US2818193A - Head closure construction for heat exchangers - Google Patents

Description

Dec. 31, 1957 F. BONl, JR 2,818,193

HEAD CLOSURE CONSTRUCTION FOR HEAT EXCHANGERS Filed Oct. 26. 1954 2 Sheets-Sheet l 7\ *4 33 Y gm a 33 23 Mae M ATTORNEYS Dec. 31, 1957 F. BONI, JR 2,818,193

HEAD CLOSURE CONSTRUCTION FOR HEAT EXCHANGERS Filed Oct. 26. 1954 2 Sheets-Sheet 2 INVENTOR.

Frank Bani, Jr.

ATTORNEYS United States Patent HEAD CLOSURE CONSTRUCTION FOR HEAT EXCHANGERS Frank Boni, Jr., Massillon, Ohio, assignor to The Griscom- Russell Company, Massillon, Ohio, a corporation of Delaware Application October 26, 1954, Serial No. 464,846

1 Claim. (Cl. 220- 50) My invention relates to high pressure head closures for heat exchangers, and more specifically to a head closure construction of the bayonet-type providing less hydrostatic end load against the head sealing gaskets, thereby permitting the design of a head closure construction of the bayonet-joint type for use with higher pressures than has heretofore been practical.

Prior constructions of bayonet-type head closures for heat exchangers have included a head having cyclindrical barrel walls terminating in a cyclindrical open end. In this construction radially inwardly projecting lugs are formed on the inner side of the barrel wall with such lugs being circumferentially spaced around the inner cylindrical surface of the barrel wall. There is also a cylindrical head cover plate having radially outwardly projecting lugs extending from the outer cylindrical periphery of the cover plate, with these lugs also being positioned in spaced-apart relationship.

The cover plate is received in the open end of the barrel wall with the lugs on the cover plate passing between the lugs on the barrel wall in the usual bayonet-joint fashion, with the cover plate being thereafter rotated to engage the lugs on the cover plate beneath the lugs on the barrel wall. When in such assembled position, the outer end of the head cover is usually in radial alignment with the outer end of the barrel wall so that a flat sealing ring may be placed over the joint between the cover plate and barrel wall to prevent fluids under pressure from passing out of the heat exchanger head between the cover plate and barrel wall. I

This sealing ring is usually retained in sealing position by clamping rings, one of which abuts the outer edge of the sealing ring and extends radially outwardly being fastened to the head barrel wall, with the other abutting the inner edge of the sealing ring and extending radially inwardly being fastened to the head cover plate. These clampingrings are usually held in place by bolts spaced around the clamping rings and threadably received in the cover plate and barrel Wall.

In such construction, it is necessary to have the radial width of the sealing ring greater than one lug Width of the lugs on the barrel wall or cover plate. Also the bolt circles of the circular rows of bolts retaining the clamping rings in place must be laterally or radially spaced a distance somewhat greater than a lug width, since the lugs must be spaced around the head barrel wall toaccommodate the bayonet-type joint. Such a construction is shown in the Price Patent No. 2,219,659.

; This prior bayonet-type head closure construction has been satisfactory for use with the normal pressures encountered in heat exchangers over the past years. Under the higher operating pressure ranges of modern steam power plants in recent years, it has been found, however, that use of this prior head closure construction has been limited by the bolting required to maintain the gasket or sealing ring against the hydrostatic end load exerted on the sealing ring and clamping rings over the fairly wide radial span between the sealing ring seats, which seats "ice are necessarily separated 'by somewhat more than one lug width. That is, for a given heat exchanger head member, the pressure that it is capable of withstanding is limited by the size of the clamping ring bolts that it is possible to use and be threadably engaged in the barrel Wall.

A reduction in the size of these bolts is possible if the distance over which the sealing ring must seal is decreased, thereby ecreasing the radial width of the sealing ring and decreasing the radial width of the clamping rings holding the sealing ring in sealing position.

It is, therefore, a principal object of the present invention to overcome the difiiculties of the prior art constructions including those enumerated above.

It is a primary object of the present invention to provide a head closure construction for heat exchangers in which less hydrostatic end load is exerted against the sealing gaskets for a given amount of hydrostatic pressure in the head.

It is another object of the present invention to provide a head closure construction for heat exchangers in which there is less load on the gasket clamping rings for a given hydrostatic pressure in the head permitting the use of lighter and narrower clamping rings.

