ML19329E357

Forwards IE Circular 77-05, Liquid Entrapment in Valve Bonnets. No Action Required

ML19329E357
Person / Time
Site:	Midland
Issue date:	03/29/1977
From:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
References
NUDOCS 8006120666
Download: ML19329E357 (1)

Text

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. CENTRAL FILES

'e MAR 2 019F Pochet To. 50-32')

Dcenct 1!o. Su--330 Con:Unces rouer Com any LTTil:

tr. :;tephen II. Ho: mil Vice President 1945 Ucct Fnrnall Bond Jacknon, '3 49201 Contiene.n:

To all c.pplicanta for, or helders of, Construction Pe.mi ts or Operetlug Licenses for Power Reactora:

The enclosed Circuler is being dictributed for infor~atica, in tiu bolict thr.t tua subject encter is of sufficicut rafety sinnf ficance to ut.rrnnt epecific attentien. A specific reply in not re unated.

Sincerely, i

Jarec C. Koppler Director

Enclosure:

IE Circular I:e. 77-05, " Liquid Entrap.snt in Valvo Dennota"

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March 29, 1977 IE Circular No. 77-05 LIQUID ENTRAPMENT IN VALVE BONNETS Description of Circumstances:

Cate valves of the type known variously as " split-disc," "ficxibic-disc," "doubic-disc," etc., have the ability to scal against both seats at the same time. Under certain circumstances, when the valve is closed, fluid may be entrapped in the bonnet cavity, and if the system is then heated up, an uncontrollable rise in pressure in the bonnet cavity can result. The reported effects of such pressure rise range from inability to open the valve, to structural failures of internal parts of the valve or failure of the bonnet. Consequences range from ?.oss of function of the valve to fluid escape and injury to personnel or damage to equipment in the vicinity. Detailed informa-tion is provided in the enclosure to thic Circular.

Discussion:

The most common cause of fluid entrap =ent is the orientation of the valve. Valves in pipelines where the pipe is horirontal, or nearly so, and where the valve stem is oriented horizontal or below the horizontal, result in the bonnet cavity constituting a drain pochet, where process fluid or condensate can collect while the valve is open.

If the valve is then closed the drainage is trapped. Valves are often installed in such positions for reasons of space or operator convenience. Other pipe and valve orientations can, under credible circumstances, entrap fluid. LAn example is filling a section of steam line for hydrostatic test, draining the line without opening that particular valve, and then heating up the line with steam. A variety of actions have been proposed to alleviate the situation, including internal pressure relief passages, external pressure relief paths, and-specially controlled procedures.

You may wish to alert your engineering, operating and maintenance staff to the existence and characteristics of the subject of this circular, and to consider the potential of your facility (s) for ain occurrence of the type described. Depending on circumstances, L

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IE Circular No. 77-05

- March 29,1977 any of a variety of corrective actions may be appropriate. Most of these arc, hot.ver, susceptibic to human error, and, to the extent fcanible, we suggest that valves be installed to minimize the potential for entrapment of fluid.

Enclosure:

Ltr., dtd 2/24/76, P.11. Avtroy, Walworth Co., to J.11. Tillou, NRC, w/cncl.

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.o Attention:

Mr. J. 11. Tillou, chief

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Licensee Contractor and Vendor Inspection Program

Subject:

Potential Overpressurization Problem in Valves l

1 Gentlenen:

Con fi rmi ng our conversation of January 30, 197G, l

this is to advi' e you of the possibility of an overpressuriza-s tion that can happen in gate valv'es-having flexible wedges or having dices with equivalent flexibility.

Our particular l

concern is with Pressure Seal steci gate.valvos having flexible wedges and being installed with the stems horizontal or below l

horizontal.

Overpressurization is covered in the following paragraphs from AflSI B31.1-1973, " Power Piping" and A!!SI B16.5-1973, " Steel Pipe Flanges. Flanged Valves, and Fittings":

l ANSI B 31_. lf l 9 7 3.

Pace 26, Paragraph 107.1C

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I Where liquid trapped in : cloted vahe c:n be heated. an uncontreibNe rite in pressure c:n result.

(An exaniric rni;Jit be a ik.sible wedre gate valve.in.-

stalled with the steni horizontal. hasics heat frorrr.

warrn up of the pipeline pplied to liquid fion the' testing.cle.'ning, or coi'de:: sed fluid. such liquid being; entrapped in the honnet section of the closed vahc.),

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TYhere such a conditiori is possible, the Owner shall' l

provide ra:ans in desi;n. inst.,112tivu.andlur op. ration j to assure that the preuvre in tiie vahe shalt not ex.

cced that allowed t>y the Code for the attainn' 1:rn.

perature. Any resultie'; penetration of the pree.ure wall of the valve shati n:< t the requirements of this Code and of drains in ANSI 1116.5.

