1
NIDHIN MANOHAR
The Boss of Control Loop,
Final Control Element
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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 CONSTRUCTION•CONTROL VALVE LEAKAGE CLASS• CONTROL VALVE CHARACTERISTICS• ARDUOUS SERVICE VALVE• NOISE REDUCTIONS PRACTICES
TODAY’S DISCUSSION
CONTENT -• WHAT IS A CONTROL VALVE ?• CONTROL VALVE ACTUATOR & ACCESSORIES•STANDARDS APPLICABLE FOR CONTROL VALVE•FLASHING•CAVITATION•CONTROL VALVE SELECTION & INTERCHANGEABILITY•VALVE GLAND PACKING & MATERIAL OF CONSTRUCTION•CONTROL VALVE LEAKAGE CLASS• CONTROL VALVE CHARACTERISTICS• ARDUOUS SERVICE VALVE• NOISE REDUCTIONS PRACTICES
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WHAT IS A CONTROL VALVE ?
CONTROL VALVEThis is a device used to modulate flow of process fluid in line by creating a variable pressure drop in the line .
Normally the pressure drop is made with respect to the control signal received 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 minute passing through the valve in full open condition with 1 PSI pressure Drop across the valve at 15 deg C temp.So essentially valve Cv is capacity of valve in terms of water which helps 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 pressure drop of 1 Bar.
Kv = 0.856Cv
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TYPE OF CONTROL VALVE
Also valves may be further subdivided as shown belowBY SHAPE BY INTERNAL BY CHAR. BY GUIDINGGLOBE PLUG EQ% TOPSINGLE SEATDOUBLE SEATBUTTERFLY CAGE LINEAR CAGEANGLE FULL BALL QUICK OPEN TOP & BOTTOMSLANT SLEEVED PARABOLIC BUSH/BEARINGY 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 which operates the valve by receiving the control signal.Type of ActuatorPneumatic - Spring Diaphragm
Piston Cylinder Electrical - Not discussedHydraulic- Not discussed
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VALVE ACTUATOR
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VALVE ACTUATOR
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VALVE ACCESSORIES VALVE POSITIONERS
PNEUMATIC ELECTRONEUMATIC SMART DIGITAL
PROXIMITY SWITCHES INDUCTIVE TYPE PNEUMATIC CAM OPERATED
SOLENOID VALVES LATCHING/ NON-LATCHING WITH MANUAL OVERRIDE
SIGNAL BOOSTERS PRESSURE VOLUME
SIGNAL INVERTERS HANDWHEEL AIR VOLUME TANK
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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 REQUIREMENTS
Example :- 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 INSTITUTE SPEC 6B :- DEFINES PIPELINE VALVESPEC 600 :- STEEL GAGE VALVES, FLANGED BUTT WELDING ENDS
CONTROL VALVE STANDARDS
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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 IS CAST IRON
CONTROL VALVE STANDARDS
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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
CONTROL VALVE STANDARDS
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Control Valves –Selection , Sizing and Specification
• DEP 32.36.01.17- Gen July 1987 &• Basic Process control & Instrumentation
Shell M114-1999• Shell Best Practice –[Ref Process
Measurement and Control Devices –Shell Canada Ltd Standard 16-1.2]
SHELL REFERENCES
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CONTROL VALVE LEAKAGE
Control Valve Leakage -Control Valve Leakage -
This is basically the fluid which passes through the valve This is basically the fluid which passes through the valve when the valve is fully closed. This value however should when the valve is fully closed. This value however should not be considered as the valve Cv at NIL Opening.not be considered as the valve Cv at NIL Opening.
So this leakage shall depend on the contact of valve plug & So this leakage shall depend on the contact of valve plug & seat with the seating force applied for holding the plug over seat with the seating force applied for holding the plug over the seat.the seat.
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CONTROL VALVE LEAKAGE
ANSI/FCI 70-2 Test Medium Pressure and temperatureClass IIClass IIIClass IVClass V Water Service DP at 10 to 52deg C
Port dia.Bubbles per
Min. mL per Min.