It is still another object of the present invention to provide a head closure construction for heat exchangers in which there is less bolt load on the clamping ring bolts for a given hydrostatic pressure in the head, thereby permitting the use of smaller bolts.

It is a further object of the present invention to provide a head closure construction for heat exchangers in which there is increased head barrel stiffness by virtue of a greater flange thickness, that is, the length of the barrel Wall from its end to the contact plane of the head cover plate and the head barrel wall bayonet lugs, thereby permittirig the use of thinner head barrel walls.

It is still a further object of the present invention to provide a head closure construction for heat exchangers in which the amount of material required for fabricating the head is less, due to the thinner barrel walls.

Finally, it is an object of the present invention to provide a head closure construction for heat exchangers which accomplishes all of the above objects in a simple and efficient manner and which is economical to manufacture.

These and other objects are accomplished by the parts, constructions, arrangements, combinations and subcombinations comprising the present invention, the nature of which is set forth in the following general statement, a preferred embodiment of which-illustrative of the best mode in which applicant has contemplated applying the principlesis set forth in the following description and illustrated in the accompanying drawings, and which is particularly and distinctly pointed out and set forth in the appended claim forming a part hereof.

In general terms the improved head closure construction for heat exchangers may be stated as including a head barrel wall which has an inner periphery or surface and which terminates in an open end, engagement means mounted on the inner surface of the head barrel wall, a head cover plate which has an outer periphery and which is received in the open end of the barrel wall, engagement means mounted on the outer periphery of the cover plate which is engaged with the engagement means on the barrel wall when the cover plate is so assembled, a laterally extending flange portion on the cover plate which fits closely within the inner surface of the barrel wall longitudinally outwardly of the barrel wall engagement means when the cover is so assembled, and sealing means mounted partially on the flange and partially on the barrel wall sealing the joint between the cover plate and barrel wall.

More specifically, the improved he-ad'closure construction for heat exchangers may "be stated as including a prefaslsgnceas erably cylindrical head-barrel wall whichhasa-preferablycylindrical inner surface and which terminates in a preferably cylindrical open end, circumferentially spaced laterally inwardly extending lugs on the innersurface and s paced from the end a of the barrel wall, a head cover plate which has an outer preferably"cylindrical periphery and" which is received in the open end? of the barrel wall, circumferentiallyspaced laterally or radially outwardly extending bags on the outer periphery of the cover plate engaged' with the lugs on the barrel wall in bayonet joint relationship when the head cover is assembled on the head, a laterally or radially outwardly extending flange which has an outer preferablycylindrical periphery formed integrally on the outer'periphery of the cover plate-which is in lateral or radial alignment'withthe end of the barrel wall when-thecover plate is assembled on the head, the outer periphery of the flange fitting closely within the inner'surfa'ce' of" the barrel wall during such assembly, a sealingring'or gasket abutting'the flange and the end of thebarrel'wall. sealingthe joint therebetween, a seal back-up ring abutting the sealing ring, a first laterally or'radia-lly extending"seal clamping" ring mounted on the flange abutting the back-up ring, and a second laterally or radially extendingclamping ringmounted-on the end of the barrel wall and also abutting theback-up ring' so that the two clamping rings retain thesealingring in proper sealing position preventing fluids under pressure within the-head from passing between the headbarre'l wall and the headcover plate.

By way of example, an embodiment of the improved head closure construction for heat-exchangers of the present invention is illustrated in the accompanying drawings forming apart hereof; wherein like numerals indicate similar parts throughout the several'views, and'in which:

Fig. 1 is a fragmentary longitudinal sectional view of the present invention are shownland' described herein. incorporated in. the construction ofa' head'clo'sure fora heat exchanger, such is merely by way of ex-ampldand the principles '0f'the present invention may beiadvantageously used in many other constructions requiring a high pressure tight'seal;

The head member, generally indicated at 1, is shown in Fig. l assembledwithausual type'heat'exchangjer, .genera'lly'indicated" at 2. The heat exchanger 2 includes a preferably cylindrical shell 3 having the usual fluid inlet 4 and fluid' outlet 5. The shell'3'- encloses the usual tube bundle, generally indicated at 6,-with the usualbafiies, generally indicated at'7, for directing the flow of fluid from the fluid 'inlet4 aroundthe tubes'8 in the tube bundle 6 and out the fluid outlet 5;

The head member 1 may be mounted on the heat exchanger 2 by the flange 9extending laterally or radially outwardly from the shell 3'with p'ref'erablj bolts 10 received through the-flange 9' and threadablyj received in the head'membe'r I as shown in Fig. 1. When the heat exchanger 2 and head member 1' arein such assembly, the-tubes 8v are received in the tube holes ll' in the tube sheet 12" and are-retained therein inpressure-tight relationship by expanding or. welding, or both.

