Note: Descriptions are shown in the official language in which they were submitted.
1~365t7~
. .
Cros's' ~e~erence-to ~'e'l'a't'ed''A~pIi,G'at'i,'ons~
NQne
... .. . .. .. . . . .. .. .. .. .. .. ..
Bac~'~rQ'un'd o~ t~e ~nven'ti`on
.
l~ The ~ield o~ art to ~h~ch the i~nvention pertainS in-
cludes the art of valves and parti~cularl~ to diaphragm-type
valves for high pressure, high temperature line servlce.
2. The need ~or reliability against stem or bonnet leak-
age in an in~line valve ls known to increase in correlation with
the pressure and temperature ser~i~ce ~or which the valve is to
be used. ~hen operatlng under severe servlce conditions on the
order o~ 2000 p. 8. i. and 650 F., it ls common to use elther a
bellows~seal construction or a multi-layer diaphragm constructlon
in combination with stem packing in order to prevent l:Lne leakage
past the stem cavity. Of the two, th~ bellows seal oonstruction
is usually the more costl~ by a aignif'icant margln. Contrlbu-
ting to lower cost o~ the diaphragm valve is the usual employ-
ment of a relatively uncostly globe valve body arrangement able
to readily accommodate lift l~m~tations associated with the dia-
phragm and constructed preferably ~n a Y-pattern to enhance flow
characterlstlcs. Conventional globe type ~-pattern valves of
this type are availa~le ~rom a variety of commercial sources.
While such diaphragm valves have en~oyed a high order of
commercial success, one characteristic deficiency has been the
relatlvely short life expectancy under severe operating service
f the diaphragm per se to on the order o~ 500-3000 open and
closing cycles. This is generally attributed to the variety o~
stresses imposed under pressure agalnst the diaphragm in belng
flexed between open and clo~ed posit~ons o~ the valve. With each
complete ~pen and closing c~cle~ at leaat the central portlon o~
the d~ph~agm ~ncurs a reYer~e ah~pi,~ng d~stortion bet~een convex ~,
to concave ~s the valve d~sc is moved to~ard and a~ay ~rom seat- ,
~ng relat~n tendlng ko cause ~uch ~ear phenomena as ~uckling, ,;
~ 3
'`~' ' ' ' .
3~
creas~ng~ ~atigue, etc~ ~ho~ld d~a~h~agm failure.be de.tected~ `
lt ~ customary to shut d~n operatii~n i~n order to. e~f~ct a ..
maintenance replacement there~or, but ~f undetected Qnly th.e
ske~ packing rema~ns as a deterrent to leakage~ With the ad-
vent o~ nuclear serv~ce to replace foss~ uel ~or p~wer genera-
tion~ the increased operational severity and malntenance diffi-
culties has rendered it incre.aslngl~ imperative to hold oper-
ational shutdown to a minimum... As a consequence, valve st.an- ..
dards for some nuclear services now require that the diaphragm
have a ~inimum li~e expectancy o~ at least about 12,000 cycles. :
Thls standard, of course, far exceeds pr:Lor art capability and
despite rec~gnltion o~ the problem a suitable construction able
to con~orm with the requirement has not hereto:~ore been known. .;
Pr-ovided as a ba¢kup to prevent leakage :Ln the event o.
diaphragm fallure in th.ese valves ~s the packing compressed in .
the bonnet base about the valve stem~ In the usual construction
to e~ect adequate pack there is included a packing gland, gland
~lange, gland bolts, nut, etc. employed in combinatlon with a
forged or cast bonnet yoke. While the high cost attributed to
this assembly combination has long been known, it has hereto~ore
been unknown how to significantly reduce this cost without sac- .
ri~icing the quality and reliability that this construction has
afforded.
