US2872065A

US2872065A - Head closure construction for heat exchangers

Info

Publication number: US2872065A
Application number: US564016A
Authority: US
Inventors: Gordon D Hamersley
Original assignee: Griscom Russell Co
Current assignee: Griscom Russell Co
Priority date: 1956-02-07
Filing date: 1956-02-07
Publication date: 1959-02-03
Anticipated expiration: 1976-02-03

Description

Feb. 3, 1959 G. D. HAMERSLEY 2,872,065

HEAD CLOSURE CONSTRUCTION FOR HEAT EXCHANGERS Filed Feb. 7, 1956 3 Sheets-sheet 1 INVENTOR. Gozdon afiamgns'leg Bygwgg.r

ATTORNEYS Feb. 3, 1959 G. D. HAMERSLEY 2,872,065

HEAD CLOSURE CONSTRUCTION FOR HEAT EXCHANGEIRS Filed Feb. 7, 1956 5 Sheets-Sheet 2 69 69 II INVENTOR.

Gordon, D. Hwmersle y BY 9W! 30 30 "30 I ATTORJVEYS Feb. 3, 1959 G. D. HAMERSLEY 2,872,065

HEAD CLOSURE CONSTRUCTION FOR HEAT EXCHANGERS Filed Feb. 7, 1956 3 Sheets-Sheet 3 INVENTOR. fiozdoulllz'wmersley BY aw?! ATTORNEYS United States Patent HEAD CLOSURE CONSTRUCTION FOR HEAT EXCHANGERS Application February 7, 1956, Serial No. 564,016 7 Claims. c1. 220-40 This invention relates to a closure construction for the head chamber of a heat exchanger. More particularly, it pertains to a head closure construction including a modified bayonet joint for the closure, particularly adapted for use to contain high pressures.

In recent years there has been a trend toward heat exchangers which must operate under conditions of higher and higher temperatures and pressures. This trend has created problems in designing the heat exchanger head members with adequate strength to contain the higher temperatures and pressures and without excessive wall thicknesses and machining costs.

Of course, the head barrel wall and the head cover may be designed to have increased dimensions. By mak- 'ing thicker head chamber walls it has been possible to design heat exchangers for operating under increasing pressures and temperatures.

However, increasing the dimensions of the head chamber creates other problems. Where larger volumes are enclosed the thickness of head chamber walls must be increased proportionally. The larger the outside diameter of the head chamber, the larger the forging cost thereof. This includes not only the cost of added metal involved but also the additional costs of fabrication. Moreover, the larger the inside diameter the thicker the head barrel wall must be. This in turn involves larger bending moments to contain the head cover. Accordingly, where higher pressures are contemplated, it is desirable to maintain the outside diameter of the head barrel at a minimum.

The device of the present invention pertains to a modification of a typical heat exchanger construction, such as shown in the Price Pat. No. 2,219,659. The Price patent shows lugs or projections extending radially inwardly of the barrel wall engaging similar lugs or projections extending radially outwardly of the cover plate for the head barrel. With such prior construction it is necessary for the assembly of the cover in the head that the lugs or projections be arranged at spaced intervals equalling the width of the lugs on the cover plate, and vice-versa. The spaces between the lugs are necessary to permit interfitting during insertion and removal of the head cover. As a result, when fully assembled the spaces between the lugs in both the head barrel and the head cover are aligned, thereby not contributing to the strength of the joint between the cover and the head. For a given heat exchanger to withstand greater pressures, it is necessary that the lugs must have greater height in order to provide suflicient contact or bearing area between the lugs.

Unfortunately, higher lugs mean a greater gap between the head cover and the barrel wall. This means that a greater hydrostatic load is created on the seal between the two members. Further, the higher the lugs the greater the inside diameter of the barrel at the lugs must be, and therefore the greater the outside diameter of head. Also, the higher the lugs, the thicker the barrel wall must be to withstand the greater bending moment about the mean diameter of the wall. The bending moment is a product of the force applied to the lugs and the distance between the lug center line and the mean diameter. Therefore, the bending moment is greater because the higher lugs result in a greater hydrostatic end force to be carried by the lugs and because the distance is greater with a higher lug.

