control valve presentation20012004123756

8/11/2019 Control Valve Presentation20012004123756

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Reliance Industries Ltd.

Jamnagar

The Boss of Control Loop,

Final Control Element


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Reliance Industries Ltd.

Jamnagar

CONTROL VALVE

AN OVERVIEW


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CONTENT -

WHAT IS A CONTROL VALVE ?

CONTROL VALVE ACTUATOR

STANDARDS APPLICABLE FOR CONTROL VALVE

FLASHING

CAVITATION

CONTROL VALVE SELECTION & INTERCHANGEABILITY

VALVE GLAND PACKING & MATERIAL OF CONSTRUCTIONCONTROL VALVE LEAKAGE CLASS

CONTROL VALVE CHARACTERISTICS

ARDUOUS SERVICE VALVE

NOISE REDUCTIONS PRACTICES

TODAYS DISCUSSION

CONTENT -


CONTROL VALVE ACTUATOR & ACCESSORIES

STANDARDS APPLICABLE FOR CONTROL VALVE

FLASHING

CAVITATION

CONTROL VALVE SELECTION & INTERCHANGEABILITY

VALVE GLAND PACKING & MATERIAL OF CONSTRUCTIONCONTROL VALVE LEAKAGE CLASS

CONTROL VALVE CHARACTERISTICS

ARDUOUS SERVICE VALVE

NOISE REDUCTIONS PRACTICES


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CONTROL VALVE

This is a device used to modulate flow of process fluid in line bycreating a variable pressure drop in the line .

Normally the pressure drop is made with respect to the control signalreceived towards flow condition correction required.


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WHAT IS VALVE FLOW COEFFICIENT ?

VALVE Cv - No. Of US gallon [ USG = 3.7 Ltrs] of water per minutepassing through the valve in full open condition with 1 PSI pressureDrop across the valve at 15 deg C temp.

So essentially valve Cv is capacity of valve in terms of water whichhelps us to identify suitable size required for any fluid in any pressure /temp. condition.

VALVE Kv - Quantity of water in M3/Hr. at temperature between 5 to

40C that will flow through the valve at a specified travel with a pressuredrop of 1 Bar.

Kv = 0.856Cv


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TYPE OF CONTROL VALVE

Also valves may be further subdivided as shown below

BY SHAPE BY INTERNAL BY CHAR. BY GUIDING

GLOBE PLUG EQ% TOP

SINGLE SEAT

DOUBLE SEAT

BUTTERFLY CAGE LINEAR CAGE

ANGLE FULL BALL QUICK OPEN TOP & BOTTOM

SLANT SLEEVED PARABOLIC BUSH/BEARING

Y TYPE V BALL

All Control valve can be divided in two category.

1. Sliding stem ( Globe valve) 2. Rotary shaft ( Quarter turn )


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VALVE ACTUATOR

Actuator- Mechanism whichoperates the valve by receiving thecontrol signal.

Type of ActuatorPneumatic- Spring Diaphragm

Piston Cylinder

Electrical- Not discussed

Hydraulic- Not discussed


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VALVE ACTUATOR


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VALVE ACTUATOR


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ANSI :- AMERICAN NATIONAL STANDARDS INSTITUTEB16.34 :- STEEL VALVES

DEFINES CRITERIA FOR VALVE WALL THICKNESS REQUIREMENTS DEFINES PRESSURE / TEMPERATURE RATINGS DEFINE HYDRO-TEST REQUIREMENTSExample :-

A351 CF8M ( Material :- 316SST; Temp range :- -425 F to 1500 F)

A216 WCB ( Material :- Carbon Steel; Temp range:- -20 F to 1000 F )

B16.37 :- HYDROSTATIC TEST PROCEDURE DEFINES REQUIREMENT FOR HYDRO-TEST = 1.5 X MWP

MWP = MAXIMUM WORKING PRESSURE

B16.104 :- CONTROL VALVE SEAT LEAKAGE CLASSIFICATION

ESTABLISHES TEST PROCEDURES AND SEAT LEAKAGE CLASSES

API :- AMERICAN PETROLEUM INSTITUTESPEC 6B :- DEFINES PIPELINE VALVESPEC 600 :- STEEL GAGE VALVES, FLANGED BUTT WELDING ENDS

