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 |  موضوع: كتاب Glossary of Valve Terms الأحد 28 أغسطس 2022, 2:15 am | |
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Glossary of Valve Terms
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Contents
Section 1
Valve Terminology 1
Engineered Surge Relief Systems 85
Conversion Tables and Equivalents 88
General Information 107
SECTION 2
SECTION 3
SECTION 4
AGA - American Gas Association
AISI - American Iron & Steel Institute
ANSI - American National Standard Institute
API - American Petroleum Institute
API SPEC 6FA
API SPEC 6D/ISO 14313
ASME - American Society of Mechanical Engineers
A society comprising gas companies set up to achieve
common goals.
An association of steelmakers which sets standards
for the chemical and physical properties of steel
and iron in various shapes and forms - pipe, tubing,
sheet, strip, wire
The principle organization in the US which oversees
the creation, promulgation and use of standards for
a wide variety of items, including the design,
fabrication, and testing of pressure piping, systems,
and components for various pipeline services.
The principal US oil company trade association. It has
some standards and specification writing functions,
such as wellhead components and pipeline valves
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 fire test,
all such valves can be identified with the above
monogram. API-6FA supersedes API-RP-6F.
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
This professional society publishes 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.
.
.
.
SECTION 1 VALVE TERMINOLOGY 12 VALVE TERMINOLOGY
ASTM - American Society for Testing & Materials
A professional society governing the detailed
physical and chemical analysis of all basic metals
and alloys used in construction. The valves of most
manufacturers have components whose materials
correspond to ASTM standards.
AWS - American Welding Society
ACCUMULATOR
ACME THREAD
ACTUATOR
ADAPTER SPOOL
A society which sets guidelines and standards for
all welds.
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.
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 US standard “V” thread
See “Operator”.
An extension which is added to a short face-to-face
valve to conform to standard API 6D face-to-face
dimensions.
.
ADAPTER SPOOL
SHORT PATTERN
GATE VALVE WITH
ADAPTER SPOOLALL WELDED CONSTRUCTION
Pertains to a valve construction in which the body
is completely welded and cannot be disassembled
and repaired in the field.
VALVE TERMINOLOGY 3
ALL WELDED CONSTRUCTION
(NO BOLTED BODY PARTS)
AMBIENT TEMPERATURE
ANCHOR PIN
The prevailing temperature of the environment
immediately surrounding an object.
A pin welded to the body of a ball valve.
This pin aligns the adapter plate and keeps
the plate and gear operator from moving while
the valve is being operated.
ANCHOR PIN
CAMERON FULLY WELDED BALL VALVE  4 VALVE TERMINOLOGY
ANGLE VALVE
A variation of the globe valve in which the end
connections are at right angles to each other,
rather than being in-line.
ATMOSPHERIC PRESSURE
BBL (bbl)
The external pressure exerted on a body by the
atmosphere: 14.7 psi (absolute) at sea level.
An abbreviation for “barrel”. Used to express liquid
volume. One barrel of oil is equal to 42 US gallons.
ANGLE VALVEBDV - 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”.
VALVE TERMINOLOGY 5
BGO - Bevel Gear Operated (or Operator)
The actuation of a 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 gear set determines the multiplication
of torque achieved. Used on gate valves.
BDV
EXTENSION
BGO
BALL VALVE WITH DRAIN LINE EXTENSION
GATE VALVE WITH BGO
BEVEL GEAR6 VALVE TERMINOLOGY
BRV - 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.
BS 6755
BVR - Ball Valve Regulator
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, all such valves can be identified
with the BS 6755 standard.
An automatic throttling valve controlling flow or
pressure in a pipeline comprising a package involving
a ball valve, actuator, positioner, and controlling
instrument.
BODY RELIEF VALVEBACK PRESSURE REGULATOR
BACK SEAT
BALL
BALL VALVE
Regulator designed to control upstream pressure.
See “Regulator”.
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.
The spherical closure element of the ball valve.
A valve using a spherical closure element (ball)
which is rotated through 90° to open and close
the valve.
VALVE TERMINOLOGY 7
GROVE B5 BALL VALVE 8 VALVE TERMINOLOGY
BAR
BDV
BELLEVILLE SPRING
BENDING MOMENT
BEVEL
BLOCK-AND-BLEED
A metric unit of pressure. One bar equals 14.5 psi.
A BDV is also a valve or a system of valves which,
when activated, initiate a blowdown of a pipeline,
plant, process, or platform; like an ESDV that shuts in
a line, except the BDV opens a line.
A spring resembling a dished washer, used in some
ball valves to push the seats against the ball.
The mechanical bending load produced by a force
applied to a part at a right angle to its surface or axis.
The product of the force times the perpendicular
distance to the point of restraint. Usually expressed
in pound-feet
A chamfer. The angle between two adjacent surfaces
(other than 90°). The word “bevel” is used in
describing weld-end preparations.
See “End Bevel”.
The capability of obtaining a seal across the upstream
and downstream seat rings of a valve when the
body pressure is bled off to the atmosphere
through blow down valves or vent plugs. Useful in
testing the integrity of seat seals and performing
minor repairs under pressure.
.BOLT
BOLT CIRCLE
A fastener which has a square or hex head and is
threaded on the opposite end to receive a nut.
Sometimes used to make up a flanged connection.
The circle on which bolt holes are located.
VALVE TERMINOLOGY 9
GROVE G4N GATE VALVE
BODY
BOLT CIRCLE
BOLT CIRCLE
DIAMETER
BOLTED BONNET
A bonnet which is connected to a valve body with
bolts.
GROVE B4 BALL VALVE 10 VALVE TERMINOLOGY
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.
BODY
CLOSURE BOLTED
TO BODY
CLOSURE
GROVE B4 BALL VALVE BORE (or PORT)
BRINELL HARDNESS NO.
The inside diameter of the smallest opening through
a valve. The diameter of the hole in the ball of a ball
valve. The diameter of the hole in the gate of a gate
valve. The inside diameter of seat rings.
A number indicating metal hardness using the Brinell
scale. Can be converted to Rockwell B & C hardness
by reference to conversion tables.
See “Rockwell Hardness No”.
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 through water. To qualify as “bubble-tight”,
no bubbles should be observed in a prescribed time span.
BUBBLE-TIGHT SHUTOFF
VALVE TERMINOLOGY 11
BONNET
BONNET
The top part of a valve, attached to the body, which
guides the stem and adapts to extensions or operators.
GROVE
G4N GATE VALVE
RING-O
DOUBLE EXPANDING GATE VALVE
BONNET12 VALVE TERMINOLOGY
BURIED SERVICE
BURST PRESSURE
BUTT WELD ENDS
BUTTERFLY VALVE
An application in which valves are installed in lines
which are buried below ground level
That pressure (psi) at which rupture of a stressed
element or pressure-containing vessel takes place.