At the same time, diaphragm valves o~ the type contemplated
hereln~ particularly in sizes 2 inches and greater typically .
impose highly complicated, con~ined and mult:L-d:Lrectional flow
patterns past the valve disc~ ~ecause lift dickated by use o~
a diaphragm is relatlvely small, a larger than normal seat diam-
eter ~s requ~red to ~bta~n the neceSsary ~low area. rrh.;is ln turn
3o cause~ the ~lo~ pakh to ~ncur a ~har~eir th.an n~rmal bend in and
about the se.ak c~nk~but~ng to a h~gh ~r~sure lo~ and conse-
quenkl~ a lo~er th.an des~ra~lè coe~ c~ent o~ ~1QW (CV~. A
~2_ .
- . . . . . . ,- - . . .... . . . .... . . . . .
- ~3657(~
2 inch ~ull ported Yal~e o~ th~s ty~pe usually has a Cv in the
range ~f ~bout 4a-6Q~ Des-pite ~ar~us a~proaGhes t~ the problem
.
these Yal~es have ~een generall~ unable to rurther increase the
c~pacity rating beyond an upper l~mi~t of about 60
Summarg of the Invention
Thi~s invention relates to Y~pattern dlaphragm valves in-
tended for high pressure, high temperature service and particu-
larly to speci~ic improvements to enhance performance and cost
factors for such valves. I~ore specif~cally, the invention re-
lates to various improvements includ~ng the diaphragm for
achieving an extended cycle life able to meet current require-
ments as to overcome the previous limitation in sLm:Llar purpose
valves o~ the pr~or art~ At the same time, a spec:L~lc ~orm of
auxillary relief in the dLscharge ~low passage substantially
straightens the ~low path in order to exceed previous limits on
flow coefficients. Yet further there ~s provided a substantially
less costly bonnet and packing construction than normally asso-
ciated with similar valves of the prior art.
The foregoing is achieved in accordance here~ith by means of
a diaphragm construction compr~sing a resiliently supported multi-
layer clamped cartridge in which at least some of the superim-
posed layers have selectively di~ferent moduli of elasticity. At
least the uppermost layer is controllably ~lotted to redistribute
cycle encountered stress loads while the upper support foundation
bearing edges are sufficiently resilient to avoid sharp stress ~,
discontinuitles thereat. ';'
Enhanced ~low characteristics are obtained by an auxiliary
porting in the downstream di~charge passage adJacent the valve
head ~n c~mb~nation with a tapered and ~a~red beltway to e~ect ' ,
a more nea~ly streaml~ned Plo~ ~,a,th ~nd ~gni~icantly reduce the ',~''
head losses prev~ously encountered. By ~eans o~ a mult~-purpose
packing gland identic~ th~eaded both inside and out, the bonnet ,,;'
'' ''` `:
-3- , ~
~.,.
:: '
"`` ~Q365~7CI
is enabled to be constructed of bar stock material eliminating
the relatively more complex and costly assembly of components
presently utilized.
In its broadest sense, therefore, the present invention
provides in a diaphragm type valve including a valve body,
a flow passage defined in the body between an inlet and an
outlet, a valve seat defined in the passage, a closure disc `
adapted to cooperate with the seat Eor opening and closing the
passage to fluid flow, a bonnet secured to the body and a stem
extending through a bore in the bonnet for operatively moving
the closure disc relatively toward and aw~y erom the seat, ;`
diaphragm means for maintaLnLng a ~eal-tight relatLon between
the paSsQge and the s~em and comprl.sLIlr, n mllLtl-lnycr eLexLb1a
stack oE load bearlng lrLdependent metaL layers posl~Lon~d :Ln
the body intervening be~ween the closure d'lsc and the stem
efEecting separation thereof with some of the layers being oE
a diEferent metal composition than others of the layers; and
support means securing the stack :Ln seal-tight relation to the
body.
Brief Description of the Drawings
Fig. l is a sectional elevation of a Y-pattern
diaphragm valve in accordance herewith;
Fig. 2 is a sectional view taken substantially along
the lines 2-2 of Fig. l;
Fig. 3 is a sectional view taken substantially along
the lines 3-3 of Fig. l; ~ `
F:Lg. 4 19 a sectionaL view ta~cen substantially along
the lines 4-4 of Fig. l;
Figs. 5 and 6 are secti.onnl elevat:Lons and planl
respectively, illustrating the flow pattern Eor valve sizes 1
inch
,~ ` .