Furthermore, because of the greater gap between the head cover and the barrel wall, the size and number of bolts required to contain the hydrostatic pressure creates an additional problem. With the trend toward higher pressures it becomes more impractical to use bolts for securing the head cover to a heat exchanger head, because of the extremely large number and size bolts indicated by calculations using a proper safety factor.

Thus, it is desirable to minimize as much as possible the height or radial thickness of the lugs which will reduce the thickness of the barrel wall and outside diameter of the head and also reduce the gap between the head cover and barrel wall. This is not possible where the typical heat exchanger construction, such as shown in the Price Pat. No. 2,219,659, is used because the total bearing area and circumferential bearing length and radial bearing width between the lugs is approximately around the head cover. Since it is necessary to provide gaps between the lugs at equally spaced intervals, the total bearing area of the lug engagement does not exceed 180. For this reason the typical heat exchanger having the equally spaced lugs around the head cover and barrel wall limits-the extent to which the pressure within the heat exchanger can be increased without entailing the disadvantages of increasing the height of the lugs.

I have discovered that a reduction in the height or radial thickness of the lugs for a given inside diameter and pressure is possible; This may be accomplished by providing at least two lugs each on the barrel wall and the head cover, the lugs on each member being located in axially spaced zones. By reducing the total number of lugs and providing them in equal numbers in spaced axial zones perpendicular to the axis of the head barrel chamber a lug may be staggered with a lug in another zone thereby providing a bearing area between the engaged surfaces of the lugs at the variou zones extending approximately 360 around the joint between the head cover and the barrel wall. Thus, the entire periphery of the cover at one or another zone or level, throughout 360, is utilized for joint bearing engagement.

In this manner, the total bearing area between the lug's is increased so that the height of the lugs may be correspondingly reduced. Thus, it is possible to increase the pressure within a heat exchanger for a given size of heat exchanger and at the same time reduce the height of the lugs.

Accordingly, it is a general object of the present invention. to provide a heat exchanger having overlapping lugs between the head cover and the barrel wall which lugs have less height than was heretofore required for.

a given size of heat exchanger.

It is another object of this invention toprovide a'joint between the barrel wall and the head cover having a smaller gap therebetween and therefore a smaller hydrostatic load on the sealing gasket therebetween than heretofore present in a heat exchanger of the same size.

Another object of this invention is to provide a joint between the barrel wall and the head cover having lugs which require a minimum of machining and chipping during fabrication. v

Another object of this invention is to .provide a joint between the barrel wall and the head cover having a more uniform distribution of hydrostatic load between the engaged lugs than present in prior structures.

Another object of this invention is' to provide a barrel "an exchanger having a given inside diameter and contained pressure.

Another object of this invention is to provide a barrel wall having an increased pressure capacity without substantially increasing the amount of metal in the wall.

Another object of this. invention is to provide a joint between a barrel wall and head cover having lugs which 'areapproximately half the size of lugs in height and width as in prior constructions of:the.same capacity.

Still another object of this invention is to provide a head cvoer having a reduced thickness due to the smaller width of. lugs thereon.v

It .is an object of this invention to provide a joint between a barrel wall and a head cover in which the sizeand number of joint sealing bolts are reduced.

Finally, it is an object of this invention to provide an improved head closure for a heat exchanger which incorporates the foregoing desiderata in an inexpensive manner.

These and other objects and advantages apparent to those skilled in the art from the following description and claims may be obtained, the stated results achieved and the described difiiculties overcome by the discoveries, principles, apparatus, parts, combinations, subcombinations and elements which comprise the present invention, the nature of which is set forth in the following statement, preferred embodiments of whichillustrative of the best modes in which applicant has contemplated applying the .principlesare set forth in the following description, and which are particularly and distinctly pointed out and set forth in the appended claims forming part hereof.