See “Ultimate Strength”.
The end connections of a valve, suitably prepared
for butt welding to connecting piping.
See “WE”, “End Bevel”.
A short face-to-face valve which has a movable vane,
in the center of the flow stream, which rotates
90 as the butterfly valve opens and closes.
.
°
WKM DYNACENTRIC HIGH PERFORMANCE BUTTERFLY VALVE BYPASS
A system of pipes and valves permitting the
diversion of flow or pressure around a line valve.
VALVE TERMINOLOGY 13
C-PACK
C.I.F. - Cost Insurance & Freight
A special stem packing designed by GROVE to give
maximum lifetime sealing in gate, ball and check
valve stems.
Shipper pays all freight and insurance charges.
Same as FOB Destination.
BYPASS OPERATOR BYPASS
BALL VALVE
GRADE
RISER
EXTENSION
MAINLINE
VALVE
BURIED VALVE SETTING14 VALVE TERMINOLOGY
C
CWP - Cold Working Pressure
CAPACITY FACTOR
CAPSCREW
CAST
CASTING
CAVITATION
CERTIFYING AUTHORITY (CA)
CHAIN WHEEL OPERATED VALVE
v
The capacity factor of a valve, also called the valve
coefficient; specifically, the number of gallons of
water per minute that will flow through a valve
with a pressure drop of 1 psi
See “MWP”.
See “C”.
A fastener with a head whose shank is normally
threaded throughout its entire length. It is not used
with a nut, but rather engagement is made with a
female thread in the piece to be joined.
The form of a particular part of a valve, where the basic
shape is formed by molding rather than fabricating.
A part which has been formed by pouring molten
metal into a mold.
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 the piping itself.
Can be the cause of excessive noise.
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 CA with information,
documents, access to works and personnel to enable
the survey to be carried out
An overhead valve operated by a chain drive wheel
instead of a handwheel
.
.
.
(or CERTIFICATION)CHARACTERIZED GATE OR BALL
CHARPY TEST
A ball or gate, the shape of whose port has been
specially altered to provide a specific throttling
capability.
A mechanical test conducted on a precisely machined
coupon of the steel to be tested. The coupon is
clamped in a special machine and subjected to a
lateral hammer blow. This test provides a relative
measure of the toughness of the steel or its
resistance to shock or impact loads. Often required
for low temperature applications where testing is
done at the expected minimum service
temperature. (Refer to Table 3.8 of API 6D.)
VALVE TERMINOLOGY 15
CHECK VALVE
A one-directional valve which is opened by the fluid
flow in one direction and which closes automatically
when the flow stops or reverses direction.
See “Clapper”.
VEE NOTCH
TEST COUPON IS SHAPED LIKE THIS
TOM WHEATLEY
SWING CHECK VALVE
TM16 VALVE TERMINOLOGY
CHEVRON PACKING
A type of packing used in packing boxes consisting
of a nest of “V” cross-section rings.
CITY GATE (or CITY GATE STATION)
CLADDING
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.
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.
CHEVRON PACKINGCLAPPER
The hinged closure element of a swing-disc check valve.
VALVE TERMINOLOGY 17
CLASS
A designation of pressure capability.
See “ASME”, “MWP”.
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.
CLEVIS
CLEVIS
CLEVIS PIN
CLAPPER
TOM WHEATLEY SWING CHECK VALVE TM18 VALVE TERMINOLOGY
CLOSURE
The end of a ball valve bolted to the body, which
often contains the seat rings. Often referred to as
part of the body.
CLOSURE ELEMENTS
COAL GASIFICATION
COMPRESSOR
CONCENTRIC
The moving part of a valve, positioned in the flow
stream, which controls flow through the valve.
Ball, Gate, Plug, Clapper, Disc, etc., are specific names
for closure elements
The process of manufacturing natural gas from coal.
A device which converts mechanical energy into gas
pressure.
Having the same centers.
.
CLOSURE
SEAT
O-RING
TWO DIAMETERS ON
SAME CENTERLINE
CONCENTRIC REDUCERCONTAMINANT
CONTROL VALVE
A particle or material which is foreign to the fluid media.
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”.
VALVE TERMINOLOGY 19
CONTROLLER
A device that measures a controlled variable, compares
it with a predetermined setting and signals the actuator
to re-adjust the opening of the valve in order to
re-establish the original control setting.
The deterioration of a material due to chemical action.
Of or using runners or slides as a guiding mechanism,
as in a “Coulisse” style gate valve
Unrefined oil. Oil as it comes directly from the well.
CORROSION
COULISSE
CRUDE OIL
.
VALVE
CONTROL VALVE
CONTROLS20 VALVE TERMINOLOGY
CRYOGENIC TEMPERATURE
CRYOGENIC VALVE
CYCLE
CYCLE TEST
CYLINDER OPERATOR
Any temperature below about -240°F (-151°C).
A valve capable of functioning at cryogenic
temperatures.
A single complete operation or process returning to
the starting point. A valve, stroked from full open
to full closed and back to full open, has undergone
one cycle.
A procedure whereby a product is put through an
interval of time during which a test process is
completed. This can be a set number of events or it
can be a continuous operation until something in
the product fails.
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 Operator”.
POWER-PISTON VALVEVALVE TERMINOLOGY 21
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.
RESTRICTING
ORIFICE
AIR DOME
POWER
CHAMBER
DIAPHRAGM
VALVE STEM
AIR-DOME
REGULATOR DIAPHRAGM
DPD - DOUBLE-POLE DOUBLE-THROW
Related to electrical switches.
See “SPDT”.
Related to electrical switches.
See “SPST”.
See “Differential Pressure”, “Pressure Drop”.
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 CA,
in conjunction with those normally required for
review and acceptance by the purchaser.
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.
DPST - DOUBLE POLE SINGLE-THROW
DELTA ( P)
DESIGN APPRAISAL
DIAPHRAGM
D22 VALVE TERMINOLOGY
DIP TUBE
Extending the blow down valve on large gate valves
requires a tube which is located inside of the valve.
This tube is called the “dip tube” and extends
through the bonnet to the bottom of the body cavity.
DISC
DISTRIBUTION LINE
DOT REGULATIONS - Department of Transportation
The closure element of a globe angle or small
regulator valve. The disc (sometimes referred to as a
“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
Pipeline which distributes gas to the service lines of
individual consumers. Usually it is small in diameter
(6” and under) and low pressure (under 150 psi).
A code of federal regulations setting forth minimum
safety requirements for the transportation of
hazardous gases or liquids by pipeline.
.
.
½” DIP TUBEDOUBLE-BLOCK-AND-BLEED
A valving arrangement which ensures no flow in a
line, even though the valve may leak. It consists of
two block valves in the main line with a small
bleeder valve draining the line between the block
valves.
