Valves Guide
Glossary of Valve Terms
ACCUMULATOR
A vessel in which a gas is trapped and compressed by the liquid in a hydraulic system, thus storing energy to supply liquid under pressure to the system when needed.
ACME THREAD
A flat topped screw thread for power transmission. This thread has a 29° included angle between adjacent thread faces compared with the 60° angle of the U.S. standard "V" thread.
ACTUATOR
Device used to operate a valve using electric, pneumatic or hydraulic means. Often used for remote control or sequencing of valve operations.
ADAPTER SPOOL
An extension which is added to a short face-to-face valve, to conform to standard API 6D face-to-face dimensions.
AGA - AMERICAN GAS ASSOCIATION
A society comprising gas companies set up to achieve common goals.
AISI - AMERICAN IRON AND STEEL INSTITUTE
An association of steel makers which sets standards for the chemical and physical properties of steel and iron in various shapes and forms; pipe, tubing, sheet, strip, wire.
ALL WELDED CONSTRUCTION
Pertains to a valve construction in which the body is completely welded and cannot be disassembled and repaired in the field.
ALLOY STEEL
A steel consisting primarily of iron with some percentage of one or more other elements such as chromium, nickel, manganese, or vanadium deliberately added to enhance its properties.
AMBIENT TEMPERATURE
The prevailing temperature of the environment immediately surrounding an object.
ANCHOR PIN
A pin welded onto the body of ball valves. This pin aligns the adapter plate and restrains the plate and gear operator from moving while the valve is being operated.
ANGLE VALVE
A variation of the globe valve, in which the end connections are at right angles to each other, rather than being inline.
ANSI - AMERICAN NATIONAL STANDARDS INSTITUTE
The principal standards writing organization in the U.S. who sets standards for a wide variety of items, including the design, fabrication, and testing of pressure piping, systems, and components for various pipeline services.
API - AMERICAN PETROLEUM INSTITUTE
The principal U.S. oil company trade association. It has some standards and specification writing functions, such as well head components and pipeline valves.
API - SPEC 6D
An API specification dealing with pipeline valves. Most pipeline valves are manufactured to this specification, and, if so, can be identified with the API 6D monogram.
API - SPEC 6FA
The API specification dealing with the fire testing of pipeline valves. Once a particular size and pressure class valve is tested and passes the API-firetest, like valves can be identified with the above monogram. API-6FA supersedes API-RP-6F.
ASME - AMERICAN SOCIETY OF MECHANICAL ENGINEERS
This professional society publishes many technical books, papers, codes and standards. Of principal interest is the...
ASME BOILER AND PRESSURE VESSEL CODE
...which is referenced for many aspects of valve making, although not for the valves themselves.
ASTM - AMERICAN SOCIETY FOR TESTING AND MATERIALS
A professional society governing detailed physical and chemical analysis of all basic metals and alloys used in construction. The valves of most manufacturers have components whose materials correspondto ASTM standards.
ATMOSPHERIC PRESSURE
The external pressure exerted on a body by the atmosphere: 14.7 psi (absolute) at sea level.
AUSTENITIC STAINLESS STEEL
The common stainless steel, where the primary micro structure is austenite and the composition primarily iron but also includes both chromium and nickel. The steels are designated as 300 series such as 304,316, CF8M, etc.
AWS - AMERICAN WELDING SOCIETY
A society which sets guidelines and standards for all welds.
B.R.V. - BODY RELIEF VALVE
A relief valve (optional) installed on ball valves used in liquid service to provide for the relief of excess body pressure caused by thermal expansion.
BACK PRESSURE REGULATOR
Regulator designed to control upstream pressure. See "REGULATOR."
BACKSEAT
A Shoulder on the stem of a valve which seals against a mating surface inside the bonnet to permit replacement, under pressure, of stem seals or packing.
BALL CHECK
A fitting with a small ball that seals against a seat preventing flow in one direction and allowing flow in the other direction.
BALL VALVE
A valve using a spherical closure element (ball) which is rotated thru 90° to open and close the valve.
BALL
The spherical closure element of a ball valve.
BAR
A metric unit of pressure. One bar equals 14.5 psi.