1~365~
and smaller;
Figs. 7 and 8 are flow patterns similar to Figs. 5 and 6
for valve sizes of 1-1/2 inch and larger;
Fig. 9 is a fragmentary sectional enlargement of the en-
circled portion of Fig. l with the valve in its open position;
Fig. 10 is a fragmentary sectional enlargement of the en-
clrcled portlon oE ~lg. 1 wlth the val~e ln lts closed posltion;
Flg. 11 ls a fragmentary further enlargement of the en-
circled portion Or Fig. lO;
Fig. 12 is a fragmentary plan view as seen substantially
along the lines 12-12 of Fig. 9; and ~,
Fig. 13 is a graphica:L representatlon of valve performance ;~
with the construction hereof.
Referring initla:Lly to ~ig. 1, there is illustrated a globe
type Y-pattern dlaphragm valve in accordance herewith comprising
a body lO deflning a flow passage 12 between an inlet lLI and an
outlet 16 and supporting a bonnet 17 threadedly connected there-
to. Defined at an intermediate location in passage 12 is a hard
annular alloy seat 18 of Stellite or the like with which a valve
disc 20 cooperates for opening and closing the passage to fluid
flow. As illustrated, disc 20 is shown in open position support- ~;
ed within a tubular guide 22 secured and aligned in the body via
a pin 23 while a surrounding cap 24 secures the disc via a retain-
ing ring 26. Compressed about the disc between the disc cap and
guide is a coiled spring 28 acting to urge disc 20 upward toward
open position against the underslde of diaphragm 30. Downwardly
operable on the top side of the diaphragm 30 as to oppose spring
28 for urging disc 20 into closed position against seat 18 is a
stem head 32 of hexagonal periphery slideably contained in hex
agonal bore 34 at the underside of bonnet 17.
For operating the valve between open and closed positlons,
there is provlded a stem 36 extending centrally outward through
~5~3~,5~
the bonnet from a ~siti~on eng~g~i~ng ~he top in~ardly d~shed top ~:.
side of head 32, A gland nùt 38 s~ecured about the stem extend~
ing to inter~or ~f the hpnnet s-~r~es to c~mpress packing 40 ;~ ~
~hi~le threadedl~ support~ng st~ 36~ I.n thi~s arrangement, rota- :
tion ~ hand ~heel 42 in one di~ecti~on ~orces head 32 and disc
20 to~ard seating relation ~or clos~ng passage 12 and when ro-
tated in the opposite direction enables line pressure in combina-
tion w~th spr~ng 28 to raise disc 20 and head 32 upwardly for
opening the passage to fluld flow.
lQ Diaphragm 30 will now be described with particular reference :.
to Figs 9-12 ~rGm which it can be seen that the diaphragm com-
prises a cartridge ~ormed of a plurality of superimposed layers
46 and 48 that are usually pre-packed and dry lubr:Lcated with
molybdenum d:Lsulphide or the like to permit some sllding move-
ment therebetween. Each o~ the layers conslsts o~ a high strength
spring grade metal in thicknesses on the order of 0.005-0.015
inches able to prov~de maximum ~lexibility while retaining suffi-
cient strength to avoid shell type cross-buckling which might
otherwise occur. The layers are slightly dished and clamped at
their edges to accommodate a val~e stroke limited to less than
pop-through deflection. Collectively, the diaphragm stack should
have sufficient inherent strength to support internal valve
pressure~ By means of radial slots 50 angularly spaced through .
the sur~ace Or top layer 46, that layer is essentially converted :
from a shell actlon to a simple beam for reasons as will be more -~
fully described below. Dependlng on load factors, slots 50 may
be in more than one of the top layers, and an angular displace-
ment between sl~ts 50 of about 30 degrees h.as been ~ound suitable :~
for that purpose.