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United States.itucleer Februa ry 24, 1976 Regulatory Conmission AllSI B16.5-1973, Pace 2, Paragraph 2 2.3:

Fluid Thermst Emansion. Certain double '

seated vs,lve designs are esp 2b!: of sealing simultane.

ously ossinst pressure differential frem the bonnet section to the adjacent pipe ist both direedons. In.

such valves, a cirecimtance in which the bonnet

. section is fil:ed with liquid and subjected to an in-crease in temperature can result in build up of pres. j sure in the bonnet section. Where such a condition !

Is po:sible, it.is the responsibility of the purchaser to prmide or require to be provided means.in de.

sir,n, installation, and/or operation to assure that the pressute in thi valve shall not exceed that al-

' lowed by this standard for the attained temperature.

For discussions and recommendations concerning this subject in the aforementioned valves, please refer to attached Exhibits A, B, and C.

11e shall be available 'for discussion relating to

'. this or shall try to supply further data if desired.

Yours very truly,,

dvd P. 11. Aut/ y Chief Eng.fnoer PHA::ac lt At tachraents t

P.S.

Concerning the Exhibi t A (BUS!!IPS Ins truction 9480.72 with its Enclosure 1), attached copics of letters of February 2 and 12 give permission to release this information.

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February 2, 1976 s

i llaval Ships Engineering Cdnter Center i;uilding

'Pr.ince Georges Center ilyattsville, ilaryland 20732 Attention:

fir. J. F. C onway, Section liend Valves, Piping Components, and Structural Analysis Secti:

Code 6153E

Subject:

' BUSHIPS 9480.72

.Sor 64SAS-303 18 Junc.1964 Gentlemen: -

Confirming our telephone conversation of today, permission is requested for llalworth Coapany to submit a copy

' of the subject letter, along with its Enclosure 1, to the United States !!uclear Regulatory Coc: mission for use by it in dealing.with a possible problem in overpressurization of valves.

I have discussed with the ilucicar Regulatory Commission

.. the possiblity of overpressurization, especially as applied to steel cate vulves having flexible wedges and mounted with the stem horizontal or below horizontal, and would like to use the

• i subject document as background material.

't If.you have any later material that could liheuise be used on this subject, I would appreciate receiving a copy

.and permission to submit it to the fluclear Regula f.ory C.ommission.

Yours very truly, P. yrg A,9 II. Autpay Chief Engineer Pila:me, t%es for i.sdvst v... everywhere e

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9505 Ser 287 12 FF* B 1975 Waluorth Cocpany P.O. Box 1103 1:nff Avenue Greencburg, Penacylvania 15601 Attention Mr. P.ll. Autroy Chief Engince:

Centlemen:

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F.nclosura (1) is forwarded in renponse to your letter of 2 rebruary 1976.

• Picace be advised that the Naval Ship Engineering Center hos no objection to enclocure (1) being used in any articias or conversations pertaining to the subject in question.

As a tadtter of infort.stion, the pertinent contents of enclosure (1) now, and have for souc years, formed an integral part of the overall steam systect design requireccats for Shipe 'of the United States liavy.

Sincerely youro, MD&W w

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Navd S:::P E':$n0Mn3 Cor.ict Encl: (1) BUSllIPS INST 9480.72 Ser 64UA5-30 of 18 June 1964 P COf't. c-f

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-._w From: Chief, Darsau*of Ships

, To:

Distribution 1.ist Sub,j:

Surface ship stema systes valves, operat.. ion of prior to vamup Enel: (1)

Requirements and Procedures for Modifying stema system Flexiblo Gate Valves as :lecessary

- ).. Puy}p_n3 To pro:.ulgate instructiens concerning the operation of valves prior to the adnission of stects to the syct,c:a.

2.

' oystenn of non-nuclear ecnstruction.fie_op,c. This instructicn applies to all v 2

It does not apply to nuclcar con-

.t.tmetion for which separate requirements have been developed.

although specifically directed at protecting ficxible wedge cate valvesFurther,.

froa overpressurit.atien, this instruction applica to all stec= syste:a valves due to the desirability of re oving water fron all co.mponents of 1

otexa :,ystems prior to warmp.

