest charges to (b) the sum of interest charges and dividends on preferred stock. Used as a measure of preferred dividend coverage or safety.
Times Fixed Charges Earned Before Income Taxes
The ratio of (a) income before interest charges, adjusted to exclude income taxes, to (b) interest charges (principally interest on long-term debt). Used as a measure of the interest coverage or safety.
Title tracking
Detailing (in confidence to the appropriate client) the sales and parties in transactions involving units of natural gas, which can be lengthy and complex.
Title Transfer
The Title Transfer Transaction is the sale/purchase and associated title transfer of the commodity ownership.
Top Sheets
The FERC Staff's written response to a company's filing for a general rate change. This is the Staff's initial position for discussion in settlement conferences and is prepared at the end of the Staff Audit. See STAFF AUDIT.
Top Storage Capacity
Top Storage Gas
Topping-Cycle Plants
Energy systems which produce electricity first and heat as a by-product.
Total Allowance
Total Depth (T.D.)
The greatest depth reached by a well bore.
Total Energy
A concept under which the electricity required by a given facility is produced on-site by natural gas and possible alternate standby fueled engines or turbines with the recovery of the equipment's heat of rejection for space conditioning and/or process uses.
Total Input Gas
Total Output Gas
Tower Scrubber
Town Border Station
Town Gas
Purified crude gas, after CO2 removal, having a heating value of 400 to 700 Btu/cf.
A special provision approved by the Commission giving the pipeline company the ability to change its rates at different points in time to recognize changes in specific cost of service items without the usual suspension period of a rate filing. Examples of costs that have been or are tracked include PGA, including GRI charge and A.G.A. charge, certain TBO costs, SRO and charges in Research and Development. See CLAUSE, ADJUSTMENTS.
Trade Ally
In DSM, an organization (architect, building contractor, etc.) that influences energy decisions of customers who are potential DSM program participants.
Process equipment composed of vessels, piping, heat exchangers, etc., required to produce SNG or also the utilization system after customer metering.
A device for converting energy from one form to another, specifically called the measurement of pressure differential in natural gas gate stations.
Transition Cost Recovery (TCR) Mechanism
A mechanism designed to recover Order No.500 take-or-pay buyout and buydown costs. See EQUITABLE SHARING MECHANISM.
Transmission and Compression of Gas By Others (TBO
Also referred to as Transportation By Others. This component of cost of service refers to charges from others (e.g., other pipelines) to transport your system supply gas to your system or other designated area.
Transmission and Compression of Gas For Others (TF
Also referred to as Transportation For Others or just Transportation. This pipeline service refers to a pipeline's transportation of gas owned by others.
Transmission Company, Gas
A company which obtains at least 90% of its gas operating revenues from sales for resale and/or transportation of gas for others and/or main line sales to industrial customers and classifies at least 90% of its mains (other than service pipe) as field and gathering, storage, and/or transmission.
Transmission System
Transmittance, Thermal (U Factor)
A device which responds to a measured variable by means of a sensing element and converts it to a standardized transmission signal which is a function only of the measurement.
The act of moving gas from a designated receipt point to a designated delivery point pursuant to the terms of a contract between the transporter and the shipper. Generally it is the shipper's own gas which is being moved.
Transportation Agreement
An agreement between a shipper and transportation company which defines the terms and conditions of the transportation services and transportation transfer to be provided.
Transportation Level
The transportation for others (TFO) volumes being applied to the cost of service to develop rates. See SALES LEVEL, THROUGHPUT LEVEL.
Transportation Service
The act of moving gas from a receipt point to a delivery point pursuant to a contract between the shipper and the transporter. To the extent the shipper has paid for guaranteed, high-priority capacity in the pipeline, that shipper is entitled to firm service. Less expensive, lower-priority transportation
A legal entity which has the capability of providing the service of transporting gas. Transporter includes gathering companies, pipeline companies and local distribution companies.
A device designed for removing liquids or solids from a gaseous stream; a low spot in a pipeline or main. Compare DRIP.
Trap, Scraper (Trap, Pig)
Triple Integrated Appliance
A Combo Heater that includes a cooling unit operated from a standard air conditioning compressor using the same ductwork.
Tube, Finned
Heat transfer tube or pipe with extended surface in the form of fins, discs, or ribs.
Tube, Injection
A tube with a venturi throat which leads from the primary air port and gas orifice or a gas burner to mixing chamber and burner ports. As the gas passes from the gas orifice through the tube, it draws air through the primary air port into the mixing chamber, after which the mixture is burned at the burner ports.
Turbine Meter
A meter using the rate of rotation of a rotor in the gas stream to measure flow rate.
Turbine Station
A compressor station in which the power is supplied by a turbine.
Turbine, Steam or Gas
An enclosed rotary type of prime mover in which heat energy in steam or gas is converted into mechanical energy by the force of a high velocity flow of steam or gas directed against successive rows of radial blades fastened to a central shaft. Compare ENGINE, RECIPROCATING.
Turbo Blower
A blower in which the rotating part is equipped with blades that rotate between stationary blades attached to the housing. The respective sets of blades are set at an angle such that, as the rotor turns, gases are pushed through the blades and discharged from the opposite side, pass through the stationary blades, and then are given another push by the next set of rotating blades, finally being discharged from the casing at the opposite end from which they entered.
Discontinuance of utility service.
Initiation of utility service.
Turn-On Charge
The fee paid by a customer to have his utility service turned on.

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