The nature of the improvements in the head closure construction of the present invention may be stated in general terms as including in a heat exchanger a barrel wall having an inner surface and terminating in an open end, apair of locking lugs extending radially inwardly of the inner surface of the barrel wall, the lugs being circumferentially staggered out of axial alignment and overlap, the lugs being axially spaced by a distance equal to at least the axial width of the lugs, a head closure member having inner and outer end surfaces, and a pair of locking lugs extending radially outwardly of the outer surface of the head closure and matching the lugs on the barrel wall.

Preferred embodiments of the invention are illustrated, by way of example, in the accompanying drawings wherein:

Fig. 1 is a vertical sectional view of the head portion of a heat exchanger provided with the new construction;

Fig. 1a is an enlarged view of a portion of Fig. 1;

Fig. 2 is an end view taken on the line 22 of Fig. 1;

Fig. 2a is an enlarged view of a portion of Fig. 2;

Figs. '3-7 are diagrammatic views showing the successive steps of assembly of the head closure member within the head member;

Fig. 8 is a diagrammatic end view of the head member showing the relative location of the locking lugs;

Fig. 9 is a vertical sectional view taken on the line '99 of Fig. 8;

Fig. 14 is a diagrammatic end view of head cover for the head barrel shown in Figs. 12 and 13;

Fig. 15 is a side elevational view of the head closure shown in Fig. 14 and showing the location of the lugs thereon;

Fig. 16 is a diagrammatic end view, partly in section, of another embodiment of the head barrel;

Fig. 17 is a vertical sectional view taken on the line 17-17 of Fig. 16;

Fig. 18 is a diagrammatic end View of the head cover for the head barrel shown in Figs. 16 and 17; and

Fig. 19 is a side elevational view of the head closure shown in Fig. 18 and showing the location of locking lugs thereon.

Similar numerals refer to similar parts throughout the various figures of the drawings.

In Fig. l a portion of a heat exchanger 1 is shown including a shell 2 and a head member 3. An annular flange 4, extending outwardly from the outer surface of the shell 2, is provided at one end thereof for the purpose of attaching the shell to the end of the head member 3 by bolts 5. The shell is also provided with a fluid inlet 6 and a fluid outlet 7.

The head member 3 includes a barrel wall 8, forming a head chamber 9. A tube sheet 10 separates the chamber 9 from the shell 2. A plurality or bundle of tubes 11 extend through the shell 2 and have ends secured in and extending through thetube sheet 10 for communication with the head chamber 9. The end of the barrel wall 8 opposite tube sheet 10 is provided with a removable head cover or closure 12.

The head chamber 9 is divided into an inlet compartment 13 and an outlet compartment 14 by a battle or partition 15 which is welded to opposite sides of the head chamber 9. In addition, an inner cover plate 16 extends across the entire head chamber 9 and is secured to the end of the baffle or partition 15 by bolts 17. The peripheral portion of the cover plate 16 is secured to an inner shoulder 19 by bolts 18 welded at 20 to the barrel wall. The aperture 21 provides for equalizing pressure on opposite sides of the cover plate 16.

As shown in Fig. l the barrel wall 8 is provided with a fluid-inlet 22 and a fluid-outlet 23 which are secured in fluid-tight manner by

similar welds

24 and 25.

The head closure or cover 12 is removably secured in place within the open end of the head member 3 by corresponding interlocking members on the head barrel and the head closure. The barrel wall 8 is provided with a number of

lugs

26 and 27 which extend radially inwardly and axially spaced from each other. The

lugs

26 and 27 are preferably two in number but may be more.

As shown in Figs. 8 and 9, the

lugs

26 and 27, being preferably two in number, extend in approximately segments or a semi-circle, around the inner wall of the head member 3. The

lugs

26 and 27 are spaced axially of the barrel wall 8, the spacing being equal to at least the width of similar lugs on the head closure member 12. In addition to being axially spaced, the

lugs

26 and 27 are circumferentially staggered preferably so that one lug is in axial alignment with the space between the ends of the other lug. For example, as shown in Figs. 8 and 9, the lug 26 is aligned with and has approximately the same circumferential length as the space between the ends of the lug 27, there being no overlapping of any portions of the

lugs

26 and 27. In the same manner, the lug 27 is axially aligned with the space between the ends of the lug 26. Likewise, the

lugs

30 and 31 on the head closure 12 are circumferentially staggered to correspond with the positions of the

lugs

26 and 27.