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gate valves in stem syst.ess it to prevent binding when the valve the closed pecition.

line expansien producc:In high pressure-ter.perature ste a syster.s,

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pipe i

tend to

• lit;htly distort the valve bodies.stresecs and st, rains at valve end connections whic 1

If the valve wedge in solid, ogd, in effect, clamp the. valve shut.thic dintor:,1cn will cause the valve se..t I

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i other by an integral hub in the cent.cr.ucdges, ubich are best desc lt Uith this design, the ved.;c will flex as the valve seats press ac,2 inst it, thus avoid.ing the clamping effect Dceause of this very desirab3 c characteristic, the !!avy, as well t.o industry tuts flexible w:dge cr.te valves in all cases where piping systen c>

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iu,a signi11 cant fact.or.

.pansion 4.

Dineuur. ion.

cteam on the line is :nentioned in several docuraev n,The necessity of d ine'tuding the UUSliIP3 Manual.

Unfortunately, it is not, adequately covered in these doctencnts l

to steam admission has been overlecked.there have been instances w and p'rior As a result, several icolated

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instances of s:rious damage to flexible s.edr,e r, ate valves have occurr:d.

• 'is characteristic of ric::ible vedr,c Cato valves that if water enter:s the body IL neck as a rer.itit of syst,en hycustatic te-ts, or by other ra:ans, wMle the

• th+ vrilvo is either opened or the water is recoved via a body Drictly, this is due to the fact that with the valvo in the closed position r.

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end a d(fferential precc'ure acrono the ucdge, the upstrea= nide of the wedga uill novo away from ite acat, pomi.ttin;; wat cr to enter the neck cavity.

An the body neck and line preucut'co equaline, or the preocure in rapidly taken off the line, the upstrer.rt side of the wedge coven back againct its scat, ncal.ing off the body, neck and trapping any water v.hich nay have entered.

If the water r> rains in the body neck, as. it idll if the valve is not ' cycled or drained, and stcaa io put, on the linc,* a situation closely allied to a boiler without a relief valve exicts.

The stem having a higher prcosure than.the water in the neck, will prevent water froa flowing into tho lino even though the upntream face coves avay from the ccat. As the pressure equalice::, the cycle whereby the watet initially became trapped, is repeated, caly this tine the water has been heated by the ince=in6 utcam.l' 1

-The otcam, however, continuca 'to heat tho' water due to its close

.prodnity *and higher tc=perature, causing the water to expand.

If the initid.

quantity o:J trapped wate,r was large enough, the initial te.parature differ-ential between steam and water great enough, and,the heating cycla continues

' uninturrupted, the end recult in predictable.

The water prescure w,*11 build

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up, due to the water's expansion being restricted, until cither,he body neck ruptures, the bo:ulet lift.c off, or the seat ringa conap c.

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It should be noted that thic phencuena has been proven by calcula-tions and controlled tests, during which a pre cure was generated in the body neck equal to ten ticas that which c).icted in the line.- M far ao actual install.ations are concerncd, there are only two known cases where this over.-

preocurication haa resulted in damage on nan-nuclear curface ships and both ocenr;ances would havo been avoided had proper vamup procedures been c:.iployed.

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Wr.,uo Proc edures.

The following steps should be incorporated into all operatinc procccures covering vamup of steam systema,.if they i-clready do not fom a part of sacc, prior to tho adsission of otcam:

(1)

Cycle au valves to accertaht t' hat they are operational and leave them in. the open posit, ion for at least one lainute to penait drainago of the body into the lino.

(2) Open oil drains on the valve bodica and in the [ine.

(3) operating procedurco. Lino up the nyatem for wamup in accordance with cristing All valve body' draina should be lef t open to petnii 40P c:dsting inctructions.drcinage throughout the warmup p'eriod.' Other dr' ins ch a

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1 hoceed with vari..up operation and clone ec1ve body draina (h) 1 at the concluulon of carac.

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Valven 'Jocated.dth theit nte.a below the horir.ontal in/'recpire modifice. tion in actition to the requirvaentu of ocction 5.c. to protect ther:. f rc.r. the poscibilit.y of everpressuriantion.

The nodifications c.nd how to perform then, as necennary,..re given in enclonurn(1). Thenc ::odificationn are generally censidered to be outside the n9real capabilitica of a chip 5 a force. Therefor, the/ should bc perfor=ed during e. nhip;ard or tender avai.1 ability period.

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BUS!! TTG,j,',.,2r. m,1 The Ihnual sdll be reviced with regard to uteem oyntcra draina;;c and tac subject will bc conciderably replified.

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Effectivp thly. This instruction becmeo cffective.;mn receipt.*

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l DISTRE11rICN LIST:

J. J. Stillwell SNDL L1 MAVSHIFIDS

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11,0 L19 UAVSHIPEPPAC

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- (1cus 29S, 293, USS DiTERPRISS CVA(M)6.f, a USS BAEDRIDOS DLGM25) 29 31 32.

