154 terms

Pipeline Vocabulary

Valve Box
A vertical section of pipe which encloses and allows access to a valve. Also can enclose anodes and other small cathodic protection devices.
Variable Pressure Pilot
An auxiliary regulator in the control piping which delivers gas at varying pressures to the loading chamber of a larger regulator. Sometimes called a duplex pilot.
An underground structure designed to house a district regulator station or MSA.
A line designed to remove any gas buildup and vent
itto atmosphere.
Vibration or Chattering
A movement or noise caused by a very rapid
movement ofloose or worn parts in a regulator. Vibration should not be confused with pulsation. A vibrating regulator generally is not causing a change in the downstream pressure
The amount of space inside a pipe, meter, or other container. Volume is expressed incubic feet.
Swing Joint
An above-ground connection which allows for movement of pipe in areas which are prone to landslides
A connection to piping through which gas may be obtained. Usually posted when it is on a pipeline, when it will have a tap number
A fitting used to connect a non-pressurized pipe lateral (3 way connection).
Tensile Strength
The highest unit tensile stress (referred to the original cross section) a material can sustain before failure, measured in PSI.
Termination Tee
A tee with no plug inside. Used when pipe is to be extended later; obsolete, but still found in some areas. An early version was known as a Monrovia fitting.
A procedure for proving the acceptability of a structure (pressure test) or a process (weld test).
A weld joining two previously completed section of piping. A wedding band should be considered as a tie-in.
Tie-In Section
A section of piping used to join two previously completed sections of piping. A tie-in section is joined to previously completed piping with a tie-in at each end.
Stop Cock (SC)
A valve used to control the flow of gas, similar to a plug valve. Now obsolete on main, but still exists in some areas.
A device for separating and collecting solid particles 1/16 inch or larger (maximum dimension) is a gas stream.
Strength Test
A test given to piping to determine ifit will fail when subjected to the pressure for which it is designed.
The internal force that resists change in the size or shape of a body subject to external forces. In standards it is the same as unit stress, which is the stress per unit area, such as PSI.
Stress Relief
The elimination of secondary stresses by the intentional creation of a stress greater than yield strength or the application of heat (as in annealing of steel).
A process for joining two pieces of metal at a temperature under 800 degrees Fahrenheit, where both pieces adhere to each other and the third metal (the solder) flows into the joint by capillary action. Distinguished from braze welding.
Specific Gravity
The ration of the weight of any volume of a substance to the weight of an equal volume of some substance taken as a standard; water is the standard for liquids and air for gases.
Spring Effect
A term applied to the degree of compression extended by the spring against the diaphragm; associated primarily with a spring loaded regulator. A fully compressed spring exerts considerably more force than the same spring when only half compressed. As a spring extends, it required less operating force, generally the downstream pressure under the diaphragm, to achieve equilibrium.. The spring effect in a spring loaded regulator is one reason the regulator will not maintain a constant downstream pressure as the volume of gas going through the regulator changes.
On copper pipe, the same operation as pinching.
Stage Regulator
One of two or more regulators in a flow stream, each of which makes a portion of the flow reduction produced by the group of regulators.
Standard Cubic Foot
The amount of gas required to fill one cubic foot of space at 14.73 PSIA and 60 degrees Fahrenheit. A standard of volume used for measuring and billing purposes.
Standard Delivery Pressure
Company terminology for gas pressure normally delivered to domestic and industrial customers: 8 inch WC, with a minimum. of 7 inch WC and a maximum of 10 inch WC.
Standard Service Regulator
A self-contained, single ported regulator of size 2 inches or less, with a resilient valve seat supplied with medium pressure gas (PSI) and delivering at pressures recommended for household appliances (inches WC). Capable oflimiting the buildup of pressure under no-flow conditions to 50% or less of the pressure maintained under flow conditions.
Sectionalizing Valve
A valve used as a shut-off when hot-tapping a pipe.
It differs in design from gate and plug valves.
Security Valve
An automatic over or under protection shutoff device which will shut off the gas flow when the pressure downstream of the regulator is in excess of or below a predetermined level. The valve may be installed either upstream or downstream from the regulator, and must be reset manually to restore gas flow.