See “Block-and-Bleed”.
“DOUBLE” PISTON EFFECT PRINCIPLE (DPE)
The sealing principle of GROVE ball valves whereby
line pressure is used on both 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 downstream seat, which, being of the DPE
design, is then pushed against the ball, and the
valve seals in both directions
.
VALVE TERMINOLOGY 23
DRAIN PLUG
A fitting at the bottom of a valve, the removal of
which permits draining and flushing of the body cavity
The vent plug assembly on some ball and gate
valves also serves as a drain valve.
See “Vent Plug”.
.
UPSTREAM
BALL DOWNSTREAM
LINE PRESSURE
HIGHER THAN
BODY PRESSURE
BODY PRESSURE
HIGHER THAN
LINE PRESSURE
SEALING DIAMETER
X
A2
A > 2 A
BY
AMOUNT X
1
A > 2 A
BY
AMOUNT X
1
A2
X
DOUBLE PISTON EFFECT PRINCIPLE
SEALING
DIAMETER24 VALVE TERMINOLOGY
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
DRY LUBE
DU BEARING
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.
Dry-film moly disulphide applied as a coating to
sliding or rotating parts to reduce frictional drag.
After application, the film is baked in an oven at
high temperature.
A bearing consisting of bronze impregnated with
TFE (Teflon) resin which is lead powder-bonded to a
low carbon steel backing. A Garlock Company
product.
“ “
STEM
DRIVE PIN
HOLES IN
BALL
BALL
DRIVE PINSVALVE TERMINOLOGY 25
ELASTOMER
A natural or synthetic material. Used in synthetic
rubber parts such as O-rings.
A female-threaded or socket fitting used for
changing direction in a run of pipe or tubing.
See “Ell”, “Street Ell”.
ELBOW
DUROMETER
DYE PENETRANT INSPECTION
EMO - Electric Motor Operated
ESDV - Emergency Shutdown Valve
ECCENTRIC
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”.
See “Liquid Penetrant Inspection”.
The actuation of a valve by electric motor.
See “Power Operator”.
A valve or a system of valves which, when
activated, initiate a shutdown of the plant,
process, or platform they are tied to.
Not having the same center.
CENTERLINES ARE OFFSET
ECCENTRIC
REDUCER
90° ELBOW 45° ELBOW26 VALVE TERMINOLOGY
ELECTROLESS NICKEL PLATING
ELL
EMERGENCY SEAT SEAL
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 produced
by controlling and adjusting the chemistry of the
plating bath.
A pipe or tubing fitting that has the shape of an “L”.
See “Elbow”.
To obtain tight shutoff 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.
EMERGENCY SEALANT
INJECTION FITTING
BODY
BALL VALVE
GATE VALVE
TO LUBE ASSEMBLY
IN BONNET
SEAT
BODY
SEALANT
PASSAGE
SEAT BALL
SEALANT
PASSAGE
GATEVALVE TERMINOLOGY 27
END BEVEL
Weld end preparations for butt welding. Governed by
ASME B31.4 and B16.25.
END CONNECTION
EROSION
EXPANDING GATE VALVE
EXPLOSION PROOF
The type of connection supplied on the end of a
valve which allows it to be installed in a pipeline.
Weld end, flanged end, screwed end.
The mechanical wearing away of a metal surface or
part due to fluid impingement. The presence of
entrained solid particles accelerates this process.
A gate valve comprised of a separate gate and
segment that, as the valve operates that 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 seats. 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.
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.
WELD END BEVELS
1/16" ± 1/32"
37 1/2° ± 2 1/2°
3/4"
10° ± 1°
T
37 1/2° ± 2 1/2°
1/16" ± 1/32"
1 1/8" R. Min.28 VALVE TERMINOLOGY
EXPORT PACKING
EXTENDED BDV - Blow Down Valve
Special packing and crating that is required for export
shipping. Includes sealing against a salt atmosphere
(sea air).
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 blow out condensates and other material which
settles out in the bottom of the body cavity.
See “BDV”.
BDV
EXTENDED
BLOW DOWN
LINE
BALL VALVE GATE VALVE
BDV
EXTENDED
BLOW DOWN
LINEVALVE TERMINOLOGY 29
EXTERNAL COATING
FAS - Free Along Side
FE - Flanged End
FEA - Finite Element Analysis
FERC - Federal Energy Regulatory Commission
Coating applied to protect valves against various
environments - sea air, salt water, earth burial, and
normal air exposure.
Term used for ocean shipment. Vendor pays
transportation only to shipping dock alongside vessel.
See “RF”, “RTJ”.
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 suitable for their intended purpose.
A United States government agency which has the
final approval of new pipelines, right of ways, etc.
EXTENSIONS
GATE VALVE BALL VALVE
EXTENSION STEM
The equipment applied to buried valves to provide
above-grade accessibility to operating gear, blow
down, and seat lubrication systems.30 VALVE TERMINOLOGY
FOB - Free On Board
FPC - Federal Power Commission
FABRICATED VALVE
FACE-TO-FACE
Transportation charges are absorbed by vendor to
the FOB point. Usually a shipment is FOB Factory,
in which case, title, and transportation charges pass
to the customer when it leaves the factory.
The United States government agency which
governs and regulates the natural gas and pipeline
industry, as well as other energy industries.
One in which the body and hub parts are not cast,
but rather are formed from plate or pipe and then
welded or bolted together.
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
interchangeable, regardless of the manufacturer.
FACING
The finish of the contact surface of flanged fittings.
DIMENSION E
IS FACE-TO-FACE LENGTH
“ “
EVALVE TERMINOLOGY 31
FAIL SAFE VALVE
FATIGUE ASSESSMENT
FEMALE THREAD
FIELD SERVICEABLE
FIRE GATE
FIRE SAFE
FITTING
A valve designed to operate to a preferred
position (open or closed) in order to avoid an
undesirable consequence in a piping system.
Refer to ESDV and BDV.
Fatigue resistance verification of a component
subjected to a number of operating cycles.
An internal screw thread designed to mate with
a component having male (external) threads of
the same size and type.
A statement indicating that normal repair of the
valve or replacement of operating parts can be
accomplished in the field without returning the
valve or part to the manufacturer.
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.
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.
Any device used for connecting elements in fluid
lines, i.e., elbows, tees, nipples, unions, flanges, etc.32 VALVE TERMINOLOGY
FLANGE
A cast or formed pipe fitting consisting of a projecting radial collar with bolt holes to provide a
means of attachment to piping components having
a similar fitting. The end piece of flanged-end valves.
FLEXFLO
FLEXIBLE TUBE VALVE
The registered trademark of a flexible tube valve
manufactured by CAMERON.
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 that
controls the opening and closing of the valve.