The he'ad'rnember. l includc's the longitudinally or axially extending preferably cyclindrical'barrelwall 13 having' the usual pressure fluid inlet 14 and-pressure fluidoutlet 15. Headmetnber 1 also includes the usual baffies 16 and 16a which are mounted on the inner side of the barrel wal113' by preferably bolts 17 and nuts 1'8,,and sealed thereon by a'ring seal 19, as shown; Battle's 16' and 4. Ma direct the flow of pressure -fluid-fromthe "inlet 14to the tubes 8 and from the tubes 8 to the pressure outlet 15. Baflie 16a is provided with an opening 20 for allowing pressure fluid to enter on both sides of the b-aflie, thereby equalizing the pressure and preventing undue stresses therein.

Thebarrel wall 13 terminatesin a preferably cylindrical open end providing the inner peripheral generally cylindrical surface 21 and the laterally or radially extending end surface 22; as best" seen-in'Fi'gI-3 The inner side of the barrelwall 1=3' is"alsoprovided'witha laterally-or radially inwardly extending surface 23 commencing at the inner end of theinnen surface'21. and extending for a distance radially inwardly.

The head bayonet lugs-24 are formed on the inner surface 21 and extend laterally radially inwardly being spaced axially outwardly from the lateral surface 23 and spaced axially inwardly from theend surface'22.- Bugs 24: are preferably formed integrally of the barrel wall 13 and" the tube sheet-1'2" thebarrel wall 13 and the lugs M'being preferably formed froma single steel forging.

Referring toFigs; 3- and 4 the lugs: 24 are; equally spaced around" the circumferenceof the peripheral surface 21 with each lug having theaxialside' surfaces25, the arcuate: axial front surface 26', the inner radial surfacezl'an'dthe-outer radial surface-28.

The cover plate 29 preferably has a solid cylindrical disc configuration and is also preferably formed from a steel forging. Cover plate 2'9 includes aninner radialend surface 30, an outer radial endsurfa'ce-or face 31 and an axially extending: peripheral surface 32 Surface 32-is slightly smaller in diamet'er than-the diameter of" the axial inner'surface 26 of'the lugs" 24 and hasmounted thereon the lugs 33 whicharein" radial alignment with its inner end surface and extend axially outwardly. Lugs 33" extend laterally'outwardly from the surface 32 and are equally spaced' around' the circumare also provided with the side axial surfaces 35; the

outer radial surfaces 36 and with their inner radial sur fa'cesas before stated; in-radial" alignment with the inner end surface 30-, and thereby forming apart' of" surface 30.

A cylindrical flange portion. 37 extends radially outwardly'ofithe peripheral' surface ialg and extends continuouslyaround the" circumference of"the= cover plate 29".

Flange 37 is provided with a cylindrical surface 38 of slightly less'diamet'erthan the inner cylindrical surface 21 on the barrel Wall 13. Flange 37has-an outer'radial surface in radial alignment withthe' endsurface 31- of the cover plate 29 and'this' radialsurfacethereby forms a part of the end surface'31. Also flange 37 is--pro-' v-id'ed with" an: inner radial surface 39 which is spaced from the radial surfaces 36" on the lugs 33' azdis'tance slightly greater than the-axial lengthof the'lugs'24 on thebarrel-wall13.

The end surface 22 of the barrel'wa'll" 13 is'- provided with an axially projecting gasket seal rib=40- extendingcontin'uously around the circumference of the ba'rrel wall 13 and" also extending from the inner peripheral surface 2'1 a distance-radially outwardly to provide -the radial gasket seal surface 4h The flange portion-yl' on'the cover plate 2'9 is' also 'provided with an axially projecting open end of the barrel wall 13 with the lugs 33 on the cover plate 29 passing between the lugs 24 on the barrel wall 13, until the radial end surfaces 30 of the lugs 33 abut the radial surface 23 of the barrel wall 13. The cover plate 29 is then rotated a partial turn so that the lugs 33 of the cover plate 29 engage beneath the lugs 24 of the barrel Wall 13 and with the radial surfaces 36 and 27 abutting, thereby providing a bayonet-type joint between the cover plate 29 and the barrel wall 13.