BBL
An abbreviation for "barrel." Used to express liquid volume. One barrel of oil is equal to 42 U.S. gallons.
BDV - BLOW DOWN VALVE
A small ball valve that is installed on the aboveground end of an extended drain line. This valve also serves to vent body cavity pressure in the "block and bleed" mode. See "Block and Bleed;" "Extended BDV."
BEARING COPPER-BASED ALLOYS
Often called "yellow brasses", when in contact with sea water or fresh water that is high in oxygen and carbon dioxide. (ASTM B61 and B62 are "red brasses" and not susceptibleto dezincification.)
BELLEVILLE SPRING
A spring resembling a dished washer, used in some ball valves to push the seats against the ball.
BENDING MOMENT
The mechanical bending load produced by a force applied to a part at right angles to its surface or axis. The product of the force times the perpendicular distance to the point of restraint. Usually expressedin pound-feet.
BEVEL GEAR OPERATOR
Device facilitating operation of a gate or globe valve by means of a set of bevel gears having the axis of the pinion gear at right angles to that of the larger ring gear. The reduction ratio of this gearsetdetermines the multiplication of torque achieved.
BEVEL
A chamfer. The angle between two adjacent surfaces (other than 90°). The word "bevel" is used in describing weld end preparations. See "End Bevel."
BLOCK AND BLEED
The capability of obtaining a seal across the upstream and downstream seat rings of a valve when the body pressure is bled off to atmosphere thru blow down valves or vent plugs. Useful in testingfor integrityof seat seals and in accomplishing minor repairs under pressure. See "Double Block and Bleed."
BODY
The principal pressure containing part of a valve, in which the closure element and seats are located.
BOLT
A fastener having a square or hex head and threaded on the opposite end to receive a nut sometimes used to make up a flanged connection.
BOLTED BONNET
A bonnet which is connected to a valve body with bolts or studs and nuts.
BOLTED CONSTRUCTION
Describes a valve construction in which the pressure shell elements are bolted together, and thus can be taken apart and repaired in the field.
BOLTING SETS
Bolts, or studs, and nuts sometimes supplied with flanged valves to install the valve between line flanges.
BONNET
The top part of a valve, attached to the body, which contains the packing gland, guides the stem, and adapts to extensions or operators.
BORE (OR PORT)
The inside diameter of the smallest opening through a valve, e. g., inside diameter of a seat ring, diameter of hole through ball in a ball valve.
BRINELL HARDNESS NO.
A number indicating metal hardness using the Brinell Scale. Can be converted to Rockwell B and C hardness by reference to conversion tables. See "Rockwell Hardness No."
BS 6755
The British Standard specification dealing with the fire testing of pipeline valves. Once a particular size and pressure class valve is tested and passes the BS 6755 fire test, like valves can bealso identified with the BS 6755 standard.
BUBBLE-TIGHT SHUT-OFF
A phrase used in describing the sealing ability of a valve. During air pressure testing of a new valve in the closed position, leakage past the seats is collected and bubbled thru water. To qualify as "bubble tight," no bubbles should be observed in a prescribed time span.
BURIED SERVICE
An application in which valves are installed in lines which are buried below ground level.
BURST PRESSURE
That pressure (PSI) at which rupture of a stressed element or pressure-containing vessel takes place. See "Ultimate Strength."
BUTT WELD END (BWE)
The end connection of a valve suitably prepared for butt welding to a connecting pipe.
BUTTERFLY VALVE
A short face-to-face valve which has a movable vane, in the center of the flow stream, which rotates 90 degrees as the butterfly valve opens and closes.
BVR - BALL VALVE REGULATOR
An automatic throttling valve controlling flow or pressure in a pipeline; comprising a package involving al ball valve actuator, positioner, and controlling instrument.
BYPASS
A system of pipes and valves permitting the diversion of flow or pressure around a line valve.
C.I.F. - COST INSURANCE AND FREIGHT
Shipper pays all freight and insurance charges. Same as F.O.B. Destination.
CAPACITY FACTOR
See "Cv"
CAPSCREW
A fastener having a head and whose shank is normally threaded throughout its entire length. Not used with a nut, but rather engagement is made with a female thread in the piece to be joined.