CONTROL VALVE STANDARDS


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VALVE ACCESSORIES

VALVE POSITIONERS

PNEUMATIC

ELECTRONEUMATIC

SMART DIGITAL

PROXIMITY SWITCHES

INDUCTIVE TYPEPNEUMATIC CAM OPERATED

SOLENOID VALVES

LATCHING/ NON-LATCHING

WITH MANUAL OVERRIDE

SIGNAL BOOSTERS

PRESSURE

VOLUME

SIGNAL INVERTERS

HANDWHEEL

AIR VOLUME TANK


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NACE :- NATIONAL ASSOCIATION OF CORROSION ENGINEERSNACE MR-01-75

DEFINES SULFIDE STRESS CRACKING RESISTANCE MATERIAL MATERIAL COMPLY TO NACE STANDARD ARE

CARBON STEEL WITH HEAT TREATMENTSST 302,304,316,17-4PHALLOY STEEL MONEY, HASTELLOY C

MATERIAL NOT SUITABLE FOR NACE ENVIRONMENT ISCAST IRON



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ISA :- INSTRUMENT SOCIETY OF AMERICA DEFINES STANDARDS FOR CONTROL INDUSTRY

Example :-VALVE SIZING EQUATIONS.NOISE PREDICTION TECHNIQUECONTROL SIGNAL 3 - 15 PSIG, 6 - 30 PSIG

OSHA :- OCCUPATIONAL SAFETY AND HEALTH ACTDEFINES CRITERIA FOR PERMISSIBLE DURATION FOR EXPOSURE OF NOISE LEVEL



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Control Valves Selection , Sizing and Specification

DEP 32.36.01.17- Gen July 1987 &

Basic Process control & Instrumentation ShellM114-1999

Shell Best Practice [Ref Process Measurementand Control Devices Shell Canada Ltd

Standard 16-1.2]

SHELL REFERENCES


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CONTROL VALVE LEAKAGE

Control Valve Leakage -

This is basically the fluid which passes through the valve when the valve is

fully closed. This value however should not be considered as the valve Cvat NIL Opening.

So this leakage shall depend on the contact of valve plug & seat with theseating force applied for holding the plug over the seat.


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CONTROL VALVE LEAKAGE

ANSI/FCI 70-2 Test Medium Pressure and temperature

Class II

Class III

Class IV

Class V Water Service DP at 10 to 52deg C

Port dia. Bubbles perMin.

mL per Min.

1 1 0.15

1 - 1/2 2 0.30

2 3 0.45

2 - 1/2 4 0.60

3 6 0.904 11 1.70

6 27 4.00

8 45 6.75

Maximum Leakage

0.5% valve capacity at full travel



0.0005ml/min/psid/in. port dia

Class VI

Service DP or 50 PSID

whichever is lowerat 10 to

52deg C

Water / Air

Service DP or 50 PSID

whichever is lowerat 10 to

52deg C

Air


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VALVE CHARACTERISTICS

Equal % - Rate of change of flow due to change of valvetravel is proportional to earlier

flow.

Linear - Rate of change of flow is same to rate ofchange of valve travel

Quick Open - Full capacity attaining without change oftravel after initial opening

On/Off - Used mainly as Isolation valves (Pumpsuction and ESD valves)


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1. CHARACTERISING FLOW Linear Cage Quick Opening Cage

Equal Percentage Cage Modified Equal percentage flow

2. NOISE ABATEMENT

3. ANTI CAVITATION

TRIM AND CAGE DESIGN


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CHARACTERIZING FLOW BY CAGE TYPE


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CHARACTERIZING FLOW

% Valve Travel0 20 40 60 80 100

100

80

60

40

20

0

Cv

DesignCv

%

Quick

Opening


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VALVE SELECTION PROCESS FOLLOWEDIN RELIANCE

If valve sizing does not give warning of cavitation, flashing or Noise level ( >85dBA) thenselect standard trim valve.

If valve sizing gives warning of cavitation, flashing or Noise level ( >85dBA) then selectarduous service trim valve.

Example:- For cavitation select CAVITROL III stage 1 to 5 valve or CAVITROL 4 valve.For noise select WHISPER I ,III or WHISPERFLO valve trim.

Select the suitable Approved vendor suiting the product .

