Glossary of Valve Terms
Valve Terminology 1
Engineered Surge Relief Systems 85
Conversion Tables and Equivalents 88
General Information 107
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
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
A society which sets guidelines and standards for
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
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
An extension which is added to a short face-to-face
valve to conform to standard API 6D face-to-face
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)
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.
CAMERON FULLY WELDED BALL VALVE ®4 VALVE TERMINOLOGY
A variation of the globe valve in which the end
connections are at right angles to each other,
rather than being in-line.
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
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.
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.
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
BODY RELIEF VALVEBACK PRESSURE REGULATOR
Regulator designed to control upstream pressure.
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
VALVE TERMINOLOGY 7
GROVE B5 BALL VALVE ®8 VALVE TERMINOLOGY
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
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.
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 ®
A bonnet which is connected to a valve body with
GROVE B4 BALL VALVE ®10 VALVE TERMINOLOGY
Describes a valve construction in which the pressure
shell elements are bolted together, and thus can be
taken apart and repaired in the field.
Bolts or studs and nuts sometimes supplied with
flanged valves to install the valve between line
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.
VALVE TERMINOLOGY 11
The top part of a valve, attached to the body, which
guides the stem and adapts to extensions or operators.
G4N GATE VALVE
DOUBLE EXPANDING GATE VALVE
BONNET12 VALVE TERMINOLOGY
BUTT WELD ENDS
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.I.F. – Cost Insurance & Freight
A special stem packing designed by GROVE to give
maximum lifetime sealing in gate, ball and check
Shipper pays all freight and insurance charges.
Same as FOB Destination.
BYPASS OPERATOR BYPASS
BURIED VALVE SETTING14 VALVE TERMINOLOGY
CWP – Cold Working Pressure
CERTIFYING AUTHORITY (CA)
CHAIN WHEEL OPERATED VALVE
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
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
A ball or gate, the shape of whose port has been
specially altered to provide a specific throttling
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
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.
TEST COUPON IS SHAPED LIKE THIS
SWING CHECK VALVE
TM16 VALVE TERMINOLOGY
A type of packing used in packing boxes consisting
of a nest of “V” cross-section rings.
CITY GATE (or 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.
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
The hinged closure element of a swing-disc check valve.
VALVE TERMINOLOGY 17
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.
TOM WHEATLEY SWING CHECK VALVE TM18 VALVE TERMINOLOGY
The end of a ball valve bolted to the body, which
often contains the seat rings. Often referred to as
part of the body.
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
Having the same centers.
TWO DIAMETERS ON
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.
VALVE TERMINOLOGY 19
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.
CONTROLS20 VALVE TERMINOLOGY
Any temperature below about -240°F (-151°C).
A valve capable of functioning at cryogenic
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
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
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.
DPD – DOUBLE-POLE DOUBLE-THROW
Related to electrical switches.
Related to electrical switches.
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)
D22 VALVE TERMINOLOGY
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.
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
“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
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”.
A > 2 A
A > 2 A
DOUBLE PISTON EFFECT PRINCIPLE
DIAMETER24 VALVE TERMINOLOGY
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
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
A bearing consisting of bronze impregnated with
TFE (Teflon) resin which is lead powder-bonded to a
low carbon steel backing. A Garlock Company
DRIVE PINSVALVE TERMINOLOGY 25
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”.
DYE PENETRANT INSPECTION
EMO – Electric Motor Operated
ESDV – Emergency Shutdown Valve
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
90° ELBOW 45° ELBOW26 VALVE TERMINOLOGY
ELECTROLESS NICKEL PLATING
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
A pipe or tubing fitting that has the shape of an “L”.
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.
TO LUBE ASSEMBLY
GATEVALVE TERMINOLOGY 27
Weld end preparations for butt welding. Governed by
ASME B31.4 and B16.25.
EXPANDING GATE VALVE
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°
10° ± 1°
37 1/2° ± 2 1/2°
1/16″ ± 1/32″
1 1/8″ R. Min.28 VALVE TERMINOLOGY
EXTENDED BDV – Blow Down Valve
Special packing and crating that is required for export
shipping. Includes sealing against a salt atmosphere
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.
BALL VALVE GATE VALVE
LINEVALVE TERMINOLOGY 29
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.
GATE VALVE BALL VALVE
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
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.
The finish of the contact surface of flanged fittings.
IS FACE-TO-FACE LENGTH
EVALVE TERMINOLOGY 31
FAIL SAFE VALVE
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
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.
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.
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
FLEXIBLE TUBE VALVEVALVE TERMINOLOGY 33
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 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
“ “ “
BEVEL GEAR OPERATOR
WORM GEAR OPERATOR
BEVEL WORM DRIVE
GEARVALVE TERMINOLOGY 35
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,
A seal or packing placed between mechanical joints
(such as flanges) to prevent the escape of the
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
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 SEAL O-RINGS
PACKINGVALVE TERMINOLOGY 37
The plate in a valve which retains the gland, gland
bushing, or stem seals, and sometimes guides the
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.
NAVCO GLOBE VALVE ®38 VALVE TERMINOLOGY
HWO – Handwheel Operated
A fitting through which lubricant or sealant is
A valve on which the handwheel drives the stem
directly to operate the valve.
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
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 CHARTS
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
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.
GROVE GATE VALVE ®40 VALVE TERMINOLOGY
HYDRAULIC MOTOR ACTUATOR ( or OPERATOR)
HYDROSTATIC TEST (or SHELL TEST)
ID – Inside Diameter
IDS – Instrument Data Sheet
INCREMENTAL SEAT TEST
Pertaining to, or using, water, oil, or other liquids
A device by which rotation of an hydraulically
powered motor is converted into mechanical
The movement of the seats in a valve that are
controlled by using water, oil, or other liquids
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
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
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
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
LNG – Liquified Natural Gas
LPG – Liquid Petroleum Gas
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.