CARBON STEEL (CS)
Iron containing carbon in the form of carbides, about 0.1 to 0.3 percent carbon with no other alloying elements other than the sulfur, phosphorus, and other elements present in almost all steels.
CAST IRON
The common term for cast gray iron or iron containing flake carbon in the range of _% to 2 _%. Cast iron is brittle, exhibiting very little ductility before fracturing.
CAST
The form of a particular part of a valve, where the basic shape is formed by molding rather than fabricating.
CASTING
A product or the act of producing a product made by pouring molten metal into a mold and allowing it to solidify, thus taking the shape of the mold.
CAVITATION
The rapid formation and collapse of vapor pockets in a flowing liquid in localized regions of very low pressure; often a cause of erosive damage to pumps, throttling type valves, and to the pipingitself. Can be the cause of excessive noise.
CERTIFYING AUTHORITY (CA) (CERTIFICATION AUTHORITY)
An independent body appointed by the purchaser to carry out a survey of the equipment and/or materials that they are buying. It is the responsibility of the supplier to provide the C.A. with information,documents, access to works and personnel to enable the survey to be carried out.
CHAIN WHEEL OPERATED VALVE
An overhead valve operated by a chain drive wheel instead of a handwheel.
CHARACTERIZED GATE OR BALL
A ball or gate, the shape of whose port has been specially altered to provide a specific throttling capability.
CHARPY IMPACT TEST
A destructive mechanical test conducted on a precisely machined coupon of steel to be tested. The coupon is clamped in a special machine and subjected to lateral hammer blow. The test provides a relativemeasure of the toughness of the steel or its resistance to shock or impact loads and is usually required for material used in low temperature applications.
CHECK VALVE
A one-directional valve which is opened by the fluid flow in one direction and closed automatically when the flow stops or is reversed.
CHEVRON PACKING
A type of packing used in packing boxes consisting of a nest of "V" cross-section rings.
CITY GATE - CITY GATE STATION
The metering and pressure reducing station where gas is transferred from a high pressure cross-country transmission line to a low pressure distribution piping system within a city.
CLADDING
A method of coating metals by which the coating becomes an integral part of the material. This can be done by casting or hot working. It is generally done on valves where special trims are required for difficult applications.
CLAPPER
The hinged closure element of a swing check valve.
CLASS
A designation of pressure capability. See "ASME," "MWP."
CLEVIS
A "U" shaped connecting yoke at the end of a stem or rod, between the ends of which a gate or other part may be pinned or bolted.
CLOSURE ELEMENT
The moving part of a valve, positioned in the flowstream which controls flow thru the valve. Ball. Gate, Plug, Clapper, Disc, etc., are specific names for closure elements.
CLOSURE
The ends of a ball valve, bolted to the body, which often contain the seat rings. Often referred to as part of the body.
COAL GASIFICATION
The process of manufacturing natural gas from coal.
COMPRESSOR
A device which converts mechanical energy into gas pressure.
CONCENTRIC
Having the same centers.
CONTAMINANT
A particle or material which is foreign to the fluid media.
CONTROL VALVE
A valve that controls a process variable, such as pressure, flow or temperature by modulating its opening in response to a signal from a controller. See "Controller"
CONTROLLER
A device that measures a controlled variable, compares it with a predetermined setting and signals the actuator to read just the opening of the valve in order to re-establish the original control setting.
CORROSION
The deterioration of a material due to chemical action.
COULISSE
Of or using runners or slides as a guiding mechanism; as in a "Coulisse" style gate valve.
CRUDE OIL
Unrefined oil. Oil as it comes directly from the well.
CRYOGENIC TEMPERATURE
Any temperature below about -240°F.
CRYOGENIC VALVE
A valve capable of functioning at cryogenic temperatures.
CV
Flow coefficient expressed as the number of gallons of water that would flow through an opening, such as a valve port, in 1 minute under a differential pressure of 1 psi. CWP: Cold working pressure - themaximum allowable pressure under non-shock conditions at ambient temperature ( -20° F to +100° F).
CYCLE TEST
A procedure whereby a product is put through an interval of time during which a phenomena is completed. This can be a set number of events or it can be a continuous operation until something in the productfails.