Example:- ABB - Introl design or CCI - DRAG design.

In case of very high DP ( DP*100/P1 > 50%) or Noise select ABB or CCI valves.

Example:- Compressor Anti - surge control valves - CCI- DRAG design.


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VALVE SELECTION PROCESS

Carbon steel WCB

Carbon steel NACE

Stainless steel 316 or 316L

Standard Materials :

ANSI rating class 150



Standard Ratings :

Is itstandaard

material

Yes

No

Is it standard

flange rating

Yes

No

0 deg. C

+ 420 deg. C

Standard Temp. RanggeIs

temperature

withing

standard

rangeYes

No

Choke Flow

Cavitation

Severe Service :

Noise above 85dbA

Oxygen service

Low temperature service

HF service

Ethylene oxide service

Vacuum service

HP steam service

Hydrogen service

Chlorine service

Is it sever

service

No

Yes

Standard valve designand application.

Ref DEP 32.36.01.17

All Section except 6and 7

Special valve designand application

ref DEP 32.36.01.17


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POPULATION OF CONTROL VALVES ATRELIANCE JAMNAGAR.

Based on above criteria RIL complex has following Installed quantity ofvalve

Fisher direct supply ( Through Bechtel ) :1800+ valves.

Fisher package supply valves :800+

Masoneilan package supply : 180 +

ABB UK direct supply :150+

CCI USA direct supply :40+

Fisher Gulde package supply : 190 +

Linde Mepag package supply : 120 +

Copes Vulcan package supply : 50 +

Keystone Biffi direct supply : 300 +

Neles Jamesbury direct supply : 630 +

Rotork MOVs direct su l : 2100 +


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VALVE INTERCHANGEABILITY

Body pressure rating and certification ( e.g. IBR )

End connection ( Ex:- Screwed or welded flange connection )

Valve Size and type.

Trim Size - Cv

Leakage classification

Body and trim material and certification ( e.g. NACE )

Plug and cage characteristics.

Actuator bench setting / spring range.

Actuator action ( AFC/ AFO )

Process temperature ( For gland packing and body - trim material )


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Flow Path through a Control Valve - Analogy

Minimum

Geometrical

Flow Area

Streamlines Contract as

Flow Approaches Restriction

Vena Contracta

(Minimum Flow Area)


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Variation in Pressure and Velocity

Valve

Inlet

Trim

Exit Vena

Contracta

Valve

OutletTrim

Inlet

Velocity

VariationP

Pressure

Variation

P1

P2


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Pressure Recovery

Valve

Inlet

Trim

Exit Vena

Contracta

Valve

OutletTrim

Inlet

P

Low

Recovery

High

Recovery


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FLASHING

Flashing :The formation of vapor bubbles in liquid flow streams at vena contracta.

As liquid passes through a restriction (vena contracta) in a control valve the liquid velocityincreases and liquid pressure decreases. And if the pressure at this point falls to or belowthe vapor pressureof the liquid, vapor bubbles form in the flow stream. Flashing results ifthis pressure remains below vapor pressure of liquid.

When a liquid flashes into vapor, there is a large increase in volume. Due to increase involume velocity will increase and hence high velocity will erode the surface.

Flashing damages can be identified by smooth polished appearance of eroded surface.Flashing damages is usually at or near seat line of the valve plug and seat ring.

Vapor pressure :- The pressure at which liquid begins to vaporize.


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FLASHING DAMAGE ( Tag no. 241FV040 )


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FLASHING DAMAGE ( Tag no. 241FV040 )


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CAVITATION

Cavitation : The formation and subsequent collapse of vapor bubbles in liquid flowstreams.As liquid passes through a restriction in a control valve the liquid velocity increases, whilethe liquid pressure decreases. The pressure reaches a minimum at a point called the venacontracta, and if the pressure at this point falls to or below the vapor pressure of the liquid,vapor bubbles form in the flow stream.

Downstream of the vena contracta, flow area increases, velocity de-creases, and pressureincreases.

If this recovered pressure is sufficient to raise the pressure above the liquid vapor pressure,

the vapor bubbles will collapse. The collapsing bubbles generate significant noise andvibration, and can mechanically attack pipe walls and valve components.

