MIL-Power Plant Handbook

MAJOR SYSTEMS

VALVE SELECTION

MATERIAL SELECTION

INSTALLATION & MAINTENANCE

VALVES FOR POWER PLANTS

MIL Controls Limited

A KSB Company

ABOUT THIS HANDBOOK

For the past 20 years, MIL Controls Limited has been one of the premier suppliers of

high speciality Control valves for the Indian Power Plant sector. Over these years our

engineers have gained enormous experience in all aspects of valve design, selection

and maintenance.

The MIL Power Plant Application Handbook tries to translate this experience into a

readily accessible reference tool, the need for which has long been expressed by many

of our clients and associates. The handbook thus encapsulates MIL’s continuing focus on

the power sector.

At a second level, The MIL Power Plant Application Handbook, also serves as a mini

catalogue for MIL’s wide range of products. It offers specific data on Valve Selection and

Operational Characteristics.

© MIL CONTROLS LIMITED, 2007. All rights reserved

MIL Controls Limited. The factory premises at Meladoor near Cochin in Kerala

REFERENCE DOCUMENT: ISA HANDBOOK FOR CONTROL VALVES.

Registered Office & Works.Meladoor , Mala, PIN 680 741, Thrissur District, Kerala, India

Tel: 91 (0)480 2890272, 2890772, 2891773. Fax: 91 (0)480 2890952. Email: [email protected]

Marketing Head Office. N.H. 47, Thaikkattukara P.O., Aluva, PIN 683 106, Ernakulam Dist, Kerala, India

Tel: 91 (0)484-2624955, 2624876. Fax: 91 (0)484-2623331. Email: [email protected]


A KSB Company

A P P L I C A T I O N H A N D B O O K

C O N T R O L V A L V E S F O R P O W E R P L A N T S



1.1 Company overview .................................................. 8

2.0 Introduction ............................................................. 9

3.1 Major systems ........................................................ 13

3.2 Condensate system ................................................ 14

3.3 Feed Water system ................................................. 17

3.4 Main Steam system ................................................ 22

3.5 Heater Drain system ................................................ 31

4.1 Typical applications. 67.5 MW ................................. 35

4.2 Typical applications. 116 MW .................................. 36



4.5 Typical applications.500 MW ................................... 42

5.1 Body material specs ................................................. 47

5.2 Allowable working pressure ..................................... 48

5.3 Trim material selection ............................................ 51

6.1 Handling & Installation ............................................ 55

7.1 Preventive Maintenance ......................................... 61

7.2 Shop Overhaul ....................................................... 62

8.1 MIL 21000 Series .................................................... 67

8.2 MIL 41000 Series .................................................... 68

8.3 MIL 78000 Series .................................................... 69

8.4 MIL 91000 Series .................................................... 70

8.5 Actuators ............................................................... 71

8.6 Accessories ............................................................ 72

9.0 Index & List of Illustrations ........................................ 74

Contents Page

1.0 Contents

7



1.1

Com

pany

ove

rvie

w

MIL Controls Limited. The Assembling Shop, a part of the world class manufacturingfacility at Meladoor near Cochin in Kerala.



Ever since its inception in 1983, MIL has been unrivalled as a supplier ofhigh performance Control Valves to the Indian power sector.

The company, which stamped its class in it’s very first set of major project supplies tothe 210 MW Neyveli TPS (Unit III&IV), the 210 MW MSEB Chandrapur TPS (Stage II),the 210 MW GEB Wanakbori TPS (Stage II) and the 120 MW NALCO CPP (all 5units) way back in 1984-85, has gone on to excel in the design and manufactureof custom-built special application Control Valves to meet the challenging processcontrol requirements in thermal power stations.

In May 2000, MIL achieved another milestone when it unveiled the MATRIXSeries extreme pressure, multi stage, multi path axial flow Control Valves. A productof months of specialised R&D, the MATRIX Series valves have been designed tokill upto 420 Kg/cm2 pressure in 40 stages. This ingenious and unique designhas a progressively declining resistance flow path and is designed to eliminateCavitation and limit Velocity in any severe service condition.

In December 2001, MIL had it’s crown of glory when it became the first Indiancompany to be accredited with the coveted CE marking (refer page 73) for ControlValves, mandatory for exports to the European Union. During 2003-2006, the majorprojects executed by MIL in the Energy Sector includes NPCIL Tarapur 2x540 MW(Unit 3 & 4 ), NPCIL Kaiga/RAPP 2x 210 MW (Kaiga 3&4, RAPP 5&6), NTPC Rihand2x500 MW (Units 3 & 4), NTPC Kahalgaon 3 x500 MW(Units 5,6&7), MPPGCLBirsinghpur 1 x500MW(Unit 5), NTPC Unchahar 1x210MW (Stage-III) etc.

Today MIL is the preferred vendor in the country for the rugged, criticalapplication Control Valves for thermal power stations, be it a 33 MW captivepower plant or a 250/500 MW utility power plant.

With a comprehensive product range, world-class manufacturing and testingfacilities, and a highly skilled work force, we are today fully geared to meet anycritical process control requirements in the power plant sector.

8


2.0 Introduction

Extraordinary demands are placed on Control Valves

used in the Energy Sector. Their operational parameters

vary widely in terms of pressure, pressure drops, flow

rates and temperature.

In addition, other crucial factors like Noise, Cavitation,

Wire drawing, Leakage Class and Flashing also play an

important part in the selection of Control Valves for

power station applications.

POWER PLANT APPLICATIONS

Factors determiningselection of Valves.

1. HIGH TEMPERATURE

2. HIGH PRESSURE

3. HIGH PRESSURE DROP

4. COMBINED HIGH TEMPERATURE, PRESSURE & PRESSURE DROP

5. CONTINUOUS THROTTLING

6. TIGHT SHUT OFF CAPABILITIES

7. AERODYNAMIC NOISE

8. HIGH RANGEABILITY

9. CAVITATION AND FLASHING


9

FIG

. 1

. G

EN

ER

AL

B

OIL

ER

(D

RU

M S

TY

LE

) F

LO

W D

IAG

RA

M

10

Thermal Power plant applications4 major systems, their characteristicsand valves used in such applications.

3.1 Major system

s

1. CONDENSATE SYSTEMCondensate Pump Minimum Recirculation Valve

Deaerator Level Control Valve

2. FEED WATER SYSTEMBoiler Feed Pump Minimum Recirculation Valve.

Boiler Feed Water Startup Valve.

Boiler Main Feed Water Control Valve.

3. MAIN STEAM SYSTEMSuperheater Attemperator Spray Valve

Reheater Attemperator Spray Valve.

Turbine Bypass Valves.

Deaerator Pegging Steam Valves.

Soot Blower Steam Pressure Reducing Valves.

PRDS System valves

4. HEATER DRAIN SYSTEMHigh pressure heater drain valves.

Low pressure heater drain valves.

The 4 major systems and critical valves .

13


Fig. 2. Condensate System.

Condensate systemThe Condensate system consists ofthe Feed Water Circuit startingfrom the Condenser Hotwell to theDeaerator. The Condenser is a formof heat exchanger that condensesthe exhaust steam of the Turbine.

The exhaust steam of the Turbinewhich is very low in pressure andtemperature passes on its heat tothe cooling water, is condensedand collects in the hotwell. Thelow pressure steam which is veryhigh in volume creates a vacuumwhen it is condensed into water.The vacuum in the Condenserincreases the Thermodynamicefficiency of the cycle. The mostcritical valves which have a bearingon the smooth operation of theplant are Condensate ExtractionPump Minimum Recirculation Valveand Deaerator Level Control Valve.

Condensate Recirculation Valve

The Condensate Pump extractsthe Feed Water from theCondensate Hotwell anddischarges to the Deaerator.

The Condensate Pump musthave a minimum Recirculation orFlow to avoid overheating of thepump and protect it fromCavitation. The CondensateRecirculation Valve recirculateswater from the pump back to theCondenser to ensure minimumRecirculation of the pump. TheCondensate Recirculation Valvehas to absorb the full pressuredrop ie., from pump dischargepressure to the Condenserpressure. Due to very nearsaturated conditions existing inthe downstream side of the valveand relatively higher pressuredrops, the valve is subject toCavitation and Flashing.

Control Valves for this applicationshould also have good shut offcapability to eliminate seatdamage during shut off conditions.Any leakage should be taken intoaccount as a form of lost energy.

3.2

Con

dens

ate

syst

em

14


3.2 Condensate system

Fig. 3. MIL 78000 Series. CondensateMinimum Recirculation Valve.

T Y P I C A L P A R A M E T E R S

Inlet Pressure: 40- 45 bar( a)

Outlet Pressure: 0.1 bar(a)

Temperature: 40- 50o C

The typical valves for suchapplications have anti Cavitationfeatures which eliminate anypossibility of Cavitation bydropping pressure over stages.

Also material selection shouldbe very discrete in suchapplications taking into accountof highly Erosive Cavitatingconditions. Use of 17-4PH,CA6NM, 440C Martensitic Steelhave yielded excellent results.

Based on the application, typicalAnti-Cavitation solutions are

41002 /41008 Series MultiPath/ Multi Stage design

or 78000 Series Multi Step /Multi Stage design.

Deaerator Level Control Valve.

The apparently mild serviceconditions mislead many Control

Valve manufacturers in thedesign of valves for this service.

The function of this ControlValve is to maintain correctlevels in the Deaerator.

The Deaerator is an open contacttype Feed Water Heater whichpurges any non condensable anddissolved gases. Also theDeaerator acts as a reservoir forFeed Water to smoothen the FeedWater supply at varying loads.

The Feed Water level in theDeaerator also helps inmaintaining the Net PositiveSuction Head (NPSH) of theBoiler Feed Water Pump. TheDALCV has to cater to the widelyvarying flow demand fromstartup conditions tofull load conditions.

Valve selection and design shouldbe based on the following factors:

During the startup the pumpdischarge pressure will be highowing to low flow requirements.Deaerator pressure during thestartup of the plant will be low.

These factors result in the valveworking at very low Cvs and theassociated low lift operations.

Also the relatively higher pressuredrops in these conditons canlead to occurance of Cavitation.

When the pump picks up load,the flow rate increases and thepump discharge pressure goesdown. At the same time, theback pressure in the Deaeratorincreases. This obviouslywarrants a higher flow capacity.

15


Such extreme conditions call forvalves with exceptionally highRangeability, besides Cavitationprotection at lower flowconditions.

Typical designs for suchapplications are the MIL 41921or the MIL 41621 Series whichincorporate an equal percentagecharacterized Trim which takescare of the high Rangeability.

The basic design is a CageGuided Plug with the Cagehaving characterized ports.

Fig. 4. MIL 41000. Deaerator level Control Valve.

The Cage design combines smallsized, drilled, anti Cavitationholes in the lower portion, andlarger holes at higher lifts.

This design gives the necessaryCavitation protection at lowerlifts and higher flow capacity athigher lifts ensuring very wideRangeability.

3.2

Con

dens

ate

syst

em


Inlet Pressure: 20- 42 bar (a)

Pressure drop: 7- 42 bar (a)

Temperature: 50 -100 o C

16


Feed Water systemThe Feed Water system includesthose parts of the system fromDeaerator to the Boiler inlet.

The system consists of Feed Waterpiping, Feed Water pumps, highpressure heaters and theassociated accessories.

The Feed Water pressure is raisedto the Boiler pressure and thetemperature is also raised to nearsaturation conditions by the highpressure heaters and Economisers.

The critical Control Valveapplications in this system areBoiler Feed Pump MinimumRecirculation Valve, Boiler FeedWater Startup Valve & Boiler MainFeed Water Control Valve.

Boiler Feed Pump MinimumRecirculation Valve.

The most critical application in aPower Station is the Boiler FeedPump Minimum RecirculationService. A pump should have aminimum Flow through it totake care of the coolingrequirements of the Pump.