As shown in Figs. 1, 2, 1a and 2a, the lug 26 is provided with a corner groove 28 at the outer end thereof and coextensive therewith. In addition, the end face ofthe barrel wall 8 is provided with an annular gasket seal rib 29 engaged by a sealing gasket.

As shown in Figs. 1, and 11; the head closure 12 includes a pair of

lugs

30 and 31 similar to

lugs

26 and 27 on the barrel wall 8. The

lugs

30 and 31 are preferably two in number and have

side surfaces

30a and 31a, respectively, engageable with corresponding side surfaces 26 and 27a on

lugs

26 and 27. Thus, as shown in Figs. 10 and 11, the

lugs

30 and 31, like the

lugs

26 and 27, are substantially semi-circular projections on the outer surface of the head closure member 12 and are spaced axially thereof by a distance at least equal to the .width of the

lugs

26 and 27 on the barrel wall 8.

When the head closure member 12 is completely assembled within the barrel wall 8 as shown in Fig. 1 there is abutting contact between the engaged lug surfaces extending 360 around the barrel wall, half between the

lugs

26 and 30 at the upper segment of the member 12 and half between the

lugs

27 and 31 on the lower segment of said member. In this respect, the instant construction differs from prior art, such as that shown in the Price Patent No. 2,219,659, in which only an approximate 180 extent of contact can be established between the engaged lugs on the corresponding barrel wall and head closure.

In addition, the head closure 12 includes a continuous peripheral flange 32 which engages the groove 28 in the lug 26 of the barrel wall 8 to prevent the closure 12 from being pushed into the head member 3 too far upon insertion. Further, the flange 32 engages the groove 28 at the same time that the lug 31 engages a shoulder 3a of the head 3 upon insertion so that the closure 12 is seated in axial alignment with the axis of the head chamber 9. Furthermore, when the heat exchanger 1 is disposed vertically, rather than on the horizontal axis as shown in Fig. l, the shoulder 3a and the flange 32 prevent the closure member 12 from dropping from lug-engaging position within the barrel wall 8 upon assembly.

A gasket seal rib 33 is provided on the outer surface of the head closure 12 and is an annular projection similar to and concentric with, the sealing rib 29 on the barrel wall 8.

As shown in Fig. l, the

seal ribs

29 and 33 cooperate to provide a fluid-tight seal between the head member 3 and the head closure 12. An annular gasket 34 is seated on the

ribs

29 and 33 and bridges the gap therebetween. A metal back-up ring 35 covers the gasket 34 and is held firmly in place by two clamping rings. One inner clamping ring 36 is secured to the head closure 12 by bolts 38 and an outer clamping ring 37 is secured to the end surface of the barrel wall 8 by bolts 39.

The steps by which the head closure 12 is inserted into and removed from the head member 3 are shown by the consecutive steps in Figs. 3-7. In Fig. 3 the closure 12 is first aligned with the open end of the head member 3 into which it is then inserted (Fig. 4) until the

lugs

30 and 31 on the closure 12

contact corresponding lugs

26 and 27 on the head member 3. The closure 12 is then rotated 180 about its axis until the extremities of the aforesaid abutting lugs are clear of each other (Fig. 5) and no longer overlap. The closure 12 may be then further inserted until lug 30 thereon contacts lug 27 on the barrel member 3 (Fig. 6). Finally, the closure 12 is rotated again 180 until abutting

lugs

26 and 30, and 27 and 31 are engaged with each other as shown in Fig. 7.

Manifestly, the closure 12 may be removed from the head member 3 by following the foregoing steps in the reverse order.

In addition to the construction shown in Figs. 1-11 in V which the barrel wall 8 and the head closure 12 are each provided with two lugs, other modified constructions may be provided as shown in Figs. 12-15 in which four lugs are provided and in Figs. 16-19 in which eight lugs are provided. Thus, the invention is not limited'to a minimtnn number of two lugs, as shown in Figs. 1-11, although two lugs are preferred.