1 1 0.151 - 1/2 2 0.30
2 3 0.452 - 1/2 4 0.60
3 6 0.904 11 1.706 27 4.008 45 6.75
Maximum Leakage0.5% valve capacity at full travel0.1% valve capacity at full travel0.01% valve capacity at full travel0.0005ml/min/psid/in. port dia
Class VI
Service DP or 50 PSID whichever is lower at 10 to 52deg C
Water / Air
Service DP or 50 PSID whichever is lower at 10 to 52deg C
Air
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VALVE CHARACTERISTICS
Equal %Equal % - Rate of change of flow due to - Rate of change of flow due to change of valve change of valve travel is travel is proportional to earlier flow.proportional to earlier flow.
LinearLinear - Rate of change of flow is same - Rate of change of flow is same to rate of to rate of change of valve change of valve traveltravel
Quick OpenQuick Open - Full capacity attaining without - Full capacity attaining without change of change of travel after initial opening travel after initial opening
On/OffOn/Off - Used mainly as Isolation valves - Used mainly as Isolation valves (Pump suction (Pump suction and ESD valves) and ESD valves)
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1. CHARACTERISING FLOW1. CHARACTERISING FLOW• Linear CageLinear Cage• Quick Opening CageQuick Opening Cage• Equal Percentage CageEqual Percentage Cage• Modified Equal percentage flowModified Equal percentage flow
2. NOISE ABATEMENT2. NOISE ABATEMENT
3. ANTI CAVITATION3. ANTI CAVITATION
TRIM AND CAGE DESIGN
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CHARACTERIZING FLOW BY CAGE CHARACTERIZING FLOW BY CAGE TYPETYPE
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CHARACTERIZING FLOW CHARACTERIZING FLOW
Equal %
Linear
% Valve Travel0 20 40 60 80 100
100
80
60
40
20
0
Cv
Des
ign
Cv%
Quick Opening
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VALVE SELECTION PROCESS FOLLOWED IN RELIANCE
• If valve sizing does not give warning of cavitation, flashing or Noise level ( >85dBA) then select standard trim valve.• If valve sizing gives warning of cavitation, flashing or Noise level ( >85dBA) then select arduous 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 W CB
Carbon steel NACE
Stainless steel 316 or 316L
Standard M ateria ls :
ANSI rating class 150
ANSI rating class 300
ANSI rating class 600
Standard Ratings :
Is itstandaardmateria l
Yes
No
Is it standardflange rating
Yes
No
0 deg. C
+ 420 deg. C
Standard T em p. R angge Istemperatu re
with ingstandard
rangeYes
No
Choke Flow
Cav itation
Severe Service :
Noise above 85dbA
Oxygen serv ice
Low tem perature serv ice
HF serv ice
Ethylene oxide serv ice
Vacuum serv ice
HP steam serv ice
Hydrogen serv ice
Chlorine serv ice
Is it severserv ice
No
Yes
Standard v alve designand application.
Ref DEP 32.36.01.17All Section except 6
and 7
Special valve designand application
ref DEP 32.36.01.17
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POPULATION OF CONTROL VALVES AT RELIANCE JAMNAGAR.
• Based on above criteria RIL complex has following Installed quantity of valve• 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 supply : 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 - AnalogyMinimum
GeometricalFlow Area
Streamlines Contract asFlow Approaches Restriction
Vena Contracta(Minimum Flow Area)
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Variation in Pressure and Velocity
ValveInlet
TrimExit Vena
Contracta
ValveOutletTrim
Inlet
VelocityVariation
PPressureVariation
P1
P2
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Pressure Recovery
ValveInlet
TrimExit Vena
Contracta
ValveOutletTrim
Inlet
P
LowRecovery
HighRecovery
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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 velocity increases and liquid pressure decreases. And if the pressure at this point falls to or below the vapor pressure of the liquid, vapor bubbles form in the flow stream. Flashing results if this pressure remains below vapor pressure of liquid.
When a liquid flashes into vapor, there is a large increase in volume. Due to increase in volume 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 flow streams.As liquid passes through a restriction in a control valve the liquid velocity increases, while the liquid pressure decreases. The pressure reaches a minimum at a point called the vena contracta, 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 pressure increases.
