Asbestos and magnesia plaster used on process equipment and piping as a thermal insulation.
Land Man
A person concerned with the acquisition of leases, clearing of land titles, payment of lease rentals, and other related activities.
Landfill Gas
Gas produced by aerobic and anaerobic decomposition of a landfill generally composed of approximately 55% methane and 45% carbon dioxide, sometimes refined with membrane methods to eliminate the carbon dioxide.
Term usually applied to an interval in the cased hole (of an oil or gas well) where the top of a liner overlaps the bottom of a string of casing.
To attach elevators to a section of pipe. Also, a slang term meaning to take hold of a variety of different objects around the drilling rig.
Latent Heat
A pipe in a gas distribution or transmission system which branches away from the central and primary part of the system.
Laws, Physical - AMAGAT'S.
See LEDUC'S below.
Laws, Physical - AVOGADROS'.
Under the same condition of temperature and pressure, equal volumes of all gases contain the same number of molecules.
Laws, Physical - BOYLE'S.
The volume of a perfect gas is inversely proportional to the absolute pressure at constant temperature.
Laws, Physical - CHARLES'.
The volume of a perfect gas under any condition of constant pressure is proportional to the absolute temperature.
Laws, Physical - DALTON'S.
Every constituent of a mass of gas enclosed within a vessel contributes to the pressure against the sides of the vessel the same amount that it would have exerted by itself had no other gas been present. The total pressure within a vessel is the sum of the partial pressures of each of the constituent gases.
Laws, Physical - GRAHAM'S.
The relative rates of diffusion of gases under the same conditions are inversely proportional to the square roots of the density of those gases.
Laws, Physical - IDEAL GAS.
The terms "ideal gas" and "perfect gas" are used in technical literature to describe a hypothetical gas which would follow a characteristic equation under all conditions; that is, PV=RT, where P=the absolute pressure, V=specific volume, R=constant for the specific gas, and T=absolute temperature.
Laws, Physical - JOULE'S.
There is no change of temperature when a gas expands without doing external work and without receiving or rejecting heat.
The cooling which occurs when a compressed gas expands in such a manner that no external work is done and no heat is interchanged.
Laws, Physical - LEDUC'S (AMAGAT'S).
The volume of a gas mixture is equal to the sum of the volumes that would be occupied by each of the components of the mixture if at the temperature and pressure of the mixture.
Laws, Physical - MARRIOTTE'S.
Laws, Physical - PASCAL'S.
A pressure exerted on a confined liquid is transmitted equally in all directions throughout the liquid.
Laws, Physical - PERFECT GASES.
Laws, Physical - RAOULT'S.
The vapor pressure of the solvent in a solution is proportional to the mole fraction of the solvent. This law has been of fundamental importance in the development of the theory of solutions.
Laying Mains
The complete operation of installing piping systems in towns or cities including trenching, joining sections of pipe, placing pipe in trenches, back-filling trenches, and cleaning up.
A solution mining process to remove salt and form gas storage caverns in salt domes.
Leak Clamp
A clamp used to press and hold tight a gasket against a leaking section of pipe or pipe joint to seal the leak.
Leak Detector
A device for identifying and locating a gas leak.
Leak Limiter
A device to limit the escape of gas from the vent opening of a regulator in the event of a diaphragm failure, to not more than 1 cubic foot per hour of a gas having a specific gravity of 0.6 at 7 inches water column.
Leakage Survey
A systematic search for the purpose of locating leaks in a gas piping system.
A contract between an owner (lessor) and a tenant (lessee), setting forth the compensation, terms, and conditions upon which the lessee may occupy or use property, real or personal, of the lessor. This may include the right to engage in exploration for and production of oil, gas, or other minerals.
Lease and Plant Fuel
Natural gas used in lease or plant operations as a fuel or for other lease or plant uses such as for gas lift operations.
Lease Condensate
A mixture consisting primarily of pentanes and heavier hydrocarbons which is recovered as a liquid from natural gas in lease or field separation facilities. See CONDENSATE.
Lease Hound
A landman whose primary duty is to procure leases on tracts of land for exploration and development of gas and oil products.
Lease Separator
A surface facility installed on a lease for the purpose of separating gases and/or water from liquid hydrocarbons.