. ynIS D1!W.CTIVE STCO:'ID AT:

copy to :

Supply D:pt., N;3sti (Unsa y23 A (l'ru.il only) tilhVYD I.nnex, Code 514.25)

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M Juno l'X>4 J plat.e should be attached in a conapic'ious location reading u7;;IS $!/.13E 1/.0 !. */.GT liOLT. I*i ?!!?. UI'~,7TJ.'. t GITis C? 'r,!E 'n?.D0'.

I? Wrk Is J1.;P.0VT,1) ::ATJ, S'JHC IT U 'll'!L'.C3D Til*-l SA:'S 1.Ti."

This t.:odification for "one vay" valv, s vill prevent over pressurization o3ne.c the hole p:9 vide.6 a conntent, vent to 1.hc upstre.m pipin:*..

Tho reaton

' for usine. thin type of iodificatica for thcae valves is to niinjnine the

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., nu.ber of drains that mat be incta.Lled.

For "two way" valyca, the drilled dioc is v.nacceptabic since it wuld provide a con: tent leaka:;: p.th throur,h the valve uhen closed, and stem presourc in applied to the side opposite the drilled hole.

Therefore, utw s,3y" valves with, the aten located belost horizontal =:t be provided with body neck drains to at::ouphere per the fol.lo dug:

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'% Incation of drain hole in the ncch should be close to the top of tho neck BUT care chould be taken not to drill through the pressure ceal regien. -

So:seplace betsteca 1/1 to 1/P. dem frc:: the top of the valve (looking at the valve in the upright.positiori) should avoid th'c region, but thic chould be checked before any drilling. See fjoto 9 2

Pre-hea.t3ng ar.d stress relieving (as necessary) should be in cecordanco I

with !!II.-STD-27Li.

3. Drain valves per IE4V-220

h. 17elding por IUL-STD-2'/,0.

5.

Drain holen into valve bodica shall bo in 'accorde.nce with liIL4TD-22A.

4 6s Drain valves and piping shall, be 1/4" 173. !!aterials casac ac i; ate valve body.

7.

1.' hen drilling hole, drill far enough off center to avoid wedga guides inoldu the valvo body.

8.

Do careful to avoid valvo stem if hole in drilled with thu valvo l

partially asse.d. bled.

9.

The prEscui:e scal region lo in the top of the valve body and i' evidenced by n ntainles:s stcul or sto111t.ed overlay; hole chould bo drill:d below this CVer. lay.

Enclosuro.(1)

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' hero is r.no other evf.r.ple, *:51ch folloss, and whleh hr.s bech incitaded to der c netrate t'm c.are thr.t wst be tak.a.t.

In de tes-sistin;, whet.hr r a valvo i t, 8'cne'; or ' tm way and, fun '.he:. '.no carc which tritst be tiaken in dete r.aining the corter.t, c.:difict. tion.

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' Tho c' bo in p.inL ia c. conventier.al reducing station, per the following a

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Tho valves to be considered here are 11,12 and 13 Yalvo 11 is a ene.27 valve, when closed, with stcaa pressure alur.ys coming frc:.1 the "L'id side.

Ynivo 12 is a thmt.tle valve, globe oc needle type, and is not irn olved.

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Valve 13 in a ono vay valvo EUT, it is a one way valvo $n the directicn

,qpno n D. r-to no - A1.

If ve.1ves 11 ma 13 'r.re closed to it,olato vrilve U.,

and 1?. is opened for operat,1cnal p.trposes, then valve 13 vill be preocu.r2.::cd fror.: the downotreata sido c.nd it e.uct be r.cdified accordir.g.y.

%o Isodifications to be applied are:lilth the cbove e.w:ples as a basis for deter:::

(t.

One way valvo - Drill a hole in the upstreva side of tho tecte.

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Two 1.ay valvo - Install a drain to trosphere in the vt.lvo neck.

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Tho hole.

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7hc "one uny" valves in the above sketch, by the afore:aintioned :

dutiniti@; nVU S> 0s 1r Ur 10*

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The "Luo vay" valvea in the above sketch, by tho aforem.entioned definitien are 3, 4 and 9.

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.o Tho " borderline" valve:, depending upon a particular Installablon are 1 and 2.

Dased on the above sketch, the definitica of'a "ono way" valvo can no expanded as follows:

a.

Any valve locat.ed in a syste:t after any cross connections so that it cannot be pressurined frca the direction that is opposite to wrmal. Refer to valve nur.bers 5, 6, 7, s, 10.

b.

Tho last valve in any system.

