NEMA SM 23-1991 Steam Turbines for Mechanical Drive Service

NEMA Standards Publication No. SM 23-1991(R1997, R2002) Steam Turbines for Mechanical Drive Service--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

Published by:

National Electrical Manufacturers Association1300 North 17th Street, Suite 1847 Rosslyn, VA 22209

O Copyright 2002 by the National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the international and Pan American Copyright Conventions.

Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA No reproduction or networking permitted without license from IHS

Licensee=Defense Contract Mgmt Command/5935922100 Not for Resale, 09/18/2006 02:36:51 MDT

NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed, Consensus does not necessarily mean that there is unanimous agreement among every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not write the document and it does not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, express or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or sellers products or services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available from other sources, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or installations for safety or health purposes. Any certification or other statement of compliance with any health or safety-related information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement.--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

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NEMA SM 23



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NEMA Standards Publication No. SM 23-1991 (R1997)

Steam Tuhines for Mechanical Dive Service

Published by:National Electrical Manufacturers Association 1300 North 17th Street, Suite i 847 Rosslyn, VA 22209

Q Copyright 1997 by the National Electrical Manufacturers Association. All rights including translation into other bnguages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American Copyright Conventions.

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TABLE OF CONTENTS

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............................................. .................... ..................................... ........................................... ....................................... .................................... CiassiedbyExhaustcaiditiasis.............................. . N Tiabmc .................................. CoadensingTUrbinc ................................... classified by Number of Stages and C a 1Valves .................... om SingleValveSingieSEagC'Iirrbint ............................ Single Vaive MuuistegeM e ............................. i n Multi* sil@ stage m e ............................ i n Muitivaive Muitisiage'ixine ............................. C i a s s i d b y ~ N e e d s................................ controlled (Alumtic) Exeraction Turbine ....................... NoncwtrolletiExtractiosi nlrbhw ............................ Noacontrolled Induction 'linbine ............................ CmmUed InQiCtim(Mixdnesslire) M e ..................... InductimExtractionTirrbine .............................. SteamIIiabinecctUl~ts.................................. Turbinecasmg ....................................... SteamInletEndseCtion ................................. ExhaustEI?dstction ................................... Irlemedia&sactiw ................................... Steam Chest (GOV~IIKN vahe Body) ............................ SteamRing ......................................... N z l s ........................................... oze StatiomyReveEngBladcs ................................ StationaryRevczsingCham~ .............................. Diciphragm ......................................... s . wnlrbirbe ........................................ ImpuIseStage ...................................... ReactianStage ...................................... shaftseals ......................................... casingshaftseals ..................................... Intemagestlaftseals .................................. BearingHousing ...................................... Bearings ........................................... RacaiBcarings ..................................... ThnistBearings ..................................... AntitiCtianBearings ................................... RotorAssembly ....................................... wheels@iscs) ......................................... Biades(Buckets) ........................................ Shroud ............................................. Handvalve@) ......................................... RotectiveDevice ....................................... COnmhgDevi~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ExtemalcontrolDevice .................................... WamingDeVice ........................................SCOPE REFERENCEDSTANDARDS AND DEPlNlONS RefaencedSEancbrrds Definithm CONSTRUCTION 'I)pesofSteamT

F R wm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OEo

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5 5 55 5 5

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Sentinel W h g Valve soleplate(s) .......................................... Basephte .........................................FeatmsandAccessan ?es

...................................

............................. Nonconp.olled InductiaiIlabines ............................. ?IiirbineRating......................................... power ............................................ speed ............................................ R t d p e ....................................... ae s e d Maximum continwuss e d .............................. pe N d Power end Speed and Steam Caiditions ..................... Stcamconditiaas: ...................................... MinimwnSteam(hKiibS ............................... MaximumStcamconditions .............................. MinimumEnergystcamccmditions .......................... Inletsteampressure ................................... ExhaiistSteampressUre .................................Extraction Steam RressiireInduction Steam Pressure ................................ Inlet Steam Tempemure ..................................

BasicFeaMesaQd............................... OptiOnalFeaMesandAccessorics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c o n t r o n e d ~ ~ a n d c o n t r o l l ?Itrrbines . . . . . . . . . . . . . . . . . ed~ Ncmwntroiled Exach Turbhes

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5 5 6

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67 7 7 7 7 7 7 7 7 7 7 7 7 7 8

................................

ExhaustSteamT~ perame

Extiaction SteamTemperatrae L d ci Steam Tempgatme n pt m Maximum Mowable Working PressuresandTeanptmtms

I

............................. .......................... Thermodynamic?Iienns .................................... SteamRateS ......................................... TheOretidSteamRate ................................. ActualsteamRates ................................... GuaranteedSteamRate .................................?Iiirbineconnectiais......................................Steamcohus AuxiliaryconnectionS LlbiClUb

DualSteamconditions

VauiationsinSteamconditions Flow Limits for an Automatic Exaaction ? M i h e . . . . . . . . . . . . . . . . . . . HowrjmitpforanInductionTurbine Units of Measurement for Absolute and Gauge Pressure . . . . . . . . . . . .

.............................. .............. .................................

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8 8 88

88 8 8

8 99

9 9 9 9 10 1010 1 0 1 0 10 10 1 0 10

outputshaftExte~..................................

NonpFessure?lSpeLubncation(Single stage lbbines) oil Lulnicztred sleeve Beanngs (HarizwEalTiirbines) G?ease or oillubricatadAntinictionBearings ..................... pressure?lslpeoilLu~ InProduction Oilnrmpr ........................................ oilReservoir

..................................... ................................... ...........................................

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.................

............................... ....................................... ....................................... oilcooler ........................................ OilFdt~zs .........................................

1011 11 11 11 11 11



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piping and Instnunentation nwisons for the Esrvin>nment Eaclosufe Exposwe to Nanrral Elements Exposure to Abnonnal Ahnphedic conditioas GeneraiRequiremeats PltsSureandTempemmRanges

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............................... ................................ .......................................... ............................... ...................... ..................................... ............................. vibration .......................................... Singlestagerbim .................................. M d t i s t a g e r b ~ ................................... clitwspeeds.L................................... NameplateData ....................................... CONTROLS .......................................... GoveaningSystem ....................................... SpeedGOmar ....................................... Multivariable Govexnor ................................... CoatmlMeChanism ..................................... GOvmorconmlled WVe(S) ............................... Servomom System ..................................... E x t e m a l C d D e v i w .................................. Speedcbangetlype ................................... RemoteSetPointQpe .................................. Valve Actuating.................................. s e d h n e ....................................... pe c a gr Speed Govaning System classification ............................ SpeedRange ........................................ Mx u s@Rise .................................... ai m m speedvariation ....................................... DeadBand ........................................ stability ......................................... Speed Regulation. Steady State .............................. steamPressurecaritrd .................................... PressureRegUlatingSysea~................................ PressureRegUlatw ..................................... Control MechaniSn ..................................... nessUre Controlled Wves ................................. pressurechanger ...................................... SteadyStatePxess~mRe guuion .............................. PressureReguiatioaiC . ............................ stability ........................................... pressure control perfamilmce ............................... Compensated coatrol System ................................. Electronic Governing System ................................. Basic Features ........................................ Accessones ......................................... Control Primiries ..................................... Control of inuctimo Extracoon ............................ r Missing Signai Detection Featrae ............................ SensorRedundancy ...................................OverSpeeaTnpGenexal

.11 12 12 12 12 12 12 12 12 12 13 13 17 17 17 17 17 17 17 17 17 17 17 17 17 18 18 18 18 18 18


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...................................... ........................................... Automatic S t a t Controls ...................................