FLOATING BALL
FLOW
FLOW COEFFICIENT
.
.
A ball valve having a non-trunnion mounted ball.
The ball is free to float between the seat rings and
thus causes higher torques.
A fluid in motion in a conducting line.
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 C of the valve
v
FLEXIBLE TUBE VALVEVALVE TERMINOLOGY 33
FLOW, LAMINAR
FLOW METER
FLOW RATE
FLOW, TURBULENT
FLUID
FORCE
FORGING
FRICTION
FULL BORE
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
An instrument used to measure flow rate or total
flow or both.
The volume or weight of a fluid passing through a
pipeline or conductor per unit of time, i.e., 3000
barrels of oil per day; 4 MMCF of gas per hour.
The random flow of a fluid in which the velocity at
a certain point in the fluid varies irregularly.
Any non-solid substance that can be made to flow.
Both liquids and gases are fluids.
The intensity of an influence tending to produce
motion, distortions or change of shape. The product
of unit force (psi) and the area over which it acts.
Usually expressed in pounds.
A part that is formed by heating and hammering
to a specific shape.
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 in pressure
See Full Opening .
“ “
“ “
.
.34 VALVE TERMINOLOGY
FULL OPENING
FULL PENETRATION WELD
Describes a valve whose bore (port) is nominally
equal to the bore of the connecting pipe.
See Venturi Valve .
Describes the type of weld wherein the weld metal
extends across the entire wall thickness of the joint.
“ “
GO - Gear Operated
The actuation of a valve through a gear set which
multiplies the torque applied to the valve stem.
See BGO - Bevel Gear Operator , MGO - Manual
Gear Operator".
“ “ “
WALL
BEVEL GEAR OPERATOR
FULL PENETRATION
WELD
WORM GEAR OPERATOR
BEVEL WORM DRIVE
GEARVALVE TERMINOLOGY 35
GALLING
GAS
GASKET
GATE
GATE VALVE
The tearing of metal when two elements rub against
each other. Usually caused by lack of lubrication or
extreme contact pressure.
A compressible fluid such as air, hydrogen,
nitrogen, etc
A seal or packing placed between mechanical joints
(such as flanges) to prevent the escape of the
flowing medium.
The closure element of a gate valve.
A straight-through 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.
.
GROVE G4 GATE VALVE 36 VALVE TERMINOLOGY
GAUGE, PRESSURE
GLAND (or GLAND BUSHING)
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.
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 , Stuffing Box .“ “ “ “
STEM
GLAND BUSHING
STEM SEAL O-RINGS
GLAND
STEM
PACKINGVALVE TERMINOLOGY 37
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. The tortuous flow path produces a
relatively high pressure loss.
STEM SEAL
GLAND PLATE
STEM SEAL
STEM
NAVCO GLOBE VALVE 38 VALVE TERMINOLOGY
GREASE FITTING
HWO - Handwheel Operated
A fitting through which lubricant or sealant is
injected.
A valve on which the handwheel drives the stem
directly to operate the valve.
HARD FACING
HEAD
HEADER
HEAT ANALYSIS
A surface preparation, such as detonation gun or high
velocity oxygen flow (HVOF), in which an alloy is
deposited on a metal surface, usually by weld overlay,
to increase abrasion and/or corrosion resistance
The height of an open column of liquid above a given
datum, expressed in linear units; i.e., feet of water,
inches of mercury, etc. It is another way of expressing
pressure.
See Manifold .
A chemical analysis, conducted by the foundry
immediately prior to pouring, which measures the
exact chemical composition of a particular batch of
molten metal. Does not include analysis of physical
properties. See Mill Test .
.
“ “
“ “VALVE TERMINOLOGY 39
HEAT TREATMENT
HEAT TREATMENT CHARTS
HOLIDAY
HOT TAPPING
HUBS
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
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.
An imperfection or bare spot in a coating or
plating.
The process by which a pipeline, under pressure, is
cut into to provide a side outlet. A flanged fitting
is saddle-welded to the pipeline and a full port
valve bolted to the flange. The hot tapping
machine, bolted to the outboard valve flange, is
operated through the open valve. After cutting
out a circular piece from the pipe wall, the
tapping machine is removed and the valve closed.
The end connection
tubes on a gate valve.
.
“ “
HUBS
HUBS
GROVE GATE VALVE 40 VALVE TERMINOLOGY
HYDRAULIC
HYDRAULIC MOTOR ACTUATOR ( or OPERATOR)
HYDRAULIC SEATS
HYDROSTATIC TEST (or SHELL TEST)
ID - Inside Diameter
IDS - Instrument Data Sheet
INCREMENTAL SEAT TEST
INERTIA
INLET PORT
Pertaining to, or using, water, oil, or other liquids
A device by which rotation of an hydraulically
powered motor is converted into mechanical
motion.
The movement of the seats in a valve that are
controlled by using water, oil, or other liquids
under pressure.
A test in which a valve is completely filled with
water and pressure tested. Used for conducting
proof pressure testing. See Proof Pressure .
The measurement of the inner diameter of a
circular part.
A table summarizing data such as service, valve
size, supply pressure, etc., necessary in
prescribed pressure steps.
The leakage testing of valve seats in an assembled
valve by increasing the applied pressure in prescribed
pressure steps.
The property of a body or mass which resists
a change in velocity.
That end of a valve which is connected to the
upstream pressure zone of a fluid system.
.
“ “
An organization which sets minimum international
standards for a wide variety of items manufactured and
used in pipeline services.
ISO - International Standards OrganizationVALVE TERMINOLOGY 41
INSIDE-OUT AIR SEAT TEST
IN SITU MAINTENANCE
INTERNAL PRESSURE RELIEF
A pressure test that can be performed only on
independent seating, trunnion mounted ball valves.
By closing the valves and pressurizing the body
cavity, all of the seals in an independent seating
ball valve can then be pressure tested.
To maintain or repair a product in its original
place , such as a top entry ball valve or regulator.
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 principle
the excessive body pressure will move the seat away
from its seating surface and relieve it to the lower
pressure side.
“ “
“
“
BALL
OUTER SEAT RING
SEAT SEAL O-RING
INNER SEAT RING
INNER SEAT RING
The inner part of a two-piece valve seat assembly.42 VALVE TERMINOLOGY
KEY STOP
LNG - Liquified Natural Gas
LPG - Liquid Petroleum Gas
LANTERN RING
LIFTING LUGS
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 adapter plate.
Natural gas in the liquid state. For the gas to remain
liquified, the temperature must be maintained in the
cryogenic region. The liquid occupies far less volume
than an equivalent volume of gas and it can be
readily transported by ship and stored ashore in
insulated tanks to await re-gasification.
Gases such as butane or propane in the liquid state.
LPG, under relatively low pressure, remains a liquid
at normal ambient temperature.