GROVE BALL VALVE ®VALVE TERMINOLOGY 43
LIQUID PENETRANT INSPECTION
LOCK UP PRESSURE
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
“ “, “ “
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
Class MWP (CWP)
MAGNETIC PARTICLE INSPECTION
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:
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)
A common pipe or chamber having several lateral
MANIFOLD46 VALVE TERMINOLOGY
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
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 TEST REPORTS
MODULUS (or COEFFICIENT) OF ELASTICITY
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.
.48 VALVE TERMINOLOGY
NDE – Non-Destructive Examination
NEMA – National Electrical Manufacturers Association
NPT – National Pipe Tapered
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
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.
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
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
Those inspection tests which are not destructive to
the valve structure or function.
See “Radiographic Inspection“, “Liquid Penetrant
Inspection“, “Magnetic Particle Inspection“, and
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
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
See Fire Safe .
The measurement of the outermost diameter of a
A double slider connection used to connect shafts
An elastomeric or synthetic seal ring of circular
OLDHAM COUPLINGVALVE TERMINOLOGY 51
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“,
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
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
“ “, “ “
A duplicate or copy, usually wooden, of a part to be
cast. Used to form the mold into which molten metal
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
PACKINGVALVE TERMINOLOGY 53
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.
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
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
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.
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
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
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.
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.
A quarter-turn valve whose closure element is usually
a tapered plug having a rectangular port.VALVE TERMINOLOGY 57
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“.
Any external device which visually indicates the open
and closed position of a valve.
See “Stem Indicators“.
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.
See “Differential Pressure“.
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.
restrictions,58 VALVE TERMINOLOGY
A switch (usually electric) activated by a rise or drop
in pressure. A transducer.
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.
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.
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.
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).
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
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
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.
See “Transition Piece“.
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.
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.
An X-ray NDE procedure for locating flaws in welds,
casting, and fabricated parts.
OCTAGONAL RINGVALVE TERMINOLOGY 61
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
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
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.
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.
A valve seat containing a soft seal, such as an O-ring,
to assure tight shutoff.
A valve stem which rises as
the valve is opened.
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
ORBIT® RISING STEM BALL VALVE64 VALVE TERMINOLOGY
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
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
A quick opening, pop action valve used for fast relief
of excessive pressure.
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
SCOTCH YOKE OPERATOR66 VALVE TERMINOLOGY
Internally threaded end connections supplied on
some valves. Usually tapered pipe threads.
A sealing element used between parts that have
relative motion, i.e.. stem seals, seat seal O-rings,
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.
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
SLAB GATE POSITIONED BETWEEN SEAT RINGSVALVE TERMINOLOGY 67
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.
A special tank used to separate gas from oil in
some crude oil gathering systems.
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.
A valve designed only for on/off service.
Not a throttling valve. Sometimes referred to as
a “block valve“.
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 BORE68 VALVE TERMINOLOGY
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.
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.
An end connection in which a pipe or tube is inserted
into a counterbored hole and then brazed or filletwelded.
TORSIONAL SPRING SLAM RETARDER
TEE WITH SOCKET ENDSVALVE TERMINOLOGY 69
A small electrically operated valve used in the
control piping of powered hydraulic or pneumatic
Natural gas containing significant amounts of
hydrogen sulfide (H2S). Requires special trim.
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“.
NORMALLY CLOSED – ENERGIZED TO OPEN70 VALVE TERMINOLOGY
See Adapter Spool .
The simplest of gears. In a gear set, the pinion and
ring gear are aligned on parallel shafts.
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.
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
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.
An instrument used to measure small or minute
distortions caused by stress forces in mechanical
A 90° pipe fitting with male
and female threaded ends.
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.
90° STREET ELL72 VALVE TERMINOLOGY
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.
The annular chamber provided around a valve stem
in a sealing system into which deformable packing
See “Packing“, “Gland“.
Underwater or subsea installation. Valves require
special treatment to protect against corrosion and
external seawater pressure.
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.
BLIND TAPPED HOLEVALVE TERMINOLOGY 73
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.
A tool for bending or forming cold metal to a
Natural gas having no significant hydrogen sulfide
SWING CHECK VALVE
A check valve in which the closure element is a
hinged clapper which swings or rotates about a
See “Clapper“, “Check Valve“.
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.
A pipe or tubing fitting with a side outlet at right
TEE74 VALVE TERMINOLOGY
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.
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.
Same as “Tensile Test“.
Documents provided by a manufacturer certifying
that required tests were performed.
The intentional restriction of flow by partially
closing or opening a valve. A wide range of
throttling is accomplished automatically in
regulators and control valves.
An expression characterizing valves when in the
open position, wherein the bore presents a
smooth uninterrupted interior surface across seat
rings and through the valve port, thus affording
minimum pressure drop. There are no cavities or
large gaps in the bore between seat rings and
body closures or between seat rings and ball/gate.
Consequently, there are no areas that can
accumulate debris to impede pipeline cleaning
equipment or restrict the valve’s motion.
Force applied to a part in a particular direction –
e.g., thrust on a valve stem.VALVE TERMINOLOGY 75
The design of a particular valve or regulator where
the unit can be serviced or repaired by leaving its
body in the line and accessing its internals by
removing a top portion of the unit.
The turning effort required to operate a valve.
Usually expressed in “pound-feet“ and in reference to
the stem nut, handwheel or operator pinion shaft.
An electrical device on a motor operator which
cuts off power to the operator when allowable
torque is exceeded, thus preventing damage to
the valve and/or the operator.
A coiled spring which exerts a force by twisting about
its axis rather than by compression or elongation.
The torsional spring in a check valve slam retarder is
restrained at one end and fastened to the clapper
shaft on the other end. As the clapper opens, the
spring resists the motion, creating a closing force.
During a rapid decrease in flow rate, the clapper is
urged toward the closed position and is virtually closed
just prior to the instant of actual flow reversal – thus
slamming is avoided.