3~ ~n a pre~erred ~mbodi~mentl la~er$~46 a~e ab~ut ~008 to .012
inch.es ~n th~c~ness and cons~St Qf ~ncon~l 718 be~ng a trademark
o~ Hunt~ngt~n Alloy Co~ ~r a h~gh n~i~ck.el chrom~um alloy hav~ng
~6- . :
., .
~365~0
a modulus o~ elasticity of about 30 x 106 p.s.i. Pre~erably,
layers 48 are about .010 to .015 inches in thickness and con-
sist of titanium 6 A14V being a highly stable titanium, alumi-
num, vanadium alloy of light weight corrosion resistant proper-
ties having a modulus of elasticity Or about 16 x 106 p.s.i.
~eglnning at the underside o~ the diaphragm for valves of 1-1/2
lnch and larger, the first eight layers as seen in Fig. 9, ;~
alternate between materials ll6 and 48 whereas the upper layers
are all of the same material 46. By alternating the layers in
this manner, the low modulus element Ll8 remains well within
elastic stability throughout the va:Lve cycle whereas the high
modulus element Ll6 carries dlsproportionate h:Lgher loading as
it approaches a local buckling condltion agalnst wh:Lch lt is
restrained by the a~Jacent layer~.
For supporting the diaphragm stack in order to minimize or
eliminate uneven cycle strain as might otherwise occur, the ;~
stack is gripped about its edges in a smoothly contoured reverse
bend between an upperly extending annular body tongue 52 and a
recess groove 54 in the underside of annular retainer 56. Retain-
er 56 is in turn secured in that relation and includes a gasket
57 which with flexible ledge 61 maintains a pressure seal against
the under~ace o~ bonnet 17. Radially inward of the bend the ~
underside o~ the stack engages a resilient support pad 58 which `
also serves to isolate the stack ~rom contact with guide 22. Con- "
comitantly therewith, the stack top side is engaged outwardly by
: .
tapered and relatively ~lexible thinning support ~lange 60 extend- ~
ing inwardly ~rom retainer 56 and centrally by a tapered relative- ~`
ly flexible and thinning support ~lange 62 on head 32. In a
pre~erred construction, both pad 58 and gasket 37 are comprised
o~ a treated graphite in a ~lexible base commercially available
from Union Carbide Corp. under the trademark Gra~oil. Important
to note in connection with this disclosure is that in the open
~ 65~ ~
position of F~g~ 9 the d~a~hrag~ stack i~s engaged ~y the entire
cant~leye~ed sur~ace o~ flex~le ~lange 6~ and onl~ partially,
if at all, b~ flange 62 ~ereas in..t~e clo~ed poslti~n of Fig
10 the opposi~te applies. ~n thi~s arrange~ent, it should likewise
be noted that in the val~e open positi~n o~ ~g. 9 the under- :
side. v~ th.e stack engages only the part~al top surface of pad
support 58 whlle ~hen in the closed position o~ ~ig. 10, it
engages the entire pad surface includlng innermost lip 59 serving
to increase supporting resilience in mov~ng from the former to
the latter~
The flexlb.~lity af~orded by flanges 60 and 62 ls selected
to match stack properties such.that throughout the cantilevered
span o~ the ~langes the contact support backing pressure de-
creases non-abruptly in a continuously decreasing manner. ~hen
reaching ultimate engagement at the ~lange t~ps, a minimum backing
pressure exists thereat yet, belng flexible, it cannot apply sharp
or hard d~scontinuous loadings to the stack. Pad 58 functions
similarly but as both a seal and a support pad allo~ing compress- ~
ing deflections occurring ~hen the valve is in its lowermost -
stroke po~ition to be absorbed ~n the lo~er diaphragm elements
~ust ins~de the clamp joint. To preclude or minimize locally in- .
creased foundation support stresses between the diaphragm and
the flexible region o~ either flanges 60 or 62, slots 50 are pro- .