Series Regulators
One of two or more regulators in pipeline at a District Regulator Station or MSA, which
progressively reduces pressure. For example, the first regulator could reduce the pressure from 100 lb to 60 lb, and the second regulator could reduce the
pressure from 60 lb to 20 lb.
A portion of the piping system which delivers gas from a main or pipeline to a MSA.
Service Regulator
A regulator that controls downstream flow at all
times. Often referred to as a 'working' regulator
Reducing Tee
A three-way fitting which may have two or three sizes of pipe connected to it.
An automatic valve which maintains a pressure in the piping downstream of the regulator at varying rates of flow and with varying inlet pressure to the regulator.
Relationship of Pressure/Flow
Pressure is inversely proportional to flow. Pressure is constant if flow is constant, increasing if flow is decreasing and decreasing if flow is increasing.
An in-line fitting used to connect two pipe segments of different diameter. Incases of extreme size difference, multiple reducers may be used in a short distance.
Reducing Ell
A fitting which changes both the size and the direction of piping.
Relief Valve
A regulator which opens on rising pressure (like a back pressure regulator) to release gas to the atmosphere at a predetermined point.
Ring Joint
A joint with a flange (flanged joint).
Saddle Weld
A kind of joint; a steel fitting is welded on steel pipe, a hole is cut in the pipe, and it is branched in another direction. The weld is shaped like a saddle.
Sample Piping
A small size of piping used to secure a sample of the gas flowing through a system; a gas sampler.
Screwed Flange
A flange which is screwed on the end of a section of pipe.
A device which filters foreign material from gas.
Secondary Stress
A device which filters foreign material from gas. The stress produced in the pipe wall by loads other
than internal fluid pressure. The stress may be
caused by traffic, backfill weight, beam activity in a span, or by other sources.
Service Tee
A steel fitting used to connect a service to a main, or two mains, when the existing main is pressurized.
Generally used on 2" and smaller pipe.
Short Static or Sense Line
A static line installed between a regulator and a downstream valve. Required on all new installations.
Slip-On Flange
A flange which slips onto the end of a pipe and is welded to it.
Small Meter
A positive displacement meter which has a capacity rating of 499 CFH or less with a pressure drop of proposed or actual metering pressures.
(1) Specification for Materials and Components; (2)
Service to Main Connection.
Specified Minimum Yield Strength, in PSI; prescribed by the specification under which pipe is purchased from the manufacturer. One of the factors on which design pressure is determined.
Socket Weld Cap
Used to enable the attachment of anode wire to pipe.
Static Lines or Sense Lines
A portion of the control piping used to transmit
changes in pipeline pressures to the regulator.
Static Pressure
Pressure introduced into the diaphragm case of a regulator to oppose the loading element. Also, the pressure introduced into the measuring element of an orifice meter gauge.
Station Piping
Piping within a compressor or regulator station, other than control, instrument and sample piping.
An alloy of iron and carbon and a small amount of other elements, with a carbon content of 2% or less. It is weldable and ductile.
A pipeline which has been cut back, terminated, or installed with the intent of tying into or extending it at a later date.
Surging Swage
An in-line fitting which connects two different-sized pipes. Usually used for small size differences, such as between 3/4 inch and 1 114 inch pipe, or 1 1/4 inch and 2 inch pipe.
Transition Fitting
A fitting used to connect plastic pipe to steel pipe; it has plastic on one end and steel on the other.
A flexible conduit with wall thickness less than 0.05 inch; see pipe for conduit with wall thickness greater than 0.05 inch.
A condition of gas in a pipeline or container caused by the gas tumbling or becoming agitated as it flows through a restriction, such as an ell, tee or orifice plate. The gas will generally become more turbulent as the flow increases, less turbulent as the flow decreases.
Two-Way Feed
Gas flow from two directions.
Underpressure Protection
A device to prevent too low a pressure downstream from a regulator if the regulator fails in a closed position. Often called standby regulation.
The direction from which the gas is flowing.
A device for stopping or manually controlling flow in pipe or tubing; there are several types of valves in use: ball, gate, and plug valves are common.
Wall Thickness
The thickness of the wall of a pipe; it is the difference between the inside and outside diameters. Generally, the larger diameter of the pipe, the thicker the wall will be.