See “Slam Retarder“.
BALL VALVE76 VALVE TERMINOLOGY
A length of pipe that is welded to a valve hub or
closure. Generally provided by the customer, it serves
as a transition from the customer’s piping to the valve
to compensate for differences in material or size.
A main pipeline transporting oil or gas from wells
or storage fields to refineries, loading docks or
distribution companies. Generally, the pipeline is
bigger than 6″ and the pressure greater than 150 psi.
Commonly refers to the valve’s working parts and
to their materials.
TRIPLE ECCENTRIC (or BUTTERFLY VALVE)
A particular design of a butterfly valve where the
stem is located behind the disc and below the centerline of the disc, and its cone axis is offset from the
centerline of the disc. This particular design is
capable of a very tight shutoff at temperatures
well above 1000°F (538°C).
That part of a ball valve which holds the ball on a
fixed vertical axis and about which the ball turns.
The torque requirements of a trunnion mounted
ball valve are significantly less than for a floating
TRUNNIONVALVE TERMINOLOGY 77
TURNS TO OPERATE
The number of complete revolutions of a handwheel
or the pinion shaft of a gear operator required to
stroke a valve from full open to fully closed or vice
TWO-INCH SQUARE OPERATING NUT
A nut attached to the valve stem or to the pinion
shaft of a gear operator. Valves so equipped are
usually situated below grade in road boxes and
are operated by long-handled “T“ wrenches.
A Sphere-Lok with two ports.
U-CUP (RING PACKING)
A U cross-section ring located in the tail end of
certain ball valve seats to retain the grease in an
emergency seat seal system.
180° TURN OF
TWO-WAY SPHERE-LOK78 VALVE TERMINOLOGY
UL – Underwriters Laboratory
An impartial testing laboratory concerned with the
safety of electrical components. Products surviving the
tests are included on a certified listing of products
by manufacturer. This does not imply UL approval.
That stress at which a material will fail.
See “Tensile Test“, “Burst Pressure“.
An inspection procedure using high frequency
sound waves to detect voids and imperfections
throughout the thickness of metal parts.
The storage of natural gas or other fluids
A small three-piece fitting used to join two lengths
of pipe. A female piece is installed on
each of the two pipe ends and the
connection is mechanically sealed
by an external nut.
VDS – Valve Data Sheet
A data sheet defining the minimum level of a valve
design, including the materials, testing, inspection
and certification requirements.
VPI – Visible Position Indicator
See “Stem Indicator“.
A space from which air or gas been exhausted until
its pressure is less than atmospheric pressure, i.e.,
any pressure below 14.7 psi absolute.
UNION CONNECTIONVALVE TERMINOLOGY 79
A device which controls the flow of a liquid or gas
in a conduit or pipeline.
A small variable profile valve put in a flow line and
used with a pilot to restrict the flow into the pilot
and make the pilot more or less sensitive to
The speed at which a fluid flows through a line in
a specified direction. Usually expressed in “feet
VENT PLUG (or VENT PLUG ASSEMBLY or SAFETY VENT
A special pipe plug having a small allen wrenchoperated vent valve. These special plugs are located
at the bottom of most ball valves. With the line valve
closed (and under pressure) the body cavity pressure
can be vented through this small valve to check the
tightness of seat seals or to make minor repairs.
Having vented the body pressure, the vent plug may
be removed to blow out debris and foreign material
or to flush the body cavity. On some gate valves,
the vent plug is installed on the bonnet for the sole
purpose of venting the body. Such valves have
separate drain valves.
See “Block-and-Bleed“, “Drain Plug“.
SPECIAL VENT PLUG80 VALVE TERMINOLOGY
A reduced bore valve. A valve having a bore smaller
in diameter than the inlet or outlet. For example,
an 8″ x 6″ x 8″ ball valve has 8″ inlet and outlet
connections, while the ball and seats are 6″. The
flow through a Venturi valve will be reduced
because of the smaller port. Venturi valves can often
be economically substituted for plug valves.
A measure of the internal friction of a fluid or the
resistance of a flow. Two fluids of identical specific
gravity may have quite different viscosities.
WE (or W.E.) – Weld End
The end connection of a valve which is to be installed
by welding into the line. To prepare the end bevel,
it is necessary to know the wall thickness and
specified minimum yield strength of the connecting
See “End Bevel“.VALVE TERMINOLOGY 81
WO – Wrench Operated
The operation of a valve by means of a handle
or lever. Used on smaller size and lower pressure
WOG – Water-Oil-Gas
Used in connection with a pressure rating. Thus:
100 WOG indicates the rated pressure is 100 psi
in water, oil, or gas service at normal ambient
WP – Working Pressure
The maximum anticipated sustained operating
pressure applicable to a pipe.
The thickness of the wall of a pressure vessel or
the thickness of the wall of a pipe.
The physical effect, often accompanied by loud
banging, produced by pressure waves generated
within the piping by a rapid change of velocity
in a liquid system.
Verification of a component’s resistance under
specific wear conditions.
WRENCH82 VALVE TERMINOLOGY
Describes a valve operator or other device that is
protected against intrusion of water, sand, dust,
or other atmospheric contamination.
A gate whose seating surfaces are inclined to the
direction of closing thrust so that mechanical
force on the stem produces tight contact with
the inclined seat rings.
See “WE“, “End Bevel“.VALVE TERMINOLOGY 83
Gears used to transmit motion or power between
right angle shafts when a high-ratio reduction is
necessary. The worm is the smaller gear which
drives the larger ring gear. Worm threads resemble
screw threads and are available in various leads
WELD NECK FLANGE
A flanged piping element with a weld neck used
in pipeline construction to provide a companion
for installation of flanged valves. Also used to
convert weld end valves to flanged valves or
A reducing fitting used on weld end piping
components to adapt from a large sized pipe to
a smaller diameter pipe or vice versa.