When in such assembled position, the radial surface 41 of the rib 40 is in substantial radial alignment with the lateral surface 43 of the rib 42. The gasket sealing ring 44- is mounted abutting the radial surfaces 41 and 43 of the ribs 40 and 42 and extends continuously around the circumference of the ribs 40 and 42 as shown. Sealing ring 44 is of any usual material used for high pressure seals.

The preferably metal back-up ring 45 abuts the outer radial surface 46 of the sealing ring 44 and also extends continuously around the circumference of ribs 40 and 42 as shown. Sealing ring 44 and back-up ring 45 are preferably rectangular in cross-section, as shown in Fig. 3.

The barrel wall clamping ring 47 includes an axially extending rib spacing portion 48 and a clamping portion 49. Spacing portion 48 extends axially inwardly from the outer peripheral surface of the ring-47 a distance substantially equal to the combined axial length of the gasket sealing rib 40, the thickness of the sealing ring 44 and the thickness of the back-up ring 45.

Thus, the inner radial surface 50 on the clamping portion 49 is axially spaced from the end surface 22 of the barrel wall 13, when the clamping ring 47 is in assembled position. Also the inner end of surface 50 abuts the outer radial surface 51 of the back-up ring 45 with the clamping portion 49 terminating in the inner cylindrical surface 52, which surface is in substantial axial alignment with the inner peripheral surface 21 of the barrel wall 13.

The bolts 53 are received in the axial bolt holes 54 formed through the clamping portion 49' spaced radially outwardly from the surface 52. Bolts 53 and bolt holes 54 are preferably equally spaced around the circumference of the clamping ring 47 with bolts 53 being threadably engaged in the barrel wall 13, as shown at 55 in Fig. 3.

The cover plate clamping ring 56 is similar in configuration to the barrel wall clamping ring 47, with the exception that the axially extending rib spacing portion 57 extends from the inner end of the clamping portion 58 and the inner radial surface 59 abuts the outer radial surface 51 of the back-up ring 45 radially outwardly from rib portion 57.

Clamping ring 56 has a smaller outer diameter than the inner diameter of the barrel wall clamping ring 47 so that the outer surface 60 of ring 56 is spaced from the inner surface 52 of ring 47, with surface 60 being in substantial axial alignment with the axial suface 38 of the flange portion 37 when the clamping ring 56 is in assembled position.

Clamping ring 56 similarly is retained in assembled position by a series of circumferentially spaced bolts 61 received through bolt holes 62, with bolts 61 being threadably engaged in the flange portion 37 of the cover plate 29, as shown at 63. Thus, with the cover plate 29 assembled in the open end of the barrel wall 13, the sealing ring 44, with the back-up ring 45, the clamping ring 47 and the clamping ring 56 retaining it in sealing position, forms a pressure-tight seal between the cover plate and barrel wall.

In the present construction, with the provision of the flange portion 37 extending continuously around the circumference of the cover plate 29, the radial distance over which the sealing ring 44 must extend is only the clearance distance between the outer cylindrical surface 38 of the flange portion 37 and the inner cylindrical surface 21 of the barrel wall 13. Flange 37 also provides a portion into which the bolts 61, retaining the inner clamping ring 56 in sealing position, may be threadably engaged. If the flange portion 37 were not provided, it would be necessary to extend the radial width of the sealing ring 44 over the entire radial distance from the barrel wall 13 to a point radially inwardly of surface 32 on the cover plate 29, since it would be impossible, in any other way, to seal the joint between the lugs 24 on the barrel wall 13 and the surface 32 on the cover plate 29.

Thus, it is possible by use of the construction of the present invention to use a sealing gasket 44 of less radial width than had heretofore been possible in bayonet-type head closure constructions. Further, the hydrostatic end load exerted on the sealing gasket is less due to the smaller area which must be sealed. Also, because of the smaller sealing gasket and the smaller hydrostatic load, it is possible to use lighter clamping rings 47 and 56 and also lighter bolts 53 and 61.

A further advantage of the construction of the present invention over prior bayonet-type head closure constructions is provided by the barrel wall 13 being of greater axial length between the radial surfaces 27 of the lugs 24 and the end surface 22 on the barrel wall 13, thereby providing greater barrel wall stiffness and permitting the use of thinner barrel walls. This not only results in the head being of less final weight, but also provides a decrease in cost of the head due to the barrel walls requiring less material.