CYCLE
A single complete operation or process returning to the starting point. A valve, stroked from full open to full close and back to full open, has undergone one cycle.
CYLINDER OPERATOR
A power-piston valve operator using either hydraulic or pneumatic pressure. A sealed piston converts applied pressure into a linear piston rod (stem) motion. See "Power Operators."
DELTA P (^P)
See "Differential Pressure," "Pressure Drop."
DESIGN APPRAISAL
A procedure by which a certifying authority, appointed by the purchaser, appraises the design parameters of the equipment and/or materials they are buying. The supplier shall submit drawings, calculations,and documents as required to the C.A., in conjunction with those normally required for review and acceptance by the purchaser.
DEZINCIFICATION
A form of pitting corrosion which attacks certain zinc.
DIAPHRAGM
A round, thin flexible sealing device secured and sealed around its outer edge - and sometimes around a central hole in the diaphragm - with its unsupported area free to move by flexing.
DIFFERENTIAL PRESSURE
The difference in pressure across a valve in a pressurized line. The difference in pressure between any two points in a pressurized system under flowing conditions.
DIP TUBE
Extending the blow down valve on large gate valves requires a tube which is located inside of the valve. The tube is called the "dip tube" and extends through the bonnet to the bottom of the body cavity.
DISC
The closure element of a globe angle or small regulator valve. The disc (sometimes referred to as "valve," "poppet" or "plug") moves to and from the seat in a direction perpendicular to the seat face. Depends on stem force for tight shutoff.
DISTRIBUTION LINE
A pipeline which distributes gas to the service lines of individual consumers. Most generally it is small in diameter (6 inch and under) and low pressure (under 150 psi).
"DOUBLE" PISTON EFFECT PRINCIPAL (DPE)
The sealing principal of a ball valve whereby line pressure is used on both the upstream and downstream floating seats to effect a dead-tight seal simultaneously on both sides of the ball. With the DPE seat configuration when the upstream seat leaks, the pressure entering into the body cavity acts on the down stream seat, which being of the PPE design, is then pushed against the ball and the valve seals in both directions.
DPST
Double-pole single-throw, as related to electrical switches. See definition of "SPST."
DRAIN PLUG
A fitting at the bottom of a valve, the removal of which permits draining and flushing the body cavity.
DRIVE PINS
The two pins which fit into the bottom of a ball valve stem and engage corresponding holes in the ball. As the operator turns the stem, the drive pins turn the ball.
DROOP
A drop in set (outlet) pressure of a regulator or control valve due to the travel of its valve or poppet, as the required flow increases from low to maximum. A slight change in the control spring length due to the valve travel, will result in spring force variations, translating into a change of set (outlet) pressure.
"DU" BEARING
A bearing consisting of bonze, impregnated with TFE (Teflon) resin and lead powder - bonded to a low carbon steel backing
DUROMETER
An instrument for determining the hardness of synthetic rubber or elastomeric materials, usually on the "Shore A" scale. Also the unit of hardness: - i.e., "90 Durometer Shore A."
ECCENTRIC
Not having the same center.
ELASTOMER
A natural or synthetic elastic material, often used for o-ring seals. Typical materials are viton, buna-n, EPDM (ethylene propylene dimonomer), etc.
ELBOW
A female threaded or socket fitting used for changing direction in a run of pipe or tubing. See "Ell," "Street Ell."
ELECTROLESS NICKEL PLATING
A plating process which requires no external electrical power and is the result of a chemical reaction between the part and the plating solution. A uniform consistent deposit and plating rate can be producedby controlling and adjusting the chemistry of the plating bath.
ELL
A pipe or tubing fitting that has the shape of an "L." See "Elbow."
EMERGENCY SEAT SEAL
To obtain tight shut off in an emergency situation, a sealant can be injected into a specially designed groove in the seat rings. Available for most ball valves and gate valves.
EMO - ELECTRIC MOTOR OPERATED
The acuation of a valve by electric motor. See "Power Operator."
END BEVEL
Weld end preparations for butt welding. Governed by ASME B16.25.