WELD NECK FLANGE
WORM GEAR84 VALVE TERMINOLOGY
See Radiographic Inspection .
The limiting stress (psi) beyond which a material
will sustain permanent deformation. Up to the
yield strength, the material will spring back to its
original dimension when the pressure is removed.
Often in valves specs, the yield strength will be
designated; this allows proper material selection.
The part of a gate valve which serves as a spacer
between the bonnet and the operator or actuator.
“ “SECTION 2 85
ENGINEERED SURGE RELIEF SYSTEMS
CONTROL OF PRESSURE SURGES IN LIQUID PIPELINES
Pressure surges in liquid pipelines occur as the result
of rapid changes in flow rate as might be caused by
sudden valve closure or pump stoppage. Surge
pressure can be either positive or negative, each
kind presenting its own set of problems to the
Positive pressure surges, or spikes, can reach dangerous
levels within fractions of a second of the triggering
event. Peak pressures can easily exceed pipeline
ratings and can occur at points in the line quite
remote from the triggering event.
Surge relief valves placed at critical locations along
the pipeline can be made to open and discharge
liquid into holding tanks as surges start to build and
thus maintain pipeline pressures at safe levels.
A flexible tube (Flexflo ) surge reliever is ideally suited
for this service. This type of reliever is the ultimate
in simplicity and reliability, featuring a synthetic
rubber tube which functions as both pressure
sensing means and the valve element
The tube, the valve’s only moving part, opens
smoothly and automatically within milliseconds to
relieve a surge and then seals off drop-tight as the
The mathematical treatment of surges in liquid
pipelines is a complex study usually involving
extensive computer analysis.
There are firms which specialize in pipeline surge
analysis and are able to include mathematical
models of the Flexflo reliever in their calculations.
.86 ENGINEERED SURGE RELIEF SYSTEMS
The Flexflo surge reliever is designed to have an
opening time in the low millisecond range when line
pressure increases over set pressure. The body cavity/
jacket space is gas loaded (usually nitrogen) to a
predetermined pressure. Rapid actuation is achieved
by high speed transfer of the gas from the jacket
space into the larger body cavity as the tube expands.
The surge is relieved by the increase of the annular
volume under the flexible tube as it expands and
by discharge of line liquid when the Flexflo opens.
Minor pipeline surges are relieved without
discharging liquid through the Flexflo. A minor
surge over set pressure causes the tube to expand
on the inlet end, increasing the annular volume,
but does not cause the Flexflo to open
The body cavity/jacket space may be pressurized to
a desired set pressure and locked in, or a pressure
regulator may be used to maintain pressure on
top of the tube. If significant changes in ambient
temperature are expected, a loading regulator is
recommended to hold the jacket pressure constant.
FLEXIBLE TUBE SURGE RELIEVER (Flexflo Surge Reliever) ®
BODYENGINEERED SURGE RELIEF SYSTEMS 87
An engineered system for the control of pressure
surge in a large liquid pipeline. This system consists
of a number of Flexflo surge relievers in parallel
responding to the same control signal.
SURGE RELIEF SYSTEM USING FLEXFLO RELIEVERS ®88 SECTION 3
CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
acres 43,560 sq. ft.
acres 4,047 sq. meters
acres 0.001562 sq. miles
acres 4,840 sq. yards
atmospheres 76.0 cm. of mercury (at 0°C)
atmospheres 29.92 in. of mercury (at 0°C)
atmospheres 1.0332 kg./sq. cm.
atmospheres 10,330 kg./sq. meter
atmospheres 14.7 pounds/sq. in.
barrels (U.S. liquid) 31.5 gallons
barrels (oil) 42.0 gallons (oil)
barrels/day (oil) 0.02917 gallons/min. (oil)
barrels/hr. (oil) 0.7 gallons/min. (oil)
bars 0.9869 atmospheres
bars 1.020 x 10 kg./sq. meter
bars 2,089 pounds/sq. ft.
bars 14.5 pounds/sq. in.
barye 1.0 dynes/sq. cm.
btu 10.41 liter-atmospheres
btu 1.055 x 10 ergs
btu 778.2 foot-pounds
btu 252.0 gram-calories
btu 3.927 x 10 horsepower-hours
btu 1,055 joules
btu 0.252 kilogram-calories
btu 107.6 kilogram-meters
btu 2.928 x 10 kilowatt-hours
btu/hr. 0.2162 ft.-pounds/sec.
-4CONVERSION TABLES AND EQUIVALENTS 89
TO CONVERT MULTIPLY BY TO OBTAIN
btu/hr. 0.07 gram-cal./sec.
btu/hr. 3.929 x 10 horsepower
btu/hr. 0.2931 watts
btu/min. 12.96 ft.-pounds/sec.
btu/min. 0.02356 horsepower
btu/min. 0.01757 kilowatts
btu/min. 17.57 watts
btu/sq. ft./min. 0.122 watts/sq. in.
candlepower 12.5664 lumens
centares 1.0 sq. meters
centigrade (degrees) (°C x 9/5) + 32 fahrenheit (degrees)
centigrade (degrees) °C + 273.18 kelvin (degrees)
centigrams 0.01 grams
centiliters 0.3382 ounce (fluid) U.S.
centiliters 0.6103 cubic in.
centiliters 2.705 drams
centiliters 0.01 liters
centimeters 0.03281 feet
centimeters 0.3937 inches
centimeters 0.01 meters
centimeters 10.0 millimeters
centimeters 10,000 microns
centimeter-dynes 0.00102 cm.-grams
centimeter-dynes 1.020 x 10 meter-kg.
centimeter-dynes 7.376 x 10 pound-ft.
centimeter-grams 980.7 cm.-dynes
centimeter-grams 1.0 x 10 meter-kg.
centimeter-grams 7.233 x 10 pound-ft.