As shown in Figs. 12-15 a barrel wall 40 may be provided with the four lugs including two

lugs

41 and 42 and two

lugs

43 and 44, each pair of lugs being disposed in axially spaced zones. Likewise, a head closure 45 may be provided with corresponding lugs including a pair of

lugs

46 and 47 axially spaced from another pair of

lugs

48 and 49. The lugs in one zone are staggered or axially aligned with the space between lugs in the other zone. In addition each lug extends over a 90 arc with a space of 90 between the ends of the lugs of each pair. The pairs of lugs in different zones are staggered so as to cover a complete 360 space around and between the barrel wall 40 and the head closure 45.

Hence, upon insertion of the head closure 45 into the barrel wall 40 the lugs of the former may be aligned with the spaces between the lugs of the latter for insertion. Thereafter, the head closure 45 may be rotated 90 until the space between the lugs of one member is aligned with the other member whereupon the head closure may be then further inserted. Finally, the head closure may again be rotated 90 until corresponding lugs are in abutment with each other so as to provide a 360 contact of lugs around the joint between the barrel wall and the head closure.

Further, a modified construction provides another embodiment in which a barrel wall 50 is provided with eight lugs including pairs of

lugs

51 and 52, 53 and 54, 55 and 56, and 57 and 58. Each lug extends 90 throughout the particular zone in which it is disposed and pairs of lugs are oppositely disposed with spaces equal to approximately 90 therebetween. Similarly, a head closure 59 may be provided with corresponding pairs of

lugs

60 and 61, 62 and 63, 64 and 65 and 66 and 67. As in the foregoing constructions the lugs ineach zone on the barrel wall 50 and the head closure 59 are circumferentially staggered out of axial alignment with the lugs in adjacent zones. Thus, the embodiment shown in Figs. 16-19 includes twice as many lugs as the embodiment shown in Figs. 12-15. The procedure for inserting and removing the head closure 59 from the barrel wall 50 includes twice as many steps as in the embodiment of Figs. 12-15. However, inasmuch as twice as many lugs are provided in two additional spaced zones, there are two series of 360 contacting or bearing area of lug engagement.

Accordingly, where desired, the number of zones of abutting contact may be increased in order to obtain 360 or more of contacting or bearing surfaces between logs of the barrel wall and the head closure.

The number of lugs in a given zone may vary and the number of zones may vary in accordance with requirements. For example, instead of two lugs being provided in two zones in the modified construction shown in Figs. 12-15 or two lugs provided in four zones as shown in Figs. 16-19, three lugs may be provided in any zone.

Accordingly, the present invention provides a new head closure construction for a heat exchanger by which increased pressures may be contained in the heat exchanger with a given outside diameter of the barrel Wall. By providing lugs in staggered arrangement and in spaced zones on the closure member and a corresponding number of lugs similarly arranged on the barrel wall, the total contacting or bearing area of lug engagement between lugs may be extended to occupy substantially 360 around the inner surface of the head barrel wall, and such complete peripheral lug engagement may be multiplied at otherspaced axial zones when desired.

Hence, a reduction in the height of all the lugs can be made, thereby substantially reducing the annular space between the inner surface of the barrel Wall and the of the' closure member to form the closure lugs.

barrel wall and closure member.

greatly reduced hydrostatic load upon the seal for the joint between said members.

'- MoreotIenthe reduction in the height of the lugs results in other advantages not heretofore obtained. Among these is a reductiori'of the thickness of the head barrel wall due to a reduced bending moment on the wall because (1) the lug center line is closer to the mean diameter'of the barrel and (2) the hydrostatic end load carried by the head closure member is reduced. As a direct result in the reduction in the height of the lugs, the inside diameter at the head lugs is substantially reduced and thereby the outside diameter of the head is reduced. I w