See Chevron Packing .
Lugs provided on larger ball, gate and check valves,
for lifting and positioning valves. Also called lifting eyes.
“ “
LIFTING LUG
GROVE BALL VALVE VALVE TERMINOLOGY 43
LIMIT SWITCH
LINE
LIP SEAL
LIQUID PENETRANT INSPECTION
LOCK UP PRESSURE
LOCKING DEVICE
LUBE SEATS
MAOP - Maximum Allowable Operating Pressure
An electrical device providing a signal to a remote
observation station indicating when the valve is
in the fully open or fully closed position. Usually
a component of a valve operator
A pipe, tube or hose for conducting fluids.
A circular seal ring of U shaped cross section
encompassing an elastomeric O-ring which
provides resiliency and ensures a seal at the inner
and outer lips of the U .
An NDE method of detecting the presence of
surface cracks and surface imperfections in welds
or castings through use of a special red dye.
The differential pressure required to produce
tight shutoff in a regulator. It is usually a few psi.
A mechanism provided on valve operators to
prevent unauthorized operation or tampering.
Seats which are equipped with a lubricant
injecting system. See Emergency Seat Seal .
.
Determined in accordance with piping codes,
DOT regulations, etc.
.
“ “
“ “
“ “44 VALVE TERMINOLOGY
MDS - Material Data Sheets
MGO - Manual Gear Operator
The material data sheets define the minimum
requirements for the required materials, i.e., chemical
requirements, manufacturing, qualification of supplier,
mechanical testing and properties, non-destructive
examination, repair, marking, and certification.
A gear operator that is operated manually (with
a handwheel).
“ “
“ “, “ “
MMCF
MO - Motor Operated
An abbreviation for million cubic feet used to
designate gas volume and gas flow rates in
pipelines (MMCF per hour or day).
See Power Operator EMO .
MSS - Manufacturers Standardization Society of
the Valve and Fitting Industry
A technical association of valve, fitting and actuator
manufacturers that writes standards and practices
for the valve and fitting industry. Recommendations
of this society are advisory only.
MANUAL GEAR OPERATOR
MOUNTED ON BALL VALVEVALVE TERMINOLOGY 45
MWP - Maximum Working Pressure (or CWP - Cold
Working Pressure)
Class MWP (CWP)
MAGNETIC PARTICLE INSPECTION
MALE THREAD
MANIFOLD (or HEADER)
The maximum working pressure (pounds per square
inch) at which a valve can be operated. The maximum
working pressure for various pressure classes, per
Table 2.1 of API 6D, within temperature limits of
-20°F and +100°F (-29°C and +38°C) are as follows:
150 275
300 720
400 960
600 1440
900 2160
1500 3600
2500 6000
An inspection procedure for detecting surface cracks
in welded areas through the use of fine iron particles
in an electrical field.
The external thread on pipe, fittings or valves used
in making a connection with mating female (internal)
threaded parts.
A common pipe or chamber having several lateral
outlets.
MANIFOLD46 VALVE TERMINOLOGY
MASS SPECTROMETER
MECHANICAL SEAL
METAL-TO-METAL SEAL
METER PROVER
METER RUN
An instrument used for sorting streams of electrified
particles in accordance with their different masses
by means of deflecting fields. The instrument can
produce a photographic or graphic record of each
compound and the percentage of the compound.
Most commonly used in analyzing petroleum and
steel products.
In a valve, a shutoff that is accomplished by a
mechanical means rather than with fluid or line
pressure. The wedging action of a gate against the
seats or the seat springs pushing the seat against the
ball or gate are examples of mechanical seals in a valve.
The seal produced by metal-to-metal contact
between the sealing face of the seat ring and the
closure elements, without benefit of a synthetic seal.
A system used to check or prove a flow meter.
A close fitting sphere is launched into a pipe of known
inside diameter. The flow medium pushes the sphere
through a measured length of pipe between two
sphere detection devices. Knowing the transit time and
the exact volume between the stations, a flow rate
is calculated and compared with the meter reading.
A section of pipeline in which a meter is installed to
measure the volume of fluid passing through the line.
“ “VALVE TERMINOLOGY 47
MILL CERTIFICATES
MILL TEST
MILL TEST REPORTS
MODULUS (or COEFFICIENT) OF ELASTICITY
MOLD
MONITORING (or MONITOR SERVICE)
NACE - National Association of Corrosion Engineers
Certificates, provided by the steel mill, indicating the
chemical analysis and physical properties of a specific
batch of steel. Mill Certs are usually required only
for pressure-containing parts. The customer's need for
such Certs must be made known when the
order is first placed, otherwise is it not possible to
trace a valve part back to the mill.
See Heat Analysis .
All tests required by the material specification. Usually
includes both the heat analysis (chemical) and the
physical properties. Sometimes also impact tests.
See Mill Certificates .
The ratio between a force per unit area (stress)
which acts to deform a body and the corresponding
fractional deformation (strain) produced by the stress.
A hollow cavity (frequently in packed sand) for giving
a desired shape to a material in a molten or plastic
state. Used in making metal castings.
A field procedure whereby two valves - usually
regulators - are installed in series and adjusted in
such a manner that, should the primary regulator
fail, the standby regulator will automatically take
over at a slightly higher pressure setting
The technical association publishes papers, articles
and standards on all aspects of corrosion and has
written the definitive standard for valve materials
for sour gas service.
“ “
“Mill “
“ “
“ “
.48 VALVE TERMINOLOGY
NDE - Non-Destructive Examination
NEMA - National Electrical Manufacturers Association
NPT - National Pipe Tapered
NEEDLE VALVE
See Non-Destructive Tests .
An association which has set up guidelines for the
manufacture of electrical equipment. Generally
applicable to specifications for switches, etc., for
electric operators.
A uniform standard governing the dimensions of
tapered pipe threads.
A type of small valve, used for flow metering, having
a tapered needlepoint plug or closure element and
a seat having a small orifice.
“ “
NIPPLE WITH
THREADED ENDS
NIPPLE
A short length of small size pipe, threaded on both
ends. Used on end connections of screwed-end valves
and in small size piping systems.
NEEDLE VALVEVALVE TERMINOLOGY 49
NORMALLY CLOSED SOLENOID VALVE
An electrically operated valve whose inlet orifice
is closed when the solenoid coil is not energized.
Energize to open. See Solenoid Valve .“ “
WEDGE GATE VALVE
WITH NON-RISING STEM
NITROGEN/HELIUM TEST
A pressure test conducted using nitrogen or helium
(inert gases) instead of air, water, or other gases to
prevent any danger of fires or explosions. Generally
specified by the purchaser when buying a valve or
regulator product.
NON-DESTRUCTIVE TESTS
NON-RISING STEM
Those inspection tests which are not destructive to
the valve structure or function.