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 and vibration, and can mechanically attack pipe walls and valve components.
Cavitation damages can be identified by rough and pitted surface. Cavitation damage may extend 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
ValveInlet
TrimExit Vena
Contracta
ValveOutletTrim
Inlet
P
P1
P2
PV
PVC’
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CAVITATION DAMAGE
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CAVITATION CONTROLS
•SYSTEM DESIGN1. LOCATION OF VALVE2. 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 :- FISHER CAVITROL DESIGN
CAVITROL - III CAVITROL - IIISTAGE - 2 STAGE - 3
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CAVITATION CONTROLS :- FISHER CAVITROL DESIGN
CAVITROL - 4
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CAVITATION CONTROLS :- ABB INTROL DESIGN
INTROL CAGE
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CAVITATION CONTROLS :- CCI DRAG DESIGN
CCI DRAG CAGE
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CAVITATION CONTROLS :- CCI DRAG DESIGN
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CAVITATION CONTROLS :- CCI DRAG DESIGN
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CHOKED FLOW
Choked flow :- Formation of vapour bubbles in the liquid flow stream cause a crowding condition at the vena contracta which tends to limit flow through the valve.
If valve pressure drop is increased slightly beyond the point where bubbles begins to form, a choked flow condition is reached. With constant upstream pressure, further increase in pressure drop will not produced increased flow through the valve.
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NOISE FUNDAMENTALS
Noise :- A random mixture of sound pressure waves of various amplitudes and frequency. Which people 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 relative to guide surfaces. The sound level produce normally will have frequency less then 1500Hz 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 and is relatively low.
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NOISE FUNDAMENTALS
Aerodynamic Noise :-
Highest energy component at same frequency where human ear is most sensitive. Large amount of energy converted to aerodynamic noise.
• High intensity noise resulting due to turbulent flow of gas, are due to high relative velocity. This can be classified as non-periodic or random noise with occurring frequency between 1 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 SELECTION CRITERIA.
DURATIO N IN HO URS PER DAY SOUND LEVEL IN DBA8 906 924 953 972 100
1-1/2 1021 105
1/2 1101/4 O R 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 <= 0.65 ), Noise reduction up to 18 dBA.• WHISPER - III ( 0.6 <= DP/P1 <= 0.99 ), Noise reduction up to 30 dBA.• WHISPERFLO (NEW DESIGN), Noise reduction up to 10 dBA.
• BY INLINE DIFFUSER • BY WHISPER DISK
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NOISE CONTROL - SOURCE TREATMENT
WHISPER - I DESIGN
WHISPER - III DESIGN
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NOISE CONTROL - SOURCE TREATMENT
WHISPERFLO DESIGN BY FISHER
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NOISE CONTROL - SOURCE TREATMENT
WHISPER DISK AND IN LINE 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 OUTLET AND 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 PRESSURESPLK = CORRECTION IN DBA FOR PIPE SIZE AND SCHEDULESPLP2 = 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. Range Common use
Suitablity for Oxygen /Oxidizing
Service
Packing material Description Stem 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 232C Vacuum, 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 chloride content ( less then 100ppm) chrome plated stem not necessary for high temperature service
371 to 649C High temperature oxidizing service
Yes Ribbon - Style graphite
Solid rings of ribbon-style graphite with sacrificial zinc 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. Essentially material for the valve is valve assembly MOC. Standard material commonly used can be listed as below -Standard material commonly used can be listed as below -Valve Body & BonnetValve Body & Bonnet - As per Process - As per ProcessInternalsInternals - As per Process . Commonly SS316 - As per Process . Commonly SS316 with or w/o with or w/o stellite. stellite.Valve GasketValve Gasket - Graphite, Metallic SS 316 or SS - Graphite, Metallic SS 316 or SS 316L316LValve PackingValve Packing - Commonly Teflon Or Graphite - Commonly Teflon Or GraphiteFastenersFasteners - B7 or B8M - B7 or B8MActuator YokeActuator Yoke - Cast Iron - Cast IronActuator Spring Actuator Spring - Spring Steel - Spring SteelActuator DiaphragmActuator Diaphragm - Nitrile Rubber with fabric - Nitrile Rubber with fabric reinforcementreinforcementAccessoriesAccessories - Commonly Aluminum. - Commonly Aluminum.