Hence even if the Feed Waterrequirements are very low (due tolow load conditions) the pumpshould handle a minimum flow.To ensure this minimum flow, acertain amount of Flow has tobe recirculated back to theDeaerator as the Flowrequirements of the Boiler maynot be sufficient to satisfy theminimum Recirculationrequirements of the pump.The parameters are obviouslyvery detrimental for any valve tohandle. The valve has to drop apressure of 220-250 bar to 10bar (Deaerator pressure). Also itmay be noted that the outletconditions of the valve are nearsaturation, and hence the valveis very susceptible to highenergy Cavitation and Flashing.

Fig. 5. Boiler Feed Pump Minimum Recirculation System.

3.3 Feed Water system


Inlet Pressure: 220-250 bar (a)

Outlet Pressure: 10-12 bar (a)

Temperature: 200o C

17


3 methods of providingFeed PumpRecirculation.

1. The Modulating Type Systememploys a Modulating Valvewhich throttles the Flow to theminimum required which is afunction of the Flow required bythe Boiler.

Suppose the required minimumRecirculation of the pump is 100tons/hr, and the Boilerrequirement is 90 tons/hr, theminimum Recirculation valve willopen so that it passes 10 tons/hrand the minimum Recirculationcondition is satisfied (90 tons/hrthrough the main line and 10tons/hr through the bypass line.Total flow through the pumpwill be 100 tons/hr ie., 90 + 10).

2. The On/Off System employsan On-Off valve which passes aconstant Recirculation Flow.Suppose the required minimumRecirculation of the pump is 100tons/hr, and the Boilerrequirement is 90 tons/hr, theMinimum Recirculation Valve willfully open so that it passes 100tons/hr so that the minimumRecirculation condition issatisfied. Once the Boilerrequirement goes above 100tons/hr the Recirculation Valvecloses fully since the Boilerrequirement is sufficient to satisfythe minimum Recirculationrequirements of the pump.

3. A third method employed byolder power plants, recirculatesa constant flow, regardless of theplant load. The pressure is killedby Series of multi hole plates.

Of the above methods the idealsystem would be the ModulatingSystem, since it is the most energyefficient . However it exertstaxing demands on Control Valvefunctioning.

Valve are subjected to highpressure drop throttling of verylow flows to full flow conditions.

The high pressure drop throttling atlow lift conditions adverselyaffect Trim durability due to wiredrawing effects and Trim Erosion.

Fig. 6. MIL 78000. Boiler feed pumpminimum Recirculation valve.

3.3

Feed

Wat

er sy

stem

18


Fig. 7. MIL 91000. Multi stage multi path, axial flow MATRIX Series valve for Boilerfeed pump minimum Recirculation service

In this context, the most costeffective solution is obviouslythe On-Off system.

The typical valve for suchapplication is the MIL 78000Series which incorporates aunique Multi Step, Multi Stagedesign which kills pressure overa number of stages.

The 78000 Series ensures ametal to metal Class V leakage.

Another salient feature is theunique Sliding Collar Seat Ringdesign for Class VIleakageshutoff.


MIL’s continuous research andinnovations in Power Plantapplication valves has bornefruit in the successfuldevelopment of the Axial Flow,Multi Stage, Variable Resistancedesign, the MATRIX Series Valvewhich is suitable for aModulating System.

The prototype was developedfor a Pump Recirculationapplication with pressure dropsof 420 bar. The salient feature ofthis design is the wide scope forcustomizing the valve to suitspecific process applications.

19


The Trim can be customized tovarious high pressure dropapplications by varying thenumber of stages.

The characteristic can becustomized by reallocating thepressure drop ratio in differentstages. The expanding flowpassages also enhance theRangeability allowing smoothand precise Flow Control even atlow lift operating flow conditions.

Feed Water Regulator Valve

Another critical application in theFeed Water System is the BoilerFeed Water Regulating Valvewhich controls flow to the Boilerfor varying loads of the system.

The valve takes the signal fromthe Feed Water Control whichemploys a three-elementcontrol. The signal is generatedas a function of Drum level,Steam flow and Feed Water flow.

Two kinds of valves are used forFeed Water regulation.

One valve is employed duringthe low load conditions or thestartup conditions of the Boiler.

Another valve is used during fullload conditions. Apparently theapplications may seem similar.

However the selectionphilosophy and design areentirely different for the twovalves. This is because of thedifferent pressure dropconditions existing at the time ofStartup and Full Load.

The typical parameters of LowLoad Feed Water Control Valveand Full Load Feed WaterControl Valve are given below.

Fig. 8. Feed Water Regulating System.

3.3

Feed

Wat

er sy

stem

LOW LOAD FEED WATER VALVE


Inlet Pressure: 170-200 bar (a)


Temperature: 230o C

FULL LOAD FEED WATER VALVE


Inlet Pressure : 220-250 bar (a)

Outlet Pressure: 210- 230 bar (a)

Temperature: 247o C

20


Fig. 9. MIL 41008. Multi stage, Low Load, Feed Water regulating valve.

The typical design for low load and full load applications is theMIL 41000 Series Valves which employ Heavy Duty Cage Guidedfeatures.

The Cage Guided design ensures good Throttling Stability andgood Rangeability to cater to widely varying flow conditions.

Where the pressure drop during start-up condition is very high,which can be detrimental in conventional valves, 41008 Series MultiCage design finds its typical application for the low load valve.

This design which features a Multi Stage Pressure Drop Trim, willtake care of the very high pressure drops encountered during start-up conditions where the drum pressure is very low and the pumpdischarge pressure is very high.


21


Fig. 10. Critical Control Valves in Main Steam Line

Boiler manufacturers employvarious methods like burner tiltmechanism, spray watersystems etc. to control thetemperature of the Main Steam .A poor temperature controlsystem may result in damages toTurbine blades, Superheatertubes, Reheater tubes etc.

Hence Attemperator valves areof critical relevance

The typical problems faced bysuper heater spray ControlValves are throttling instabilityand wide Rangeability.

The design parameters of thespray system include thoseconditions which account forthe excessive heating of theTurbine at full load, with theFeed Water at its maximumtemperature, clean Boiler tubesand most favourable conditions.

Main Steam SystemThe Main Steam System consistsof the steam circuit from the Boileroutlet, Superheater System, SootBlowing system, Turbines,Reheater System to Condenser.The steam fully extracted of theenergy is finally dumped into theCondenser, which is the heat sink.

The most critical application valvesin this system are: SuperheaterSpray Control Valves, SuperheaterSpray Block Valves, Reheater SprayControl Valves, Reheater SprayBlock Valves, Soot Blower PressureControl Valves, PRDS SystemControl Valves, Main SteamPressure Reducing Valves, PRDSSpray Control Valves and DeaeratorPegging Steam Valve.

Super Heater Attemperator Valve

The temperature of the mainsteam coming out of the Boiler isvery critical from the point ofThermodynamic Efficiency ofthe heat cycle and the Turbineblade protection.

3.4

Mai

n st

eam

syst

em

22


Fig. 12. MIL 41200. Superheater Attemperator valve.

Fig. 11. MIL 41100. Superheater Attemperator valve.

3.4 Main steam

system

23


Fig. 13. MIL 41400. SuperheaterAttemperator block valve.

However the above conditionsseldom come into play due todeterioration of Boiler tubes dueto Scale build up and theconsequent heat transfer loss.

Also the situation is furthercompounded by withdrawal ofheat through the Soot Blower.All these factors result in a drasticreduction of spray waterrequirements.

Hence in practice the SprayWater Valve will be seldom takeninto full capacity. The valve will beworking at lower lift conditionsdue to above said reasons.

Another critical factor influencingthe selection of Control Valve isthe Leakage Class.

Any excessive leakage will resultin thermal shocks in SecondarySuperheater Tubes and erosionof Turbine blades.

MIL offers special designs likethe 41100 Series and the 41200Series for such applications.

The 41100 Series features anunbalanced Cage Guided design.This combines the twin benefitsof the good throttling stability ofCage Guided valves with the shutoff capability of single seatedunbalanced designs.

For higher sizes (2” and above)the Actuator thrust requirementswill be very high due to theunbalanced design of the 41100Series design.

The 41200 features a balanceddesign with a novel Static Sealconcept. The 41200 design hasthe same advantages that the41100 Series besides the addedfeature of a balanced plug.

Another application of SpraySystem is the block valve.

The block valves assists the sprayControl Valves effect ing a tightshut off. Another requirement of ablock valve is faster response.Hence the Spray System employs apneumatically operated On OffControl Valve for this application.

The typical MIL designs for blockvalve applications are the 41400Series and the 41200 Series. The41400 design is a Cage Guideddesign where the main plug isassisted by an auxiliary pilotplug to effect tight shut off.

3.4

Mai

n st

eam

syst

em


Inlet Pressure:181-200 bar (a)


Temperature: 247o C

24


Reheater Attemperator Valves

This application is also similar tothe Superheater Spray ControlValve application.

However fluctuations intemperature is not varying as inSuperheater Spray Control.

The Leakage Class is very criticalsince excessive leakage can leadto Erosion of low pressureTurbine blades.

The valve selection depends onthe pressure drop across thevalve. It may be noted here thatreheater pressure is the outletpressure of the high pressureTurbine. The pressure dropacross the valve depends on thesource of the spray water.

Fig. 15. MIL 78000. ReheaterAttemperator Control Valve.

3.4 Main steam

system

The source of the Spray Watercan either be the Feed Waterpump outlet or the inter stagetapping of the pump.

In case of the former, thepressure drop can be as high as100-120 bar, and latter, it can beupto 60-70 bar.

The MIL solution to suchapplications are the 78000Series or the 41008 Series forhigh pressure drops (100-120bar). In the case of moderatepressure drops, it is the 41121Series or the 41221 Series.

The Reheater Spray Block Valveapplication is similar toSuperheater Spray Blockapplications, and the selectionphilosophy is similar to that forSuperheater Spray Block service.

Fig. 14. MIL 41008. ReheaterAttemperator Control Valve.


25

Deaerator Pegging Steam Valve

The Deaerator is a direct contacttype heater which removes noncondensable gases like Oxygenand Carbon dioxide from theFeed Water. These gases, if notexpelled, will attack and corrodepiping and Boiler tubes. The hotsteam is mixed with the FeedWater entering the Deaeratorbringing it to saturationtemperature and therebyliberating any undissolved ornon condensable gases.

Steam is supplied to theDeaerator for deaeration ofFeed Water and also to maintaina positive pressure in theDeaearator. Deaerator acts as aFeed Water storage tank to theBoiler Feed Pump. Maintaining ahigher pressure in the Deaeratorhelps in maintaining the NPSHof the pump.

Normally the steam is takenfrom the Auxiliary Steam Headerupto 15% MCR condition.Above this and upto 40% MCR,the steam is taken from the ColdReheat Header (Steam tappedafter the High Pressure Turbine).In full load conditions, steam istaken directly from the Turbineextraction line.Typical valves in this system are:

Fig. 16. Deaerator Pegging Steam System.

3.4

Mai

n st

eam

syst

em

1. DEAERATOR PEGGING FROMAUXILLIARY STEAM HEADER


Inlet Pressure: 16 bar (a)

Outlet Pressure: 3.5 bar (a)

Temperature: 220o C

2. DEAERATOR PEGGING FROMCOLD REHEAT STEAM HEADER


Inlet Pressure: 21 bar (a)

Outlet Pressure: 3.6 bar (a)

Temperature: 330o C

26


Fig. 17. MIL 41003. Deaerator peggingsteam Control Valve

The problems encountered invalve selection for suchapplications are the high noiselevels associated with this valve.MIL offers special low noise Trims(Lo-dB Design) for suchapplications. The 41000 SeriesCage Guided valves with specialLow Noise Trim have been foundexcellent for such services.Additional noise attenuation canbe achieved with double stagepressure drop designs such asdouble Cage or diffuser optionsin the 41000 Series.