Cavitation damages can be identified by rough and pitted surface. Cavitation damage mayextend to the downstream pipeline if that is where the pressure recovery occurs.Phenomenon of Cavitation is experienced in CV and PUMPS


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CAVITATION

Valve

Inlet

Trim

Exit Vena

Contracta

Valve

OutletTrim

Inlet

P

P1

P2

PV

PVC


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CAVITATION DAMAGE


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CAVITATION CONTROLS

SYSTEM DESIGN

1. LOCATION OF VALVE

2. CASCADING

MATERIAL SELECTION

HARDEN MATERIAL,

LIKE 17-4 pH, 440C, 420SST HT

AND 316/COLMONOY 6 / ALLOY 6


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CAVITATION CONTROLS

ANTI - CAVITATION PRODUCTS

CCI DRAG DESIGN, UP TO 380 BAR PRESS. DROP.

FISHER CAVITROL - III DESIGN

CAVITROL - III WITH 1 STAGE- UP TO 99 BAR.

CAVITROL - III 2-3 STAGES- 99 TO 207 BAR.

CAVITROL -4 , ABOVE 200 BAR, SIZE LIMIT 2 TO 6.

ABB INTROL DESIGN


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CAVITATION CONTROLS :- FISHERCAVITROL DESIGN

CAVITROL - III CAVITROL - III

STAGE - 2 STAGE - 3


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CAVITATION CONTROLS :- FISHERCAVITROL DESIGN

CAVITROL - 4


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CAVITATION CONTROLS :- ABB INTROLDESIGN

INTROL CAGE


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CAVITATION CONTROLS :- CCI DRAGDESIGN

CCI DRAG CAGE


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CHOKED FLOW

Choked flow :-

Formation of vapour bubbles in the liquid flow stream cause a crowdingcondition at the vena contracta which tends to limit flow through the valve.

If valve pressure drop is increased slightly beyond the pointwhere bubbles begins to form, a choked flow condition is reached. Withconstant upstream pressure, further increase in pressure drop will notproduced increased flow through the valve.


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NOISE FUNDAMENTALS

Noise :- A random mixture of sound pressure waves of various amplitudes and frequency. Whichpeople do not like to hear.

Sound Wave :- A pressure wave with a fixed frequency and amplitude traveling through a medium.

Unit of Noise :- dBA ( Decibels )= 20 Log( Existing sound pressure level / 0.0002 microbars )

Source of valve noise:

Mechanical Noise :-It produces high mechanical stress - fatigue failure of vibrating part.Mechanical noise can be solved by improved design to suppress vibration

by good guiding and rugged construction.

Vibration of valve components :- This is due to lateral movement of valve plug relativeto guide surfaces. The sound level produce normally will have frequency less then1500Hz and is describe as metallic rattling.

Fluid impingement upon the movable of flexible part ( Metallic chattering )

Components resonates at its own natural frequency ( single tone 3KHz to 7KHz)

Hydrodynamic Noise :-It is due to cavitation. It is because of implosion of vapor bubbles andis relatively low.


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NOISE FUNDAMENTALS

Aerodynamic Noise :-

Highest energy component at same frequency where human ear is most sensitive. Largeamount of energy converted to aerodynamic noise.

High intensity noise resulting due to turbulent flow of gas, are due to high relativevelocity.

This can be classified as non-periodic or random noise with occurring frequency between1 KHz to 8 KHz.

Valve pressure drop ( Main source ),

Obstruction in flow path,Valve style , having more flow directional changes,

Degree of turbulence varies with valve style1,

Valve size.


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PERMISSIBLE EXPOSURE DURATIONS NOISE

LEVEL

OSHA :- OCCUPATIONAL SAFETY AND HEALTH ACTDEFINES CRITERIA FOR PERMISSIBLE EXPOSURE DURATIONS NOISE LEVEL

IN JAMNAGAR COMPLEX MAX. 85 dBA IS CONSIDERED AS A VALVE SELECTIONCRITERIA.