END CONNECTION
The type of connection supplied on the ends of a valve which allows it to be installed in a pipeline. Weld end (WE), raised face flange (RF), ring type joint (RTJ), screwed end (SC).
EROSION
The mechanical wearing away of a metal surface or part due to fluid impingement. The presence of entrained solid particles accelerates this process.
ESDV - EMERGENCY SHUT DOWN VALVES
A valve or a system of valves which, when activated, initiate a shut-down of the plant, process, or platform they are tied to.
EXPANDING GATE VALVE
A gate valve that is comprised of a separate gate and segment that as the valve operates the gate and segment move without touching the seats, permitting the valve to be opened and closed without wear. In the closed position the gate and segment are forced against the seat. Continued downward movement of the gate causes the gate and segment to expand against the seats. When the valve reaches its full open position, the gate and segment seal off against the seats while the flow is isolated from the valve body.
EXPLOSION PROOF
The prevention of explosion, triggered by electrical components, through containment in special housings. A requirement for electrical devices, such as solenoids and switches, when exposed to a potentially explosive environment.
EXPORT PACKING
Special packing and crating that is required for export shipping. Includes sealing against a salt atmosphere (sea air).
EXTENDED BDV (BLOW DOWN VALVE)
Used on buried valves where the drain plug is inaccessible. Instead, a line is piped above grade, terminating in a small valve. Line pressure is used to blowout condensates and other material which settles out in the bottom of the body cavity. See "BDV."
EXTENSIONS
The equipment applied to buried valves to provide above grade accessibility to operating gear, blowdown and seat lubrication systems.
EXTERNAL COATING
Coating applied to protect valves against various environments - sea air, salt water, earth buried, normal air exposure.
F.A.S. - FREE ALONG SIDE
Term used for ocean shipment. Vendor pays transportation only to shipping dock alongside vessel.
F.E. -
Flanged End: See "R.F." and "RTJ"
F.E.R.C. - FEDERAL ENERGY REGULATORY COMMISSION
A United States government agency which has the final approval of new pipelines, right of ways, etc.
F.O.B. - FREE ON BOARD
Transportation charges are absorbed by vendor to the F.O. B. point. Usually shipment is F.O.B. factory. In which case, title and transportation charges pass to the customer when shipment leavesthe factory.
F.P.C. - FEDERAL POWER COMMISSION
The United States government agency which governs and regulates the natural gas and pipeline industry, as well as other energy industries.
FABRICATED VALVE
One in which the body and hub parts are not cast - but rather are formed from plate or pipe and the welded, or bolted together.
FACE-TO-FACE
The overall dimension from the inlet face of a valve to the outlet face of the valve (one end to the other). This dimension is governed by ASME B16.10 and API-6D to ensure that such valves are mutually inter changeable, regardless of the manufacturer.
FACING
The finish of the contact surface of flanged fittings.
FAIL SAFE VALVE
A valve designed to fail in a preferred position (open or closed) in order to avoid an undesirable consequence in a piping system.
FATIGUE ASSESSMENT
Fatigue resistance verification of a component subjected to a number of operating cycles.
FEA - FINITE ELEMENT ANALYSIS
A state of the art method of analyzing complex shapes by organizing the shapes into a series of smaller elements which can be more accurately analyzed to determine whether or not components are suitablefor their intended purpose.
FEMALE THREAD
An internal screw thread designed to mate with a component having male (external) threads of the same size and type.
FIELD SERVICEABLE
A statement indicating that normal repair of the valve or replacement of operating parts can be accomplished in the field without return to the manufacturer.
FIRE GATE
A gate or ball valve which is positioned in a pipeline at the entrance to a compressor station. This valve is closed in case of fire in the compressor station. Closing the valve prevents the gas in the pipeline from feeding the fire.
FIRE SAFE
A statement associated with a valve design which is capable of passing certain specified leakage and operational tests after exposure to fire. Must be referenced to a particular specification. See API Spec. 6FA and BS Spec 6755.
FITTING
Any component, other than valves, used with pipe as part of the pressure system and normally referring to items covered by a national standard.
FLANGE
A cast or formed pipe fitting consisting of a projecting radial collar with bolt holes to provide means of attachment to piping components having a similar fitting. The end piece of flanged-end valves.