vided in the uppermost diaphragm la~ers 46... The slots enable :
those layers to act more as a load distribution pad by functioning
as an array of simple beams or cables to withstand only simple beam
stresses rather than concurrent normal circumferential shell
stresses~ In this manner, the most cr~tically located and fail-
ure suscept~ble d~a~hragm el~ments ~re rende~ed better able to ~.
withstand~ng gre~ter l~d~ng and c~cl~ng cond~t~ons ~rom a moreun~ m d~str~but~on o~ t~e ~oundat~i~n edge lcad~ng ~ects ~n
rad~al d~rectlon generall~ par~llel to the slots~
-8
. - . . : ~ ;. ; . . :
~365qo
The packing gland construction in accordance herewith will
now be described with reference again to Fig. l. In this arrange- ;
ment, gland 38 functions as both a packing gland and a thread
bushing, the latter of which transfers the lift forces of stem
36 to valve bonnet 17. In its packing capacity, gland 38 is
threadedly connected at 61l internally of the bonnet to compress
several layers or a continuous sleeve 66 of packing llo supported
between graphite fiber rings 68. Packing llO preferably comprises
a Grafoil composition as described above for pad 58. As a bushing,
gland 38 is threaded at 72 for supporting threaded stem 36 which ~;
can be rotatably advanced on the gland threads in either direc-
tion for operation of valve stem disc 20. By gland khreads 6ll
and 72 having the same lead in the same direct:lon, the gland can
be tightened against the packing w:lthout movin~ the stern whether
the valve is seated or backseated. Set screw llll secures the
position of gland 38 after the packing has been appropriately com-
pressed. Should the occasion arise for removing the packing, it
can be readily accomplished by threading gland 38 outwardly with-
out otherwise disturbing the valve. With a durable quality pack-
ing such as Gra~oil supra, usable life expectancy of the packing
usually exceeds that of plant equipment rendering the need to re-
tighten seldom, if ever, necessary. Likewise, with this material,
the need to remove stem packing is so rare that use of this im-
proved and simpliried bonnet construction is more than acceptable.
By virtue of the simplicity afforded in this arrangement, bonnet
17 can be readily formed of relatively inexpensive bar stock
material thereby eliminating the prior requirements for bolts,
nuts, flanges and yoke previously utilized in such valves.
With reference to ~igs. 1-8 and 13, features ~or improving
~low characteristlcs of the valve will now be described. As in
all valves of this basic type, flow entering passage 12 through
inlet lLI flows past open seat 18 toward outlet 16. ~y virtue of
. ~ .
_9_ ,.. '
~.~3t~S7~
the small l~ft as~soci~ated w~t~ a d~a-phragm valye dictated by
deflect~on ~ropertie$ of the diaphragm, ~low ente:rs the seat
flo~ annulus perm~tting a ~ufi~tant~al port~on ~bout 75~ of
the flow to proceed generally u~ward. At that point th.e upper
flow normally bends 90 toward the outlet to circulate about
guide 22 into a ~eltway flo~ path be~ore ~erging downstream with
remaining flow wh~ch mo~es past the annulus directly downstream.
To offset the bend losses and th.ereby enhance the flow co-
efficient in accordance herewith., th.ere is provided a combination
Of an auxiliary porting relief with a tapered and faired beltway. ::
Comprising the auxlliary porting relief are separate apertures
78 and 80 openly communicat~ng on th.eir undersides with passage
12 (.F~g. 2) The ax:~s o~ the pas~ages are arranged ~lverg:Ln~
from each other in a common plane, ~hlch ls shown at 82 angular-
ly o~fset from the ax~s of passage 12. Inlet to the relief aper-
ture~ ~s located slightly above ~assage 12 immediately contiguous
to the upper port~on of gu~de 22 about where the sharp bend in
flow has previously occurred. B~ virtue o~ the bend elimination,
which the relief apertures provide~ the flo~ pattern therethrough . -
2~ is more nearly streamlined ~n the manner speci~ically illustra-
ted in F~g. 7~ ~ith this construct~on, therefore, the porting
relief creates a more direct route or shortcut for the fluid as
it rises in the valve cavity and begins lts turn downstream to-
ward outlet 16. Since the flow pattern is more direct and less
inclined without the previous offset, a larger percentage of flow
is able to enter the upper half of th.e downstream port resulting
in a more gradual and average bend to enhance ~low dlstribution and
reduce pressure drop there~t.