A reduction in the diameters and thickness-of the head barrel wall provides a number of other advantages. First,

the reduced height of the lugs permits a reduction in the width of the lugs which in turn affords a reduction in the total thickness of the head closure member between the inside and outside surfaces thereof. Second,

the size and number of bolts necessary to provide a fluid seal between the head barrel wall and the closure may be reduced. This, in turn, reduces the time required to assemble or disassemble the heat exchanger. Also machining time, i. e., time required to contour fewer lugs, is reduced. Also, because of the reduced size and number of head bolts, the clamping or hoop rings may be reduced in size.

v.Thelprovision of bearing engagement between the barrel wall and closure lugs extending throughout the 360 .cbrriplerrintof the telescoped barrel Wall and closure surfaces achieves other benefits. These members normally are made as forgings with wall thicknesses and surface configurations arranged so as to permit the blanks to beforged. Metal must in effect be machined, chipped or whittled out to form the lugs on the barrel wall.

Similarly, metal must be removed from the periphery Such machining operations necessarily stress the forged metal. Thus, warping due to stress relief is apt to occur.

-Where the lugs extend from 90 to 180 around the inner surface of the barrel wall substantially less warping will occur thanwhen the lugs are whittled out as gcar-tooth-like lugs in accordance with prior practice. For example, one or more of the prior art gear-tooth-like lugs may Warp out of position on either or both of the If this occurs it is possible that no lug bearing engagement will result at the particular location, thus increasing the load at adjacent engaged lugs.

With the improved construction, such warpage is minimized because of the extended length of the lugs, and the load is therefore more evenly distributed between the engaged lug surfaces, and is carried throughout the entire-360 complement.

The long length lug characteristic of the improved construction provides a certain hoop or ring effect to the lugs which stiffens the same due to their circumferential extent, so that they resist warpage which might otherwise tend to occur because of stress relief or for any other reason.

The 360 load bearing characteristic is sometimes referred to herein as substantially 360. Obviously it is necessary to provide clearance between the ends of lugs at different zones for permitting easy insertion of the closure member within the barrel member. Such clearance is indicated at 53 and 69 in Figs. 8 and 10.

The illustration of certain elements in the diagrammatic views of Figs. 3 through 19 has been omitted to clearly illustrate generally the mode of assembly of and the cooperative relation between the elements of the improved closure construction. For instance, no tubereceiving openings are illustrated in the tube sheet portion of the head member.

The function of the flange 32 in cooperation with the ingthe inserting procedure has been described. Where thereare only two lugs, .each extending throughout an approximate arclwithin the barrel wall, the provision of the shoulder 3a is important. However, where there are two or more lugs at each Zone, such as the

lugs

41 and 42 in Figs. 12 and 13, or 51 and 52 in Figs. 16 and 17, relative axial tilting between the closure and barrel wall while finally seating the. closure is controlled and prevented by the closure flange 32 alone and the barrel wall shoulder 3a is unnecessary, thereby permitting the head chamber diameter to be increased by the elimination of the shoulder 3a and thus space for additional tubes may be provided without otherwise increasing the size of the heat exchanger head construction.

Finally, the many new results obtained by the improved construction have led to a metal savings alone amounting to hundreds or thousands of dollars over the cost of metal heretofore required to build an otherwise equivalent heat exchanger.

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

Moreover, the embodiments of the improved construction illustrated and described herein are 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 features, constructions and principles of invention, the characteristics of the improved head closure construction for heat exchangers, and the advantageous, new and useful results provided; the new and useful discoveries, principles,-parts, elements, combinations, subcombinations, structures and arrangements, and mechanical equivalents obvious to those skilled in the art, are set forth in the appended claims.

I claim:

1. Head closure construction for heat exchangers, including an annular head barrel wall having an inner annular surface defining the open end of the head, two closure-engaging lugs projecting radially-inwardly of the inner surface of the barrel wall, the lugs being axially spaced and circumferentially staggered, a closure member within the open end of the barrel wall, two engaging lugs extending radially-outwardly from the outer surface of the closure member, said closure member lugs being axially spaced and circumferentially staggered to match the spacing and staggering of the barrel wall lugs, the axial spacing between the barrel wall lugs beat least as great as the axial width of the closure lugs, the two closure-engaging lugs projecting inwardly of the inner surface of the barrel wall, each extending through a circumferential segment of substantially 180 free of axial overlap so constructed that the extent of circumferential connection of the two axially spaced barrel wall lugs with the barrel wall is approximately 360 around the circumference of the inner barrel wall surface.