FLAT FACE (FF)
A flange surface in which the gasket sealing area is the entire surface from the ID to the outside edge. Usually used for class 125 cast iron valves.
FLEXIBLE TUBE VALVE
A special valve using a flexible sleeve or tube which acts as the closure element. Pressure applied to the jacket space surrounding the outside of the tube, controls the opening and closing of the valve.
FLOAT VALVE
A valve which automatically opens or closes as the level of a liquid changes. The valve is operated mechanically by a float which rests on the top of the liquid.
FLOATING BALL
A ball valve having a non-trunnion mounted ball. The ball is free to float between the seat rings, and thus causes higher torques.
FLOW COEFFICIENT
The number of gallons of water per minute that will flow through a valve with a pressure drop of 1 psi. Also referred to as the Cv of the valve.
FLOW LAMINAR
The flow of a viscous fluid in which the fluid moves in parallel layers with a fixed velocity gradient from the centerline to the containing walls of the conduit. Sometimes referred to as "streamline" flow.
FLOW METER
An instrument used to measure flow rate or total flow or both.
FLOW RATE
The volume or weight of a fluid passing thru a pipeline or conductor per unit of time, i.e., 3000 barrels of oil per day; 4 MMCF of gas per hour.
FLOW, TURBULENT
The random flow of a fluid in which the velocity at a certain point in the fluid varies irregularly.
FLOW
A fluid in motion in a conducting line.
FLUID
Any non-solid substance that can be made to flow. Both liquids and gases are fluids.
FORCE
The intensity of an influence tending to produce motion, distortion or change of shape. The product of unit force (PSI) and the area over which it acts. Usually expressed in pounds.
FORGING
A metalworking process that involves hammering or squeezing, with or without a die, at hot working temperatures to form a specific shape.
FRICTION
The resistance to motion between two contacting surfaces or substances. Friction is also developed between a flowing fluid and the inner wall of the conducting pipe - resulting in a drop inpressure.
FULL BORE (FULL PORT)
Describes a valve in which the bore (port) is nominally equal to the bore of the connecting pipe.
FULL OPENING
Describes a valve whose bore (port) is nominally equal to the bore of the connecting pipe.
GALLING
The tearing of metal when two elements rub against each other. Usually caused by lack of lubrication or extreme contact pressure.
GAS
A compressible fluid - such as air, hydrogen, nitrogen, etc.
GASKET
A component whose purpose is to seal a joint between two larger components, softer than the surfaces of the joint being sealed and usually squeezed by means of bolting to effect the seal.
GATE VALVE
A straight-thru pattern valve whose closure element is a wedge or parallel-sided slab, situated between two fixed seating surfaces, with means to move it in or out of the flow stream in a direction perpendicular to the pipeline axis.
GATE
The closure element of a gate valve (sometimes called wedge or disc).
GAUGE, PRESSURE
An instrument, usually with a threaded connection, for measuring and indicating the pressure in a piping system at the point at which it is connected.
GLAND FOLLOWER OR GLAND FLANGE
The component used to hold down or retain the gland in the stuffing box.
GLAND OR GLAND BUSHING
That part of a valve which retains or compresses the stem packing in a stuffing box (where used) or retains a stem O-ring, lip seal, or stem O-ring bushing. Sometimes manually adjustable. See "Packing," "StuffingBox."
GLAND PLATE
The plate in a valve which retains the gland, gland bushing or stem seals and sometimes guides the stem.
GLOBE VALVE
A valve whose closure element is a flat disc or conical plug sealing on a seat which is usually parallel to the flow axis. Can be used for throttling services.
GO - GEAR OPERATED
The actuation of a valve thru a - ear set which multiplies the torque applied to the valve stem. See "BGO", "MGO."
GRAPHITE
Flexible carbon material used to make gaskets and packing. The gaskets may be flat graphite sheet or have metal inserts for added strength. The packing is a combination of lattice braided rings used asanti-extrusion or wiper rings and die-formed rings which are compressed to effect the seal.
GREASE FITTING
A fitting through which lubricant or sealant is injected.