See “Radiographic Inspection“, “Liquid Penetrant
Inspection“, “Magnetic Particle Inspection“, and
“Ultrasonic Inspection“.
A gate valve having its stem threaded into the gate.
As the stem turns, the gate moves but the stem does
not rise. Stem threads are exposed to line fluids.50 VALVE TERMINOLOGY
NORMALLY OPEN SOLENOID VALVE
OCMA - Oil Companies Materials Association
OD - Outer Diameter
OLDHAM COUPLING
An electrically operated valve whose inlet orifice
is open when the solenoid coil is not energized.
Energize to close.
See Solenoid Valve .
An association of British oil companies which has
written a standard for fire safe testing of soft
seated valves.
See Fire Safe .
The measurement of the outermost diameter of a
circular part.
A double slider connection used to connect shafts
“ “
“ “
“ “
O-RING
An elastomeric or synthetic seal ring of circular
cross-section.
O-RINGS
OLDHAM COUPLINGVALVE TERMINOLOGY 51
OPERATING TIME
OPERATOR
OS&Y - Outside Screw and Yoke
The time required for a power operator to stroke
the valve from a full open to full closed position
or vice versa.
A device which converts manual, hydraulic,
pneumatic or electrical energy into mechanical
motion to open and close a valve.
See “Power Operator“, “EMO“, “GO“, “HWO“,
“MGO“, "MO".
A valve in which the fluid does not come in contact
with the stem threads. The stem sealing element is
between the valve body and the stem threads.
OUTER SEAT RING
The outer metal piece of a two-piece seat ring unit.
See Inner Seat Ring .“ “
WEDGE GATE VALVE WITH OS&Y52 VALVE TERMINOLOGY
PSI (psi)
PACKING
An abbreviation for
orce per unit area exerted against a resisting body.
The deformable sealing material inserted into a
valve stem stuffing box, which, when compressed
by a gland, provides a tight seal about the stem.
See Gland Stuffing Box .
“pounds per square inch“. The
f
“ “, “ “
PACKING GLAND
PATTERN
PEAK SHAVING
See "Gland".
A duplicate or copy, usually wooden, of a part to be
cast. Used to form the mold into which molten metal
is poured.
When daily usage of natural gas is charted on
graphs, it will show high peaks (of usage) during
the winter months. These peaks can be shaved
(averaged out) when the daily consumption is
augmented with standby supplies of synthetic natural
gas, propane, or methane
“ “
.
GLAND
PACKINGVALVE TERMINOLOGY 53
PHENOLIC COATING
PIG
A thermo-setting resin applied to valve interiors and/
or exteriors to inhibit corrosion. A plastic material.
A device, closely conforming to the pipe bore, which
is forced through a pipeline to clean the pipe of all
foreign material and debris. The valves in a pipeline
that will be pigged must be through-conduit, full
port; otherwise the pig will not pass through them.
PILOT
A spring-loaded pressure regulator used to control
the pressure and flow of other larger pressure
regulators or instruments.
24” PIG WITH URETHANE BLADES54 VALVE TERMINOLOGY
PILOT-OPERATED REGULATOR
A regulator which is controlled by a second small
volume, high accuracy regulator or pilot. This arrangement has the advantages of improving performance
by minimizing the effects of unbalanced pressure and
droop. The number of possible applications are also
increased since a wide range of pilot configurations
are feasible.
PILOT
REGULATORVALVE TERMINOLOGY 55
PINION SHAFT EXTENSION
On a buried valve, the gear operator pinion shaft
must be extended above grade to permit the valve
to be operated.
PINION SHAFT
PINION SHAFT
The external input shaft of certain gear operators
which drives the internal reduction gearing. The
pinion shaft can accept a handwheel or power
operator.56 VALVE TERMINOLOGY
PLUG
PISTON EFFECT
The sealing principle involved in utilizing line pressure
to effect a seal across the floating seats of some valves.
PITCH AND LEAD
Pertaining to screw threads, the pitch refers to the
measurement between adjacent threads. The lead
refers to the distance the screw advances in one
complete revolution. Worm gears of gear operators
are also identified by pitch and lead. Speed of
operation and torque required are related to pitch
and lead.
PLASTICS
A broad classification covering a variety of nonmetallic, synthetic or organic materials capable of
being molded or formed into desired shapes. Also
used as a protective coating for valves.
PLUG
The rotating closure element of a plug valve. Also a
threaded fitting used to close off and seal an opening
into a pressure-containing chamber, e.g., pipe plug.
PLUG VALVE
A quarter-turn valve whose closure element is usually
a tapered plug having a rectangular port.VALVE TERMINOLOGY 57
PNEUMATIC
Pertaining to, or using, air or gas.
POLY PAK STEM SEAL
(A Parker Seal Company Product)
An O-ring energized lip seal which replaces the
O-ring stem seal in certain gate valves. Also used for
stem seals in some ball valves.
See “Lip Seal“.
POSITION INDICATOR
Any external device which visually indicates the open
and closed position of a valve.
See “Stem Indicators“.
POWER OPERATOR
Powered valve operators are of the following
general types: Electric Motor, Pneumatic or
Hydraulic Motor, Pneumatic or Hydraulic Cylinder.
Operators can either be adapted directly to the
valve stem or side mounted on existing gear or
scotch yoke operators.
PRESSURE
See “PSI“.
PRESSURE DIFFERENTIAL
See “Differential Pressure“.
PRESSURE DROP
Decrease in pressure along the direction of flow in
a piping system caused by fluid friction,
and change-of-direction fittings. Pressure drop is
related to velocity, specific gravity, viscosity and the
size and roughness of the pipe interior.
See “Differential Pressure“.
PRESSURE REDUCING REGULATOR
Regulator designed to control downstream pressure.
See “Regulator“.
PORT
See “Bore“.
restrictions,58 VALVE TERMINOLOGY
PRESSURE SWITCH
A switch (usually electric) activated by a rise or drop
in pressure. A transducer.
PRESSURE TEST
A test using specified pressures of liquid or gases,
which can be used to check the sealing, integrity, design
standards, etc., of a particular product.
PRODUCT ANALYSIS
A verification conducted by the valve manufacturer
to assure that the chemical composition of received
material coincides with the heat analysis and with
requirements of the applicable specification.
PRODUCT STANDARDIZATION
The process by which purchasers ensure consistency
of a product's quality by the approval of the vendors'
standardized documentation. This is normally used
as the basis for blanket purchase agreements.
PROOF PRESSURE
A hydrostatic test pressure, usually 1 1/2 times the
rated working pressure, applied to an assembled
valve to verify the structural integrity of the pressurecontaining parts. Synonymous with hydrostatic shell
test. (Table 5.1, API 6D).