2. Head closure construction for heat exchangers, including an annular head barrel wall having an inner annular surface defining the open end of the head, four closure-engaging lugs projecting radially-inwardly of the inner surface of the barrel wall, the lugs being axially spaced and circumferentially staggered, a closure member within the open end of the barrel wall, four engaging lugs extending radiallyoutwardly from the outer surface of the closure member, said closure member lugs being axially spaced and circumferentially staggered to match the spacing and staggering of the barrel wall lugs, the axial spacing between the barrel wall lugs being at least as great as the axial width of the closure lugs, the four closure-engaging lugs projecting inwardly of the inner surface of the barrel wall, each extending through a circumferential segment of substantially 90 free of axial overlap so constructed that the extent of circumferential connection of the four axially spaced barrel wall lugs with the barrel Wall is approximately 360 around the circumference of the inner barrel wall surface.

3. Head closure construction for heat exchangers, including an annular head barrel wall member having an inner annular surface defining the open end of the head, at least two closure-engaging lugs projecting radially-inwardly of the inner surface of the barrel wall, the lugs being axially spaced and circumferentially staggered, one circumferential end of one of the lugs being substantially in axial alignment with the opposite circumferential end of an adjacent axially spaced lug, the other end of said one lug being substantially in axial alignment with the opposite circumferential end of an adjacent axially spaced lug, said axially spaced and circumferentially staggered lugs having connection with the barrel wall for approximately 360 around the circumference of the inner surface of the barrel Wall, a closure member within the open end of the barrel wall, at least two engaging lugs extending radially outwardly from the outer surface of the closure member, said closure member lugs being axially spaced and circumferentially staggered to match the spacing and staggering of the barrel wall lugs, and the axial spacing between the barrel wall lugs being at least as great as the axial width of the closure lugs.

4. Head closure construction for heat exchangers as defined in claim 3, in which the closure member is telescopically and rotatably positioned Within the barrel wall member to establish lug engagement, and in which means is provided extending continuously circumferentially around one of the barrel wall and closure members engageable with the other member to prevent overinsertion of the closure member Within the barrel wall member.

5. Head closure construction for heat exchangers as defined in claim 4, in which the continuously extending means includes a continuously extending outwardlyprojecting flange at the outer end of the closure member engageable with one of the barrel wall member lugs.

6. Head closure construction for heat exchangers as defined in claim 4, in which the continuously extending means includes an annular flange projecting from the closure member engageable with a barrel wall member lug, and an annular barrel wall member shoulder engageable with the closure member lug.

7. Head closure construction for heat exchangers, in cluding an annular head barrel wall member having an inner annular surface defining the open end of the head, closure-engaging means projecting radially-inwardly of the inner surface of the barrel wall, the closure-engaging means including lug means located at axially spaced Zones, the lug means at one Zone being out of axial alignment with and extending substantially throughout the circumferential space between the ends of the lug means located at the second axially spaced zone, each circumferential end of any lug means at one zone being substantially in axial alignment with the opposite circumferential end of an adjacent axially spaced lug means located at the second zone whereby the lug means at said two zones have connection with the barrel wall for approximately 360 around the circumference of the inner surface of the barrel wall, a closure member within the open end of the barrel wall, engaging means extending radially-outwardly from the outer surface of the closure member, said engaging means on the closure member comprising lug means located at axially spaced zones and matching the spacing of the barrel wall lug means, and the axial spacing between the barrel wall lug means at said two zones being at least as great as the axial width of the closure member lug means.

References Qited in the file of this patent UNITED STATES PATENTS 837,648 Strom et al. Dec. 4, 1906 2,342,186 Fischer Feb. 22, 1944 2,473,555 Weiss June 21, 1949 2,652,170 Lotter et al. Sept. 15, 1953