Refer to varve numbers 5, 8,10.

'Any valve located before any cross connection.: from other f~

c.

yste:ss,which has a valvo located batueen it an;l the c= o.*:r. connection, o that it can be isolated if the cross-connect valve is open.

For c amplo, dvcs 1 and P. can be isolated if the croca-connect valvo 9 is opened, y closit:g valves 3 and 4, respectively.

Sinec these valves will only calice pressurce froa the boiler side no:r. ally and can be isolated from

,l' J.hcr systems, they can be considered a: "one way" valves.

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.Valven 1 and 2.therefore.are c==ples of the " border line" I

nces inentioned above.

If valves 3,'and/or 4 were not present, then valvea

. and/or 2 munt be censidered as "two vay" valves since it uuttld not bo ossible to isolate then if valvo.9 vere open.

.j ho. definition of "two iray" valves can be expanded as follo.c:

n.

Any vdvc uhich vill be pres:ntriced4 in the direction

. - l-y;asite tb nor.nl when crocs connections are opened.

Ecfor.to valva nbers 3 and 4 which are nor:'all7 prescurined* fron the boile: side but

.E closed and the cross-connect valve is open (valvo 9), they would bo

.l rassurined from the opposite direction.

b. - Any valves in branch connectichs khich lead to $ cor:on header hat cannot be isolated from the header by closure of a vdve between the=

l nd the header. Refer to vdvc n::chers 3 and 4.

If boiler "B" was secured ud vdves 2.,nd 4 closed to isolato it, then valvo 4 sould be pressurised*

m the boiler "A" cido, or oppsalt e to noz.=1.

Reversal of this preceduro Ould thcn replaco valvo 4 with valvo 3.

,..y; The tores "pressul-i:*.ed", "realine pre: sure, etenterr., refer to on valves being subjected to a preesure (U.frorential :laen in the clooed

?cition.

nelosuro (1)-

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.ll Juno 1964 i

1[EQUllO:7.UTO A::D P!(OCECUI53 TO:t.MODH'fll:0 ST!M SISTEI FLE7.JBl.3 C/.T3 VAL'/ES AS '.20100ARY

.lf a cate valve is inatalled with it: steza located belcu the horinental and a drain is not. located en t.hc valve acch, therc is no trana of rcnov-ing any,.*ater which might be located therein except by cycling, the valve.

The ucdge or dice entering t.he ncek cavity 411 displai its volu;:.e of vater into the piping cyctea, where it cr.n he drained off.

Unfo rtur.at ely,

. the quantity of w.ccr re=0ved by thic acticn fro:n the oceks 'of flexible vedge nate valvec -ay not, prevent overprest.urinstica because the ucdge only displaces about 30 percent of the neck cav'.ty, which is not enough.

Additier. ally, thern is no way'of preventing some of the displaced water from re-enbering the ncch cavity as the ucdge is moved to the closed panition.

s

• Thic being the caso, modification:.eay be nececcary to all inverted flon '

ucdge gate valves in steam systcas, if prevention of overpressuritation

. is to be gw.re.nteed.

If these valvea already have body neck drains, no modifications are neccccary.

The regaired codifications in turn, are depen-dcnt upon whether a valve is considered as being a "one way" or "tuo vay"

~

veuvc.

Briefly, a one way valve in ar.y valve which when closed, will rec.line -

c. pressure differential frem only cne directica under any conditieno.

Any valve whose location fallo cutcide of this li:nitation is, of necessity, con-cidered a two vay valyc.

T.....

, Jalves 1.hich are borderlinc eases and/or can fall into cither r

category, particularly if en error in line up is :.ude. Therefore, the

'. I foMoving r. ketches and more detailed deceri'ption have been included to

' clarify what deter:tinca whether a particular valve is "one way" or "t1u tay" It ubonid be noted that these examples do not tcl<c operator error

.into account.

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[ T' x,[-m%.3./.'., ';: '/

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YALVE BYP.MS Any onstnTAT13;l

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,.).. Body neck "C" should ha vented to pipe run "A" or "B" that is dpstream by seating or backscating bypass valve.

. P,.

)!1tn bypass valve in mid-position, b[pa::s action will occur between "A" and "D" with "C" vented to both.

i

'3.

Piping and operation miy vary wi!.h particular bypass valve tised.

Appro-priate tag describing operation shculd be attached in cor.spicuous location.

4.

Piping may be installed below main valve.

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I'.0DIflCATION OF A FLEXIHLE

!!!:KiE CATE VALVE t.li?E H.0N IMY BE Ill CITilER DIRF.CTIO:t t

CXIIIDIT B

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