Warming Lines
Additional piping installed between first and second stage regulation to allow the gas to warm up between the two stages of regulation, because the pressure drop causes the gas to drop in temperature (see freezing). Other methods include wrapping the regulation equipment with insulating material, and installing thermostatically controlled electric heating elements.
Water Column (WC)
A measurement of pressure, expressed as inches of water column, where 27.7 inches is equal to I PSI at 60 degrees Fahrenheit.
Wedding Band
An axially split, short length of cylindrical plate, i.e., two half-cylinders of plate, used to join two pieces of pipe by welding both halves of the band together and to each piece of the pipe. The inside diameter of the band is the same as the outside diameter of the pipes to be joined.
Working Regulator
A regulator which at all times controls downstream pressure. This regulator is :frequently called a service regulator and is identified by a metal tag stamped with the letter 'S'.
A portion of the houseline located between the MSA and the house piping of the structure served, usually underground. Generally found when the MSA is at or near the curb.
Yield Strength (Pipe)
The pressure at which a type of pipe (steel or plastic) will rupture under laboratory conditions.
The amount of gas, either in a container or expressed as rate of flow, corrected to standard conditions of
14.73 PSIA and 60 degrees Fahrenheit (760 mm Hg and 270 K)
Rectifier Station
Converts alternating current (AC) to direct current (DC) to cathodically protect large areas of steel pipeline.
Pressure Gauge
A pressure measuring device generally consisting of a very carefully calibrated bourdon tube. A pointer or indicator is fixed to the free end of the tube, and will register the pressure within a container or pipe to which the gauge is connected. This gauge normally does not measure atmospheric pressure. These
gauges are frequently referred to as spring gauges or as Laboratory test gauges, and are also identified by a pressure rating of 30#, 60#, 100#, 500#, and so on. This pressure rating is the highest pressure the gauge will measure.
Pressure Limiting Device
An overpressure protection device which will limit pressure to prevent overpressure downstream piping. It may be a regulator, relief valve, or automatic shut off.
Pressure Limiting Valve (PLV)
An automatic overpressure shut-off device which will shut off the gas flow when the pressure downstream of the regulator exceeds a predetermined amount. The PLV is provided with a breakable element which ruptures and shuts the valve and, when ruptured, must be replaced in order to reopen the valve.
Pressure Reducing Regulator
A regulator which maintains or limits downstream pressure.
Pressure Relieving Device
Usually called a relief valve; an overpressure protection device which will vent gas to atmosphere or to a lower pressure installation when the pressure delivered by the regulator exceeds a predetermined amount.
Proportional Band
Ina regulator, the difference in controlled (downstream) pressure between closing and maximum flow. A regulator may be adjusted to deliver a definite pressure, such as 3 lb, into a pipeline when there is no gas being used. Then as the volume of gas used increases, the pressure will gradually drop until the regulator has reached its maximum capacity. At this point the downstream pressure may have dropped to 2.4 lb. The proportional band of this regulator is 0.6 lb.
The application of heat to the base metal prior to welding or putting the metal.
Pressure (PSIG)
The force per unit area exerted by a fluid, expressed in pounds per square inch above atmospheric pressure, i.e., gauge pressure or PSIG. Inthis glossary, gauge pressure is implied by the term PSI.
Pressure Control Bottom Out Fitting (BO, PFBO, PCFBO)
A fitting which allows mechanical interruption of
gas flow by inserting a rubber stopper into the fitting, and also allows gas to be diverted through the
bottom of the fitting, to supply a new section of piping.
Plastic Pipe
Pipe made of high-density polyethylene (HDPE), which is more flexible than steel and will not corrode. It is easier to damage with construction equipment than steel pipe, however, and is not currently available in sizes over 8 inch.
An extra piece of flat steel taken into the field to use for various purposes.
One-Way Feed
Gas flow from one direction only.
An restriction installed in piping to limit flow or produce a pressure differential.
Outlet Pressure
The pressure at the outlet of any device such as a regulator, meter, MSA, a section of piping, or a District regulator Station. Frequently called downstream pressure
Overpressure Protection
A device or method to prevent excessive pressure downstream of a regulator if the regulator fails in an open position. It may be a regulator, a pressure relieving device, or pressure limiting device.
Pilot Flow
The amount of gas needed to supply only pilots of
the customer's appliances. A house-type regulator set to deliver 8 inch WC pressure under flow conditions should deliver no more than 10 inch WC pressure during pilot flow.