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S h i j l p i D g R e ...................................... ~ Shipneat ............................................ W i t and Storage of Equipmeat .............................. INSTALLAIION In-tion ........................................... SupervisionOfIaseallation

......................................... ......................................... ......................................... Overspeed'LtipSystem ................................... OverspeedScnsingD ................................. n i p speed .......................................... nipvalve .......................................... Combined 'Ltip and IhrottltValve ............................. overspeednipsystemsetting ............................... FACIDRYTESTING ..................................... 'Iiirbine ............................................. HydroTd .......................................... NoLoadRUnmngTesc ................................... SOUNDPESSUREJEVELS ................................ Gtaeral ............................................. swnd3essweLev& ..................................... soSmd~LevelMtasuremcntprocedme ........................ Camction for BacLgrwnd Noise ............................... souadResolution ....................................... Instnuneats........................................... S d A e nd o n ....................................... PRapARATI0NFORS"TANDSTORAGE ....................PRECTiON BasicFeaues UanUalTrip

p.pc23 23 23 23

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seCtrOn9

........................ ............................... .................................. ................................. .................... .......................................... ........................................... .................................... ...................................... Grwting ............................................ FlushingiiSystem ...................................... OPERATONANDMAINTENANCE ............................The Piping noblem as Applied to ?brbines FbmsDue to S e r Pressure tan FbmsDue to Temperatwe FarcesDue to Dead Weight AuowaMe Fces and Moments on Sttam Turbines DrainPiping Iak-ofli Fuil-FiowReii &Device CoUptingAlignmcnt

....................................... ................................... ........................................... Fouudation ......................................... steam Inlet and Exhaust Piping ............................... Cieamngof~SteamPiping ............................. SteamPipingSystems ..................................... I n e t i o n .........................................

3 6 36 38 4041 42 42 42 44 44 44 51 51 51 51 51 51 51

In-tim

operatioa ............................................ Noncondensing 'hbine opetatiano aMultisragecondensia ' f . g'Ihrbine .......... 'I)pical SEertmg Seqaence fima Steam nirbine ........................Maintlmance Intluduction

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UitemalWaterWashing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . steamhinty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INQUIRYGUIDE.. .....................................

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ForewordIlhis standard has been developed by the Steam "wbiine Section of NEMA. In its preparation andrevision,considaationbas been given to the work of other organizations. such as the American National Standards institute, the American Peuoleum institute, the AmericanBoiler Manufacturas Association, and the Amencan SoCiety of Mechanical Engineers, striving toward the deveiopment . ofstandards,anddtishaebygiventoaii whosesiandardsmayhavebeenh~~inthepreparatian of this publication. nK purpose of this standard f a singie stage and multistagemechanid drive steam turbines is to faciiitate the appiication of the.se turbines by engineers, users, aad conuactas, t promote o ecwomieS m driving rotalhg mechanical equipment, and to assist in the proper seiection and app~ofthedifferingmechantcal designs of turbines. NEMA Standards P u b l i a SM 23-1991revises and SupeISedes the NEMA StandardsPubliCation Steam Turbinesfor Me~hanical z)rive S e M e , SM 23-1985. User needs have been considertd throughout the development of this standard. Proposed M r c m m e revisions should be submitted t : eo m dd oVice Resident,E g n e i g Depamnent niern NationalEiecaicalManufacturersAssociation 2101 L S l E a Nw, suite 300 Washnigton,DC 20037 (202)457-8400

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Section 1 REFERENCEDSTANDARDS AND DEFINITIONS

AmtriamNationolStandandsInstitute1430Broadway NewYork,NY 1 0 8 01 S1.4-1983 s1.11-1%ANSUASME B1 . - 9 9 6118 B16.5-1988 B.0118 12.-93 B31.1-1989Spcjficprionfor Soundikwl Meters Spe@hations for Octave-Bad, Fractional Octaw-Band Anolog Md

DgM Fms

Can Iron Pipe Flanges mid Flanged Fttings,Class25,125,250a nW piPC F b g e s and Flrurged F&gs General Purpose Pipe ThrecuFr (Inch) PowcrPpngJ h t Ililrinnfactprors Association 25 North Broadway -,NY 151 09

The S t a d a d sf the IIqmsion Jont Matu#actmrs AssocirrtiOn (1980) (198s Addendum).Riuiont-An -t deviarian in SM caiceaoicityiodicattdbytheoatputofaprmimityprobc whichisduetovariatiaas in the electricalcondllctivjtymagnetiCpopertiesOfthtobsavedshaftsraface.

EntrrippedEwrgy-'Ibe~whichcemainsintk

volume of steam bappad betweem the turbine and a trip valve u notmew Valve. r FhibleShriPt-Ashaftwhichisintendedfmapera0ioaatspeedsgreaterthanthe firstlateral c r i h i speed. Hmting-Te oscillationof speed o other c011PD)led r pamnmx above and b l w the mean vaiue. An MsEable eo

coaditioll.Hydno --A test fm leairs and mtegrity 0fthepn~smecontainingcompentsofthe turbinebypressip1pag with water. ntemaiWaterW~g-Aproceduremwhichsteam having a high percentage of moisture is hjecte into the tuhine forthepinpose of removhg water soiuble &posits from the tirrbine blades and aozzles.

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STDmNEMA SM 23-ENGL 1991 W b 4 7 0 2 4 7 O524305 bLOSM 23-1991 Page 2Laterpl C r i h l Speeds-The speeds at Which the ~ITIplitude of die iaterai vibration o a machine rotar due t f o shaft rotation I.each their maximum due. Proximity Probe-A non-contacting device which eiecronidy measures the position o displacement mor tion of an obsexve surface relative t the probe position. o Purge A i r 4 method of seaihg in which air (or ineat gas) is b into the seal ar housing to maintain a slight i d positivep.essrireandthuspreventtheentranceofcoaruuninants.

criticalspeed.Therm0coupl-A &vice for Sensing temperatures in which a pair of dissimilar conductors are pined at two pints so that an electromotive force is developed by thermoeiectric effects when the junctions are at merenttemperature.NEMAStandard 130-91.

ResiSEnace lkmperaure Detector (RTD)-A device fr d o g temperature in which the ewhicai resistance of tbe &vice changes with mperaiure. Respoase The-'ib time required to m v e r to the d y suue operatingvalue afterasudden change in bad. Service Factor-he factor by which the maximum power capability of a device exceeds its rated m.



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SpeeiTied Conditions-Specified conditiolls are aU customer d e f d power, speed and steam conditions at which the turbine must operate. Steam liirbine-A prime mover which converts the thermal energy of steam directly into mechanical energy of d o n . SifShaft-A shaft which will not be operated during tf n o d circumstancesat speedsgreaterthan the nrst lrrl aea

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Section 2 CONSTRUCTION2 TYPES OF STEAM TURBINES 1

2.1.1

clsssified by Exhaust conditkns

2.1.1 .I NO"DPISING TURBINE A noncondengng turbine is a steam turbinedesigned to aperate with an exhaust steam pressureequal to ur greatex tbanatmospkricpressure. NEMA11-13-1969. 21.12 CONDENSING TURBINE Amturbine is a sream Wn designed to ieoperatewithanexhauststeampressurebelowamia6p~c

2.1 3.2 N O " T R 0 U D EXTRACTlN TURBYSE A nonconmiied exnaction turbine is a steam trrranC which has an opening(s) in the turbine casing for thc extraction of steam but which does not have means f a cantrollingthe presswe o the extracted steam. fNEMA SIPndard 6-21-1979.

2.1.3.3 NO"TR0LLED N ITuRBWE A I1oI1contTdled mduction turbine is a steam Mbine whichhas an opening(s) in the airbinecasingfainductioa of steam but which does not have means for CQltlDUiilie the pressureof the inducted steam. NEMA S W d d 11-14-1W.m D INWCTION

P=-=

NEMAStandard 1-30-91. 2.1 6 4

(m

2 1 2 CWslfedbyNunberofStegesand ClwvahreaSTAGE TURBINE 2.1 2.1 SINGLE VALVE -LE A singie valve single stage turbine is a steam airbine w i h has one govmor conmiled valve and one stage. hc

NEMA-

6-21-1979.

P E S R )m E RSUE B W A controlled induction (mixed pressiire) turbine i a s steam turbine which is povided with sepirate inlccs far steam at two pressures and has an automatic device f a conb.olling the f o of steam to the turbine stages followlw ing the induction opening. NEMA stendprd 6-21-1979. 2.1.3.5 INDUCTION EXTRACT" T R I E U BN An induction exmtion Mbinc is one which combincs t e fatum of extraction (controlled ar nanconmikd) h with the featuresof induction. NEMA standerd 6-21-19B. 2.2 STEAM TURBINE COMPNENTS 2 2 1 nirblnecaslng A turine casing is the e n c l o m which sumomis tbc rotating element of the turbine and supports the s t a t i m steamparts.CasingsshallbeaxiallysplitJadiauysplifa a combination thereof. he turbine casing W be divideaintotwourmon sections as follows: NEMA Standard 6-21-19B. 2.2.1.1 S E M INLR ENDSECTION TA T e steam inletend section is that portion o the riffpinn h f which containsthe higher pressure steam. NEMAStandard 6-21-197W. 2.2.1.2 EXHAUST ENDSECTION The exhaust end section is that partion of the cssing which contains the exhaust connection and the steam at exhaust conditions.It sha also contain the l w pressnn o stage(s) of a multistage turbine. NEMA Standard 6-12-1979.