Another problem associated withthis service is high exit velocitiesdue to volumetric expansion ofthe steam when the pressuredrops. MIL offers special lownoise cartridges which dividethe pressure drop between thevalve and the cartridges.

The effective pressure drop ratioacross the valve is reduced whichresults in low exit velocities andnoise levels.

3.4 Main steam

system

Soot Blower Valve

The effectiveness of the heattransfer through Boiler tubes isadversely affected by the build upof soot. Also the rapid build up ofsoot in the tubes can lead to thedevelopment of hot spots in theBoiler tubes. The Boiler tubesshould be frequently cleaned toremove the soot. The normalpractice is to use high velocitysteam jets to blow the soot fromthe tubes. The soot removal iseffected through Soot Blowers.Some Soot Blowers use air alsofor the removal of soot.

One of the major challenges here isto select and design a ControlValve for the Steam Soot Blowers.

The problems unique to thisservice are High pressure drop,High noise levels and Thermalcycling of the valve body andvalve internals.

Soot blowing valves are normallyisolated by an upstreamisolation valve. Hence the valveis not subjected to high pressureand temperature when not inservice. However when the SootBlowing is being done, the valveis subjected to very highpressures and temperatures.


Inlet Pressure - 170 bar (a)

Outlet Pressure - 20 bar (a)

Temperature - 540o C


27

Fig. 18. MIL 71114. Soot blower pressure reducing Control Valve

Hence the valve is subjected tothermal cycling which can causeWarpage and Creep in theconventional cast globe valvebodies.

The obvious solution would beto use forged angle bodies orforged inline bodies with specialmulti stage low noise Trims.

Here MIL offers it’s 41114 Series(Cage Guided inline body withdouble stage pressure drop), orit’s 71114 Series (Cage Guidedangle body with double stagepressure drop). The body shallbe forged design and chromemolybdenum steel (ASTM A 182Gr. F22)

3.4

Mai

n st

eam

syst

em

28


PRDS Station Valves.

Apart from steam being used forpower generation and sootblowing, steam is used for otherauxiliary services like glandsealing of Turbines, SteamEjectors in Condensers andDeaerator pegging.

The main steam has to beDesuperheated by reducing itspressure and temperature toutilise the steam for the abovementioned applications.

Fig. 19. Typical Auxiliary PRDS System

The steam Desuperheating iseffected through PRDS stations– Pressure ReducingDesuperheating System.

The PRDS system consists of aDesuperheater pressurereducing valve and atemperature Control Valve. Thepressure reducing valve reducesthe pressure of the steam beforeentry into the Desuperheater.

The temperature Control Valveregulates the spray waterquantity into the Desuperheater.

3.4 Main steam

system

MAIN STEAM PRESSUREREDUCING VALVE





TEMPERATURE CONTROL VALVE(SPRAY WATER)






29

The critical factors that governselection of Main Steam PRV are:High pressure drop, Hightemperature, High noise levelsand Material selection for hightemperature.

MIL offers the 41912 Series or the41914 Series for this application.This design features a CageGuided Trim with special LowNoise multiple holes controllingthe flow. Optional double stagedesign is also available which isvery effective in noise attenuationat higher pressure drop ratios.

For Class V leakage, the 41413Series is the appropriateselection. The 41413 Seriesdesign is a Cage Guided designwhere the main plug is assistedby an auxiliary pilot plug toeffect the tight shut off.

The Cage design includesmultiple holes to attenuate thenoise. The flow direction of thevalve is Over the Plug.

A seat ring - basket diffuser isprovided for effective noiseattenuation at higher pressuredrop ratios.

The temperature Control Valve isanother critical valve coming inthe system. As in the case ofReheater Spray Control Valve,the selection of this valve is alsogoverned by the source of theSpray Water. The source of theSpray Water can either be fromFeed Water Pump outlet or interstage tapping of the pump.

In the case of the former, thepressure drop can be as high as100-120 bar, and in the lattercase, it can be upto 60-70 bar.

The MIL solution to suchapplications are the 78000 Seriesor the 41128 Series for highpressure drops (100-120 bar).

In the case of moderate pressuredrops the design shall be the41121 Series or the 41221 Series.

Fig. 20. MIL 41914 Main Steam Pressure Reducing Valve.

3.4

Mai

n st

eam

syst

em

30


The Heater Drain SystemThe heater drain system consists ofthe Feed Water heaters coming inthe Condensate system and FeedWater system. The Feed Waterheaters coming in the Condensatesystem are called low pressureheaters which heats the Condensateto saturation point before entry intoDeaerator.

The heaters coming in the FeedWater system are the High pressureheaters which heat the Feed Waterto near saturation point before theentry into Boiler.

The HP heaters and LP heaters arebasically heat exchangers – shell andtubetype. The heating media for HPheaters is the steam extracted fromthe reheat cycle, whereas for LPheaters the steam is extracted fromthe low pressure Turbine.

The heating media, i.e., the steam isintroduced into the heaters, cooledand ultimately condensed back toliquid. The level in the heaters are tobe closely controlled to maintain theThermodynamic efficiency of thesystem. The Condensate in theheaters are at saturation condition,and when the Condensate isdrained to either Deaerator or theCondensate flash tank, the fluidlosses pressure and flashes.

The critical factors that influencethe selection of the valves are:Body and Trim material, Valvesize and Valve flow capacity

Flashing problems encounteredin these services cause materialerosion.

The liquid droplets acceleratedby relatively high velocityvapour phase, impinges on thematerial surface of body andTrim causing heavy wear.

Generally Chrome Molybdenumsteels have exhibited excellentresistance to Flashing Erosion.

Even though ASTM A 217 Gr C5is recommended by some users,it is being increasingly replacedby ASTM A 217 Gr WC9material as C5 has somesignificant manufacturingproblems, in addition to poorweldability, and is thus difficultto weld repair.

Another issue is the selection ofvalve body size. It is alwaysrecommended to select higherbody sizes with a reducedcapacity Trim.

The body size selection criteria isthe outlet Flashing velocity.

MIL offers it’s 21000 Series andthe 4100 Series Valves for theseapplications. The body materialis either WC6 or WC9.

Fig. 21. MIL 21000. Heater Drain Valve

3.5 Heater drain system


31

Fig. 23. HP Heaters System

Fig. 22. LP Heaters System

3.5

Hea

ter d

rain

syst

em

32


Typical InstallationsChoosing the right valve makes all the difference

FE

ED

WA

TE

R C

ON

TR

OL V

ALV

ES

Pro

ject

: TIS

CO

1X

67

.5M

WC

ust

om

er: B

HEL

Mad

ras

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

1FW

-5LO

W L

OA

D F

EED

WA

TER

FLO

W C

ON

TR

OL

38-7

8101

3 in

.15

00F1

115

17

0 k

g/c

m2

2350

C1

2FW

-2FU

LL L

OA

D F

EED

WA

TER

FLO

W C

ON

TRO

L38

-419

216

x3 in

.15

00W

C6

140

17

0 k

g/c

m2

2350

C1

3FW

-8FU

LL L

OA

D F

EED

WA

TER

FLO

W C

ON

TR

OL

(BY-

PASS

)90

-419

216

x3 in

.15

00W

C6

140

17

0 k

g/c

m2

2350

C1 4.1 Typical applications. 67.5 M

W

1A

S-9

HIG

H C

APA

CIT

Y S

TEA

M P

RES

SUR

E R

EDU

CIN

G38

-419

126

x3 in

.15

00W

C9

120

100

kg/c

m2

5200

C1

2A

S-3

LOW

CA

PAC

ITY

STE

AM

PR

ESSU

RE

RED

UC

ING

38-4

1412

2 in

.15

00W

C9

121

00

kg

/cm

252

00C

1

3BV

-01

CO

MM

ON

BLO

CK

VA

LVE

FOR

PR

DS

SPR

AY

37-2

11X

42

in.

1500

WC

C15

18

5 k

g/c

m2

1750

C1

4SW

-10

HIG

H C

APA

CIT

Y S

PRA

Y W

ATE

R C

ON

TRO

L V

ALV

E38

-781

011

.5 in

.15

00A

105

1.2

18

5 k

g/c

m2

1500

C1

5SW

-4LO

W C

APA

CIT

Y S

PRA

Y W

ATE

R C

ON

TRO

L V

ALV

E38

-781

011

in.

1500

A10

50

.318

5 kg

/cm

215

00C

1

PR

DS V

ALV

ES

Pro

ject

: T

ISC

O 1

X6

7.5

MW

Cu

sto

mer

:BH

EL M

adra

s

* A

NSI

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

SP

RA

Y &

SO

OT

BLO

WE

R V

ALV

ES

Pro

ject

: T

ISC

O 1

X6

7.5

MW

Cu

sto

mer

: BH

EL T

rich

y

1SD

-5.S

D-6

SH S

PRA

Y C

ON

TRO

L38

-410

242

in.

1500

WC

C8

18

5 k

g/c

m2

2500

C4

2SD

-23

SH S

PRA

Y B

LOC

K38

-414

X1

2 in

.15

00W

CC

401

85

kg

/cm

225

00C

2

3SD

-7IN

TER

MIT

TEN

T BL

OW

DO

WN

VA

LVE

38-7

8001

2 in

.15

00A

105

41

10

kg

/cm

235

00C

2

4S5

7. S

69

SH S

PRA

Y B

YPA

SS V

ALV

ES90

-410

242

.5 in

.15

00W

CC

2018

6 kg

/cm

224

20C

4

5SB

4SO

OT

BLO

WER

STE

AM

PR

.RED

UC

ING

VA

LVE

38-7

0571

2 in

.25

00F1

16

17

3 k

g/c

m2

4130

C2

6SD

-8SO

OT

BLO

WER

STE

AM

PR

.RED

UC

ING

VA

LVE

38-7

0571

2 in

.25

00F2

210

110

kg/c

m2

4200

C4

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

Cap

acity

67.5

MW


35

36


FEED

CO

NTR

OL V

ALV

ES

Pro

ject

: Ah

emed

abad

Ele

ctri

city

Co

mp

any.

Cu

sto

mer

: BH

EL B

ang

alo

re

1C

V-5

.6FE

ED R

EGU

LATI

NG

VA

LVE

IN H

P BF

P D

ISC

H.L

INE

38-4

1621

2 in

.30

0W

CC

261

5 k

g/c

m2

121

0C

2

2C

V-7

.8FE

ED R

EGU

LATI

NG

VA

LVE

IN H

P BF

P D

ISC

H.L

INE

(FU

LL L

OA

D)

37-4

1612

3 in

.90

0W

C6

9511

5 kg

/cm

212

1oC

2

3C

V-9

.10

FEED

REG

ULA

TIN

G V

ALV

E IN

HP

BFP

DIS

CH

.LIN

E (L

OW

LO

AD

)38

-780

012

in.

900

A10

54

115

kg/c

m2

120

oC

2

* A

NSI

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

SP

RA

Y V

ALV

ES

Pro

ject

: A

hem

edab

ad E

lect

rici

ty C

om

pan

y.C

ust

om

er:B

HEL

Ban

gal

ore

1C

V-1

1.12

HP

STEA

M B

YPA

SS V

ALV

ES38

-414

126

in.

1500

WC

614

57

0 k

g/c

m2

480o

C2

2C

V-1

3.14

HP

BYPA

SS S

PRA

Y V

ALV

ES37

-211

X5

2 in

.60

0W

CC

461

3 k

g/c

m2

50oC

2

3C

V-1

5.16

LP S

TEA

M B

YPA

SS V

ALV

ES38

-414

218

in.