Pilot Regulator
A small regulator used to operate a larger regulator.
A method of stopping the flow of gas in both mains and services by pinching the pipe walls together. On copper pipe it is usually called squeezing.
Metering Station
Facilities used to measure gas, other than for customer consumption. Stations which provide both metering and pressure control functions are pressure control stations.
Mill Test
A hydrostatic test given to pipe before delivery by the manufacturer, to insure its strength. The test pressure is determined by specification and is a factor in determining its design pressure
Miter Bend
A method of changing pipe direction by cutting the pipe at an angle and welding the cut ends. Used for angles which are too large for simple bends and for which ells cannot be used.
Multiple Meter Set Assembly; usually called a header; an MSA with more than one meter on a single service.
Modulating Valve
A power-operated valve that partially opens and closes as required by gas pressure in a pipeline.
Leak Test
A test of piping to determine that it will not leak when subjected to the pressure for which it was designed. Itmay be a pressure stand-up test or a bubble test. All new mains are pressure tested.
Line Pressure
The gas pressure inside a pipeline.
Load -Demand
The volume of gas required in the downstream piping to maintain the necessary supply to the customer or service facility.
Location Class
The type of area, based on population density and other characteristics, which determines the construction type.
The condition where there is no leakage through the valve in the regulator.
Lockup Difference
The minimum amount of pressure increase in a regulator from its gauge pressure to lockup pressure.
Lockup Pressure
The minimum pressure at which the regulator achieves lockup.
Low Pressure
Company terminology for gas pressure of 12 inch WC or less.
A segment of the piping system which delivers gas to services and to other mains.
Major Pressure Control Station
The facilities used to control pressure where inlet pressure is more than 400 PSI and flow is 5 MMCFH or more. Sometimes called Pressure Limiting Station.
Malleable Iron
Annealed cast iron. It is non-weldable but moderately ductile.
General Order (G.O.)
G.O. 112 is a document of the California PUC
setting out rules governing design, construction, testing and maintenance of gas transmission and distribution piping systems.
Half Sole
Half of a wedding band, used for reinforcement.
A pipe on which one or more lateral connection are provided; particularly used for multiple meter assemblies (MMSA).
High Pressure
Company terminology for gas pressure of 60 lb or more.
Hoop Stress
The stress in a pipe wall acting circumferentially in a plane perpendicular to the longitudinal axis of the pipe (that is, around the pipe and at a right angle to its centerline) and produced by the pressure of the fluid (the gas) in the pipe.
Hot Pinch
A method of closing steel pipe; to heat the pipe and pinch closed.
Hot Spot Anode
An extra anode in a location where there is a lot of corrosion. Not usually recorded on atlas sheets.
Hot Tap
A tap made on piping while it contains gas under pressure.
All piping installed beyond the last fitting on the outlet side of the meter set, up to the customer's appliances. It is owned by the customer. Ifa portion of the houseline is located between the MSA and the house piping of the structure served, it is referred to as yardline, and is usually buried.
Houseline Pressure
Pressure delivered to the customer.
Impressed Current Anode
An anode with current run through it for better cathodic protection.
A descriptive term to distinguish large consumers from small consumers. It does not conform to the rate paid.
Inlet Pressure
The pressure at the inlet of any device, such as a regulator, meter, a section of piping, or a district regulator station. Frequently called upstream pressure.
Flange Tee
A fitting used for making connections between services and large mains, or for lateral connections to the top of pipelines. An insulated connection used on pipe of 3 inch or larger diameter.
Freezing or Icing
The formation of frost or ice inside the regulator and adjacent piping. Pressure drop across the regulator reduces the temperature of the gas, and may cause
:freezing of the moisture in the gas.
Full Encirclement Reinforcement
A band that goes around the entire pipe for
Fusion Coupling
A connection method used on plastic pipe.
Extension Fitting
A connection on the side of a pressurized steel pipeline, already attached to pipe; obsolete.
Extension High Head Grease
A fitting on top of a valve; a tube which pumps grease into the valve so it will not stick and may be turned easily.
A segment of piping used to supply other segments, which are normally of smaller size; usually a large mam.