2.1 2.2 SINGLEVALVEMULTISTAGE BN TRIE U A single valve multistage turbine is a steam trirbine w i h has one govmorconaoued valve and two or more hcstagts,

NEMASEendard 6-21-1979.

2.1 9.3 MULTIVALVE SINGLE STAGE TURBINE A mdtidve A i stage turbine, i a steam turbine ge s wbich has two or m a t governorcontmkdvaives and onestage.

NEMA spnd9id 6-21-1979.

2.1 9.4 YULTIVALVE MuLTWTAOETURBPIE Amuitivaive muitistageturbine is asteamuxbine which has two ar more governar Caimlled valves and two OT -stages215 C ~ b y P F o c e s S N e e b s2.1 3.1

NEMAStandard6-21-1979.

mTRIE U BN

D ( A W W A C ) EXTRACTION

A controlled (automatic) extraction turbine is a steam turbme w i h has an opening(s) in the turbme casing for hc the extraction of steam and which is provided with means far directly reguiacing the flow of steam t the turbine ostages following the extraction opening for the purpose of

mmiiingextraction pressure.

NEMAStandaid 6-21-1979.

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2.2.8.1.1 Aptsure impulse ur Rateau stage coLIsi8t8 d smionmy expnshx~ nozze(s) and one row o rotatiag f bkides. 2.2.8.1.2 A velocity-compoanded impuise o Curtis r stageconsistsofstationaryexpansionnozzle(s)Imdtwoa more rows of rotating blades. 2.2.8.13 A v e l o c i t y ~ p u n i d e d i m p u i s e ~ ~ s i a g e umsists of Srationary expansion nozzie(s), am?IOW at

rotatiogbladesandoneormorereversingchambas.TbepressmdropacrossaRateanstageisreiativelybw inwmpoaisontothepssmdmpacmsaCmtis~.Authorized E n g W n g l t l h n a h6-21-1070.

2.2.8.2 R ~ C T I OSTAGE N A reaction stage consists of stationary expanSionnozzie(s)discharginghighvelocitysteamjetsaitherotat-

ingblades.Apressuredropoccursinboththesiatioaary and rotatingelements.NEMAStandard-21-107B.

229 shaftseals--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

2.28.1 CASING SHAFT SEALS Casingshaftsealsminimizetheleakageofsteamoutof uie casing dong tbe shaft. For condensing turbines, seals are arranged t jxemt o rhe entnuiceof airinto the casingdong the ShaR *yare aaraaged fur the admifipimi of steam a a canstant low t pressmcand low m eam . prl eNEMAStandard6-21-1979.INTERSTAQE S A T S A S H F E L

Interstage shaft sas minimize the leakage of steam el h g the shaft between stages m amuitisfage m r b hNEMAStandaid6-21-1979.

2.2.10 Beerlngtlouslng Abearing housing Coataias andsupputs abeariagfs)

andisequippedwithseaistopreventlccageofdaodttie entnince of m o h , dust,and foreign matmi&.NMEA6-21-1970.

2.2.11 mtln(Y 2.2.11.1 RADIAL BURINOS Raclialbearingsarebearings Which s u p p a r t t b e ~

elementinhorimtalshaftbirbines.Iheyareofihtsl~~, tilting pord mnircin type. In verticat tmbrnes,these atfito bearings tnri;sllv positiOn the mtar assembly.NEMAStandrurl6-21-1970.

2.2.11 9 T H R W BEARINGS

Thrust bearings rn m g s which trammitthe a i xd thrust of the rotatllig dement t the beaping bousmg and o maintain the axial position of the mux assenibly m the



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casing. They m of the antifrictm, laad, ar scgmeniai tutuigpadtypt.NEMASWdaid6-21-1939.

2.2.113 ANTFRICTION BURIN08

2.2.18 ConadllngDeVice Acoatrolliagdevice is OM which manidly icaliy initiates action of a system which caaerols a(MnB1 apaationofthetiirame.NMEA 11-13-1968.

Antiictim bearings stmuid have a minimum rating l f ie of3 yearsa25 o0Ohoursw h e n a p e r a t e d ~ ~ a t 2219 ExtemalcontrdDwlce maxgnumtblUStdradislloadsaodat~speed. An extanal control devi is an element which is EAuthorized Engheeiing Inkrmillion 6-21-1979. sponsive to signais other than turbine spaad, ie., flow, The rating life is tbe number of houisatcunstant speed presswe, -,and soforth,dacis toconirol the tbat9perctntofagroupofidcnticalbearhgswiiiopcratc fbw o steam t the turbiDe. shalt be pnemwid f o Y* befcxe the fitaevie-nce of fatigue devebps. mecbanidy, hydraulically.or electricany actuated fiom kthomed E n g i i n g Inbnnaakn 6-21-1979. the signal sollfcc to position the governor vaive@). (Ref2.2.12 RotorA88etnbly mm Section 3.1.6.) NEMAStandard 6-21-19'19. "be r ~ oassembly is the rotlltingelemnt of the turbine t

u

whichinclubesaipartsattachedtotheshaft,excludiugthc caipling(S) unless coupling i integral Witb the shaft. sNM EA 621-1979.

2.2.13 W h 0 d s m ) wheels arediscs which are inmgrai witb,orxcdto, the ~ieshaftandoawhichbladesaremounted,orinwwhich

2220 WamlngDeVlce A warning de* is one w i h by vse o auiblc hc, ii l r means, or both, indicates that an abnomai apefatingumditionexiscs,NEMAStandard6-21-1879.

bladesorbuclrmsaremachined.

NMEA

6-21-1979.

2.2.21 Sentlnel Wamlng Valve A sentiael waming valve is a pressure warning device whichopenswhaithesteampressurerisestoapredetermined1eveLThedeVicesha dischge tothe atmosphere andshallbesolocatedasto be plainly visible& For condcaskig tl&K%% it shall be set a 5 psig 135 t kFa(gauge)]. For noocondensing me the minimm ns i seing shall beeither 10 percent o 10psi (OLpa) above r maximnm exhaust steam pftssuR, Whichever is greater.NEMA standard 6-21-1979.

A sentinci warning vaive is not recoaimended for the

following applications: a i n e s which um volatile gase^ t d locatiais where the discbarge of steam to the am+

-

2.2.16 H a n d W 0 ( S ) A hand vaive@) i the valve which isalates steam flow s to a gmup afnozzle(s) to pennit e&cient apetriton a t

- Mbineswhicbareanangedforauiomaticworunatm e start-up dd

sphaeisobjcctionable,hamdousorpmhibkdbyhw

redmtdpowerawithdualsteamconditionsHaudvalvalves can be either manuaily condied or arbomated and are used on singie valve turines oniy.NEMA SiaKliUd6-21-1979.

hir these applicaliom, an alteniate wanimg device optionaitrip device is iecommended.Authorued Enginwing Information 1-91.

2217 PmtecthreDeVice Apotective device is one which, alone oras p?* Qf a sy9iem,respondsinsomepredetemiinedmannerto,~sormalconditionsaoendllig theopewtion ofthe unitorsystem towhichit is connected.NEMA Standard6-21-1979.

2.222 s o w w s ) A soleplate(s) is a machined fiat steel piate(s) o castr ing(~)for mounting o the equipment supports and far f biting and grouting to the foundatiar.NEMAStandard 11-13-1689.

2 2 3 mapiate .2 Abaseplate is a fabricated of cast continuwsstructure havingmachinedpads for mountingof the equipment and for bolting and grouting t the foundation. oNEMASQndard 11-13-lQ69.