150

WC

C64

07

kg

/cm

214

7oC

2

4C

V-1

7.1

LP B

YPA

SS S

PRA

Y V

ALV

ES38

-211

X5

1 in

.60

0W

CC

3.8

13

kg

/cm

250

oC

2

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

1C

V-2

3PR

DS

PR. R

EDU

CIN

G V

ALV

E IN

HP

STEA

M L

INE

TO A

UX

.HD

R.

38-4

1412

2 in

.15

00W

C6

307

0 k

g/c

m2

480o

C1

2C

V-2

4PR

DS

SPR

AY

CO

NTR

OL

VA

LVE

38-7

8003

1 in

.90

0A

105

0.3

11

9 k

g/c

m2

121o

C1

PR

DS V

ALV

ES

Pro

ject

: A

hem

edab

ad E

lect

rici

ty C

om

pan

y.C

ust

om

er:B

HEL

Ban

gal

ore

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

4.2

Typi

cal a

pplic

atio

ns. 1

16 M

WC

apac

ity 1

16 M

W


37

FE

ED

PU

MP

RE

CIR

CU

LA

TIO

N V

ALV

ES

Pro

ject

: Ah

emed

abad

Ele

ctri

city

Co

mp

any.

Cu

sto

mer

: BH

EL B

ang

alo

re

1C

V-2

5.26

.27

REC

IRC

ULA

TIO

N V

ALV

E FO

R H

P BF

P37

-780

031

.5 in

.90

0A

105

4.5

11

5 k

g/c

m2

122o

C3

2C

V-2

8.29

.30

REC

IRC

ULA

TIO

N V

ALV

E FO

R L

P BF

P37

-211

X5

1in

.60

0W

CC

3.8

18

kg

/cm

212

2oC

3

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

* A

NSI

HE

ATE

R D

RA

IN V

ALV

ES &

CO

ND

EN

SA

TE

SYSTE

M V

ALV

ES

Pro

ject

: A

hem

edab

ad E

lect

rici

ty C

om

pan

y.C

ust

om

er:B

HEL

Ban

gal

ore

1C

V-1

MA

IN C

ON

DEN

SATE

CO

NTR

OL

VA

LVE

38-4

1621

6 in

.30

0W

CC

360

13

kg

/cm

248

oC

1

2C

V-2

MIN

. FLO

W R

ECIR

CU

LATI

ON

CO

NTR

OL

VA

LVE

37-4

1612

2 in

.30

0W

CC

25

13

kg

/cm

248

oC

1

3C

V-3

EXC

ESS

RET

UR

N C

ON

TRO

L V

ALV

E37

-416

212

in.

300

WC

C65

13

kg

/cm

248

oC

1

4C

V-4

DEA

ERA

TOR

OV

ERFL

OW

TO

DM

STO

RA

GE

TAN

K38

-414

X1

3 in

.15

0W

CC

155

7 k

g/c

m2

120

oC

1

5C

V-1

9PR

ESSU

RE

RED

UC

ING

VA

LVE

TO D

EAER

ATO

R38

-416

213

in.

150

WC

C95

7 k

g/c

m2

147

oC

1

6C

V-2

0PR

ESSU

RE

RED

UC

ING

VA

LVE

TO D

EAER

ATO

R38

-416

218

in.

150

WC

C50

07

kg

/cm

214

7oC

1

7C

V-2

1.22

PREH

EATE

R IN

LET

CO

NTR

OL

VA

LVE

37-4

1621

4 in

.30

0W

CC

225

13

kg

/cm

211

8oC

2

8C

V-3

1N

OR

MA

L M

AK

E-U

P V

ALV

E37

-211

251

in.

600

CF8

M6

10

kg

/cm

240

oC

1

9C

V-3

2D

UM

P M

AK

E-U

P V

ALV

E38

-211

252

in.

600

CF8

M46

10

kg

/cm

240

oC

1

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

4.2 Typical applications. 116 MW

Cap

acity

116

MW

38


FEED

CO

NTR

OL V

ALV

ES

Pro

ject

: R

aich

ur

TP

S U

nit

IVC

ust

om

er: B

HEL

Mad

ras

1FW

-FC

V-1

FULL

LO

AD

FEE

D W

ATE

R F

LOW

CO

NTR

OL

(MA

IN&

BYPA

SS)

38-4

1921

12

x8 in

.25

00W

C6

575

28

6 k

g/c

m2

250

oC

2

2FW

-FC

V-2

LOW

LO

AD

FEE

D W

AT

ER F

LOW

CO

NT

RO

L38

-414

126

x4 in

.25

00W

C6

452

85

kg

/cm

225

0oC

1

* A

NSI

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

PR

DS V

ALV

ES

Pro

ject

: R

aich

ur

TP

S. U

nit

IVC

ust

om

er:B

HEL

Mad

ras

1M

SPC

V-1

AU

X.P

RD

S 10

0%ST

EAM

PR

. CO

NTR

OL

VA

LVE

38-4

1412

6x3

in.

25

00

SPL

WC

950

16

5 k

g/c

m2

540o

C1

2M

SPC

V-2

AU

X.P

RD

S 10

%ST

EAM

PR

. CO

NTR

OL

VA

LVE

38-4

1012

2 in

.2

50

0SP

LW

C9

61

65

kg

/cm

254

0oC

1

3SP

TCV

-1A

UX

.PR

DS

100%

SPR

AY

FLO

W C

ON

TRO

L V

ALV

E38

-781

021

.5 in

.25

00A

105

2.4

28

6 k

g/c

m2

250o

C1

4SP

TCV

-2A

UX

.PR

DS

10%

SPR

AY

FLO

W C

ON

TRO

L V

ALV

E38

-781

011

in.

2500

A10

50

.32

86

kg

/cm

225

0oC

1

5V

2505

111

BLO

CK

VA

LVE

ON

SPR

AY

WA

TER

TO

AU

X. P

RD

S37

-211

X4

2 in

.25

00W

CC

152

86

kg

/cm

225

0oC

1

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

SP

RA

Y &

SO

OT

BLO

WE

R V

ALV

ES

Pro

ject

: U

nch

ahar

TP

S 2

x21

0 M

WC

ust

om

er:B

HEL

Tri

chy

1SD

-4SH

STA

GE

I BLO

CK

38-4

10X

46

x4 in

.25

00W

CC

195

26

5 k

g/c

m2

260o

C2

2SD

-5.6

.7.8

SH S

TAG

E I C

ON

TRO

L38

-410

242

.5 in

.25

00W

CC

3026

5 kg

/cm

226

0oC

8

3SD

-9SH

STA

GE

I I B

LOC

K38

-410

X4

2.5

in.

2500

WC

C60

26

5 k

g/c

m2

260o

C2

4SD

-10.

11.1

2.13

SH S

TAG

E II

CO

NTR

OL

38-4

1024

1.5

in.

2500

WC

C3

.82

65

kg

/cm

226

0oC

8

5SD

-14

RH

BLO

CK

CO

MM

ON

38-4

10X

42

.5 in

.25

00W

CC

602

65

kg

/cm

226

0oC

2

6SD

-15.

16.1

7.18

RH

BLO

CK

BR

AN

CH

38-4

10X

41

.5 in

.25

00W

CC

402

65

kg

/cm

226

0oC

8

7SD

-19.

20.2

1.22

RH

CO

NTR

OL

38-7

8103

1.5

in.

2500

A10

53

.62

65

kg

/cm

226

0oC

8

8PC

V-8

502A

.BSO

OT

BLO

WER

STE

AM

PR

.RED

UC

ING

VA

LVE

38-4

1012

2 in

.25

00F1

125

185

kg/c

m2

440o

C4

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

4.3

Typi

cal a

pplic

atio

ns. 2

10 M

WC

apac

ity 2

10M

W


39

FE

ED

PU

MP

RE

CIR

CU

LA

TIO

N V

ALV

ES

Pro

ject

: R

op

ar T

PS

Cu

sto

mer

: BH

EL H

yder

abad

1FE

ED P

UM

P M

INIM

UM

REC

IRC

ULA

TIO

N37

-781

034

x2 in

.25

00A

105

152

60

kg

/cm

225

0oC

2

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

HE

ATE

R D

RA

IN V

ALV

ES &

CO

ND

EN

SA

TE

SYSTE

M V

ALV

ES

Pro

ject

: V

ijaya

wad

a T

PS

Stag

e II

Un

it V

&V

IC

ust

om

er:B

HEL

Del

hi

1P

AS-

1PE

GG

. STE

AM

FR

OM

AU

X. S

TEA

M H

EAD

ER T

O D

EAER

ATO

R38

-419

126

in.

300

WC

C30

02

0 k

g/c

m2

230

oC

2

2PC

R-1

PEG

G. S

TEA

M F

RO

M C

RH

TO

DEA

ERA

TOR

38-4

1912

10 in

.60

0W

CC

430

48

kg

/cm

235

0oC

2

3D

R-2

HPH

-6 N

OR

MA

L D

RA

IN T

O H

PH-5

38-4

1321

3 in

.60

0W

C6

564

8 k

g/c

m2

215

oC

2

4D

R-6

HPH

-6 N

OR

MA

L D

RA

IN T

O D

EAER

ATO

R38

-413

213

in.

600

WC

656

48

kg

/cm

221

5oC

2

5D

R-9

HPH

-6 N

OR

MA

L D

RA

IN T

O F

LASH

BO

X-2

38-4

1321

3 in

.60

0W

C6

564

8 k

g/c

m2

215

oC

2

6D

R-1

2H

PH-5

NO

RM

AL

DR

AIN

TO

DEA

ERA

TOR

38-4

1321

4 in

.30

0W

C6

902

0 k

g/c

m2

180

oC

2

7D

R-1

5H

PH-5

NO

RM

AL

DR

AIN

TO

FLA

SH B

OX

-238

-413

214

in.

300

WC

690

20

kg

/cm

218

0oC

2

8D

R-1

7LP

H-3

NO

RM

AL

DR

AIN

TO

LPH

-238

-416

213

in.

300

WC

C14

08

kg

/cm

213

0oC

2

9D

R-2

0LP

H-5

NO

RM

AL

DR

AIN

TO

FLA

SH B

OX

-137

-416

214

in.

300

WC

C22

58

kg

/cm

213

0oC

10D

R-2

2LP

H-2

DR

AIN

TO

LPH

-138

-416

218

in.

300

WC

C57

58

kg

/cm

210

0oC

2

11D

R-2

5LP

H-2

DR

AIN

TO

FLA

SH B

OX

-137

-416

218

in.

300

WC

C57

58

kg

/cm

210

0oC

2

12D

R-4

1D

EAER

ATO

R O

VER

FLO

W T

O D

RA

IN T

AN

K38

-416

X1

10 in

.30

0W

CC

1000

11

kg

/cm

217

0oC

2

13C

D-1

4M

AIN

CO

ND

ENSA

TE38

-416

2110

in.

300

WC

C9

00

25

kg

/cm

255

oC

2

14C

D-2

3C

ON

DEN

SATE

EX

CES

S R

ETU

RN

38-4

1612

6x4

in.

300

WC

C14

52

5 k

g/c

m2

55oC

2

15C

D-1

9C

ON

DEN

SATE

MIN

IMU

M R

ECIR

CU

LATI

ON

37-7

8003

6 in

.30

0A

105

702

5 k

g/c

m2

55oC

2

16C

D-7

8H

P D

RA

INS

MA

NIF

OLD

SPR

AY

37-2

11X

51

in.

300

WC

C12

25

kg

/cm

255

oC

2

17D

M-1

DM

MA

KE-

UP

TO H

OTW

ELL

(LC

)37

-416

112

in.

300

CF8

M30

10

kg

/cm

250

oC

2

18D

M-2

DM

MA

KE-

UP

TO H

OTW

ELL

(HC

)37

-416

113

in.