PROTECTIVE SLEEVES
A circular “pipe-like“ sleeve inserted in place of
the ball and seats of a top entry ball valve. This
protective sleeve remains in place inside the valve
during valve installation and ultimate pigging of
a pipeline to clear debris from the line before
placing the pipeline into service. Once the pipeline
has been purged of all debris, the protective sleeve
is removed entirely from the ball valve cavity, and
operating trim (i.e., ball and seats) is then installed
for normal service conditions.VALVE TERMINOLOGY 59
PULSATION
Rhythmical throbbing or vibrating. In pipelines, a flow
or pressure oscillation which is identically repeated
in every fixed time interval. Pulsation is an inherent
characteristic of reciprocating gas compressors and
reciprocating liquid pumps. Pressure and flow
pulsations interact with piping systems to cause
vibration, metering errors and potential equipment
damage.
PUMP
A rotary or reciprocating device using mechanical
energy to propel liquids through pipelines or to
draw liquids from tanks or sumps by suction.
PUMP CONTROL VALVE
A ball valve that is not meant for on-off service,
but whose specific function is to control flow and
prevent cavitations in pumps on liquid pipelines.
PUPS
See “Transition Piece“.
QUALIFICATION TEST
An investigation, independent of a purchasing
function, that is performed on a product to
determine whether or not the product conforms to
all of the requirements of a particular specification.
This is generally done by a third independent party
to qualify a product for a specific application.
QUALITY ASSURANCE
Planned regular and/or preventive actions which
are used to ensure that materials, products, or
services will meet specified requirements.60 VALVE TERMINOLOGY
RF - Raised Face
The raised area of a flange face which affords a seal
with a mating flange face by means of a flat gasket
of the same diameter as the raised face.
RPM - Revolutions Per Minute
Rotational speed, turns per minute. For example, the
RPM delivered by a power operator to the pinion
shaft of a gear operator.
RTJ or R.T.J. - Ring Type Joint
A flange connection using a specially shaped soft metal
ring as a gasket. Generally used on high pressure valves
and not widely used in the pipeline industry.
RADIOGRAPHIC INSPECTION
An X-ray NDE procedure for locating flaws in welds,
casting, and fabricated parts.
RAISED FACE
OVAL RING
OCTAGONAL RINGVALVE TERMINOLOGY 61
RATCHET DRIVE
A shaft or valve that is operated by means of a
ratchet mechanism. The ratchet delivers an
intermittent stepped rotation through a gear in
one direction only.
REDUCED PORT (or REDUCED BORE)
See “Venturi“ Valve.
REGULAR PORT VALVE
A term usually applied to plug valves. The “regular“
port of such a valve is customarily about 40% of the
line pipe area. Hence, it corresponds to a VenturI or
reduced bore valve of the same nominal pipe size.
Venturi ball valves are often a logical alternative to
plug valves with advantages in price torque and low
maintenance.
REGULATOR
A throttling valve which exercises automatic control over
some variable (usually pressure). Not an on-off valve.
GROVE MITY-MITE PRESSURE-REDUCING REGULATOR
IN OUT62 VALVE TERMINOLOGY
RELIEF VALVE
A quick acting, spring-loaded valve that opens (relieves)
when the pressure exceeds the spring setting. Often
installed on the body cavity of ball and gate valves
to relieve thermal overpressure in liquid services.
See “B.R.V“ and Section 2.
REMOTE CONTROL
The operation of a valve or other flow control device
from a point at a distance from the device being
controlled. Can be accomplished by electrical,
pneumatic or hydraulic means.
RESILIENT SEAT
A valve seat containing a soft seal, such as an O-ring,
to assure tight shutoff.
RISING STEM
A valve stem which rises as
the valve is opened.
RISING STEM
GATE VALVEVALVE TERMINOLOGY 63
RISING STEM BALL VALVE
A single-seated ball valve that is designed to seal by
using the valve's stem to mechanically wedge the
valve's ball into a stationary seat, effecting a bubbletight seal. The valve's stem operates through a
guide sleeve assembly that guides the stem through
a quarter turn of rotation as the stem is raised or
lowered by a handwheel (or actuator).
The mechanical action of the stem moves the ball
away from the seat prior to the 90° rotation of the
ball. The design provides lower operating torques
and longer seat life while assuring bubble-tight
shutoff.
ORBIT RISING STEM BALL VALVE64 VALVE TERMINOLOGY
ROAD BOX
A concrete or metal box with a removable cover,
enclosing and providing access to valves installed
in buried lines alongside roads or streets. The
valves are operated by removing the box cover
and inserting a long-handled “T“ wrench which
engages a 2” square nut attached to the valve stem
or to the pinion shaft of geared valves.
ROCKWELL HARDNESS NO.
A numerical expression of the hardness of a metal
as determined with a Rockwell Hardness Tester.
There are several hardness scales. The most
commonly used are the Rockwell B scale for soft
metals and the Rockwell C scale for hard materials.
RUPTURE DISC (or BLOW-OUT DISC)
An emergency over pressure relief device, a
relatively thin diaphragm designed to burst at
a specified pressure. It cannot be reset, but must be
replaced after rupture event.
SNG - Synthetic Natural Gas
A substitute natural gas made from the byproducts of chemical plants and refineries.
See “Coal Gasification“.
SPDT - Single-Pole, Double-Throw
See “SPST“.
SPST - Single-Pole, Double-Throw
Refers to the function of an electrical switch often
used in the control system of electric valve operators.
SSIV - Subsea Isolation Valve
A valve used underwater, generally in a manifold
that will close and isolate a particular pipeline or
process in an emergency.
SY - Scotch Yoke
See “Scotch Yoke Operator“.THE PRESSURE AT WHICH
VALVE RELIEVES IS SET BY
ADJUSTING SPRING FORCE
SPRING-LOADED SAFETY VALVE
VALVE TERMINOLOGY 65
SAFETY VALVE
A quick opening, pop action valve used for fast relief
of excessive pressure.
SCHEDULE
A system for indicating the wall thickness of pipe.
The higher the schedule number, the thicker the
wall for a certain pipe size.
SCOTCH YOKE OPERATOR
A quarter-turn operator for use on quarter-turn
values using a scotch yoke mechanism rather than
gears. The scotch yoke has a torque output at the
beginning and ending of its stroke that is generally
twice the magnitude of the torque output in the
center of its stroke.
GUIDE BAR YOKE
VALVE STEM
SCOTCH YOKE OPERATOR66 VALVE TERMINOLOGY
SCREWED ENDS
Internally threaded end connections supplied on
some valves. Usually tapered pipe threads.
See “NPT“.
SEAL, DYNAMIC
A sealing element used between parts that have
relative motion, i.e.. stem seals, seat seal O-rings,
etc.
SEAL, STATIC
A sealing element used as a gasket between two
non-moving parts, i.e., valve bonnet O-rings, ball
valve body O-rings, flange gaskets, etc.