centimeters of mercury 0.01316 atmospheres
centimeters of mercury 0.4461 ft. of water
C90 CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
centimeters of mercury 136.0 kg./sq. meter
centimeters of mercury 0.1934 pounds/sq. in.
centimeters/sec. 1.969 feet/min.
centimeters/sec. 0.0328 feet/sec.
centimeters/sec. 0.036 kilometers/hr.
centimeters/sec. 0.0194 knots
centimeters/sec. 0.6 meters/min.
centimeters/sec. 0.02237 miles/hr.
centimeters/sec. 3.728 x 10 miles/min.
centimeters/sec./sec. 0.0328 ft./sec./sec.
centimeters/sec./sec. 0.036 km./hr./sec.
centimeters/sec./sec. 0.01 meters/sec./sec.
centimeters/sec./sec. 0.0224 miles/hr./sec.
centipoise 0.01 gr./cm.-sec.
centipoise 6.72 x 10 pound/ft.-sec.
circumference 6.283 radians
cubic centimeters 3.531 x 10 cubic ft.
cubic centimeters 0.06102 cubic in.
cubic centimeters 1.308 x 10 cubic yards
cubic centimeters 0.001 liters
cubic centimeters 0.001057 quarts (U.S. liquid)
cubic feet 0.178 barrels (oil)
cubic feet 28,320 cu. cm.
cubic feet 1,728 cu. inches
cubic feet 0.02832 cu. meters
cubic feet 0.03704 cu. yards
cubic feet 7.48052 gallons (U.S. liquid)
cubic feet 28.32 liters
cubic feet/min. 62.4 pounds water/min.
cubic feet/sec. 448.8 gallons/min.
cubic inches 16.39 cu. cm.
-6CONVERSION TABLES AND EQUIVALENTS 91
TO CONVERT MULTIPLY BY TO OBTAIN
cubic inches 5.787 x 10 cu. ft.
cubic inches 1.639 x 10 cu. meters
cubic inches 2.143 x 10 cu. yards
cubic inches 0.01639 liters
cubic meters 6.28 barrels (oil)
cubic meters 8.38 barrels (U.S. liquid)
cubic meters 1,000,000 cu. cm.
cubic meters 35.31 cu. ft.
cubic meters 61,023. cu. inches
cubic meters 1.308 cu. yards
cubic meters 264.2 gallons
cubic meters/hr. 151.0 barrels/day (oil)
cubic meters/hr. 4.403 gallons/min.
cubic yards 27.0 cu. ft.
cubic yards 46,656. cu. inches
cubic yards 0.7646 cu. meters
deciliters 0.1 liters
decimeters 0.1 meters
degress (angle) 0.01745 radians
dekagrams 10.0 grams
dekaliters 10.0 liters
dekameters 10.0 meters
drams 1.7718 grams
drams 27.344 grains
drams 0.0625 ounces
dynes/sq. cm. 0.01 ergs/sq. millimeter
dynes/sq. cm. 9.869 x 10 atmospheres
dynes/sq. cm. 2.953 x 10 in. of mercury (at 0°C)
dynes/sq. cm. 4.015 x 10 in. of water (at 4°C)
-492 CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
dynes 0.00102 grams
dynes 1.0 x 10 joules/cm.
dynes 1.0 x 10 joules/meter (newtons)
dynes 1.020 x 10 kilograms
dynes 7.233 x 10 poundals
dynes 2.248 x 10 pounds
dynes/sq. cm. 1.0 x 10 bars
erg/sec. 1. dyne-cm./sec.
ergs 9.486 x 10 btu
ergs 1. dyne-centimeters
ergs 7.376 x 10 foot-pounds
ergs 2.389 x 10 gram-calories
ergs 0.00102 gram-cm.
ergs 3.7250 x 10 horsepower hr.
ergs 1.0 x 10 joules
ergs 2.389 x 10 kg.-calories
ergs 1.020 x 10 kg. meters
ergs 2.773 x 10 kilowatt-hr.
ergs 2.773 x 10 watt-hr.
erg/sec. 5.668 x 10 btu/min.
erg/sec. 4.426 x 10 ft.-lb./min.
erg/sec. 7.3756 x 10 ft.-lb./sec.
erg/sec. 1.341 x 10 horsepower
erg/sec. 1.433 x 10 kg.calories/min.
erg/sec. 1.0 x 10 kilowatts
exajoules 1.0 x 10 joules
18TO CONVERT MULTIPLY BY TO OBTAIN
fathoms 1.8288 meters
fathoms 6.0 feet
feet 30.48 centimeters
feet 0.3048 meters
feet 1.894 x 10 miles (stat.)
feet of water 0.8826 in. of mercury
feet of water 0.03048 kg./sq. cm.
feet of water 0.4335 pounds/sq. cm.
feet/min. 0.01667 feet/sec.
feet/min. 0.01136 miles/hr.
feet/sec. 0.6818 miles/hr.
feet/sec./sec. 0.3048 meters/sec./sec.
foot-pounds 0.001286 btu
foot-pounds 0.1383 kg.-meters
foot-pounds/min. 0.001286 btu/min.
foot-pounds/min. 3.030 x 10 horsepower
foot-pounds/min. 2.260 x 10 kilowatts
foot-pounds/sec. 0.001818 horsepower
foot-pounds/sec. 0.001356 kilowatts
gallons 3,785. cu. cm.
gallons 0.1337 cu. feet
gallons 231.0 cu. inches
gallons 0.003785 cu. meters
gallons 3.785 liters
gallons of water 8.331 pounds of water
gallons/min. 34.28 barrels/day (oil)
gallons/min. 0.002228 cu. feet/sec
gallons/min. 0.06308 liters/sec.
gills (U.S.) 0.25 pints (liquid)
grams 980.7 dynes
CONVERSION TABLES AND EQUIVALENTS 9394 CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
grams 15.43 grains (troy)
grams 0.001 kilograms
grams 0.03527 ounces (avoir.)