300

CF8

M60

10

kg

/cm

250

oC

2

19C

D-4

7C

ON

DEN

SATE

FO

R V

ALV

E G

LAN

D S

EALI

NG

38-4

1621

1.5

in.

300

WC

C14

25

kg

/cm

255

oC

2

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.


Cap

acity

210

MW

40


FEED

CO

NTR

OL V

ALV

ES

Pro

ject

: C

ESC

Bu

dg

e B

ud

ge

TP

S. 2

*2

50

MW

Cu

sto

mer

: BH

EL D

elh

i

107

28.1

&2

FULL

LO

AD

FEE

D W

ATE

R F

LOW

CO

NTR

OL

(MA

IN&

BYPA

SS)

38-4

1921

14x1

0in.

2500

WC

690

033

0 kg

/cm

224

8oC

4

27

28

.3LO

W L

OA

D F

EED

WA

TER

FLO

W C

ON

TR

OL

38-4

1921

6x4

in.

2500

WC

622

53

30

kg

/cm

224

8oC

2

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

PR

DS V

ALV

ES

Pro

ject

: B

SES

DA

HA

NU

2x2

50

MW

Cu

sto

mer

:BH

EL B

ang

alo

re

1A

S-2

2M

S PR

DS

STEA

M C

ON

TRO

L38

-414

126

x4in

.2

50

0SP

LW

C9

110

16

9 k

g/c

m2

545o

C2

2FD

-22

MS

PRD

S SP

RA

Y C

ON

TRO

L38

-780

021

.5in

.2

50

0SP

LA

105

2.4

26

7 k

g/c

m2

170o

C2

3FD

-23

MS

PRD

S SP

RA

Y C

ON

TRO

L38

-410

241

.5in

.25

00W

CC

62

67

kg

/cm

217

0oC

2

4A

S-3

2C

RH

STE

AM

PR

DS

38-4

1012

2.5

in.

600

WC

C20

48

kg

/cm

236

0oC

2

5FD

-29

CR

H P

RD

S SP

RA

Y C

ON

TRO

L38

-780

011

in.

2500

A10

50

.32

67

kg

/cm

217

0oC

2

6FD

-30

CR

H P

RD

S SP

RA

Y C

ON

TRO

L38

-780

011

in.

2500

A10

50

.32

67

kg

/cm

217

0oC

2

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

SP

RA

Y &

SO

OT

BLO

WE

R V

ALV

ES

Pro

ject

: B

SES

DA

HA

NU

2x2

50

MW

Cu

sto

mer

:BH

EL T

rich

y

1SD

-4SH

SPR

AY

STA

GE

I BLO

CK

38-4

14X

16

in.

2500

WC

624

02

62

kg

/cm

226

0oC

2

2SD

-5 T

O S

D-8

SH S

TAG

E I S

PRA

Y C

ON

TRO

L38

-410

242

.5in

.25

00W

C6

301

82

kg

/cm

226

0oC

8

3SD

-9SH

STA

GE

II S

PRA

Y B

LOC

K38

-414

X1

3in

.25

00W

C6

752

62

kg

/cm

235

0oC

2

4SD

-10

TO S

D-1

3SH

STA

GE

II S

PRA

Y C

ON

TRO

L38

-410

241

.5in

.25

00W

C6

81

82

kg

/cm

235

0oC

8

5SD

-14

RH

SPR

AY

MA

IN B

LOC

K38

-414

X1

3in

.25

00W

C6

302

82

kg

/cm

235

0oC

2

6SD

-15

TO S

D-1

8R

H B

RA

NC

H B

LOC

K38

-211

X4

2in

.25

00W

C6

152

82

kg

/cm

235

0oC

8

7SD

-19

TO S

D-2

2R

H S

PRA

Y C

ON

TRO

L38

-780

032

in.

2500

F11

3.5

18

2 k

g/c

m2

350o

C8

8SD

-23

SOO

T BL

OW

ER S

TEA

M P

R.R

EDU

CIN

G V

ALV

E38

-705

712

in.

2500

F22

131

82

kg

/cm

245

0oC

2

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

4.4

Typi

cal a

pplic

atio

ns. 2

50 M

WC

apac

ity 2

50 M

W


41


FE

ED

PU

MP

RE

CIR

CU

LA

TIO

N V

ALV

ES

Pro

ject

: K

oth

ag

ud

em

TPS, 2

*250 M

W C

ust

om

er:

BH

EL

Hyd

era

bad

1FE

ED

PU

MP

MIN

IMU

M R

EC

IRC

ULA

TIO

N3

7-7

81

03

4x2

in

.2

50

0A

10

51

52

60

kg/

cm2

25

0oC

2

HE

ATE

R D

RA

IN &

CO

ND

EN

SA

TE

SYSTE

M V

ALV

ES

Pro

ject

: K

oth

ag

ud

em

TPS, 2

*250 M

WC

ust

om

er:

BH

EL D

elh

i

1A

S-2

PEG

G. S

TEA

M F

RO

M A

UX

. STE

AM

HEA

DER

TO

DEA

ERA

TOR

38-4

1912

8 in

.30

0W

CC

315

14

kg

/cm

222

0oC

2

2C

RH

-2PE

GG

. STE

AM

FR

OM

CR

H T

O D

EAER

ATO

R38

-419

1210

in

.60

0W

CC

500

48

kg

/cm

236

0oC

2

3D

R-2

HPH

-6 N

OR

MA

L D

RA

IN T

O H

PH-5

38-4

1521

3 in

.60

0W

C6

504

8 k

g/c

m2

215

oC

2

4D

R-6

HPH

-6 A

LT.

DR

AIN

TO

DEA

ERA

TOR

38-4

1921

3 in

.60

0W

C6

504

8 k

g/c

m2

215

oC

2

5D

R-9

HPH

-6 A

LT. D

RA

IN T

O H

P FL

ASH

TA

NK

37-4

1921

3 in

.60

0W

C6

564

8 k

g/c

m2

215

oC

2

6D

R-1

3H

PH-5

NO

RM

AL

DR

AIN

TO

DEA

ERA

TOR

38-4

1521

4 in

.30

0W

C6

120

20

kg

/cm

217

5oC

2

7D

R-1

6H

PH-5

ALT

. DR

AIN

TO

HP

FLA

SH T

AN

K37

-419

214

in.

300

WC

612

02

0 k

g/c

m2

175

oC

2

8D

R-1

9LP

H-3

NO

RM

AL

DR

AIN

TO

LPH

-238

-415

214

in.

150

WC

C17

08

kg

/cm

213

0oC

2

9D

R-2

2LP

H-3

ALT

. DR

AIN

TO

LP

FLA

SH T

AN

K37

-416

214

in.

150

WC

C17

08

kg

/cm

213

0oC

2

10D

R-2

5LP

H-2

NO

RM

AL

DR

AIN

TO

LPH

-138

-415

218

in.

150

WC

C57

58

kg

/cm

210

5oC

2

11D

R-2

8LP

H-2

ALT

. DR

AIN

TO

LP

FLA

SH T

AN

K37

-416

218

in.

150

WC

C57

58

kg

/cm

210

5oC

2

12D

R-3

8D

EAER

ATO

R O

VER

FLO

W T

O L

P FL

ASH

TA

NK

38-4

19X

13

in.

300

WC

C10

01

1 k

g/c

m2

170

oC

2

13C

D-1

4&C

D-1

7M

AIN

CO

ND

ENSA

TE C

ON

TRO

L38

-415

2112

in

.30

0W

CC

900

27

kg

/cm

255

oC

4

14C

D-2

5C

ON

DEN

SATE

EX

CES

S PU

MP

MIN

. REC

IRC

ULA

TIO

N37

-780

033

in.

600

A10

545

27

kg

/cm

255

oC

2

15C

D-2

1EX

CES

S C

ON

DEN

SATE

DU

MP

CO

NTR

OL

38-4

1612

6x3

in

.30

0W

CC

952

7 k

g/c

m2

55oC

2

16C

D-5

3H

P D

RA

INS

FLA

SH T

AN

K S

PRA

Y37

-211

X5

1 in

.30

0W

CC

1,7

30

kg

/cm

255

oC

2

17C

D-5

8EM

ERG

ENC

Y M

AK

E-U

P TO

CO

ND

ENSA

TE H

OTW

ELL

37-4

1612

3 in

.15

0W

CC

958

kg

/cm

255

oC

2

18D

M-2

(LO

W)

DM

MA

KE-

UP

TO H

OTW

ELL

(LC

)37

-415

123

in.

300

CF8

M45

8 k

g/c

m2

40oC

2

19D

M-5

(HIG

H)

DM

MA

KE-

UP

TO H

OTW

ELL

(HC

)37

-416

124

in.

150

CF8

M12

08

kg

/cm

240

oC

2

Cap

acity

250

MW

42


* A

NSI

4.5

Typi

cal a

pplic

atio

ns. 5

00 M

WC

apac

ity 5

00 M

W

FEED

CO

NTR

OL V

ALV

ES

Proj

ect :

NTP

C T

alch

er T

PS 2

x500

MW

STP

PC

usto

mer

: Kel

tron

Con

trol

s

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

1FC

V-0

65

7LO

W L

OA

D F

EED

WA

TER

FLO

W C

ON

TR

OL

37-4

1512

12

x8 in

.25

00C

547

53

60

kg

/cm

220

0oC

2

SP

RA

Y &

SO

OT

BLO

WE

R V

ALV

ES

Proj

ect :

NTP

C R

ihan

d TP

S 2x

500

MW

STP

P(U

nit 3

&4)

Cus

tom

er:B

HEL

Tric

hy

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

1SD

35

SH C

OM

MO

N L

INE

SPR

AY

BLO

CK

38-4

14X

16

2500

WC

C23

035

618

52

2SD

36

TO S

D 3

9SH

BR

AN

CH

LIN

E SP

RA

Y B

LOC

K38

-413

X1

425

00W

CC

9035

618

58

3SD

40

TO S

D 4

3SH

SPR

AY

CO

NTR

OL

38-4

1238

425

00W

CC

3035

618

58

4SD

44

RH C

OM

MO

N L

INE

SPRA

Y BL

OC

K38

-412

X1

315

00W

CC

7517

618

52

5SD

45

TO S

D 4

8R

H B

RA

NC

H L

INE

BLO

CK

38-4

12X

12

.515

00W

CC

4017

618

58

6SD

49

TO S

D 5

2R

H S

PRA

Y C

ON

TRO

L38

-412

312

.515

00W

CC

817

618

58

7SD

55

100%

PN

EUM

ATI

C S

OO

T BL

OW

ER S

TEA

M P

R. R

EDU

CIN

G V

ALV

E38

-411

343

2500

WC

930

198

483

2

8SD

56

100%

MO

TOR

ISED

SBP

RV

90-4

1134

325

00W

C9

3019

848

32

9SD

57

40%

PN

EUM

ATI

C S

OO

T BL

OW

ER S

TEA

M P

R. R

EDU

CIN

G V

ALV

E38

-411

142

2500

WC

912

198

483

2

HE

ATE

R D

RA

IN &

CO

ND

EN

SA

TE

SYSTE

M V

ALV

ES

Pro

ject

: N

TP

C R

ihan

d T

PS

2x5

00

MW

ST

PP

(Un

it 3

&4

)C

ust

om

er:B

HEL

Del

hi

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

1A

SV 8

D/A

PEG

GIN

G F

RO

M A

UX

. ST

M.