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S T D -NEMA Sfl 23-ENGL

m 6470247 05243q 266

2.3 FEATURESANDACCESSORIES

9. Insulation for the high tempemm section of tht Wine to limit exposed siirfaoe temperatme to 16pF (74OC) or other tempemture specified by the10. Steampresswegaugestoindi~inletsteam,~

.P -

Ionment.15. Supemhry instniments to m n t r such a vibraoio s tion, axial shaft movement,tempemtms, etc. 16. Shaftgroundingdevicetocarrytogromdanysatic charge which might be developed on the hirane romandwhichmayotherwisebuildtoLevelswhich ddamageturbhcbearings. 17. Rotor turning gear togeUier with driving maus, engagement and isengagementfeaiures, and lube oil pressure interlocks to permit s o turning of the lw

18. AlbusSm trip valve which provides a means far quick and positive shutof of admjssion stcam f a emegencY tnppuig. 19. Nonretuni valve(s) for blocking ihe revme flow of steamfkom~intotheturbmethrough~ orextractioaopenings. 20. Redmiantoverspeedtrip. 21. Exhaustreliefvalveornrptriredisctopre~over piessrning of the exhaust end section (see S ci e tm8.7).

mtorsystemonstatt-upandsbutdown. ..

22. Vacuumbreakertoadmitairiatotheexhau9tam nections d a condensing turbiue in cmk t reduce ocoastdowntime. Additbd items may be availsble.Authorized E n g i i t q ~ infamaiion 11 -.

2 s ControlledEXttadknandmledkd d n r l e r u k m bn s Conwlle exmaion, ccmtrolled indoction, and ummlled induction exmction turb8nes &ail include basic



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ring, nrststage,dexhauststenimpressure. 11. Coupling between the turine and driven machine (normaiiy fumhhed by the m8nufacturea of the dnven equipment). 12. coiipling guard SuppOIted frwi tbe baseglate oc adjacent bealing housmg(s). Tbe couplmg guard shouldbecasilyremovableandbe~ientlyrigid to withsiand deflection and plevent rubbing as a resuuofnamalt!odilycaitsctbypersonnel.Wbco continuauslylubaicatedcouplragsare~the coupiing guard housing should be fitted so that oil leaks will b p t d e me . 13. GlandleakageevacUatingappIiratuswhendiegland casngdesignrequiresitsuse. 14. Tachometer of the vibaatuig mai, machanical, r a e~type;iodicatiagspeedsfroniabovethcip speed to M o w the minimum aperatiag speed. Thchometers shall be suitale for the specifmed eavi-

SM 23-1991 page 7

features W i n items 1 thrwgh 6ofU.1, together Witti those lisied in 23.3.1 through 23.3.4.2.33.1 Controlled extraction turbhm shall bave apre+ 8utt regdath8 SySteB for mtroiiing mt p s s m of the extracted ste9m by regulaiing the fbwo steam to the f turbine stages fallowing the extracth opening(s). Anonreturn valve br the extraction apallng(s), which is also actpated by the ovaspetd tip s s e . is nquind far ytm installationintheexoactimsteamline(s).

242 speed2.4.2.1 RATED SPW Ratcdspeedisthespeedcanesponduig toratedpowa. * It is measiaed at the output shaft of the turbw, is expressed in rievdutioas per minute, and is quai t M less o than m8ximm~ u o u speed. s NEMA standprd 6-21-1979.

2.3.3.2 controlled mduction turbines Shan imve apesme regdating sysrem for cantrolling tticpm5urcof the imjucth steam toregulate t h e b w ofsteam tothe turbine

2.4.2.2 W u u Com~uous SPEED Mx u conhinuous speed is the highest specifiad ai m m speed at whicb a turbine can be operatcd continwusly pwidedproperovaspeed~goverwr- a r e

iastalledand operatianal.corabns

stagesfoiowingthein&ctionopening.Atripvaivewbi& isalsoactuatedby theoverspeedmpsystemisnquired fnrinstallaaon intheinductionsttamk. .NM EA190-1991.

2 ~ 3 NomralPower,SpeedandSteam hJ power, and cooditionsaretbost caiditionsfwadmd~aadatwbichrhesteam ratcwillbeguafan~NM EA6-21-1979.

233.3 Dependmg on the source of induction steam, the usashould consider the need for a steam ssainer in t i i s h e to protect the loweapressure stages of me turbine.2.3.3.4

m

-

NM EA

621-1979.


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AumaiEed Engineering Infornietion 11-14-1985.

U A S~Conditlons2.4.4.1 WNuW S W C t d m T Mmm steam ~ t i ~ a thelowest i l t stcam nu ii r e ne pressure and tempemm and lowestexhaustprcssm t o which theturbineissubjectedincontinuwSopaatiOa. NEMA stadard 6-21-1979.2.4.4.2 M A # ~ ~ ~ ~ T E A ~ ~ ~ N ~ T K I N ~ Maximum steam CDnditiOIls am thehighest inlet steam pitssrrre and imperature and exhausspIesllm to Whicb the tiirbmeis subjectedincaltinuousopaation.NM EA621-1979.

Controlled extraction turbines and controlledinduction turbines shall have a multivariablem l system i m which provibes interconnectiOn die pressiut rCguiatingsystemaadthespeedgovemingsystem.

2.335 conarouedinductim ~rtractioa trabinesshall inchdethecombinationofthefcxegoingitems.NMEA11-14-1085.

23A ~ ~ E x t r a c t b n T i a M n e r Nncmidxncinubnsblicuebac ocmieetitotriesalnldtbs

feaaacsiistedinitemsl througIi60f2~.1,togctfrtr~ith mwisecmnvatve(s)far theextractionopening(s). 'he quan2.4.4.3 Wuuu E N m v Smw tity and lomion of nomearni valves are tobedetermhl MniInm~geamconditi.Mlsiuetbe~inltt bythetrirbincman~basedonentrappedaiergy steam presswe and t e m m and the highest CxImust ~redimdaacypolicy. pmsm at which the turbine i requucd to produ a s NEMAStandard 130-1991. specinedpower~speed 2.3.5 N ~ l l e d k i $ u k n n i i b l I l @ S 2.4.4.4 hLET STEAM PRESSRE N ac n I e induction turbines sha inchidethe basic o i o mI d uiietsteampressiireis the pressureof the steam supplied feahaeslistBdinitnS1 tl1rough6of23.1,togetheswirb t o t k tUrbii.Jtis mwredat the $tcf3minlet conncctim a trip vaive@)for the induction opening(s). of the airbine and is e x m a s a gauge piessure.NMEA11-14-1985.

NEMAStandard6-21-1979.

24 TURBINE RATING .2A.i

PowerNEMA Standard 6-21-1979.

Rated power is the maximum specifiedpower output o f the~ine.Itismeasuredattheoutpitshaftofthearrbine.

2.4A.5 EXHAUST STEAM PRESSURE Exhaust steam pressure is the pressure of the steam system to w i h the turbine exhausts. It is measured at the hc exhaust connection of the turbine and is expressed as a

gauge pressure far n ' airbineSandasanabsolute pressrrre for condensing tuhines.NEMAStandard6-21-1979.


STD.NEMA SM 23-ENGL 1971 D b470247 0524311 9L4

2.4.4.6 ExtRAcT#))JSTEAM PRESSURE Extraction steam p s is the pressine of the steam mm extractedfrom the turbine. it is measuredat theextraction wnnecticm of the turbine, and is expressedas a gauge

2.4.4.13 DUAL Srrrun CNMl"S Dual steam conditiansare two ofmmcombin8tons of iniet steam pressme, inlet steam tempenitine, o exhaust r -pressure.NEMAStandard6-21-1979.

P===

NEMA-6-21-1979.

2.4.4.7 hwCnON STEAM PRESSURE Inductionsteam~isthepIessureofthesecoadary steam supplied to the Wn .it i measureatthe induci e s tionconnectian of thetrirbineandis expressedasagaugep#rsiae.NEMASEandaid6-21-1979.

2.4.4.14 VARIAl"S IN STEAM CCXJITlONS The Iatng, capability, steam flow, speed re , and pressme control shall be basedon operation at maximum stcam unutions as defined m 2.4.42. Steam Mbiaes shall be capable of operating under the followingvariatioasininletpressureandm~but p e ? f ~ s h a l l n o t n e c e s s a r ylbem accardance with * i

2.4.4.8 INLET STEAM TEMPERATURE conditions.continuousopetatiaiatotherthanmaximum Inlet steam tempeniture is the total teInof the steam conditioI1s sha require review by the turbiw mansteam supplied to the turbine. It is nreasiireda thesteam t ufacturer. inletcmnectionoftheturbineandisex~inde~ NEMAStandard6-21-1979. Fatireobeit~indegrces e . CW NEMAStandard6-21-1979. 2.4.4.14.1 VARUTKJNS FROU hhXUuUINLET STEAM

thestandaadsestab~foroperatmgatmaximumsteam

2.4.4.9 EXHAUST STEAM T M E A U E E PRTR luhapststeam temperameis the totai t e m m of the steam cxhartpted from the tinrbine. It is r n d at the cxhailst CoMectiOn o the tuxbine and is expresd m f degrees Fahrenheit or in degrees Celsius.NEMAStanderd6-21-1979.