grams 0.002205 pounds
grams/cm. 0.0056 pounds/in.
grams/cu. cm. 62.43 pounds/cu. ft.
grams/cu. cm. 0.03613 pounds/cu. in.
grams/liter 0.06247 pounds/cu. ft.
grams/sq. cm. 2.0481 pounds/sq. ft.
gram-calories 0.003968 btu
gram-calories 4.184 x 10 ergs
gram-calories 3.086 foot-pounds
gram-calories 1.5596 x 10 horsepower-hr.
gram-calories 1.162 x 10 kilowatts-hr.
gram-calories 0.001162 watt-hr.
gram-calories/sec. 14.286 btu/hr.
gram-centimeters 9.297 x 10 btu
gram-centimeters 980.7 ergs
gram-centimeters 9.807 x 10 joules
gram-centimeters 2.343 x 10 kg.-calories
gram-centimeters 1.0 x 10 kg.-meters
hectares 2.471 acres
hectares 107,600. sq. feet
hectograms 100.0 grams
hectoliters 100.0 liters
horsepower 42.44 btu/min.
horsepower 33,000. foot-lbs./min.
horsepower 550.0 foot-lbs./sec.
horsepower 10.7 kg.-calories/min.
-5TO CONVERT MULTIPLY BY TO OBTAIN
H I J
horsepower 745.7 watts
horsepower-hours 2,547 btu
horsepower-hours 1.98 x 10 foot-lb.
horsepower-hours 2.737 x 10 kg.-meters
horsepower-hours 0.7457 kilowatt-hr.
inches 2.54 centimeters
inches 0.0254 meters
inches 25.4 millimeters
inches of mercury 0.03342 atmospheres
inches of mercury 1.133 feet of water
inches of mercury 0.03453 kg./sq cm.
inches of mercury 0.4912 pounds/sq. in.
inches of water 0.002458 atmospheres
inches of water 0.07355 inches of mercury
inches of water 0.00254 kg./sq. cm.
inches of water 0.03613 pounds/sq. in.
joules 9.486 x 10 btu
joules 1.0 x 10 ergs
joules 1.0 x 10 exajoules
joules 0.7376 foot-pounds
joules 2.389 10 kg.-calories
joules 0.102 kg.-meters
joules 2.778 x 10 watt-hr.
joules/cm. 1.020 x 10 grams
joules/cm. 1.0 x 10 dynes
joules/cm. 100.0 joules/meter (newtons)
joules/cm. 723.3 poundals
joules/cm. 22.48 pounds
CONVERSION TABLES AND EQUIVALENTS 9596 CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
K Pascal (KPa) 0.145 pounds/sq. in.
kilograms 980,665 dynes
kilograms 1,000 grams
kilograms 2.2046 pounds
kilograms 0.001102 tons (short)
kilograms/cu. meter 0.06243 pounds/cu. ft.
kilograms/cu. meter 3.613 x 10 pounds/cu. in.
kilograms/meter 0.672 pounds/ft.
kilograms/sq. cm. 9.807 x 10 dynes/sq. cm.
kilograms/sq. cm. 0.9678 atmospheres
kilograms/sq. cm. 32.8 feet of water
kilograms/sq. cm. 28.96 inches of mercury
kilograms/sq. cm. 14.22 pounds/sq. in.
kilograms/sq. meter 9.678 x 10 atmospheres
kilograms/sq. meter 9.807 x 10 bars
kilograms/sq. meter 0.003281 feet of water
kilograms/sq. meter 0.002896 inches of mercury
kilograms/sq. meter 0.001422 pounds/sq. in.
kilograms/sq. meter 98.067 dynes/sq. cm.
kilogram-calories 3.968 btu
kilogram-calories 3,086 foot-pounds
kilogram-calories 0.001163 kilowatt-hr.
kilogram-calories/min. 51.43 ft.-lb./sec.
kilogram-calories/min. 0.09351 horsepower
kilogram-calories/min. 0.06972 kilowatts
kilogram-meters 0.009296 btu
kilogram-meters 7.233 foot-pounds
kiloliters 1,000 liters
kiloliters 35.316 cubic feet
kiloliters 264.18 gallons (U.S. liquid)
kilometers 1.0 x 10 centimeters
5TO CONVERT MULTIPLY BY TO OBTAIN
kilometers 3,281 feet
kilometers 1,000 meters
kilometers 0.6214 miles (statute)
kilometers/hr. 27.78 cm./sec.
kilometers/hr. 54.68 feet/min.
kilometers/hr. 0.9113 feet/sec.
kilometers/hr. 16.67 meters/min.
kilometers/hr. 0.6214 miles/hr.
kilowatts 56.92 btu/min.
kilowatts 44,260 foot-lb./min.
kilowatts 737.6 foot-lb./sec.
kilowatts 1.341 horsepower
kilowatts 14.34 kg.-calories/min.
kilowatts 1,000 watts
kilowatt-hr. 3,413 btu
kilowatt-hr. 2.655 x 10 foot-lb.
kilowatt-hr. 1.341 horsepower-hours
kilowatt-hr. 860.0 kg.-calories
kilowatt-hr. 3.671 x 10 kg.-meters
knots 1.8532 kilometers/hr.
knots 1.151 statute miles/hr.
league 3.0 miles (approx)
light year 5.9 x 10 miles
liters 1,000 cu. cm.
liters 0.03531 cu. ft.
liters 61.03 cu. inches
liters 0.001 cu. meters
liters 0.001308 cu. yards
liters 0.2642 gallons (liquid)
liters 2.113 pints (liquid)
liters 1.057 quarts (liquid)
CONVERSION TABLES AND EQUIVALENTS 9798 CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
liters/min. 5.886 x 10 cu. ft./sec.
liters/min. 0.004403 gallons/sec.
liters/min. 0.2642 gallons/min.