SEAT
That part of a valve against which the closure
element (gate, ball) effects a tight shutoff.
In many ball valves and gate valves, it is a floating
member containing a soft seating element (usually
SEAT
GATE
SLAB GATE POSITIONED BETWEEN SEAT RINGSVALVE TERMINOLOGY 67
SELF RELIEVING
The process whereby excessive internal body
pressure, in some valves, is automatically relieved
into either the upstream or downstream line by
forcing the seats away from the closure elements.
SEPARATOR
A special tank used to separate gas from oil in
some crude oil gathering systems.
SHORT GATE
A gate valve whose seat rings contact the gate
only in the closed position. Such valves are not
through conduit, as the gate is completely withdrawn from the flow area in the open position.
SHORT PATTERN VALVE
A valve whose face-to-face dimension is less than
the API 6D standard.
SHUTOFF VALVE
A valve designed only for on/off service.
Not a throttling valve. Sometimes referred to as
a “block valve“.
SLAB GATE
A gate having flat, finely finished, parallel faces
as opposed to a wedge gate. Such a closure
element slides across the seats and does not
depend on stem force to achieve tight shutoff.
GATE
BORE
SLAB GATE
GATE BORE68 VALVE TERMINOLOGY
SLAM RETARDER
A device to prevent the clapper of a check valve from
slamming as it closes upon flow reversal. Hydraulic
damping cylinders, rotary vanes and torsional springs
are all used for this purpose.
SLURRY SERVICE
An application involving a flow medium consisting of
small solid particles suspended in a liquid. Coal slurry,
consisting of about equal parts of coal and water, is
transported by pipeline from coal mines to Dower
plants where the coal is de-watered and burned.
A specially modified GROVE B5 ball valve is offered
for this service.
SOCKET END
An end connection in which a pipe or tube is inserted
into a counterbored hole and then brazed or filletwelded.
CLAPPER SHAFT
TORSIONAL SPRING SLAM RETARDER
TEE WITH SOCKET ENDSVALVE TERMINOLOGY 69
SOLENOID VALVE
A small electrically operated valve used in the
control piping of powered hydraulic or pneumatic
cylinder operators.
SOUR GAS
Natural gas containing significant amounts of
hydrogen sulfide (H2S). Requires special trim.
SPECIFIC GRAVITY
The ratio of the weight of a given volume of fluid
to the weight of an equal volume of water (if the
fluid is a liquid) or to the weight of an equal
volume of air (if the fluid is a gas).
SPHERE-LOK (a GROVE trade name)
A ball valve having a blind pocket in the ball rather
than a through hole. The valve will catch and hold
a metal sphere and then launch it down the pipe.
Used in meter prover systems to accurately measure
flow rates and calibrate flow meters.
See “Two-Way Sphere-Lok“, “Meter Prover“.
MAGNETIC COIL
ARMATURE
NORMALLY CLOSED - ENERGIZED TO OPEN70 VALVE TERMINOLOGY
SPOOL PIECE
See Adapter Spool .
SPUR GEAR
The simplest of gears. In a gear set, the pinion and
ring gear are aligned on parallel shafts.
STEM
A rod or shaft transmitting motion from an operator
to the closure element of a valve.
STEM INDICATOR (or VPI - Visible Position Indicator)
A position-indicating rod supplied with gate valves.
It extends from the top of the valve stem and serves
to indicate the relative position of the gate.
“ “
STEM NUT
A one or two-piece nut which engages the stem
threads of a valve and transmits torque from an
operator to the valve stem.
STEM INDICATOR (VPI)
VALVE STEMVALVE TERMINOLOGY 71
STOP COLLAR
The collar on a ball valve which restricts the ball
to 90° of rotation from the fully closed position.
See “Key Stop“.
STOPPLE (or STOP OFF)
A procedure used in the repair of a pipeline to
isolate a section of line in the absence of a shutoff
valve. After welding a flanged saddle to the pipe,
the line is “hot tapped“and an expanding resilient
plug is inserted into the pipe bore. When the
repair is completed, the plug is withdrawn and a
valve, installed on the saddle flange, is closed.
STRAIN GAUGE
An instrument used to measure small or minute
distortions caused by stress forces in mechanical
components.
STREET ELL
A 90° pipe fitting with male
and female threaded ends.
STRESS
An engineering parameter used in the design of
valves. The value of unit force (psi) produced
within a material as the result of an applied force
or load. Developed stress must be held well below
the yield strength of the material.
STOP COLLAR
90° STREET ELL72 VALVE TERMINOLOGY
STUD
A bolt, threaded on both ends, often used in bolting
together two members, one of which has blind
tapped bolt holes. Comprises the bolting sets of
GROVE G5D and G9 gate valves.
STUFFING BOX
The annular chamber provided around a valve stem
in a sealing system into which deformable packing
is introduced.
See “Packing“, “Gland“.
SUBMERSIBLE SERVICE
Underwater or subsea installation. Valves require
special treatment to protect against corrosion and
external seawater pressure.
SURGE
To rise suddenly to an excessive or abnormal value;
a transient sudden rise of pressure in a pipeline.
Pipeline surges can be positive or negative and are
caused most frequently by the sudden closure of
a block valve or emergency shutdown of a pump.
Surge pressure in excess of the rated capacity of a
pipeline can cause ruptures of the piping system.
See Section 2.
STUD-BOLTS
JOINING TWO
FLANGES
BLIND TAPPED HOLEVALVE TERMINOLOGY 73
SURGE RELIEVER
A valve designed to relieve pressure surges in
liquid pipelines, thus preventing line rupture due
to transient pressures exceeding design limits of
the pipe. A special flexible tube valve can function
as a fast-acting surge reliever.
See Section 2.
SWAGE
A tool for bending or forming cold metal to a
required shape.
SWEET GAS
Natural gas having no significant hydrogen sulfide
content.
SWING CHECK VALVE
A check valve in which the closure element is a
hinged clapper which swings or rotates about a
supporting shaft.
See “Clapper“, “Check Valve“.
SYSTEM ENGINEERING
That engineering approach which deals with the
design and integration of multiple components
and controls into an assembled piping complex
to accomplish a specified function or functions.
The skid-mounted Arcron Surge Reliever is an
example of system engineering.
See Section 2.
TEE
A pipe or tubing fitting with a side outlet at right
angles.
TEE74 VALVE TERMINOLOGY
TENSILE STRENGTH
The highest tensile stress that a material can
withstand before failure or rupture occurs with
force being applied in a direction tending to
elongate the material.
TENSILE TEST
A test performed on specially machined specimens
taken from material in its delivered condition, to
determine physical properties, i.e., yield strength,
ultimate strength and percent elongation.
TENSION TEST
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