Finally, in the head closure construction of the present invention, the maximum pressure for which the head may be designed is not limited by the size of the bolts used for retaining the sealing ring gasket in sealed position against the hydrostatic end loads. Since the size of bolts required for a given pressure to be contained within the head is much smaller, it is possible to design this im proved construction for much higher operating pressures.

In the foregoing description, certain terms have been used for brevity, clearness and understanding, but no unnecessary limitations are to be implied therefrom, because such words are used for descriptive purposes herein, and are intended to be broadly construed.

Moreover, the embodiment of the improved construc tion illustrated and described herein is by way of example, and the scope of the present invention is not limited to the exact details of construction shown.

Having now described the invention, the construction, operation and use of a preferred embodiment thereof, and the advantageous, new and useful results obtained thereby, the new and useful constructions and reasonable mechanical equivalents thereof, obvious to those skilled in the art, are set forth in the appended claim.

I claim:

High pressure head closure construction for heat exchangers, including a generally cylindrical head barrel wall having an inner cylindrical surface defining an open end of the head, said wall terminating in a generally radially extending end surface, said barrel wall inner surface being provided with a plurality of circumferentially spaced lugs extending radially inwardly of the barrel wall inner surface and spaced axially inwardly of said end surface, a generally cylindrical head cover plate within the barrel wall open end 'having an outer end face, the periphery of the cover plate being provided with a plurality of circumferentially spaced lugs extending radially outwardly of the periphery of the cover plate and spaced axially inwardly from said cover plate end face, said cover plate lugs being formed complementary to said barrel wall lugs and being engageable with the barrel wall lugs by telescoping the cover plate within the barrel wall open end and rotating the cover plate with respect to the barrel wall, the cover plate having a radially outwardly extending cylindrical flange axially adjacent the end face of the cover plate and axially outwardly of the cover plate lugs, said-cover plate flange ha -in'g acylindricahperiphery;

locating; and fitting closely within: andzhavingga slightly less diameter than said cylindrically formed-(- barrel wall surfaceaxially outwardly of said barrel wallllugs forming, acylindrical' continuous clearance space circumferenti-a'lly continuously surrounding the cylindricaL periphery of said cover plate flange, the barrel wall endsur-faoeand the-cover plate outer end facev being substantially radiallyaligned at the cylindrical continuous clearance space lie-'- tweenthe; barrel wall and cover'plate-fiange, afirst sea-ling rib formedionlthe barrel wallzprojectingzaxially. outwardly from. the barrel wall end surface-incaxiali alignment with the barrel wall inner cylindricalsurface, .a; second-sealing; rib formed on'the cover: plate projecting axially outwardly from the cover plate) flange in axial: alignment with saidflange cylindricalperiphery, said first and: second. sealing ribs having, generally radially extendinggandaligned' outer end surfaces, gasket sealing ring: means seatingizagainstz said barrel Wall and cover plate; flange; ribsand extending between the cover plate flange and thezbarrel-twall'spanening and sealing the cylindrical continuousiclearancaspace between the cover plate flange and barreltwallgt ai first clamping ring bolted to thebarrelwall clampin'grthe sealtending spacing projection formed thereon sp'acedi radially ou-hvanlly rfromrtlieabarrelzwallsealingjrihzatsecondrclamp ing; ring; bolted tm thecover plate clamping; the sealing ring,- against! the: cover plate sealing; rib; said second clamping ring,havingg anaxially inwardly extendingspaeingprojections formed thereon spacedradially' inwardly from. the/cover plate-flange sealing-irib, lthe first and second cla-rnpi-nga ringszbeingg bolted to their respective barrel wall and coverpl'ate? at: points located radially; between thebarrelrwall; and coverz plate 'sealing'zribs andthe clamping; ring-spacing; projections; and the first clamping ring terminating, radially inwardly and the second clamping ring terminating; radially! outwardly inv substantial axial References fiite'dr-irr the: file of this 'patent UNITED; STATES PATENTS? 1%03255029 Rapp July 16, 1912 159021862 Kerr etal. Mar. 28, 1933 958,582" Kerret al'. May- 15, 1934 23"219;659"-' Price Oct: 29; 1940 2 37 83032 Snieg Apr. 24; 1956'

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