HEA

DER

37-4

1914

1030

0W

CC

300

2024

02

2C

RH

V 6

D/A

PEG

GIN

G F

RO

M C

RH

LIN

E38

-419

1212

600

WC

972

554

360

2

3C

DV

22

& 2

5M

AIN

CO

ND

ENSA

TE C

ON

TRO

L38

-416

3114

"30

0W

CC

1600

3955

4

4C

DV

10,

12,

14

CEP

. A

,B,C

MIN

IMU

M F

LOW

REC

IRC

ULA

TIO

N37

-780

036

300

WC

611

039

556

5C

DV

43

EXC

ESS

DU

MP

CO

NTR

OL

37-7

8003

630

0W

C6

110

3955

2

6C

DV

39

GSC

MIN

IMU

M F

LOW

REC

IRC

ULA

TIO

N37

-781

036

300

WC

670

3955

2

7C

DV

67

CO

ND

ENSA

TE F

OR

SD

FLA

SH T

AN

K37

-411

X2

130

0W

C6

3.8

3955

2

8C

DV

72

CO

ND

ENSA

TE F

OR

VA

LVE

GLA

ND

SEA

LIN

G37

-411

211

300

WC

62

.539

552

9D

RV

2H

P-6A

NO

RM

AL

DR

AIN

TO

HPH

-5A

38-4

1611

360

0W

C6

3054

220

2


43

* A

NSI


Cap

acity

500

MW

HE

ATE

R D

RA

IN &

CO

ND

EN

SA

TE

SYSTE

M V

ALV

ES

Pro

ject

: N

TP

C R

ihan

d T

PS

2x5

00

MW

ST

PP

(Un

it 3

&4

)C

ust

om

er:B

HEL

Del

hi

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

10D

RV 8

HP-

6B N

OR

MA

L D

RA

IN T

O H

PH-5

B38

-416

113

600

WC

630

5422

02

11D

RV 5

HP-

6A A

LT D

RA

IN T

O H

P D

RA

IN F

/T37

-412

134

600

WC

995

5428

02

12D

RV

11

HP-

6B A

LT D

RA

IN T

O H

P D

RA

IN F

/T37

-412

134

600

WC

995

5428

02

13D

RV

15

HP-

5A N

OR

MA

L D

RA

IN T

O D

EAER

ATO

R38

-416

114

300

WC

695

2218

021

14D

RV

22

HP-

5B N

OR

MA

L D

RA

IN T

O D

EAER

ATO

R38

-416

114

300

WC

695

2218

02

15D

RV

18

HP-

5A A

LT D

RA

IN T

O H

PD F

/T37

-412

136

300

WC

921

022

225

2

16D

RV

25

HP-

5B A

LT D

RA

IN T

O H

PD F

/T37

-412

136

300

WC

921

022

225

2

17D

RV

28

LPH

-3 N

OR

MA

L D

RA

IN T

O L

PH-2

38-4

1612

330

0W

C6

957

120

2

18D

RV

31

LPH

-3 A

LT D

RA

IN T

O L

P D

RA

IN F

/T37

-413

114

300

WC

920

57

140

2

19D

RV

34

LPH

-2 N

OR

MA

L D

RA

IN T

O L

PH-1

38-4

1611

630

0W

C6

300

775

2

20D

RV

37

LPH

-2 A

LT D

RA

IN T

O L

P D

RA

IN F

/T37

-413

116

300

WC

940

07

115

2

21D

RV

48

DEA

ERA

TOR

OV

ERFL

OW

TO

LP

DR

AIN

F/T

37-4

13X

16

300

WC

916

011

175

2

22D

MV

38

DM

NO

RM

AL

MU

TO

HO

TWEL

L37

-412

333

300

CF8

M95

1050

2

23D

MV

63

DM

EM

ERG

ENC

Y M

U T

O H

OTW

ELL

38-4

1233

830

0C

F8M

255

1050

2

24D

MC

W 8

3EC

W S

YST

EM F

OR

BO

ILER

AU

X.

37-4

1631

630

0C

F8M

360

1060

2

25D

MC

W 6

7EC

W S

YST

EM38

-416

3112

300

CF8

M12

6010

602

SC

AP

H C

ON

TRO

L V

ALV

ES

Pro

ject

: N

TP

C R

ihan

d T

PS

2x5

00

MW

ST

PP

(Un

it 3

&4

)C

ust

om

er:B

HEL

Ch

enn

ai

No.

Tag

Serv

ice

Mo

del

Size

Rat

ing

*B

od

yC

vPr

.Te

mp

.Q

ty.

1AS

SV10

2,10

3,14

2&14

3A

UX

. ST

EAM

TO

SEC

ON

DA

RY

SC

APH

A&

B37

-419

216

300

WC

C36

020

260

8

2A

SSV

7,

8, 4

7 &

48

AU

X.

STEA

M T

O P

RIM

AR

Y S

CA

PH A

&B

37-4

1631

430

0W

CC

190

2026

08

3A

SSV

219

& 2

20PR

IMA

RY S

CA

PH D

RA

IN T

O L

P FL

ASH

TA

NK

38-4

1621

330

0W

C6

903

.520

04

4A

SSV

204

& 2

05SE

CO

ND

AR

Y S

CA

PH D

RA

IN T

O L

P FL

ASH

TA

NK

38-4

1621

330

0W

C6

140

3.5

200

4

5BD

06,

06A

CBD

LEV

EL C

ON

TRO

L38

-416

213

300

WC

614

010

200

4

Material selection GuidelinesStandardised Materials for high performance

Temp. 150#ANSI 300#ANSI 600#ANSI 900#ANSI 1500#ANSI 2500#ANSI

< 93ºC 18.3 52.7 105.5 158.2 263.7 439.4

149ºC 16.2 51.3 102.3 153.6 255.9 426.8

204ºC 14.1 49.6 99.1 148.7 248.2 413.4

260ºC 12.0 46.8 93.5 140.3 233.8 389.5

316ºC 9.8 42.5 85.1 127.6 212.7 354.4

371ºC 7.7 40.1 79.8 119.9 199.7 332.6

427ºC 5.6 35.9 71.4 107.2 178.6 297.4

482ºC 3.5 31.6 63.3 94.9 157.8 263.3

538ºC 1.4 25.7 51.0 76.6 128.0 213.0

593ºC 0.0 22.9 45.3 67.8 113.2 188.8

PRESSURE RATING. CEILING VALUES *

MATERIAL SELECTION

* Max.. Working Pressure in Kg/cm2 for ANSI 150# to ANSI 2500#, Extracted from ANSI B16.34 - 1996. Varies

with material, See pages 48-50 for max. allowable working pressures for WCC, WC6 & WC9, the most

common body material used for Control Valves in power plant applications.

CONTROL VALVE. PRESSURE CONTAINING MATERIAL

General Classification Castings Forgings Max. Operating Temp.

Carbon Steel ASTM A 216 Gr. WCB / WCC ASTM A 105 427ºC

Alloy Steel, 1 ¼ Cr - ½ Mo ASTM A 217 Gr. WC6 ASTM A 182 Gr. F11 566ºC

Alloy Steel, 2 ¼ Cr - 1 Mo ASTM A 217 Gr. WC9 ASTM A 182 Gr. F22 566ºC

Alloy Steel, 5 Cr - ½ Mo ASTM A 217 Gr. C5 ASTM A 182 Gr. F5a 566ºC

Stainless Steel, Ty. 316 ASTM A 351 Gr. CF8M ASTM A 182 Gr. F316 566ºC

5.1 Body material specs

Correct material selection is extremely important to ensure

proper functioning and longevity of Control Valves in Power

Plant applications. The service conditions vary widely in

pressure and temperatures, design pressure can go up as high

as 360 kg/cm2 and temperatures upto 566oC. The Body and

Trim material selection should also take into account the

detrimental effects of Cavitation / Flashing / High Velocity

which are inherent to such severe applications.


47

Allowable working pressure for ASTM A 216 Gr. WCCA

llowable w

orking pressure (Kg/cm

2)

Operating temperature (oC)

5.2

Allo

wab

le w

orki

ng p

ress

ure

48


Allow

able working pressure (K

g/cm2)


5.2 Allow

able working pressure

Allowable working pressure for ASTM A 217 Gr. WC6


49

50


Allow

able working pressure (K

g/cm2)


5.2

Allo

wab

le w

orki

ng p

ress

ure

Allowable working pressure for ASTM A 217 Gr. WC9


51

5.3 Trim m

aterial selection

GEN

ER

AL C

LA

SSIF

ICA

TIO

NA

STM

CO

DE

MA

X. T

EM

P.H

AR

DN

ESS

GE

NE

RA

L A

PP

LIC

ATI

ON

GEN

ERA

L S

ERV

ICE

SS 3

16

Bar S

tock

: AST

M A

479

Ty. 3

1659

3ºC

14 H

RC

max

.N

on-E

rosi

ve, C

orro

sive

,Mod

. Pre

ss. D

rop.

Cas

ting

s: A

STM

A 3

51 G

r. C

F8M

Mos

t cor

rosi

on re

sist

ant o

f 300

Ser

ies

TOU

GH

SER

VIC

E

Ty.

41

0 S

tain

less

Ste

elBa

r Sto

ck: A

STM

A 4

79 T

y. 4

1040

0ºC

35 H

RC

min

.Er

osiv

e &

Non

- C

orro

sive

Ser

vice

(Har

dene

d &

Tem

pere

d)

Ty.

41

6 S

tain

less

Ste

elBa

r Sto

ck: A

STM

A 5

82 T

y. 4

1640

0ºC

31-3

8 H

RC

Eros

ive

& N

on-

Cor

rosi

ve S

ervi

ce(H

arde

ned

& T

empe

red)

No.

6 St

ellit

e H

ard

Faci

ngN

A65

0ºC

38-4

7 H

RC

Slig

htly

Ero

sive

& C

orro

sive

Ser

vice

No.

6 St

ellit

e So

lid (<

2”)

NA

650º

C38

-47

HR

CEr

osi

ve &

Co

rro

sive

Ser

vice

No.

5 C

olm

onoy

Har

d Fa

cing

NA

650º

C45

-50

HR

CEr

osi

ve &

Co

rro

sive

Ser

vice

.C

orro

sion

resi

stan

ce s

imila

r to

Inco

nel

No.

6 C

olm

onoy

Har

d Fa

cing

NA

650º

C56

-62

HR

CEr

osi

ve &

Co

rro

sive

Ser

vice

.C

orro

sion

resi

stan

ce s

imila

r to

Inco

nel

17

.4 P

H S

tain

less

Ste

el B

ar S

tock

: AST

M A

564

Gr.

630

400º

C40

HR

C m

in (H

900)

Ero

sive

& C

orr

osi

ve S

ervi

ceC

asti

ngs:

AST

M A

747

CB7

CU

132

HR

C m

in (H

1075

)

CA

6NM

Sta

inle

ss S

teel

Cas

ting

: AST

M A

743

Gr.

CA

6NM

650º

C28

HR

C m

in.

Ero

sive

& C

orr

osi

ve S

ervi

ce.

(Hea

t Tre

ated

)(7

00-1

000

HV

Aft

er c

ase

hard

enin

g, e

xcel

lent

for h

igh

afte

r Nitr

idin

g)te

mp

erat

ure

ser

vice

.

Ty. 4

40

C S

tain

less

Ste

elBa

r Sto

ck: A

STM

A27

6 Ty

.440

C40

0ºC

58 H

RC

min

.V

ery

Ero

sive

Ser

vice

.

Handling and InstallationA list of safe practices

Fig. 24. Clearance requirements for Globe Control Valves

1. Do not lift large size valvesby the Actuator. Lifting Lugsprovided on the Actuators arefor lifting the Actuator alone.

2.The Actuator Diaphragmcase, Eye Bolts etc. are notdesigned to lift the heavyvalve body assembly.

3. Do not turn the Actuator,keeping the coupling tight.

4. In case of Bellow SealedValves, never rotate theValve stem.

5. Valves on smaller pipingand tubing may need to bemounted in Brackets.

6. While choosing thelocation to mount the valve,provide adequate space forfuture occasions when it maybecome necessary to removethe Body and Actuatorfor repairs.