PRESSURE

The turbine shali be capable of operating without damageat less than the guaranteedsteam flow tothe Mbine with average Wet pressure of 105 percent of maximum idet steam pressure. (This pemisible variation recognizesthe~inpressurewith~insteamflOW


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2.4.4.10 W A l STEAM T M E A U E R C" E PRTR Exaaction steam temperatureisthetotalteInperatureof the steam extracte from the turbine. It is measuredat the exixmirn connection of the tintiineandis eJtpressedin egreesFahrenheit o m degrees Celsius. rNEMASEendaid6-21-1979.

encountered in operahion.) The inlet steam pxsure shall average not more thanmaximum pressiire over any 12 month opedug period, Theinlttsteamprwsureshailnotexceed110perccmd maximumpressurein maintainingtheseaverages,e;xcept during a b d COilClitioI1S. During abmnmal c sdtm the steam paessare at the o i ii , tiirbineinletconnectionshallbepermitredtoexdmaxh u m pressure briefly by as much as 2pesent, buthe aggre@e drnation of such swings beyond 1M percent of maximumpssure shallnotexceed 12hwrsper 12mondi operatingpenod.NM EA 6-21-19m.

244.11 1NDUCTK))II STEAM TENPERATURE Uiductioosteamtempenimreisthetotalm~of t h e ~ s t e a l n ~ W t o t Itislmasmtd h e ~ a the iiiductionconnectimof die turbine and is expressed t in de Fahrenheitorin Celsius.NEMASEandaid-21-1979.

2.4.4.14.2 VARIATIONS FROU WXiNUM INLET STHMmPERAlURE

Theinietsteamtempeniturestaveragenotmorethan maximum tempexatme over any 12 month operatmg p e riod. In maintaining this average, the tempemm shall n t o exceedmaximum tempemureby nme than 1fl(8oc) exceptduringabnnmalcoaditions.Duringabaonnalcooditions, the tempcratiae shall not exceed maximum ternperature by m m dian m ( 1 4 O c ) fwojmathgperiods


-

~

~

S T D - N E M A SI 23-ENGL L77L

H 6470247 0524312 850

SM 23-1991 page9

h2-theenthalpyofsteamatwrhaustsLeam paeasiiredinitialenaopy. NEMA s&idard -21-197Q.2.5.1.2 AcniAL STEAM R A 26.1.2.1 TURBINE

-TE rbinesmunrateisthequaatityofrmctsteamnqairad by the tlirbioe per miit of power outpit, lneasmdattbt ouiputshaftofthe tmbme. I isd t y-e i pounds n ofsteamperhorstpower-hour(orinkilogremsasteem pa kilowatt-hour).2.51 -2.2 TURBINE GEAR STEAM WlE

-

Whenagearisprovidedytheturbineman~,thtturbine gear steam rate is the quantity o inlet weam f required by the turbine gear set per unit of power outpiit, measured at the output shaft of the! gear. It is &y



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STDeNEMA SM 23-ENGL 3993

M b470247 0524333 797

SM 23-1991Page 10eqxessed mpoundsof steam pet harsepower-hour (or in kil~0fsteampexkilowa#-hour.NEMAStendard-21-1979.

intenial taper threads conforming to ANSI/ASME B 1.20.1-1983.NEMAStandard 11-14-1@8!5.

2.5.1.3 GUARANTEED STEAM RATE' Theguarauteed steam rate is thesteam rate which will not be exceeded When the turbine isoperaredat w)rmal power, speed. and steam condkions.NEMAStenderd6-21-1979.

26.3

ArorlllaryConneUtons

ANSVASME B120.1-1983. W y , these are a d ring prtssure gauge - , drain CoNEMA-

AuxiliarycotlIlectiomthataredireadedshallconf~to efat

2.6 TURM"CO"ECTK)NS u 1 o u t p u t s h a f f ~

casingandsteamchest,casingsealingglandsandbeariqg h~~,cooling~,valve~l~~,and~fforih11-14-1086.

-

2.7 LUBRICATKIN 2.7.1 2.7.1.1

26.1.1 Omput shaft cxtensionS shall be Spatable for a cyimdrical coupling bore and provided with a keyway(& tapaed ooupling bom with a keyway(s), tapered for a hydraulic ft, or ntted with an hie!@coupling hub.N E M A W 11-14-1985.

NipressueTypekibrcation(Singieste(leWW)

2.6.1 2 When a tapered shaft extension with keyway(s) is specied,the taper, wupiing hub, andmupiingnut sha be in accardancewirb Figure 2-1. NEMA taper diameteSS areavailablefarshaflextenshsfrwi2 inches m 5 inches.NEMA11-14-1985.

2.6.1.3 if cyhdrical shaft Cxtension is specfied, it is ncommendedthat the cwpling-to-shaftfit be an inmfer-

ence fitNME A 11-14-1985.

OIL LUBRlCATESLEEVE BWNS (tiomzomL~~meB) a LU~~WOIIbe prended by oil l h ~SimShould ilar means. b Beating housings should be large enough to peanit . solidsor water m d e to the bottarn and should haw a dtain connection at the lowest point, ol fiil i fittings, and an oil level indicam. g C. . F ~ i l i h f o r c d i nshouldbeprovided~hcnne^essary to assure the proper oil temperahrre. nie cooling water should be supplied a a temperame t not exceeding 9 % 3 O ) 0(2c. GREASE OIL LLJBUCAE A N i F H C " ORBEAWNGS

26.1.4 When a hydraulic fit coupling is s e i i d the pcfe, mountiug method should be reviewed with the turbine lnallllfimmr.NEMAStandard 11-14-1985.

2.7.1.2

2.6.1.5 Recommended use o one and two keys and f keyways is as shown in Tbble 2-1.Authid Enginwring Intomiobon 11-14-1986. *

SteamComecUons 'Iiirbmeflangedsteam Connections shallbe facedand drilled for bolting to flanges w i h arem accordancewith hc ANSUASME B16.1 o B16.5. r CastiNnlflaagecOM~nsshallbeflatfaced The thicknessof cast iron exhaust flanged connections under 1 0 m c h e s ( 2 s o m m ) i n d ~ b e n o t l e s s m Class 25 o ANSUASME B 16.1. f Singie vaive single stage hariuwall Ysplitcasinganbines shall have steam cannectionsm the bwexhaifdthe trnbiae. connections for making up topipenot0ver2 inches in diametex (So m m nominal diamtter) shall have

22 &

Gmse-lubricated autifriction bearings should be regreaseable ~ Ikid. Grease fittings should exdie I tendtotheoutsideoftheniachiaetopermitregreasingduringopemion. Means should be provided far venting grease lutNicated bearings to pment the buildup of pnssure within the housing. Facitiesforcoolingshouldbeprovidedwbennecessary to assure the proper lubricant tempemme. The cooling water shouid be suppiied at a temperature not exceeding 909: (32Oc).27.2

Pressum tLpe Oil Lubrlcatii

2.7.2.1 ~ O D U C T I N It is recognized that there is awidevariation in turbine Szesandapplicaths which makes it impracticai t have o one recommended lubrication systcm ckign. However,

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STD.NEMA

SM 2 3 - E N G L 1991 H 6470247 0 5 2 4 3 1 4 623

SM 23-1991Page 11

the foilowingdiouidservewagenaal design guide totheoeafur~hisraquirements.

total cooling loadandshouidbearrangedandventedf? maintaining eitha cooler with the Wire in ojmation.

27292

OILPWPS

2725 ...