liters/sec. 15.852 gallons/min.
lumen 0.07958 spherical candle power
lumen/sq. ft. 1. foot-candles
meters 100.0 centimeters
meters 3.281 feet
meters 39.37 inches
meters 0.001 kilometers
meters 6.214 x 10 miles (statute)
meters 1,000 millimeters
meters 1.094 yards
meters of water 1.421 pounds/sq. in.
meters/min. 1.667 cm./sec.
meters/min. 3.281 feet/min.
meters/min. 0.05468 feet/sec.
meters/min. 0.06 km./hr.
meters/min. 0.03728 miles/hr.
meters/sec. 196.8 feet/min.
meters/sec. 3.281 feet/sec.
meters/sec. 3.6 kilometers/hr.
meters/sec. 0.06 kilometers/min.
meters/sec. 2.237 miles/hr.
meter-kilogram 7.233 pound-feet
microns 1.0 x 10 meters
miles (statute) 1.609 x 10 centimeters
miles (statute) 5,280 feet
miles (statute) 1.609 kilometers
miles (statute) 1,760 yards
5TO CONVERT MULTIPLY BY TO OBTAIN
miles/hr. 44.7 cm./sec.
miles/hr. 88.0 ft./min.
miles/hr. 1.467 ft./sec.
miles/hr. 1.6093 km./hr.
miles/hr. 0.8684 knots
miles/hr. 26.82 meters/min.
miles/hr. 0.01667 miles/min.
miles/min. 2,682 cm./sec.
miles/min. 88.0 feet/sec.
miles/min. 1.6093 km./min.
miles/min. 60.0 miles/hr.
milliers 1,000 kilograms
milligrams 0.001 grams
milligrams/liter 1.0 parts/million
milliliters 0.001 liters
millimeters 0.1 centimeters
millimeters 0.03937 inches
millimeters 0.001 meters
million gal./day 1.5472 cu.ft./sec.
mils 0.00254 centimeters
mils 0.001 inches
miner’s inches 1.5 cu.ft./min.
minutes (angles) 0.01667 degrees
minutes (angles) 2.909 x 10 radians
myriagrams 10.0 kilograms
myriameters 10.0 kilometers
myriawatts 10.0 kilowatts
nails 2.25 inches
newtons 1.0 x 10 dynes
newtons 0.2248 pounds
newton/meters 0.7376 ft./lb.
newton/meters 8.851 in./lb.
CONVERSION TABLES AND EQUIVALENTS 99100 CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
ounces (avoir) 16.0 drams
ounces (avoir) 437.5 grains
ounces (avoir) 28.349 grams
ounces (avoir) 0.0625 pounds
ounces (avoir) 0.9115 ounces (troy)
ounces (fluid) 1.805 cu. inches
ounces (fluid) 0.02957 liters
ounces (troy) 480.0 grains
ounces (troy) 31.103 grams
ounces (troy) 1.097 ounces (avoir)
ounces (troy) 20.0 pennyweights (troy)
ounces (troy) 0.08333 pounds (troy)
ounces/sq. in. 0.0625 pounds/sq. in.
pace 30.0 inches
parsec 1.9 x 10 miles
parsec 3.084 x 10 kilometers
parts/million 0.0584 grains/U.S. gal.
parts/million 0.07016 grains/imp. gal.
parts/million 8.345 pounds/million gal.
pascal 1.45 x 10 pounds/sq. in.
pascal 1.0 newtons/sq. meter
pecks (U.S.) 0.25 bushels
pecks (U.S.) 537.6 cubic inches
pecks (U.S.) 8.8096 liters (dry)
pecks (U.S.) 8.0 quarts (dry)
pints (dry) 33.6 cubic inches
pints (dry) 0.50 quarts (dry)
pints (dry) 0.5506 liters
pints (liquid) 473.2 cubic cm.
-4TO CONVERT MULTIPLY BY TO OBTAIN
pints (liquid) 0.01671 cubic ft.
pints (liquid) 28.87 cubic inches
pints (liquid) 0.125 gallons (liquid)
pints (liquid) 0.4732 liters
poise 1.0 gram/cm.-sec.
poundals 1.3826 x 10 dynes
poundals 0.0141 kilograms
poundals 0.03108 pounds
pounds (avoir) 256.0 drams (avoir)
pounds (avoir) 7,000 grains
pounds (avoir) 453.6 grams
pounds (avoir) 0.4536 kilograms
pounds (avoir) 16.0 ounces (avoir)
pounds (avoir) 14.58 ounces (troy)
pounds (avoir) 1.2153 pounds (troy)
pounds (avoir) 5.0 x 10 tons (short)
pounds (troy) 5,760 grains
pounds (troy) 373.24 grams
pounds (troy) 13.166 ounces (avoir)
pounds (troy) 12.0 ounces (troy)
pounds (troy) 240.0 pennyweights (troy)
pounds (troy) 0.8229 pounds (avoir)
pounds (troy) 3.6735 x 10 tons (long)
pounds (troy) 3.7324 x 10 tons (metric)
pounds (troy) 4.1143 x 10 tons (short)
pounds of air 13.1 std. cubic feet
pounds of water 0.01602 cu. ft.
pounds of water 27.68 cu. inches
pounds of water 0.1198 gallons
pounds of water/hr. 0.002 gallons/min.
pounds of water/min. 2.670 x 10 cu. ft./sec.
pounds-feet 0.1383 meter-kg.
pounds/cu. ft. 0.01602 grams/cu. cm.