Field Fabricated
Usually refers to a dead end plate made by a crew from a piece of plate, but may include also risers and reducers if the situation requires. Pressure fittings can be field fabricated by boring, in order to make a larger piece of pipe fit them.
Expansion Joint
A gas-tight fitting that allows for horizontal movement of the pipeline; obsolete, but still found in some areas. Similar to a swing joint in some ways.
Extended Static or Sense Line
Sometimes called 'long static'; a static line installed across a valve downstream from a regulator. Used only when needed to compensate for drop across a valve or fittings, or to obtain a better sensing point.
Any device used to screen foreign material from gas flowing in a pipeline.
A method of closing steel pipe; the pipe is pinched twice, a piece is removed, then the pinch is welded closed.
A fitting using a gasket and bolts as a means of connecting pipelines.
Gas Pressure
The action of the gas against some opposing force, for example the walls of a pipe or a container of any sort. Particularly used of gas in measuring devices.
Gas Stop
A device for stopping flow in pipe or tubing.
Gate Valve (GV)
A device used as a shut-off for stopping the flow in piping. A common,type of valve.
Gear Box
A box on the side of a valve, containing gears to help turn a large valve on or off. In the largest sizes may be motorized.
Instrument Piping
Small-sized piping which transmits pressure or flow to instruments.
Insulating Kit
Accompanies the flanges of an insulating joint. It
prevents metal-to-metal contact.
A nonconductive material applied to piping to prevent or slow electrical current or heat from entering or leaving piping.
Intended Operating Pressure (IOP)
The pressure, as established by the design engineer, at which a segment of piping is intended to operate for greatest efficiency. IOP is primarily determined by operating conditions and foreseeable future planning, rather than physical equipment.
A controlled bleed, applying only to atmospheric bleed. By using certain types of controllers or pilot installations it is possible to restrict a bleed to atmosphere to positive limited periods when changes are being made in the downstream pressure. Also, intermittent as opposed to constant bleed.
A fiberglass fitting which acts as an insulator.
Lap Joint
Ajoint with a flange; also, ajoint where two pieces overlap and are welded or fused.
Large Meter
A positive displacement meter which has a capacity of more than 1200 CFM or greater, with a pressure drop of 112 inch WC, at standard pressure or actual metering pressures. All rotary displacement meters are large meters.
A segment of piping used to deliver to another segment which normally is of larger size and supplies other laterals; pipe normally installed at right angles to the supplying segment. Also a branch supply line, usually designated by a letter or a letter and number at the end of the supply line number, such as SL 30-02A.
Lead Coupling, Lead Diaphragm Coupling (LC, LDC)
A section of steel pipe with a lead disk inside which stops the flow of gas. When the pipe is extended, the section may be heated to melt the lead and allow gas to flow through. Obsolete, but still found in some areas.
Leak Clamp
A clamp with a rubber sheet inside, which goes around the pipe to seal off a leak. Used on steel pipe mostly for temporary repairs.
A pressure measuring device consisting of a length of transparent tubing bent sharply into a U, a scale, and suitable mounting. The scale is mounted alongside or behind the tubing and is calibrated both up and down from a zero point midway in the length of the U. The tube is half filled with water. The water manometer is used for measuring gas pressure in inches of water column (WC). The scale is marked and read in inches and tenths. At 60 degrees Fahrenheit, 27.73 inches of water is equivalent to 1 PSI. Occasionally this device may be called a water
column or U gauge. Another type of manometer used by some units in the Company is a well-type device where the height of a single column of fluid is read from a scale.
Maximum Allowable Operating Pressure. The maximum pressure at which a portion of the piping system is qualified to operate. Ifthe term is applied to an entire system, the MAOP should be no greater than that of the weakest segment in the system.
Maximum Test Pressure
The maximum internal fluid pressure permitted by standards for testing materials. Inthe case of valves, regulators, and flanges, this is determined by the manufacturer.
Medium Meter
A positive displacement meter which has a capacity rating of 500 - 1199 CFH with a pressure drop of 112 inch WC at standard pressure, regardless of the proposed or actual metering pressures.
Medium Pressure
InCompany terminology, gas pressure of at least 12 inches WC, but less than 60 PSI.
A device for measuring gas quantity or usage. It includes rotary displacement, diaphragm displacement, and orifice type meters.