DURATION IN HOURS PER DAY SO UND LEVEL IN DBA

8 90

6 92

4 95

3 97

2 100

1-1/2 102

1 105

1/2 110

1/4 OR LESS 115


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NOISE CONTROL

PATH TREATMENT

INSULATION OF PIPE

HEAVY WALLED PIPE

SILENCER

SOURCE TREATMENT

VALVE CAGE STYLE ( TRIM )

WHISPER - I ( DP/P1


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NOISE CONTROL - SOURCE TREATMENT

WHISPER - I DESIGN

WHISPER - III DESIGN


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WHISPERFLO DESIGN BY FISHER


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WHISPER DISK AND INLINE DIFFUSER

DESIGN BY FISHER


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NOISE CALCULATION

SPL = SPLP + SPLCG + SPLP/P1+ SPLK + SPLP2

SPL = OVERALL NOISE LEVEL IN DECIBLE ( 1 METER DOWNSTREAM OF VALVE OUTLETAND 1METER FROM THE PIPE SURFACE )

SPLP = FUNCTION OF PRESSURE DROP ACROSS THE VALVE ( MAJOR COMPONENT )

SPLCG = GAS SIZING COEFFICIENT ( MAJOR COMPONENT )

SPLP/P1= RATIO OF PRESSURE DIFFERENTIAL TO INLET PRESSURE

SPLK = CORRECTION IN DBA FOR PIPE SIZE AND SCHEDULE

SPLP2 = DOWNSTREAM PRESSURE

SIMPLIFIED EQUATION ( WITHOUT MUCH LOSS OF ACCURACY ) :

SPL = SPLP + SPLCG


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CONTROL VALVE GLAND PACKING


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CONTROL VALVE GLAND PACKING

Temp.

RangeCommon use

Suitablity

for Oxygen

/Oxidiz ing

Service

Packing material DescriptionStem

friction

Special

consideration

-73 to 232C Non-Radioactive YesPTFE impregented

composition

Split rings of braided

composition impregented with

PTFE

Low -

All chemicals ( Except

Molten alkali) Non

radioactive

No single PTFE V - Ring Solid rings of molded PTFE Low

Vacuum Pressure /Vacuum

No Double PTFE V - Ring Solid rings of molded PTFE Low

-84 to 232CVacuum, All chemicals

( Except molten alkali )Yes Chesterton 324

Split rings of braided,

preshrunk PTFE yarn

impregented with PTFE;

available with copper rings at

top and bottom of packing

box to meet UOP

specification 6-14-0 for acid

service.

Low -

-18 to 538C

Water, Stem Petroleum

products, Radiactive

and Non-radiactive

nuclear

Yes but upto

371C

Graphite/

Ribbon/Filament

Ribbon style graphite rings

and rings of braided graphite

fibers with sacrificial zinc

washer

High

Low chloridecontent ( less then

100ppm) chrome

plated stem not

necessary for high

temperature service

371 to 649CHigh temperature

oxidizing serviceYes

Ribbon - Style

graphite

Solid rings of ribbon-style

graphite with sacrificial z inc

washers

High -

-40 to 232C

Required 2 to 4

micro inch RMS

valve plug stem

finish


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VALVE MATERIAL

Essentially material for the valve is valve assembly MOC. Standardmaterial commonly used can be listed as below -Valve Body & Bonnet - As per ProcessInternals - As per Process . Commonly SS316 with or w/o

stellite.Valve Gasket - Graphite, Metallic SS 316 or SS 316LValve Packing - Commonly Teflon Or GraphiteFasteners - B7 or B8MActuator Yoke - Cast Iron

Actuator Spring - Spring SteelActuator Diaphragm - Nitrile Rubber with fabric reinforcementAccessories - Commonly Aluminum.


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TECHNOLOGY

With the advent of new technology Control Valve hasundergone rapid change in terms of change in Internals,Capacity Increase, Guiding, Leakage Class Improvement,Treatment of Noise And Cavitation And FinallyDIGITAL.

About 30 years back control valves were only availablewith top guided or top & bottom guided design with

asbestos packing and practically no solution availablefor Hi Pressure drop application leading to Noise for Gasservice Or Cavitation for Liquid Service.


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TECHNOLOGY

Now a days we are also having control valve with digital technology,where valve positioner is digital in nature and able to provide PIDfunction at the valve itself. Digital positioner can provide the followingapart from acting as interface between controller and valve actuator -

1. Provide HART feedback.2. Can couple with Foundation Fieldbus.3. Can provide valve diagnostics.4. Helps in Asset Management.5. Provide lock, soft alarms and data logging facilities.6. Can achieve split action, remote calibration etc.


