Valves PPT.pptx

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    September2012

    Control Valves&

    On-Of Valves

    By Baishakhi Bhattacharyya

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    IN!"Defnition : ValveDefnition : Control ValvesParts o Control ValvesDefnition : On-O ValvesNeed and Application o On-o valveTypes o Valve

    Globe ValveBtter!y ValveBall ValveGate Valve"ccentric #otary pl$

    C%aracteristic O Control ValvesActator

    Accessories&ea'a$eCavitation ( )las%in$ and t%eir *iti$ationNoise and Noise #edction+o, to *a'e valves fre-sae".D Tri$$ersPeror*ance TestsPartial .tro'e test.tandards #elevant to Control Valves.tandards #elevant to On-O ValvesTest and Certifcation #elevant to Control ValvesTest and Certifcation #elevant to On-o ValvesControl valve si/in$

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    What is a Valve?

    A valve is nothing but a restriction. A valveis a device that regulates, directs or controls

    the flow of a fluid (gases, liquids, fluidized solids, or slurries) by oening, closing, or

    artially obstructing various assageways.

    V#$V!

    Control valve On-of valve%otor Operate

    valve

    A !ontrol valve is a

    restriction which is

    caable of being"odulated in a conduit

    that contains a flowing

    fluid

    An #$%#&&'shut down

    valve (also referred to as

    "ergency shutdownvalve, V, *, or

    *V) is an actuated

    valve designed to sto

    the flow of a fluid

    +otor #erated valve is a valve

    where the Actuator art is

    relaced by a "otor. +#V arenor"ally used for -arger

    rocess lines where the

    neu"atic ressure is not

    enough to rovide required

    torque Valves "ove"ent.

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    CON'(O$ V#$V!

    he "ost co""on final control ele"ent in the rocess

    control industries is the control valve.A !ontrol valve is a restriction which is caable of being

    "odulated in a conduit that contains a flowing fluid.

    !ontrol valves are co"rised of two "a/or arts0

    the valve body, which contains all the "echanical

    co"onents necessary to influence fluid flow1 and the

    valve actuator, which rovides the "echanicalower necessary to "ove the co"onents within the

    valve body.

    2A 34.54 defined control valve as a ower oerated

    device which "odifies the fluid flow rate in a rocess

    control syste".

    2t consists of a valve connected to an actuator"echanis" that is caable of changing the osition of a

    flow controlling ele"ent in the valve in resonse to a

    signal fro" a controlling syste".ingle%seat globe valve

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    PAR

    TS

    OF

    CONT

    ROL

    V

    ALV

    E

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    Valve Body-The main pressure boundary of the valve that also provides the pipe connecting ends and thefluid flow passageway, and supports the valve trim.

    BonnetAssembly-The portion of the valve that contains the packing box and stem seal and also may guidethe stem. t may also provide for the attachment of the actuator to the valve body. Typical bonnets are bolted,threaded, welded, pressure-sealed, or integral with the body.

    Trim-The internal components of a valve that modulate the flow of the controlled fluid. !n a globe valvetypically, it would include plug, seat ring, cage, stem"

    Valve#lug-The movable part of the valve that is positioned in the flow path to modulate the rate of flowthrough the valve.

    $uide Bushing-The bushings fitted into the body, bonnet, bottom flange to guide the plug%s post.

    &age-A part of a valve trim, in a globe or angle body, that surrounds the closure member and whose flowpassages may provide flow characteri'ation and(or a seating surface. t may also provide stability, guiding,balance, and alignment.

    )eat*ing-A part of the valve body assembly that provides a seating surface for the closure member and mayprovide part of the flow control orifice.

    )eat-The line of contact between the closure member and its mating surface that establishes valve shutoff.

    )tem&onnector-The device that connects the actuator stem to the valve stem.

    +oke - The structure that rigidly connects the actuator power unit to the valve.

    Actuator- The purpose of a actuator is to provide the motive force to operate a valve mechanism.

    #ositioner- a positioner is a device attached to an actuator that receives an electronic or pneumatic signalfrom a controller and compares that signal to the actuators position. f the signal and the actuator positiondiffer, the positioner sends the necessary power, usually through compressed air to move the actuator untilthe correct position is reached.