7. Ensure that recommendedmounting orientations arealways followed.

8. Ensure that the FlangeBolts or Tie Rods can beremoved easily.

9. Leave adequate space foropening/adjusting Positionersand Accessories.

6.1 Handling &

InstallationA P P L I C A T I O N H A N D B O O K

55

Fig. 25. Alternate orientations for Control Valves (position-1 is preferred)

10.Positioner Gauges andTravel Indicators must alwaysremain clearly visible.

11.Careful choice of locationhelps to prevent Cavitation.When flow is upward, and ifthe fluid partially vaporizesbecause of lower hydrostatichead, locating the Valvetowards the lowest part of thepiping can prevent two phaseflow through the Valvethereby minimizingCavitation.

12. Valves in Flashing serviceare to be located as close tothe receiving vessel aspossible. A very short lengthof Discharge Pipe, and anIsolation Valve are permitted.

13.Special attention must begiven not to place an elbowor pipeT less than 5 pipediameters downstream of avalve to avoid interferencewith the Valve’s FlowCapacity. In high pressure gasor steam pressure reducingapplications, try to have onlystraight pipes downstream ofthe valve, or alternatively usea long sweeping elbow toavoid added pipe noise.

14. In critical applications,provide a manually operatedthrottling valve in a bypassaround the valve. This allowsfor replacement or repair ofthe Control Valve withoutshutting down the process.

6.1H

andl

ing

& In

stal

latio

n

56


Fig. 26. Typical satisfactory arrangement of upstream and downstream piping

Fig. 27. Less satisfactory arrangement of upstream and downstream piping

15. Since Control Valves will require maintenance from timeto time, Block Valves at Upstream and Downstream areessential. Bleed and drain valves may be necessary for safety.

16.On occassions when the Control Valve is out of service, if aBypass Valve is being provided along with isolation valves inorder to have flow, the style of the Bypass Valve should besimilar to that of the Control Valve. Or else an identical ControlValve should be chosen as the Bypass Valve.

17. In cases of extreme ambient temperatures (over 80ºC)where a valve is located, the valve and accessorymanufacturers should be consulted for proper, hightemperature replacement material.

6.1 Handling &

InstallationA P P L I C A T I O N H A N D B O O K

57

Maintenance GuidelinesHow to ensure peak performance of

Control Valves in power plant applications

B E F O R E S TA R T- U P

7.1 Preventive maintenance

1. It should be appreciatedthat during plant start ups,abnormal operatingconditions can adverselyaffect the performance of theControl Valve and some timesseverely damage the valve.It is very important that theseabnormal conditions berecognized and the ControlValve is selected taking intoaccount these conditions.

2.Ensure that misalignmentalong the pipe line is notcorrected using the valve.Pipeline stress on the valvemay cause misalignment ofthe stem or plug/seat joint. Itcan also cause flange leak orpacking leak.

1. PREVENTIVE MAINTENANCE

3.Ensure that therecommended mountingorientation is followed. If avalve is mounted with it’sstem travelling in thehorizontal plane, it must beproperly supported.

4.Ensure that the mandatory‘flow through’ directionindicated on the ControlValve (by an arrow mark) isalways followed.

5.Piping should be flushedbefore installing the valve. Ifadditional flushing is doneafter installation, it may benecessary to remove theinternals, Especially if anti-Cavitation or low noise Trim isin place.

Continued in next page

A F T E R S TA R T- U P

1.Periodic field inspectionsshould be made.

2.Remember that high-friction packing needs to becompressed after insertion.Packing will compress furtherin service, and the packingcompression may have to bereadjusted. Tighten thepacking nuts when foundnecessary.

3. If dusty or dirty conditionsprevail, provide a rubber bootaround the stem to protect thepacking.

4.Cover the valve suitablywhen process dripping orcorrosive atmosphericconditions prevail. Special careto be given to the valveaccessories.

5.Air sets usually have filtersthat can clog; the drain cockshould be opened from time totime to be sure trapped liquid isdrained.

6.Monitor the performanceof the valve accessories as ithas a significant effect on thevalve performance.


61

7.2

Shop

ove

rhau

l

1. Valves and valve internalin hazardous service shouldbe cleaned thoroughly beforeundertaking any repair.Depending on contaminant,water wash, steaming orspecial heat treatment maybe resorted to.

2.Ensure that the person whois disassembling the ControlValve is thorough with therelevent procedure.

3. Before disassembly, markthe Actuator orientation withrespect to the body flanges.

6. If line trash like weld chips,rust etc. are expected in thepipeline, temporary strainersshould be installed upstream.If the process stream normallycontains Scale, dirt or otherforeign material, it isrecommended thatpermanent strainers or filtersbe installed. Strainers shouldbe installed far enough toallow non-swirl flow at thevalve inlet. Note thatstrainers that efficientlyprotect the pump may not beadequate when it comes toremoving debris that candamage the valve Trim.

7.Ensure that the air supply isclean and devoid of oil.

2. SHOP OVERHAUL

4.Remove the bonnet fromthe body, and then the glandpacking components. Furtherremove the Trim and thebottom flange.

5.Disassemble the Actuatorand examine components fordamage. Afterwards cleanthe parts carefully.

6. Inspect the disassembledcomponents thoroughly anddetermine the extent ofreconditioning and repair thatis required.

Continued in facing page

8. Air lines to be connected tothe Control Valves should beblown clean of oil and debrisbefore they are attached.

9.Avoid using Teflon® tapesin instrument air lines. WhileTeflon® tape is an excellentthread lubricant and seal forscrewed connections, itnevertheless can break off insmall bits if not carefullyapplied. And these bits oftenmigrate to orifices inpneumatic accessories andcan clog them.

10.Do not start up a ControlValve without first checkingthe packing tightness.

Maintenance. Before startup CONTINUED FROM PREVIOUS PAGE

62


7.2 Shop overhaul

7. If the body is rusted,descale the body. Whilehandling the body, the flangesurfaces must be protected toprevent any gasket leakage.

8. Assess the need forremachining of Body andTrims. First the plug and seatshould be perfectly matched,by precise machining, then byhand grinding or lapping.Make sure that even finetraces of lapping compound iscleaned off.

9.The lapped contact shouldnot be too wide. If the contactband is too wide, a machinecut to renew the angles of themating pieces is necessary.The angles of the matingpieces are slightly different toallow a narrow seating band.

10. For problems like marredstem surface, replacementwith a factory finished stem isthe only practical solution.The finish of the Control Valvestem is so fine that highlypolished surfaces are requiredto give the best possiblepacking seal, and to minimizethe hysteresis.

11. If the Trims are beyondrepair, replace them withgenuine spare parts. ValveTrims are amongst the mostprecision of instrumentationcomponents.

12.Avoid use of nonstandard Trims. These cannotmatch the metallurgy andworkmanship of factoryfinished spares.

13. Reassemble the valvebody using the reconditioned/new parts. Ensure that glandpacking and gaskets arechanged every time the valveis opened and reassembled.Use only OEM* glandpacking and gaskets. Lowquality gaskets can causeirreversible damage to thevalve by seat area Erosion,body bonnet Erosion etc.

14.While tightening thebonnet and bottom flanges, itis important to tighten thediagonally opposite bolts toensure even gasket loading.Over tightening can causeexcessive elongation of thegaskets thereby resulting inpoor joints.

15.Assemble parts of theActuator barrel, install thediaphragm case using newcap screws and nuts, andcheck for pneumatic leaks.

16.Adjust the spring rangeand stroke of the Actuator.

17.Giving air supply to theActuator, keep the Actuatorin mid stroke and mount theActuator on the valve body.

Shop Overhaul CONTINUED FROM PREVIOUS PAGE

*Original Equipment Manufacturer


63

64


20.Tubing connections forsignal and operating airshould be checked with soapywater or other leak detectingfluids.

21.Carry out hydrotest, seatleakage test and calibrationas per relevant standards.

22.When repair to anexisting valve isuneconomical, replace it witha new valve from a high-quality OEM to avail of bettersizing, better materials, betterdesign, and most likely, betterservice too. Processconditions should bestabilized and determinedaccurately in case they werenot correctly anticipatedwhen the original valvewas specified.

23. Do not buy valves orreplacement parts fromnon OEMs. Overemphasison short-term cost savingscan sometimes lead tohazardous workingenvironments for personnel,process downtime andincreased operating costs.

7.2

Shop

ove

rhau

l

18.Tighten (finger tight) thecoupling. Apply air or removeair to ensure proper seating ofthe valve. Then tighten thecoupling and adjust the travelindicator.

19. Mount the accessoriesback on to the Control Valve.Several of the most commonaccessories (Air Sets,Positioners, Transducers etc.)have Rubber Diaphragmsthat will harden and crack.Some have O Rings thatdeteriorate. It would beeconomical to replace thewhole accessory with spares(and repair faulty modelsduring slack time) rather thanrepairing them On Site. In thiscontext, it may also be notedthat accessories like SmartValve Positioners are highlysensitive to the quality ofInstrument Air. GenerallyManufacturers recommendInstrument Air to be free ofoil, water and dust to DIN/ISO 8573-1, Pollution and oilcontents according to Class 3and Dew point 10 K belowoperating temperature.

Shop Overhaul CONTINUED FROM PREVIOUS PAGE

The MIL RangeHigh performance Control Valves for power plants

8.1 MIL 21000 Series

For severe service, specialdouble stage valves withsimultaneous throttling in theplug and Cage also is available.

Tight Shut-Off: Class IV leakageis standard. Optionalconstructions meet Class V &Class VI leakage.

Quick Change Trim. Optionalclamped seat ring facilitates easyTrim removal.

Angle Body (70000 Series).Optional angle body designwith Venturi seat is ideally suitedfor special applications likeFlashing liquids and otherchoked flow conditions.

F E A F E A F E A F E A F E AT U R E ST U R E ST U R E ST U R E ST U R E S

Heavy Top Guiding. The Valveplug shank is Guided within thelower portion of the bonnet andthis heavy and rugged guidingensures plug stability andeliminates Trim vibration.

AntiCavitation/Low Noise Trimsreplacing conventional plugwith the Lo-dB plug providesexcellent noise attenuation andCavitation control.

Available Sizes & Rating

½” to 2”: ANSI 150# to ANSI 2500#

3” to 1 0”: ANSI 150# to ANSI 600#

Seat leakage class as per ANSI/FCI 70.2

Standard: Class IV.

Optional: ClassV & ClassVI

MIL 21000Rugged, heavy top Guided, singleseated Control Valves

67

A P P L I C A T I O N H A N D B O O KA P P L I C A T I O N H A N D B O O K



¾” to 14”: ANSI 1 50# to ANSI 2500#

16” to 20”: ANSI 150# to ANSI 600#

Seat Leakage Class as per ANSI/FCI 70.2

Standard: Class III & Class IV

Optional: Class V

8.2

MIL

410

00 S

erie

s

MIL 41000Heavy Duty Cage GuidedControl Valves.

F E AT U R E S

High allowable pressure drops.Cage Guided valves provideexceptional performance over awide range of pressure drops insevere services. They also handlemost shut off pressures withstandard pneumatic springdiaphragm Actuators.

High capacity with low pressurerecovery. Flow capacities remainat top levels, and are attainedwith minimum pressure recoveryreducing the possibility ofCavitation in liquid service.

Standardised high performancematerial. This ensures troublefree operation even inapplications with inherent highpressure drops and extremetemperatures.

Tight shut off valves. For lowersizes, unbalanced design resultsin Class V leakage.

For higher sizes, the exceptionalsingle seated leak tightness ofClass V is achieved by thefollowing special options:

1. Auxiliary shut-off pilot plugcloses the balancing holeslocated in the main plug in shut-off conditions.

2. Self energised seal ringspressing against walls of theCage & Plug arrests leakage pastthe seal ring.

Lo-dB/Anti-Cavitation Cages:Noise attenuation andCavitation control achieved byreplacing conventional Cageswith Lo-dB Cages.