CONVERSION TABLES AND EQUIVALENTS 101102 CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
P Q R
pounds/cu. ft. 16.02 kg./cu. meter
pounds/cu. ft. 5.787 x 10 pounds/cu. in.
pounds/cu. in. 27.68 gram/cu. cm.
pounds/cu. in. 2.768 x 10 kg./cu. meter
pounds/cu. in. 1,728 pounds/cu. ft.
pounds/ft. 1.488 kg./meter
pounds/in. 178.6 grams/cm.
pounds/sq. ft. 0.01602 feet of water
pounds/sq. ft. 0.01414 inches of mercury
pounds/sq. ft. 4.882 kg./sq. meter
pounds/sq. ft. 0.006944 lb./sq. in.
pounds/sq. in. 0.06804 atmospheres
pounds/sq. in. 2.307 ft. of water
pounds/sq. in. 2.036 inches of mercury
pounds/sq. in. 703.1 kg./sq. meter
quadrants (angle) 5,400 minutes
quadrants (angle) 1.571 radians
quarts (dry) 67.2 cu. in.
quarts (liquid) 946.4 cu. cm.
quarts (liquid) 0.03342 cu. ft.
quarts (liquid) 57.75 cu. in.
quarts (liquid) 0.9463 liters
radians 57.3 degrees
radians 3,438 minutes
radians 0.6366 quadrants
radians/sec. 57.3 degrees/sec.
radians/sec. 9.549 revolutions/min.
radians/sec. 0.1592 revolutions/sec.
radians/sec./sec. 0.1592 rev./sec./sec.
reams 500.0 sheets
4TO CONVERT MULTIPLY BY TO OBTAIN
revolutions 360.0 degrees
revolutions 4.0 quadrants
revolutions 6.283 radians
revolutions/min. 6.0 degrees/sec.
revolutions/min. 0.1047 radians/sec.
revolutions/min. 0.01667 rev./sec.
rev./min./min. 0.001745 radians/sec./sec.
rev./min./min. 2.778 x 10 rev./sec./sec.
revolutions/sec. 360.0 degrees/sec.
revolutions/sec. 6.283 radians/sec.
revolutions/sec. 60.0 rev./min.
rev./sec./sec. 6.283 radians/sec./sec.
rev./sec./sec. 3,600 rev./min./min.
rods 5.029 meters
rods 5.5 yards
rods 16.5 feet
seconds (angle) 0.01667 minutes
seconds (angle) 4.848 x 10 radians
slugs 14.59 kilograms
slugs 32.17 pounds
sphere (solid angle) 12.57 steradians
square centimeters 0.001076 sq. ft.
square centimeters 0.1550 sq. in.
square centimeters 1.0 x 10 sq. meters
square centimeters 100.0 sq. millimeters
square feet 2.296 x 10 acres
square feet 929.0 sq. cm.
square feet 144.0 sq. in.
square feet 0.0929 sq. meters
square feet 0.1111 sq. yards
square inches 6.452 sq. cm.
CONVERSION TABLES AND EQUIVALENTS 103104 CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
square inches 0.006944 sq. ft.
square inches 645.2 sq. millimeters
square inches 7.716 x 10 sq. yards
square kilometers 247.1 acres
square kilometers 1.076 x 10 sq. ft.
square kilometers 1.0 x 10 sq. meters
square kilometers 0.3861 sq. miles
square kilometers 1.196 x 10 sq. yards
square meters 2.471 x 10 acres
square meters 10.76 sq. ft.
square meters 3.861 x 10 sq. miles
square meters 1.196 sq. yards
square miles 640.0 acres
square miles 2.788 x 10 sq. ft.
square miles 2.590 sq. km.
square miles 2.590 x 10 sq. meters
square miles 3.098 x 10 sq. yards
square millimeters 0.01 sq. cm.
square millimeters 1.076 x 10 sq. ft.
square millimeters 0.00155 sq. in.
square yards 2.066 x 10 acres
square yards 8,361 sq. cm.
square yards 9.0 sq. ft.
square yards 1,296 sq. in.
square yards 0.8361 sq. meters
square yards 3.228 x 10 sq. miles
steradians 0.07958 spheres
steradians 0.1592 hemispheres
steres 1,000 liters
steres 1.0 cu. meters
-7TO CONVERT MULTIPLY BY TO OBTAIN
temperature (°C + 273) 1.0 abs. temp (°kelvin)
temperature (°C + 17.78) 1.8 temperature (°F)
temperature (°F + 460) 1.0 abs. temp (°rankine)
temperature (°F – 32) 0.5555 temperature (°C)
tons (long) 1,016 kilograms
tons (long) 2,240 pounds
tons (metric) 1,000 kilograms
tons (metric) 2,205 pounds
tons (short) 907.2 kilograms
tons (short) 2,000 pounds
tons (short)/sq. ft. 9,765 kg./sq. meter
tons (short)/sq. ft. 13.89 pounds/sq. in.
tons of water/24 hr. 0.1664 gallons/min.
tons of water/24 hr. 1.3349 cu. ft./hr.
watts 3.4129 btu/hr.
watts 0.0569 btu/min.
watts 1.0 x 10 ergs/sec.
watts 44.27 ft.-lb./min.
watts 0.7378 ft.-lb./sec.
watts 0.00134 horsepower
watts 0.00136 horsepower (metric)
watts 0.01433 kg.-calories/min.
watts 0.001 kilowatts
watts (abs.) 1.0 joules/sec.
watt-hours 3.413 btu
watt-hours 3.6 x 10 ergs
watt-hours 2,656 foot-lb.
watt-hours 860.5 gram-calories
watt-hours 0.00134 horsepower-hours
watt-hours 0.8605 kilograms-calories
CONVERSION TABLES AND EQUIVALENTS 105106 CONVERSION TABLES AND EQUIVALENTS
TO CONVERT MULTIPLY BY TO OBTAIN
watt-hours 367.2 kilogram-meters
watt-hours 0.001 kilowatt-hours
watt (international) 1.000165 watt (absolute)
weeks 168.0 hours
weeks 10,080 minutes
yards 91.44 centimeters
yards 9.144 x 10 kilometers
yards 0.9144 meters
yards 5.682 x 10 miles (statute)
yards 914.4 millimeters
years 365.26 days (mean solar)
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