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TECHNOLOGY
With the advent of new technology Control With the advent of new technology Control Valve has undergone rapid change in terms of Valve has undergone rapid change in terms of change in Internals, Capacity Increase, change in Internals, Capacity Increase, Guiding, Leakage Class Improvement, Guiding, Leakage Class Improvement, Treatment of Noise And Cavitation And Treatment of Noise And Cavitation And Finally DIGITAL.Finally DIGITAL.
About 30 years back control valves were only About 30 years back control valves were only available with top guided or top & bottom available with top guided or top & bottom guided design with asbestos packing and guided design with asbestos packing and practically no solution available for Hi practically no solution available for Hi Pressure drop application leading to Noise for Pressure drop application leading to Noise for Gas service Or Cavitation for Liquid Service.Gas service Or Cavitation for Liquid Service.
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TECHNOLOGY
Now a days we are also having control valve with digital Now a days we are also having control valve with digital technology, where valve positioner is digital in nature technology, where valve positioner is digital in nature and able to provide PID function at the valve itself. and able to provide PID function at the valve itself. Digital positioner can provide the following apart from Digital positioner can provide the following apart from acting as interface between controller and valve actuator acting as interface between controller and valve actuator --1. Provide HART feedback.1. Provide HART feedback.2. Can couple with Foundation Fieldbus.2. Can couple with Foundation Fieldbus.3. Can provide valve diagnostics.3. Can provide valve diagnostics.4. Helps in Asset Management.4. Helps in Asset Management.5. Provide lock, soft alarms and data logging facilities.5. Provide lock, soft alarms and data logging facilities.6. Can achieve split action, remote calibration etc.6. Can achieve split action, remote calibration etc.
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Trouble Shooting in Control Valves.
TR O U B L E S H O O TIN G
To C h eckG la n d P ack in g
In c reas eA c tu a tor
C h ec k V lvG u id in g
H ig h S tem F ric tion
H U N TIN G(A t an y vlv op en in g )
R ed u ce d P
U s e S m allerC v va lve
O vers iz in g
C h an g eF low d ir.
F low to C loseflow d irec tion
H U N TIN G(N e ar to vlv c los e p os n )
IN S TA B IL ITY C Y C L IC M O TIO N
P o orP ip in g
In c reseS u p p ort
O th ersou rce
F in d
P lu g g u id ewe ar & tea r
R ep lac ew ith n ew
A t an y vlvop e n in g
In c reas ep ip e s u p p ort
Th ro tle p u m pd isch arg e
va lve
R es on an c e o fV ib ra t ion
C h an g ep lu g
p rofile
C h an g eC v va lu e
R es on an c eN o ise
of vlv p lu g
A t s p ec ificvlv op en in g
V IB R A TIO N (N O IS E ) D U L L R E S P O N S E N O T W O R K IN G
A C TIO N L E A K A G E O TH E R S
M A L FU N C TIO N
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Trouble Shooting in Control Valves.
Trou b le S h oot in g
C Y C L IC M O TIO N
D issem b le &C lean
E n larg eg u id e rin g
b leed er h o le
P rovid eflash in g p o rt
U se jac k etedvlv b od y
U s e ro taryor an g le typ e
va lve
S lu rry/s lu d g ein vlv g u id e
A c tu ato rp is ton rin gwea r & tea r
C h an g eP is ton rin g
G lan d p kgh ard en ed
C h an g eg lan d p kg
Trave l N otsm ooth
(In b o th d ir)
C h an g ed iap h .
L ea k inA c tu ato r
d iap h .