OIL FILTER(S)

Single or twin oil tilters may be used. Afiltafs) shoptd 2 2 2 1 A main ol pump drive^ from the turbine shaft 7.. i be capable of nmving panicles iarger than 25 micmns. ar a seperately driven pump to provi& oil for lubrication When the film is clean, the pmsurc drop sbould not aadgovemingshouldbepm4de.d. exceed5 Pgi (35 kPa)atdesign t a n m a a d flow. Tiviu flters should be piped i paraiicl witha c n n ofkw 272.2.2 Anauxiliaryoilpumpforuseduringthc starttransfervalve t permit the transfa of oil fiom 011c filta o u p ? s h p t - Q w n p e M d s h w l d b e ~ w h e n r e q ~ t o t h e o c h a w i t b u' tg~ oil flow. Each nUa the by bic design ? whan qecihd. niiS pump should be should be sized fm the total oil flow end sbaild bc Upowaedbyadiffemismceofeaagythanthemainoil ranged aad vented for lminmining uthu filtawirh tbe pimp.AprrssurtsensingdeviceshouMbeprovidedfcx tiirbineinoperation.Acommontrsasfavalvemaybt~ aptomatically sfming the ruailiary oil pump when the oil fortheoilflteIsaQdcoolas.m?l~cartridgeshouldbe pmsmeintbcmainsystemdmpsbebwapredetermined camsion nesisauu. Filter cases should be suitable for vl am opaationatapressurenotlesstbanthcreiidvahn~ For a Mbinedriven auxiliary oil pump, the turbine oftbepmitivedispiacementoilpumpsoratthemaximum 8bOdd d m to all of the @pli* pvisim of diese shut off discharge pressiire of cenhifugal oil pump.sltmd&L

272.3 OILRESERVOIR A samate ail ~ ~ S U V O ~ T should have

2726 RPNAND INSTRWEWTAT" ... 27261 Pressure sensitive devices sboahl be prwidad .... forea&prtssurclevel(forwrampie,oii h&tokarings, discharge 6rom oil pumps, befase and afta flta(s) and c ~ n h oil). Means should be pwidad fm BII ai-liee ~lmain~asappropriaie.Authorired Engineering Inforniafion l - C O s lllB.

a

ac .dt .

f .2.7204 oLcoolar(s) The oii coola should be capable of maimhhg the empuame oftbc oil supplied to the bcaringsatamaximimi d 120F (49oc), with a maximum woling water tmrpaaaarcmx excealhg 90F (32OC). It should have a f w l i n g f C ~ o f O .onlthe wataside fopcoaliag towel ~ water an afouling faaor asncommendcdby the manu-

27262 if bearing mctal thenwconples ot #Il)s arc .... not pvic, tben thamometers should be povidad for oilwtlet fromcachbesring housing.Tbemiametasmay be provi&dbefore and after oil d e r @ ) . Thermowells should b e p v i d d in the piping f a t h e m ofthCrm e t e r repiacemaitwhile oniine.Tbenmweiasshouki begaSfilledOrcrnrosion-resistantbimetalliCtypc.AuthorioedEngineeringI n

11-14-1985.

27263 An oil sight flow indicatm wbui spccifia .... shouldbe provided m the oil return from each caringhousing where thedesign permisAuthofbd Engineering Infotmatm 11-14-1985.


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nicMafarothtrcoolingwate?sources.'Ibemo~sbould be suitable fora working pressmeof notkss than 75 psig [517 kPa (gauge)] m the w w side. Singkartwin~kmmaybeused.Eechcoolershould be capable of operatioa a a pressure quai to o peat ter t r tima the ni f valve setting of positive displacement ol le i pumps o ofth maxllnum shutoff dischargepressiae of r ca~trifugali pumps. M coolets should be piped in ol paraciwith acontintmusflow transfervalve t pert., ,ithe o traas6er of ol from one cooler to the ocher without interi rupting the oil flow. Each cooler should be sized for the

27264 A pressiire regulam o relief vaive should be .... r providedto maintain the oil pressure level(s).A u t h o n z e d E n g t n e a r i n*g I ~ 11-14-10Bti.

2.7.2.6.5 Afterfabricafim,pipingshauldbecleanedd passivated by mechanical an4or chemical means.Authomed EngVieering I n h i i o n 6-21-1879,

2.8 PROVISIONS FOR THE ENVIRONhENT

2.8.1

Encksure Steam turbines shoud pfembly be installed in enciosedareas.Thee?Fe!&tsofundseMceconditi~may



b470247 0524335 5bT

m

SM 23-1991 Paga 12

be mi@ted by the use o one or moxe of the measmes f bescribed i 2.82 and 2 8 . n .3Authobd Engineefing Infonnetkn 11-14-1985.

2 ExporiuretoNaifal~ m in general, d exposed surfaces should be potected againstrusting by apaotectivecoatiagor paint after instalhion of the unit. Enposed workiqg parts which affect aperation d the u i such as govexnor, govexnor inkage, nt fuiuum pomts, Valve s e s and imilw elements should tm. b e ~ a g a i a s t ~ g i s t u i g the useof comwionresisbytantmatenalS. Equipment having nonpressure lubricated bearingsy x bearinghai9ngs. EqpipntnthaMig~l&iCaboihydrauEicgovaning systans,or both, shouldbepruwtedasbilowx

Exposu~toAb110mialAtm0spheric oondltkns if possible, the turbine should be located away froin damaging f m and vapars, or abrasive, magnetic ai ua metallic dust. If ti i not pnictical, the atmospheric hs s candirioas should be called t the aaention of the manuo factufft. Suitable materialsor protective coatings may be23 ..

requiredtoansetthecomisiveeffectsofthefumes.When necessary, purge air connections on bearing housings, glaad cases,and govemm should be provided.Auth#ired EnQnWringInfonnaoion 11-14-1s.

2.9 GENERAL REQUIREMENTS

sbouldbedcsignedtopvcnthetnaruiceof dust, and fmign mamiais t the governing s o

*

2.82.1 The lULnisystem 09 goveanar system, 09 both, should be protected againstthe entrance of water or foreign materials by proper seaiing devices. The points to beprotectedinchideallcofinectuwis - orapeningstotbeoil EaleVoir, goveznor. g r m t r bearing housings, and B o o , o

PmssureanTemperaaireRanges Sieam turbines shouidbe designed and proportionedfar operationatmaximumsteamconditions.Genedpressnre and tempexatme ranges utsown in Figure 2-2. The ranges are general, accmding to tempeam&xsure cambinationsat w i h pomt material or design changes, hc OrbOth,~~berequired.2.9.1Authorlled EngineeringInformation6-21-1978.

sidarelements.Tbereservoirshouieprovi&xiwirha ventwithanairierandcarnectionstofacuitsteremovd of water.2.8.2.2 In addition to the foregoingprotectivemeasum, tbe following should be included when ambient ttmpezgtrires will be less than 4?F (4%) 1. Far use durhg down times,drains sbaild vi&d whee water can colkctforallsteam,d, and waterlines, the turbme casing and steam chest, and the oil aad water si& of the ol coolex. Pneumatic i "blow down- may benectssary m someiostances. 2 Aheater for the ail mservoir.Ifaa electric heater is specineditmustbeofawifncicntlylowwaadeasity topmt coking of lkoilAn auxiliary pump may be reqiiired to eosure ol CircUlatBon for unitonn i

Vlbratlon T e vibmion of the turbine rotar (double ampitude) h within thespecifedoperatingspeedrangeas measuredon thesprfacedtheshaftadjacenttotheradialbeaaingsshall be m accadancewith the foilowing:2.9.22.9.2.1 SINGLE STAGE TURBINES The maximum permissible w i o n sha be not peatex than 2.0 mils for speeds 4ooo rpm and lower, or 1.5 mils for speeds 4001 rpm and higher.NEMAStandard 11-10-1985.

~resuat-protectionoypa.asa.

demaisoatedthatmtcbanid&electncalnmoutis~ent, this sha be added to the abwale vibration level op toamaximum 25 peacent of thedioweddoubleampiitude v i o 2 mils, whichever is greater. r 5NEMAStendard 6-21-1978.

AuthobdEngineeMgInfomiehon 11-14-1985.



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heating. o 3. An enclosure or bood witb venting t cover the govemlg system may be provided, and heating shouklbesuppliedtoprevent icing. The amountand type of enclosure and heating wiii be governed by localconditions. 4. Protection against fieeziag for instnuaenBand dPi@& 5. m e manufacturer shouid identay those lines i n

2.9.2.2 MULTISTAGE TRBINES T e maximum permissi'ble vibratian shall be inaccarh daace with F g r 2-2. The absolute values for vibrath iue levels above 3ooo rpm can be derived from the following formule 1 M Shaft mechanid and electrid runout sbaii be determined by slow rolling the rotor in its bearings while measming the Nwut witb a proximity probe. if it can be


6470247 05243Lb 4Tb

SM 23-1991 Page 13 not have the specified margins betweem the apaatingspeadsand~speeds.nthiscasetheturbinedesigna should Catculanerotor response to unbalance. The prime caisiderationisseasitivitytom~ Authorired Enghming Inlonnation 6-21-1985.