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Trouble Shooting in Control Valves.

TROUBLE SHOOTING

To Check

Gland Packing

Increase

Actuator

Check Vlv

Guiding

High Stem Friction

HUNTING

(At any vlv opening)

Reduce dP

Use Smaller

Cv valve

Oversizing

Change

Flow dir.

Flow to Close

flow direction

HUNTING

(Near to vlv close posn)

INSTABILITY CYCLIC MOTION

Poor

Piping

Increse

Support

Other

source

Find

Plug guidewear & tear

Replacewith new

At any vlv

opening

Increase

pipe support

Throtle pump

discharge

valve

Resonance of

Vibration

Change

plug

profile

Change

Cv value

Resonance

Noise

of vlv plug

At specific

vlv opening

VIBRATION (NOISE) DULL RESPONSE NOT WORKING

ACTION LEAKAGE OTHERS

MALFUNCTION


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Trouble Shooting

CYCLIC MOTION

Dissemble &

Clean

Enlarge

guide ringbleeder hole

Provide

flashing port

Use jacketed

vlv body

Use rotary

or angle type

valve

Slurry/sludge

in vlv guide

Actuator

piston ring

wear & tear

Change

Piston ring

Gland pkg

hardened

Change

gland pkg

Travel Notsmooth

(In both dir)

Change

diaph.

Leak in

Actuator

diaph.

Change

stem seal

Use dust

seal bellow

Leak from

Act. stem

seal

Travel Notsmooth

(In one dir)

DULL RESPONSE NOT WORKING


MALFUNCTION


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Trouble Shooting

CYCLIC MOTION DULL RESPONSE

Trouble in

air source

Trouble in

electric source

Leakage from

tubing

Check comp.

elec source &Main air tubing

No signal &

supply pr.

Trouble in

controller

Check

Controller

Control sig

leakage

Check

air tubing

Act diaph

air leak

Change parts

Positioner

air leak

Change bellow

or diaph

No signal pr.

sup pr. avl

AFR

contamination

Clean

Filter

Pn tubing

Leakage

Check Tubing

(mainly air

conn.)

Trouble with

AFR

Check

AFR

No sup. pr.

Signal pr. avl

Trouble in

posn pilot

relay

Check

Act diaph

air leak

Change

parts

Posn O/P Nil

Stem/guide

galling / jamming

Disassemble

& check

Foreign particle

in vlv port

Disassemble

& check

Stem Bend Change

parts

Trouble in

Actuator

Check

Act Stroke

Actuator not

working with

air sup.

NOT WORKING


MALFUNCTION



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Enlarge

compressor

capacity

Exclusive

compressor

Too much air

consumption

in other line

Check AFR

Trouble in

AFR

Drift ofair sup pr.

Insert vol tank

& restriction to

air signal loop

Control loop

Resistance

Check

Controller

Trouble in

Controller

Hunting ofSig air pr.

Check posn

parts friction

Check posn

pilot relay

Positioner

loop hunting

Decrease dP

Higher size

Actuator

Shift in plug

reaction force

Hunting ofVlv stem

CYCLIC MOTION


MALFUNCTION



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Remachine & Lap

seat surface

Change

seat & plug

Corrosion & erosionof vlv seating

surface

Change seat

& seat gasket

Check

seat design

Corrosion & erosionof seat ring thread

or gasket

Tack weld

defect area

Change vlv

body

Leakagethro' inner

vlv body wall

Valve Closed

Reduce dP

Increase

Actuator size

Too high dP

Check for

Foreign parts

Remachine

galling portion

Galling onguide or port

Valve not

able to close

Seat Leak

Tightenpkg. nut

Insufficient

pkg nut tight

Provide

lub or chg pkg.

Pkg Lub

missing

Change

pkg

Wear & tearof pkg

Change parts

or remachine

Use dust seal

bellows

Damage of stemsurface

Examine part MOC

Change gasket

Corrosion/erosion

of seat gasket

surface

Gland Leak

LEAKAGE

Change seat ringor plug

Corrosion / erosion

of plug or S. ring

Rangeability narrowed

because of

control position

changed

OTHERS

MALFUNCTION



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control valve presentation20012004123756

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