Leased Storage
Natural gas storage facilities owned and controlled by a storage operator, quite often the interstate pipeline's affiliate. Capacity within these facilities is leased by customers, such as LDCs, who use the stored gas during cold weather. Leased storage gas is returned to the customer either in the market area (close to the recipient) or supply area (close to production).
Leasehold Costs
All costs related to obtaining an oil and gas lease.
Least-Cost Planning
A piece of pipe of the length delivered from the mill. Each piece is called a length regardless of its actual dimensions. This is sometimes called "joint", but "length" is preferred.
A rock formation of local extent, formed by variation in sedimentation in the original formation of sedimentary beds.
Life-of-the-Field Contract
A contract where the producer commits his reserves for the life of the field.
Lifeline Rates
A rate structure applicable for residential customers which includes a specified block of energy use which is priced below the allocated cost to serve. The block of energy may be priced at a flat amount for the entire block or on a per unit basis.
Last-in, first out method of inventory valuation in which the earliest acquired inventory is assumed to be still on hand; the most recently acquired is assumed to be sold first.
One of the movable sections of a liquid-sealed gas holder. The vertical distance a liquid is pumped.
Line Loss
The amount of gas lost in a distribution system or pipeline. Compare UNACCOUNTED FOR GAS.
Line Pack
Natural gas occupying all pressurized sections of the pipeline network. Introduction of new gas at a receipt point "packs" or adds pressure to the line. Removal of gas at a delivery point lowers the pressure (unpacks the line).
Line Pack, Gas Delivered From
That quantity of gas delivered to the markets supplied by the net change in pressure in the regular system of mains, transmission, and/or distribution. For example, the change in the content of a pipeline brought about by the deviation from steady flow condition.
Line Packing
Increasing the amount of gas in a line section by increasing pressure to meet a heavy demand, usually of short duration.
Line Pipe
Steel pipe generally used to construct pipelines to transport petroleum and natural gas.
Line Rider
An employee who inspects a pipeline right-of-way for leaks or potential hazards. At one time, the line rider walked or rode horseback. Today, an automobile or light aircraft is used.
An employee who inspects a pipeline right-of-way for leaks or potential hazards. At one time, he walked or rode horseback; today, he uses an automobile or a light aircraft.
Liquefaction of Gases
Any process in which gas is converted from the gaseous to the liquid phase.
Liquefied Natural Gas (LNG)
Natural gas which has been liquefied by reducing its temperature to minus 260 degrees Fahrenheit at atmospheric pressure. It remains a liquid at -116 degrees Fahrenheit and 673 psig. In volume, it occupies 1/600 of that of the vapor at standard conditions.
Liquefied Petroleum Gas (LPG)
A gas containing certain specific hydrocarbons which are gaseous under normal atmospheric conditions, but can be liquefied under moderate pressure at normal temperatures. Propane and butane are the principal examples.
Liquids, Natural Gas
Those liquid hydrocarbon mixtures which are gaseous at reservoir temperatures and pressures but are recoverable by condensation or absorption. Natural gasoline and liquefied petroleum gases fall in this category.
Live Oil
The amount of gas delivered or required at any specified point or points on a system; load originates primarily at the gas consuming equipment of the customers. Also, to load a pressure regulator is to set the regulator to maintain a given pressure as the rate of gas flow through the regulator varies. Compare DEMAND.
Load Center
A point at which the load of a given area is assumed to be concentrated.
Load Curve
A graph in which the load of a gas system or segment of a system is plotted against intervals of time.
Load Density
The concentration of gas load for a given area expressed as gas volume per unit of time and per unit of area.
Load Dispatching
Load Diversity
The difference between the sum of the peaks of two or more individual loads and the peak of the combined load. See DIVERSITY FACTOR.
Load Duration Curve
A graph made by plotting data in order of magnitude against time intervals for a specified period. The ordinate may be an absolute quantity or percentage.
Load Factor
The ratio of the average requirement to the maximum requirements for the same time period, as one day, one hour, etc.
Load Profile
Pattern of a customer's gas usage, hour to hour, day to day, or month to month.
Load Research
The systematic gathering, recording, and analyzing of data describing customers' patterns of energy usage.
Load Shape Effects
The estimated changes in energy usage at specific times during the year that are caused by a DSM or other measure.