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    !S Operate)ON-O**V#$V!S

    #n ON-O**)s%t do,n valve+also re,erre to as "*er$encys%tdo,n valve ".V ".D or".DV. is an act/ate valveesine to stop the o o, aha3aro/s /i or e4ternal

    hyrocarbons +ases. /pon theetection o, a anero/s event5

    !S)!SV valves provies e,enseaainst process miscreations5

    !S ) !SV valves are connecte

    to 6rorammable $oic Controller+6$C. an toether ith sensors,orm the Sa,ety $oop5

    'hey enerally have a 'a Namestartin as "V or "V5

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    N!! #N #66$IC#'ION

    'he lack o, sprin ret/rn capabilities on theiferent electric act/ator esins on the marketan its epenence on the s/pply so/rce tooperate an react to any iven sit/ation kno

    makes the /sers v/lnerable to anero/ssit/ations an potential environmentalcatastrophes5

    #lso ith toay7s environmental stanars an

    re8/ire practices the nee to have !Scapabilities becomes prevalent an chanes theoperational ,/nction o, sectionin valves5

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    Nee & #pplication +Cont5.

    'his provies protection aainst possibleharm to people e8/ipment or theenvironment5

    Sh/ton valves ,orm part o, a Sa,ety

    instr/mente system +SIS.5 9henever sensors ienti,y an abnormalanero/s process sit/ation the 6$Cisconnects the poer to !S solenoi valvean the valve oes to esire ,ail sa,e moe

    by means o, sprin ,orce +*ail Close)*ailOpen.5

    'he process o, proviin a/tomate sa,etyprotection /pon the etection o, a ha3aro/sevent is calle */nctional Sa,et 5

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    VA-V

    6-#7 789&-: 7A--

    2$6-

    A*

    *2A;9A6+

    *#87-

    A*A$6- < WA: 6+$* ' V%$#!; &8-- 7#9

    +2=2$6*2V92$6

    6A

    T+#) / VA0V)

    !!$92!

    9#A9: -86

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    1a2orly the following kind of valves are used for &ontrol valves3

    -$lobe

    -Butterfly

    -ccentric *otary #lug

    -)egmented ( V-4otch Ball

    1a2orly the following kind of valves are used for 4(// purposes

    -Ball Valve

    -Butterfly Valves

    -$ate Valves

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    G&OB" VA&V"

    6lobe valves are na"ed for their sherical body shae

    with the two halves of the body being searated by an

    internal baffle.

    $lobe valves restrict the flow of fluid by altering the

    distance between a movable plug and a stationary

    seat.

    When the lug is fitted into the seat, it stos the flow of

    water. he lug can be left in any osition fro"

    co"letely closed, to co"letely oen, deending on

    the required flow of fluid.

    $0B VA0V

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    )i'e0

    > to >@1 higher size available on request.

    Application0

    he globe valve design is one of the "ost oular valve designs

    used in throttling service.

    o control large range of rocess ara"eters, secially in

    etroche"ical, che"ical, fertilizer, oil and gas, ower, and other

    rocess lants.

    6lobe valves are frequently used for control alications because

    of their suitability for throttling flow and the ease with which they

    can be given a secific characteristic, relating valve oening to

    flow.

    !ontrol Valve 7ody

    $0B VA0V

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    Sinle seate lobe valve

    /low through a single seat

    ingle%seated valves are the "ost widely used of the

    globe body atterns.

    here are good reasons for this0

    ;igh flow caacity

    ight shut off

    ;igh rangeability

    hey are available in a wide variety of

    configurations, including secial%urose tri"s.

    hey are available with wide range of

    interchangeable tri" size.

    hey have good seating shut%off caability, are less

    sub/ect to vibration due to reduced lug "ass, and

    are generally easy to "aintain.

    /eatures0

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    /eatures0;igh flow caacityight shut off;igh rangeability. Valve flow rangeability, is the ratio of "aBi"u" rated flow to "ini"u"

    controllable flow. he governing ara"eter is 9ated !v.;igher urndown, is the ratio between the valveCs "aBi"u" and "ini"u" controllable flow

    rate at stated oerating ressures.Various tye of tri" e.g. contour, single stage, "ulti stage low noise, anti%cavitation tri"s, etc.Wide range of interchangeable tri" size.Available characteristics % DuicE oening, -inear F qual ercentage. he valve tri" consists

    of the internal arts contained within the body and wetted by the rocess fluid. he "ain

    co"onents are the lug and ste" and the seat rings.'he trim esin also serves to

    etermine the inherent o characteristics o, the valve5

    Valve plug shapes to produce the three

    common flow characteristics:

    equal percentage, linear, and q