HAND WHEEL
A wheel-shaped valve operating device intended to be grasped with one or both hands which allows turning the valve stem or operator shaft to which it is attached.
HARD FACING
A surface preparation in which an alloy is deposited on a metal surface usually by weld overlay to increase resistance to abrasion and or corrosion.
HEAT ANALYSIS
A chemical analysis conducted by a foundry immediately prior to pouring which measures the exact chemical composition of a particular batch of molten metal.
HEAT TREATMENT CHARTS
Furnace charts providing a temperature vs. time record of the heating and cooling cycle, required by a specific heat treatment process for a particular furnace load of steel or steel parts.
HEAT TREATMENT
Describes any process or procedure by which the internal structure of steel is altered by heating to produce desired physical characteristics. This is usually accomplished by furnace heating followed by controlled cooling.
HOLIDAY
An imperfection or "bare spot" in a coating or plating.
HOT TAP
A connection made to a pipeline while the line is under pressure or in service. A special procedure is required to make an opening in the pipe without leaking any of the line contents.
HOT TEARS
A defect occurring in castings caused where partially solidified or weak, newly solidified sections are subjected to a pull resulting from the contraction of thinner parts that have solidified earlier. A hot tear is an intergranular failure.
HUBS
The end connection tubes on a gate valve.
HUEY TEST
A corrosion resistance test for stainless steels, most useful for predicting resistance to intergranular corrosion.
HWO - HANDWHEEL OPERATED
A valve on which the handwheel drives the stem directly to operate the valve.
HYDRAULIC MOTOR ACTUATOR (OPERATOR)
A device by which rotation of a hydraulically powered motor is converted into mechanical motion.
HYDRAULIC SEATS
The movement of the seats in a valve that are controlled by using water, oil, or other liquids under pressure.
HYDRAULIC
Pertaining to, or using, water, oil, or other liquids.
HYDROSTATIC TEST (SHELL TEST)
A test in which a valve is completely filled with water and pressure tested. Used for conducting proof pressure testing. See "Proof Pressure."
IBBM
Iron body, bronze mounted - common term for valves with cast iron body and bonnet and bronze trim (seating surfaces, stem, bushings).
ID
The measurement of the inside diameter of a circular part.
IDS (INSTRUMENT DATA SHEET)
A table summarizing data such as service, valve size, supply pressure, etc., necessary for actuator sizing.
INCREMENTAL SEAT TEST
The leakage testing of valve seats in an assembled valve by increasing the applied pressure in prescribed pressure steps.
INLET PORT
That end of a valve which is connected to the upstream pressure zone of a fluid system.
INNER SEAT RING
The inner part of a two-piece valve seat assembly.
INSIDE-OUT AIR SEAT TEST
A pressure test that can be performed only on independent seating trunnion mounted ball valves. By closing the valve and pressurizing the body cavity, all of the seals in an independent seating ball valve can then be pressure tested.
"INSITU" (MAINTENANCE)
To maintain or repair a product "in its original place," such as a top entry ball valve or regulator.
INTERNAL PRESSURE RELIEF
A self relieving feature in non-independent seating valves that automatically relieves excessive internal body pressure caused by sudden changes in line pressures. By means of the piston effect principal the excessive body pressure will move the seat away from its seating surface and relieve it to the lower pressure side.
ISO (INTERNATIONAL STANDARDS ORGANIZATION)
An organization which sets minimum international standards for a wide variety of items manufactured and used in pipeline services.
ISRS
Inside screw, rising stem - common term for any valve design in which the stem threads are exposed to the fluid below the packing and the stem rises up through the packing when the valve is opened.
KEY STOP
A method of restricting the travel of a ball valve from fully open to fully closed. The stem key bears against the ends of an arc machined in the adaptor plate.
LANTERN RING
See "Chevron Packing."
LEVER
A handle type operating device for quarter-turn valves.
LIFTING LUGS
LINE
MOLD
NIPPLE
O.D.
OD
OPERATOR
PACKING
PATTERN
PIG
PLASTICS
PUMP
QUALITY ASSURANCE
REGULATOR
REMOTE CONTROL
RS
SCHEDULE
SEAT
SPECIFIC GRAVITY
SPECIFICATION
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