Load Water
Water used to prime a well after acidizing.
Load, Base
Load, Connected
The sum of the capacities or ratings of the gas-consuming apparatus connected to a supplying system or any part of the system under consideration.
Load, Net
The active requirement for gas at a particular time. Compare LOAD, CONNECTED.
Local Distribution Company (LDC)
Lock In (Unlock)
Generally, to unseal a gas meter and start gas service by opening the meter stop (valve). Compare TURN-ON.
Lock Out (Lock)
Generally, to seal and lock a gas meter and shut off the stop (valve) so that gas cannot be used. Compare TURN-OFF.
Lock-Up or Lock-Off
The point at which a regulator or governor shuts of completely.
Locked-In Period
Normally settlement rates are developed using actual cost experience of the base period, as adjusted in the test period, allocated to estimated annual sales volumes. The company is at risk for any variations in costs and sales volumes. On rare occasions a pipeline company may settle on the basis of actual costs and sales volumes for a defined period of time called the locked-in period. The company has less downside risk in this type of settlement.
Lockout Timing
That period of time between the initial ignition trial and lockout by the ignition system.
A record of performance. (a) The record of an engine, boiler, or other test. (b) A record of the progress in drilling a well.
Log, Electric
The recorded graph of the natural and induced electrical characteristics of rocks used as an indication of permeability and porosity and the possibility of contained fluids.
Logging, Mud Analysis
A continuous examination of the drilling fluid circulating in the well bore for the purpose of discovering evidence of oil or gas regardless of how small the quantities may be entrained in the fluid. When this service is utilized, a portable mud logging laboratory which is incorporated in a trailer is set up at the well. This method is widely used in drilling wildcat wells.
Logging, Radioactive
The logging process whereby a neutron source is lowered down the hole followed by a recorder. When a hydrogen-bearing strata is located (which may be petroleum or water), the neutrons are absorbed. They disintegrate the hydrogen atoms, releasing alpha particles. The higher the alpha concentration, the higher the hydrogen concentration.
Long-term Burst
The internal pressure at which pipe or fitting will, most likely, fail after 100,000 hours (11.43 years).
Long-term Hydrostatic Strength
The estimated tensile hoop stress in the wall of the pipe along the circumferential direction that when applied continuously will cause failure of the pipe, at 100,000 hours (11.43 years). This strength value is usually obtained by extrapolation of log-log regression equations or plots.
Longitudinal Seams
The weld which is used to manufacture pipe rolled or formed from plate.
A paralleling of an existing pipeline by another line over the whole length or any part of it to increase capacity.
Loss of Load Risk
The evaluation of the risk of a system not adequately meeting the load demand of firm customers under normal operating conditions. It is based upon the evaluation of supply and capacity reliabilities and the uncertainty of demand forecast, weather variability, and other uncertainties.
Lost Opportunity
In DSM, an efficiency measure that is cost-effective but does not get installed, and which is unlikely to be cost-effective at a later time.
Lost Opportunity Resources
DSM resources that, if not installed initially, become more costly to exploit. An example is extra insulation when constructing a new building.
Lost Revenues
Revenues not collected by a utility due to the loss of sales as a direct result of DSM programs.
Overlapping and sloping slats arranged to prevent entrance or exit of some substances but allow ventilation air to pass.
Low Btu Gas
Gas with a heating value of less than 250 Btu's per cubic foot. Typically heating values fall between 120 and 180 Btu's per cubic foot.
Low Pressure Distribution System
Low Priority Users
An interruptible, industrial customer that has the ability to switch to an alternate fuel.
Low Sulphur No. 6 Oil
Oil with sulphur content of 1% or less.
Low Water Cut-Off
A device constructed so as to automatically cut off the gas supply when the surface of the water in a boiler falls to the lowest safe water level.
LP Gas
LP Gas--Air Mixtures
Liquefied petroleum gases distributed at relatively low pressures and normal atmospheric temperatures which have been diluted with air to produce desired heating value and utilization characteristics.
Loan-to-Value Ratio is the amount a lender will lend on a project relative either to its total appraised value or to its costs.
Lubricated Plug Valve
Lurgi Process
A coal gasification process which produces gas through the controlled reaction of coal and oxygen in the presence of excess steam in a reactor.

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