~ar ~nsuring most e~c~ent u$e of the aux~l~ary relle~
3a ports 78 and 8Q, there ~s ~rov~d~d ~n c~m~nat~ion there~ith a
v~r~ng th~c~ess belt~a~ flo~ ~ath..at the locat~on des~gnated
84 ~g~ 8~ extend~ng ab.out the u~pe:r~st c~rcum~erence of guide
~lû~
~ . .. .. ~..... . ..
~36570
22 FQrml~ng the belt~a~ ~s the:pa~age area betw.een the inside
eccentric ~all surface 76 above cGncentri~c wall surf~ace 74 of' ~-
the valYe ~ody and the ~uts~de ~ur~ace o~ gulde 22. Both the .
wall surf'ace and guide surface~ are a~prcpriately contoured with
the latter terminating a~ a teardrop 86 merging Into the axis
of' passage 12. Teardrop 86 also serves to minlmize possibility :~
of cavitat,ion from f~orming and h.elps to more efficiently orient ~ ~.
the f'low with a minimum, if' an~, turbulence.. Thickness of' the
flow belt increases at thi~s location ~rom the upstream slde of' .
the beltway to uniformly and efficiently collect the seat flow :':
without sudden enlargements or sharp changes in f'low dlrection. .. .
From that point, the beltway directs ~low toward and through the
auxiliary portin~ relie~ apertures 78 and 80. For va.Lve s:Lzes
1 inch and smaller, use of' the relle.~ apertures and tapered belt-
way are relatively unnecessary and are theref'ore shown elimina~
ted from Figs. 5 and 6~
E~ects of the ~oregoing can be readily appreciated from
the graphical illustration of Fig. 13 in which for a 2 inch dia-
phragm valve ~ith 3/8 inch lift the flow coefficient Cv is enabled ~
to increase at full open to 6a and beyond. This compares to a ~:
Cv of about 37 fcr the same valve without the auxiliary relief ~ '
and beltway formation hereof~ At the same time, a relatively ..
linear throttling curve is maintained such. that it can be readily ~.
utiliæed to set and control systems for partial load operation.
By the above description there is disclosed novel improve-
ments for enhancing operation and diaphragm li~e expectancy o~ a
high pressure, high temperature Y-~attern diaphragm valve. ~hrough
use of a novel construction for both the diaphragm and its support, ...
;~. ....
life e~pectancy of the diaphragm i~ gni~cantly extended as
30 compared to previous de$~gns~ r~ng ~he diaphragm o~ superim-
posed layer~ o~ controlled th~cknesses~ and selectiYely di~ferent
materials, in combination ~th a ~up~ort ~h~ch functions ~hen the
`~,~',''`~
., . .... . ,. :
~L~36S~0
valve ~ ~n 1~s lowermost :~os~t.~on.to allo~-compre$s:i~e de~.lec-
t~on~ o~ the d~aphragm to ~e ahs~bed ~n~de the clamped ~oint,
suhst~ntiall~ overcomes th.e previous~ s~tress caused b~ ~uckling, ..
creasing and/or ~atigue ~a~lure~ ~et, ~urther, an auxiliary
relief and ~low feathering c~nstruction substantially enhances
the ~low coefficients for such valves as c~mpared to similar
purpose valves of the prior art~
S~nce many changes could ~e made ~n the above construction
and man~ apparently ~idel~ di~erent e~bodiment$ of this inven- :
tion could be made ~ithout departing ~rom the scope thereof, it ~:
is intended that all matter contalned in the drawlngs and speci-
~ication shall be interpreted as illustrative and not in a limit-
ing sense.
~12
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