C h an g estem se a l
U se d u s ts ea l b e llow
L eak fromA c t. s tem
s eal
Trave l N otsm oo th
(In on e d ir)
D U L L R E S P O N S E N O T W O R K IN G
A C TIO N L E A K A G E O TH E R S
M A L F U N C TIO N
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Trou b le S h o o tin g
C Y C L IC M O TIO N D U L L R E S P O N S E
Trou b le ina ir so u rce
Trou b le ine lec tr ic so u rce
L ea ka g e fromtu b in g
C h e ck co m p .e lec sou rc e &
M a in a ir tu b in g
N o s ig n a l &su p p ly p r.
Trou b le inco n tro lle r
C h e ckC o n tro lle r
C on tro l s igle ak ag e
C h e cka ir tu b in g
A c t d iap hair le ak
C h an g e p a rts
P o s it io n era ir le ak
C h an g e b e llo wor d iap h
N o s ig n a l p r.su p p r. a vl
A F Rco n ta m in a tio n
C leanF ilte r
P n tu b in gL eaka g e
C h eck Tu b in g(m a in ly a ir
co n n .)
Trou b le w ithA F R
C h eckA F R
N o su p . p r.S ig n a l p r. avl
T rou b le inp osn p ilo t
re la y
C h e ck
A c t d iap hair lea k
C h an g ep arts
P o sn O /P N il
S te m /g u id eg allin g / jam m in g
D isassem b le& c h eck
F ore ig n p art ic lein vlv p o rt
D isassem b le& c h eck
S te m B e n d C h an g ep arts
T rou b le inA c tu a tor
C h eckA c t S tro ke
A c tu a tor n o two rk in g w ith
a ir su p .
N O T W O R K IN G
A C TIO N L E A K A G E O TH E R S
M A L F U N C TIO N
Trouble Shooting in Control Valves.
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E n la rg ecom p ress or
c ap ac ity
E xc lu s ivecom p ress or
Too m u c h a irc on s u m p tionin o th e r lin e
C h eck A F R
Trou b le inA F R
D rift o fa ir s u p p r.
In s e rt vo l tan k& res tric tio n toa ir s ig n a l loop
C on tro l loopR es is tan c e
C h ec kC on tro lle r
Trou b le inC on tro lle r
H u n tin g o fS ig a ir p r.
C h eck p os np arts fric t io n
C h eck p os np ilo t re lay
P os it ion erloop h u n t in g
D ec rea se d P
H ig h er s iz eA c tu a to r
S h ift in p lu greac tion fo rc e
H u n tin g o fV lv s tem
C Y C L IC M O TIO N
A C TIO N L E A K A G E O TH E R S
M A L F U N C TIO N
Trouble Shooting in Control Valves.
60
R e m ac h in e & L apsea t s u rfac e
C h an g es ea t & p lu g
C o rro s io n & e ros iono f v lv s e at in g
s u rfa c e
C h an g e s ea t& se a t g as k e t
C h ec ks ea t d es ig n
C o rro s io n & e ro sio nof s e at rin g th rea d
or g a sk e t
Ta c k w eldd e fec t a rea
C h an g e vlvb o d y
L e akag eth ro ' in n e r
vlv b od y w all
V alve C los ed
R ed u ce d P
In c rea seA c tu a to r s iz e
To o h ig h d P
C h ec k fo rF oreig n p arts
R em a c h in eg a llin g p o rtion
G a llin g o ng u id e o r p ort
V a lve n o tab le to c los e
S e a t L e a k
Tig h tenp k g . n u t
In s u ffic ien tp k g n u t t ig h t
P ro vid elu b or c h g p k g .
P k g L u bm is s in g
C h an g ep k g
W ea r & tea rof p kg
C h an g e p a rtso r rem a c h in e
U se d u s t s ea lb e llo w s
D am a g e o f s te msu rfac e
E xam in e p a rt M O CC h an g e g as ke t
C o rros io n /e ros io nof s eat g as k et
su rfac e
G lan d L eak
L E A K A G E
C h an g e s ea t rin gor p lu g
C o rros io n / eros iono f p lu g o r S . rin g
R an g eab ility n arro w edb ecau s e o f
c o n tro l p os itionc h a n g ed
O TH E R S
M A L F U N C TIO N
Trouble Shooting in Control Valves.
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