2.9.4 NAMEPUTEDATA nie following minimum data tiabiae nameplale:1. 2 3. 4. 5. 6. 7.

Manufacainr'snameandbcatioa SaialnumWRatedborsepower

Ratedspeed Maximuminletste9mpressureMaximmillletsteamtunpenitiite

fied).

StlfJu

be given on the

8. Maximumexhauststeampressure 9. M a M m u m e x ~ ~ p r t s s u r e ( i f ~ blc) 10. Tripspeed 11. Maximum continuous speed (ifdifmnt fim ratedrg6ed). 12 F lataalcritical speed m i 13. purchaser's equipmeat item number (when speciNEMA standard 6-21-1979.

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STD-NEMA SM 23-ENGL

1993

m

6470247 0524337 332

m

L

ft +'

I

I

CIE



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S T D - N E M A S U 23-ENGL

1991

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RPM. THOUSANDS

Figure 2-2 MAXIMUM PERMISSIBLE SHAFT VIBRATION

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SM 23-1991 Page 16

Table 2-1 RECOMMENDED KEY FITS--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

(up to & including) 1-50 2 250 3 3504

40 5065 75 90 100 115 125 140 150 165 180 190

450 5 550 6 650 7 7.50 8

rn230w)

910

Twokeys may be used in any c89e.

Table 24 GENERAL PRESSURE AND TEMPERATURE RANGES



S T D I N E M A SU 2 3 - E N G L 199L

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steam 00 cnmthe turbine. nie pilotvaivecoatroistbc flow of highpnssme fluid t the power cylink. This f o d o lw highpressmfluidcausesthepistonmthepowcrcyinda t move in rcspaise to the signai h m thegovanar oconQo1mechasiism.NEMA612-1986.

81.6 Extemalcontrol-' Extanal calm1 devices shall be m of thne Eypcs e

deaibedbebw:3.1.6.1 SPEED CHANGER TYPE -mchangatypeisdirtcts,iaDothe governing system which in hun positions the g o m a r coatrolled vaivt(s). The govenoat shall be !Aaxcd toprovidethe9pecinedadjustaiespecrange.

3.1.6.2 ReuOlESET Popsr TYPE ?be remote set poiat type is mcorparated dinxtly mio

thegovanmgsystemwhichinmposi~tbegovam ancudfd valvc(S). Tbc gwawr shall be 8ekctcd to provide the specincd adjustableranges f ai watroing patameta9

3.14 3 VALVE ACTlJAlW TYPE Tbe valveacluating typeissepame h n l ttlegovan. 'e extaaal signai acts t positiaa e i t k tbe gmaacr o coamiied valve@) or a separate liac mounted valve In thiscase.tbe govemxacts oniy asa speehiting @eemergeacy)goveniar.

NMEA

11-14-1985.

3.1.7 speed changer Thespeed changa is a device fwcbging the setting 0fthegoverningsy~withinthe~ifiedspeedrange while the turbineis in aperation.NEhkStrvidard 6-12-1885.

32 .

SPEU) GOVERNING SYSTEM

CLASSIFICATION SpeedgoYeaningsystemSs h a l l b e c ~ a s s h o w n m

Tbt 3-1. alNEMA standatd 6-12-1985.

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STD.NEMASM 23-1991 Page 18

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TWb 3-1 SPEED GOVERNING SYSTEM CLASSIFICATION

(SeeF g r 3-1for agraphic repmentationof speed rise iue charactexisticsof a Class D govenior.)3 . speedvariation 23 Speed variaiion, expressed as a percentage of rated speed, is the t t l magnitude of speed change or fluctuaoa tions h m the speed setting uner the steady state caditiom given in 33.4. 'Lhe speed change is dehedas the difem m speed variation between the governiag system in Operation and the goveZnmg system biocked tobe inoperative,withalloiherconditionswnstant, Sjmdvari&an includes dead band and sustained osciiiati~Speed variation (+ a) =

A

1 06

B C

0.75 0.50

13*7* 7*

40.50~ ~~~~

02 .5O Z~~

D

7*

* niese Maximum speed Rise Percent values can be achievedunderthef~wi43conditians: a Govemor system is adjustedfop maximum sensitivity. b. Rotational inertia of the equipment is relatively iargeforthepowerrating. c. Steam mditionsproduce a relatively low theoreticalsteamrate. Agowrnor s s e in seMce which meets ali the foliowytm

2xratedspeed

(See Figure 3-2 for graphic npresenratiai of speed variation charactaisticsof a Class D governor.)3.23 DEADBAND Deadband i the ttimagnia>dtofthechange in steady s oa state speed within w i h thereis no &ring measiirable hc change in the position of the governor conmilexivaive@). It is a measure of the speed gweming system insensitivity and is expressed in percent of xated speed 9.232 S MU r i n Sabiity is theability of the speedgoveming system to position the goveniar conmlied valve@) so that a sustained osciliath of sped or o enezgy input to theturbine fisnotproducedbythespeedgovemingsystemchniag

ingwnd.itionsshallbecapableofiimiingspeedtopreventoverspeed trip when load is suddedy reduced f o rate rm to zero: a nie driven machine is synchronous perator. b. Thegovernorsystemisoperatinginamodeinwhich it m s t demand for electrical power. o c niesteamturbinehasaninletpressureofatleast . 150 psig i1035 kPa (gauge)]. d Tbsteamturbineexmuastoaccm&~. .-Range Speed range, expressed as a percentage of rated speed, is the specined range of opeming speedsbeiow or above rated ,$xx!d, or both, for w i h the governor shall be hc d j d e when the tucbh is Operatmg nnder the control--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

operation under sustaid load demand or following a o change t a new sustainedload demand.324 Speed Regulation, steady State Speed regdation, expnxsed as a percentage of rated speed,is the change in gli5t8ined speed when thepower output of the turbine is gradually changed fmn rated power oulput to zen, power outpit mider the following steady state conditions: 1. when the steam mditiom (inlet inlet temand exhaust pressrire) 8Ic set a rated tvaluesandheidconstant 2. When the speed changer is adjusted to give rated speed with rated power OUlpUL 3. When any exteanai conmldeviisrenderedinoperative and blocked in the open positfon so as to offexnoresaictionstothefreefiowof steam tothe goveanar controlled valve(s).

of~~goveanor.

NEMAStanclard6-12-1985.

3 2 8bximunSpeedRlse .2 The maxjrnum speed rise expressedasa percentage of ratedspeed,isthemaximummomentaryincxeaseinspeed which is obtaine when the turbine is dcveiopmg rated p w r output atnited speed and the bad i suddenly and oe s unnpletelyreducedtozeao. Maximum speed rise (%) =



S T D - N E M A SI 23-ENGL

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107%

100.0%

i Iw O

a wt

I

I

I

1

I

I

O

LOU)

'

100%

J

I I I

Figure 3-1 SPEU) RISE NEMA CLASS D GOVERNOR

259

t

Figure 3-2 SPEED VARIATION NEMA CLASS D GOVERNOR

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STD.NEMA SM 23-ENGL 1991SM 23-1991 Page 20--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

m

b470247 0524323 6 3 6

=

P

O

LOAD

1oOY

I

flgure3-3 STEADY STATE SPEED REGULATION NEMA CLASS D GOVERNOR

335 ..

PmssunChanger

Thepressurechangerisadevicebymeansofwichthe setting of the pressure regdating system maybe changed for the piirpose of aajusting the p m s m o the exhaust f s a n o ofthe extraction or mduction steam w i e the tu r hi turbme is m @on.NEMA standard 6-12-1985.

3. SteaiyStatePressureRegulation .6 3 F r controlid extraction or conmiled induction type a turbines,the steady stare ~ ~ g u l a t i O n i s t h e C h a n g e in sustained extraction or induction pressure when, with identicalsettingsofall parrs of thespeedgoverningsysttm and of the presswe reguiating system(s), the exmxtmn a iaductian flow is gradually changed from rated flow I o zero flow. Fornoncondensmgturbioesprovidedwithexhauscpres sureregdatas,the steady s r a t e p r e s s u r e r e ~ the i s change i sustained exhaustpmsurewhen. with identical n seings of ail parts of the speed govemiag system and through tbe action ofthe p r t s m r r e m , the powaoutputofthesteamtucbineispduayreduced6romrate power output to zero power outpit.NEMAStandard6-12-1985.