S P E C I A L O P T I O N S

Static Seal Ring, Double Cage design,Two stage design with diffuser seatring, Multi-Stage Valves

MIL 41008 . These Multi-Stage valvesincorporate a unique Trim design toabsorb high pressure drops thatprevent Cavitation and maintainconstant velocity throughout thepressure dropping stages.Concentric Cages incorporate atortuous flow path, which causesnumerous velocity head losses withoutappreciable pressure recovery. Highpressure recovery factors at lower liftseliminates Cavitation. High impedanceflow path reduces pressure by frictionand turbulence, maintaining constantvelocity throughout.

68




½” to 6”: ANSI 900# to ANSI 2500#

Seat leakage Class as per ANSI/FCI 70.2

Standard: ClassV

Optional: Class VI

or High Noise Levels commonlyassociated with conventionallydesigned Control Valves.

High allowable pressure drops.No individual stage is exposedto the full pressure drop, thusextending Trim life substantially.

Adiabatic Flow with Friction.Reduces pressure much in thesame way as pressure lossoccurring in a long pipeline.

Low pressure recovery. Thisminimises Cavitation potentialand contributes towardsreduction of Noise for all fluids.Pressure recovery factors as highas 0.998.

Standardised high performancematerial:To ensure materialintegrity, 78000 Series valves aremachined from solid steelforging. High performance Trimmaterial ensures durability inany severe application.

Balanced Trims: Available forsizes 2" and above, allow muchhigher shut-off pressures withconventional Actuators.


Soft seat construction withencapsulated inserts, Angle & Inlinebody configurations.

8.3 MIL 78000 Series

F E AT U R E S

Multi Step Axial Flow HighResistance Trim. Pressurereduction occurs along thelength of the plug in a series ofthrottling stages. The fluid alsotakes a tortuous flow path,which adds resistance andtherefore velocity head loss.

The special design providescontrol of high pressure fluidswithout the Erosion, Vibration

MIL 78000Anti Cavitation &Low NoiseMulti-step High Pressure DropControl Valves

69



8.4

MIL

910

00 S

erie

s

MATRIX Series valvesMIL 91000Extreme Pressure Multi-stage,Multi-path, Axial Flow Anti-Cavitation High Pressure DropControl Valves

F E AT U R E S

Varying and expanding flowpassage. This enables near ZeroPressure Recovery thus ensuringthat stage wise Pressure Dropsare limited below the CriticalPressure Drop. Likelihood ofCavitation is ruled out even inextreme conditions.

Ingenious Flow Path. Reducesdownstream Velocity. ExitVelocity and Kinetic Energy keptunder limits. Erosion eliminated.

Pressure recovery factor (Cf) ashigh as 0.9999.

As many as 50 PressureDropping stages.

Ruggedness of design. Ensureslongevity even in the severest ofapplications.

Axial Flow design. Eliminateswire drawing effects on theleading edges of the plug.

Flow to Open flow direction.Eliminates Dynamic Instabilityinherent to Flow to Close valves.

Tortuous flow path with HighImpedance for energyabsorption limits Trim Velocity.

Modified equal % characteristicswith 100 : 1 Rangeability.Characteristics can becustomised to suit specificprocess applications.

Self energised body and seatgaskets. Ensures Zero Leak, andoptimises bonnet/bolting design.

Ingenious design. Results in asimpler manufacturing process.Consequently this makesMATRIX Series Valves betterpriced than other valves in thisleague.


Available with Soft Seat with a specialsliding collar to protect the Soft Seatfrom high pressure fluids.



70

8.5 Actuators

71



MIL has a wide range of High Performance Pneumatic Actuatorsdesigned for all ranges of process control applications. Key Models are...

Actuators

MIL 67 / 68

MIL 57 / 58

MIL 37 / 38

MIL 37-38 Pneumatic SpringDiaphragm Actuators

Sizes : 11", 13", 15", 18" & 24"Travel : <_ 4"Supply Pressure : 20 psig to 65psig

MIL 57-58 Pneumatic Multi-Spring Diaphragm Actuators

Sizes : MS 11 & MS 13Travel : <_ 1.5"Supply Pressure : 20 psig to 45 psig

MIL 67-68 Double ActingPiston Cylinder Actuators

Sizes : 16”, 20”& 24”Travel : <_ 12"Supply Pressure : 60 psig to 100 psig

8.6

Acc

esso

ries



Standard Accessories

MIL 7400 Pneumatic Positioner

MIL 496 Limit Switch

MIL 8013 Electro Pneumatic Positioner

MIL 400 Position Transmitter

MIL 7400 Positioners employ aforce balance system to ensure thatthe position of the valve plug isdirectly proportional to the controlleroutput pressure, regardless ofpacking box friction, diaphragmactuator hysteresis or off-balanceforces on the valve plug.

MIL 8013 Positioners provideprecise and reliable valve positioningand superior dynamic response, bydirectly comparing valve stemposition with controller DC outputsignal, provide dynamic responseand positioning accuracy notobtainable with transducer andpneumatic positioner combination.

MIL 496 Rotary Limit Switches(with SPDT / DPDT Microswitches orProximity sensors) are used forelectrically indicating one or twopredetermined positions in thestroke of a control valve. They maybe connected to audible alarms orsignal lights for warning of valve orsystem malfunction or used toactuate solenoids, relays and otherelectrical devices.

MIL 400 Electronic Position Trans-mitters are capable of transmittingangular movements as well as linearmovements of control valves (withproper linkages) as 4-20 mA outputsignal. MIL 400 Position Transmittersare available in following variantsMIL 400A: RVDT- Rotary VariableDifferential Transformer- operated(used for control valves havingstroke less than 3/4"). MIL 400X:

MIL also offer Profibus or Hart or Foundation Field Bus based SMARTPOSITIONERS.

Inductive Type (Used for control valves with higher stroke lengths, startingfrom 3/4") MIL 400L: LVDT- Linear Variable Differential Transformer -operated Position Transmitter.72

MIL is the first Control Valve manufacturer in India to have been awarded theprestigious CEMarking Certificate by RWTUV, Germany.



73

9.0

Inde

x &

List

of I

llust

ratio

ns

I N D E XAAllowable working pressure 48Accessories 72Actuators 71

BBlock Valve 24Body Material Specs 47Boiler Feed Pump Min. Recirculation Valve 13, 17, 18Boiler Feed Pump Minimum Recirculation System 17Boiler Feed Water Startup Valve 13, 17Boiler Main Feed Water Control Valve 13, 17

CCE Marking 8, 73Company overview 8Condensate Recirculation Valve 13, 14Condensate system 13, 14Condenser 14

DDeaerator 14, 15, 17Deaerator Level Control Valve 13, 14, 15, 16Deaerator Pegging Steam System 26Deaerator Pegging Steam Valve 13, 22, 26, 27

EEconomisers 17

FFeed Pump Recirculation 18Feed Water Control 20Feed Water Heaters 31Feed Water Pumps 17Feed Water Regulating System 20Feed Water Regulator Valve 20Feed Water System 13, 17Foster Wheeler 8Full Load Feed Water valve 20

GGeneral Boiler Flow Diagram 10

HHandling and Installation 53Heater Drain System 13, 31Heater Drain Valve 31High pressure heater drain Valves 13HP Heaters 31HP Heaters System 32, 55

LLow Load Feed Water valve 20Low pressure heater drain valves 13LP heaters 31LP Heaters System 32

MMain Steam Line 22Main Steam Pressure Reducing Valve 22, 29, 30Main Steam System 13, 22Maintenance Guidelines 59Martensitic Steel 15Material Selection Guidelines 45, 47MATRIX Series 8, 19, 70MIL 21000 31, 67MIL 41000 16, 21, 27, 31, 68MIL 41003 27MIL 41008 15, 21, 25MIL 41100 23, 24MIL 41114 28MIL 41121 30MIL 41128 25MIL 41200 23, 24MIL 41221 30MIL 41400 24MIL 41621 16MIL 41912 30MIL 41914 30MIL 41921 16MIL 70000 67MIL 71114 28MIL 78000 15, 18, 19, 25, 69MIL 91000 19, 70MIL Controls Limited 6, 8Modulating Type System 18

OOn/Off System 18Original Equipment Manufacturer 63

PPositioner Gauges 56PRDS Spray Control Valves 22PRDS Station Valves 29PRDS System Control Valves 22PRDS System Valves 13Pressure Reducing Desuperheating System 29Preventive Maintenance 61

RReheater Attemperator Control Valve 25Reheater Attemperator Spray Valve 13Reheater Spray Block Valves 22Reheater Spray Control Valves 22Reheater System 22Remachining 63RWTUV 73

SShop Overhaul 62Sliding Collar Seat Ring 19Soot Blower 24, 27Soot Blower Pressure Control Valves 22Soot Blower Steam Pressure Reducing Valves 13Soot Blower Valve 27Soot Blowing System 22Soot Blowing Valves 27Steam Ejectors 29Steam Soot Blowers 27Strainers 62Super Heater Attemperator Valve 22, 23Superheater Attemperator Block Valve 22, 24Superheater Attemperator Spray Valve 13Superheater Spray Control Valves 22Superheater System 22

TTeflon® tapes 62Temperature Control Valve(Spray water) 29Trim material selection 51Turbine Bypass Valves 13Typical Applications 116 MW 37Typical Applications 210 MW 39Typical Applications 250 MW 41Typical Applications 500 MW 43Typical Applications 67.5 MW 35

UUpstream Piping 57

I L L U S T R AT I O N SFig. 1. General Boiler (Drum style) Flow Diagram 10Fig. 2. Condensate System 14Fig. 3. MIL 78000 15Fig. 4. MIL 41000 16Fig. 5. Boiler Feed Pump Min.Recirculation System 17Fig. 6. MIL 78000 Feed pump Min. Recirculation valve 18Fig. 7. MIL 91000 19Fig. 8. Feed Water Regulating System 20Fig. 9. MIL 41008 Multi stage, Low Load Valve 21Fig. 10.Critical Control Valves in Main Steam Line 22Fig. 11.MIL 41100 Superheater Attemperator Valve 23Fig. 12.MIL 41200 Superheater Attemperator Valve 23Fig. 13.MIL 41400 Superheater Attemperator block 24Fig. 14.MIL 41008 Reheater Attemperator Control Valve 25Fig. 15.MIL 78000 Reheater Attemperator Control Valve 25Fig. 16.Deaerator Pegging Steam System 26Fig. 17.MIL 41003 27Fig. 18.MIL 71114 28Fig. 19.Typical Auxiliary PRDS System 29Fig. 20.MIL 41914 30Fig. 21.MIL 21000 31Fig. 22.LP Heaters System 32Fig. 23.HP Heaters System 32Fig. 24.Clearance requirements for Valves 55Fig. 25.Alternate orientations for Control Valves 56Fig. 26.Typical satisfactory piping 57Fig. 27.Less satisfactory arrangement of piping 57


74

© MIL CONTROLS LIMITED, 2007. All rights reserved

Control Valves for Power Plants.Application HandbookThe MIL Power Plant Handbook providesa broad overview of the various systems ina Thermal Power Plant to help you select theright valve for each application.

The handbook also offers expert tips forproper Installation and Maintenance ofyour Control valves.

Registered Office & Works.Meladoor , Mala, PIN 680 741, Thrissur District, Kerala, India.Tel: + 91 (0)480 2890272, 2890772, 2891773.Fax: + 91 (0)480 2890952. Email: [email protected]

Marketing Head Office.Thaikkattukara P.O., Aluva, PIN 683 106, Ernakulam Dist, Kerala,India.Tel: 91 (0)484-2624955, 2624876. Fax: 91 (0)484-2623331.Email: [email protected]

HB/

Pow

er/R

ev-B

/01·

2007


A KSB Company

Documents

MIL-Power Plant Handbook