STD-NEMA

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1991

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3.3.6.1 PRESSURE REGULA^ Rcssueregulationiscoasideredpositivewhcnprtssure iacreaseswith decrease in steani flow.NEMASEandard6-12-1985.

3.3.7 Stablltty Stabiity is the capabiiity of the pessure regulating NEMASEandaid6-21-1979. system(s) to position the pressurt controlled vaIve(s) so that sustained oscillationsof the coaadled pressrno(s) ar 3 ELECK= GOVERNING SVSTEM . 5 theeaxzgy~puttothesteamturbincarenotproducedby the pressrire regulating S Y drnmg m m undfx 3.5.1 BaslcFeatures m An electronicgovanhg system shaincludethe foilowmstaimfiow demands or fauowing achange to another value of sustained flow dtmand. ingbasiccompooeprs: 1 ~ For Ihe pirpose of this standad ~ ~ i l . l a t i Sensorswhichmeasureanoperat8igparamctaof the turbineai system, andpoduce ~bY~pressureregulatiagsysteniOfelectricsipah. pressurtar of encrgy inpt are definedas the dinaence b c t w c c n t h o s e e ~ w i t h t h e p r e s 9 u r e r e ~ s y s t e m 2 Agovamx which compares ( s ) fnw dic seagor(s) witb the seiectcd set point(s) and padeces a in semicc and thme existing with thepressrinregularing Qgnal(s)fobthevalveactuator(s)tomaintainsystem system blocked o inaperstve. rNEW-6-12-1985.

34 COMPENSATED CONTROLSYSTEM . Acompcrisatedcontral system is one w i h is provid hc with intaconneciions between its conml mechanisms so that the action dthe speed governar or of the pressure qdator(s) also directly actuates the Othet control mechanism.

Parametebs3. An actuam@)whicb positions the valve(s) directly or though a a m l nucbamm i n I e s p s e t o h * gov=SiEm. one or mon of followingparameters shallbecxxumlld bythegovemingsystem: a speed . b. Eachinduction/exaaction~ c. othersforspecificapplicatiom.NEMASE8ndard 11-14-1985.

338 Pressum~rolperformanee A Class D goveniOringsystem (see 3.2) shall exhibit the following characteristics when u t i h in a cm oconml s s e : ytmw . 1 changeinsuseainedspeedshallbe196maximum for any sustamed change i flowwithin limits of 5%and n 95%of maximum inductionorexmuionfbw guaranteed forthatload.NME A 11-14-1985.

3.3.8.2 Steady state plessare regdation shall be 0.5 psi (5 3 kpa) maximmor496 of ratedexbaust, extrauion.n indmion plesule wtpressed m psig oc kPa ( b ou ) a s l e; whichever is larger.N E W S U d d 11-14-1985.

332The following are accessories which may be selected, aependingonratingaod~u . 1 CONTROLP~ES Asignal selectmmay be incorporated intbegOVUIIOrt0 aowthegovenwrrtoreceivesignalsfromse.veralscnsus and tochoose the signal, which wiii result in thc piopa

3.3.8.3 sustained 0Scillat.i~ canttolled pressure, of wiien aprating a C O I I S E B ~ ~ demaad op foiiowing a t flow change to another canstant flow, Shan notcxcetdoa psi (1.7 kPa) ar 2% of thecon~fledpnsnireexptssedn psi i ob kPa (absolute); whichever is larger.NMEA11-14-1985.

valveopening. Any prm. may be primary which the governing a. m a as constant during IK)iTmBI operation. SyAny panunetex could be secondary which i i g n d as s lcQgasitisbelow the preset value.

-

334.4 s ~ o s c i l l a t i ~ o f e i a e r g y i n p u ~ w h e n o p 3.599 CONTROLOF INDUCTION OR E X T R A m &gatconstant f o demand or foilowing achange to lw The governor may be designed to control the low presanorher~tfiow,shaUnote~4% ofratedpcwer. surevahrt(s) daninductim urextlxtion m e in coni n junctian wih the high pressure nive(~). t i case,the in h s 338.5 The range of adjustment for ptsmre change(s) governar wnmls the flow t maintain the steam pressure o sha pennit adjustment of exhaust, extraction, or iaducat each controlled extraction or induction opening while tion pressure betweem f5 p i g (35 kPa) M f10% of the simuuaneously controlling speed when necessary for the coamlled pressure expressed i psi or kFa (absolute); n appiication. whichever is iarger. NEMA11-14-18!j.



S T D m N E M A SM 23-ENGL L991

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Agoveniar with h i s capability incorporatesfeatUtes to adjustaii the ccmtroiied valves i mponse to a change in n any controlled parameters.NEMAStandard 1-1-1991.

352 MISSHG SIGNAL DRECllONFEAtLIRE ..3 nie missing signai &tecrion feature monitors all input signahandaetaminesifthey are in the cmect range. Any signai that is out o range shwld cause immediate action f by the electmiic govexnor to enSure safe operation of the tmbine,and should cause an alami indication.

3 5 . SENSOAREDUNDANCV .248.5.2.5 OVU1SPEEDTmP nie overspeed trip feature in the governor can be provided in addition t the primary trip. o

theirassociafedWiringshouldbepro~fmnheat,weat and induced signais Local codes and area classifshould be cn oWhenmi~basedturbinecontrolsystemsIrre provided which interface with plant distributed control systems, there may be some overlap of control loops and confusionregardinginpuWoutputs.in these cases the pni chaser and the vendor should mutually agree upon scapt and responsibility spiiL Extemal selpointscan come knn the piant DCS but the turbine control loop should be suppiie by the Wine manufacturer. A typid eiec&onic governor schematic is shown m Figure 34.NEMAStandard 1-30-1991.

3 5 2 other demonic governor accessories m a y be ..6 available.GENERAL Caw shouid be talren in each installation to provide for adequate wiring. in addition, elecmnic governors and

3.6 AUTOMATIC START CONTROLS Automatic start controls are avaiiabie for turbine and driven machine. nie Wn manufacturer should t mie e suited for recommendedequipment and pnicediiresAuaionred~neeringInfonnabon * 6-12-1mS.

INPUTS

Figure 3 4 ELECTRONIC GOVERNOR FOR PUMP OR COMPRESSOR CONTROL



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353 ..

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Section 4 PROTECTION4 1 BASICFEATURES Thefollowmgfeaturesandaccessoriesarenecessaryfar the proper functioning of equipment and safety of opera41.6 Comblned mp and mmle mive Thecambineatrip,and throttle valve is separate fmm the govelnor controlled valve@) and is closed (tripped) m response t the action of the overspeed sensing &vicc, o other safety &vices or manuai trip device. ?his vaive pennits manual ttirottling of steam to the turbine. NEMA standard 6-21-1978. 4.197

tion:11.1Ananugill@

Each turbine shall be pvided with amanual tripping device to ciose h i p valve o hip and throttic valve. rNEMASEandard612-1985.

overspeed

m h g

4.12 ~ M p s y s t e m Theoverspeedtrip system shall besparkpioofandshall include the overspeed sensing &vice, linkage. and a (rip valveora combined trip and bottle valve sepatate from the spce governor conmiled valve@).NEMA11-14-1985.

The tnp speedseauigsshowninTable4-1 be above shall the speedreacbeddue t the maximum speedrisecharaco Eeristic of the govetning system to avoid tripping the turbine on sudden loss of load.NEMA Standd 6-12-1985.

A13 overspeedsensingDevlce The ovaspeed smsing device mc1Udes those elements which are direcily responsive to speed and which initiate action to close the trip valve at apmkammd -speed NEMA standard 621-1979. 41A

when design or application of driven equipment requires trip speeds other than thoseshown in Thble4-1, the trip speed should be specified.Authohcl Engineering Infomiation6-21-1979.

Table 4-1 TRIP SPEED SEmNGS

mp e s ed Tbt trip speed is the speed at which the overspeed ansing device i set sNEMAStandard6-21-1979.

A B

41.5 TpVahre "be hip vaive i separate f o the goveanor conmiied s rm vaive@)and isclosed (tripped) in responset the action of o UaiIripdeVice.NEMA6-21-1079.

C D

115 10 1 10 1 10 1

theoverspbedscnsingdcvice,othasaf~&~orman-

*An vrluaueinpe

Documents

NEMA SM 23-1991 Steam Turbines for Mechanical Drive Service