US2191179A - Self-seating gasket - Google Patents

Description

Feb- 20, 1940 E. M. o'DoNNE1 SELF-SEATING GASKET 2 Sheets-Sheet 1 Filed Sept. 5. 1939 UX l N 1 X" I. W QN "1 L l A/ 9 511% 1m n N Q l1 1 1 l! A. .illL/ N N S11 1 n# i Y l m. QM mm m `m y ...uw- WH/f. di 1 .K m 1 n A TTORNEY.

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Feb. 20, 1940. E. M. O'DONNELL SELF-SEATING GASKET Filed Sept. 5, 1959 2 SheelLS--Sl'leeI 2 INVENTOR. www mgm@ ATTORNEY.

Patented Feb. 20, 1940 y n PATENT I fori-lcs tamu-1 M. onennen, ssn mneiseo, cam. Appuemen september s, 1939, serial No. 293,411

lClaim.

This invention relates to packing gaskets oi' the type employed to prevent leakage from one pressure chamber to another, and especially to a gasket or packing strip'iwhich is self-seating s and which is maintained on its seat by the pressure maintained on a duid or liquid circulated` throughthe chamber.

In the operation of heat exchangers or like apparatus, in which the heads disposed `at the opl positeends of the .heating chamber are crossribbed to form a multiplicity o! chambers to permit the liquid or other substance treated tobe circulated back ,and forth through ,the tubes within the heat eneiiager, consider-eme trouble` l is encountered in preventing leakage or short circuiting of the liquid between the chambers, as it is almost impossible to maintain unii'orm seats for the receptiorioi packing gaskets, due to `variations in expansion and contraction oi the sev--` 50 eral parts forming the heat exchanger, and also due-to pressure variationsl at different points within the heat exchanger.

The object ofthe present invention is generally to improve and simplify the construction and 25 operation of heatexchangers and like apparatus, and especially to provide a gasket or packing strip which is self-seating and which is malntained in its seat by duid pressure. 1

The invention is shown by` way of illustration 3g in the accompanying drawings, in which Fig. l is a central, vertical, longitudinal sec-` tion through a heat exchanger; .i l

Fig. 2 is an end view looking at lthe interior face of one of the exterior heads;

35 Fig. 3 is a perspective view of a portion of one oi' the packing strips, showing the manner in which it is retained; and

Fig. 4 is an enlarged detail cross sectional view showing a modified form of packing gasket inter- 0 posed between one of the heads and tube sheets.

Referring to the drawings in detail, and particularly to Fig. l, A indicates a cylindrical elongated housing which may be constructed of steel, cast iron, or any other suitable material.

5 Formed at one end oi the housing is an annular ilange 2 and secured thereto by bolts 3 or other suitable means is a tube sheet l. Slidably mounted on the opposite end of the housing is a iloating head member i. This head member is cirn cular ln shape and angular in cross section. It forms a support for a second tube sheet la, said tube sheet being secured by bolts or the like. Secured between the tube sheets 4 and la are a plurality of tubes 1.

1 constructed of copper, or like materials hence if Ila by a clamping ring and bolts I2. formed by the bolts II and I2 and the cooperat- These tubes are preferably the housing is constructed ofsteel and the tubes oi copper the diierence in coeilicients of expansion between the same is considerable. It is for this reason that the iioating head 5 has been provided for the support of the tube sheet 4a. 5 By providing the noating head, free expansion and contraction of the tubes 'I can `taire place without throwing any stress or strain on the housing, or the tube sheets. 1

In as much as the tubes 1 are heated by steam, 10 or a similar medium, admitted through the connection shown at 8 under pressure, considerable leakage might occur between the iloating head and the housing, and a seal in the form of a iiexible ring 9, which lss-shaped in cross section, is l5 employed. The sealing member is secured at one end to an annular flange I6 formed on the nous ing by means of a clampingringand bolts I l, and the opposite `end is secured to the tube sheet The joints lng clamping rings are leak-prooi', and any pressure desired may thus be employed. In the operation of heat exchangers of the character here disclosed, accessibility for inspection, cleaningsterilizing, repair. etc., is exceedingly important, as the apparatus must be thoroughly cleaned, inspected and sterilized at least once duringeachtWenty-four hours of operation. To promote such accessibility and to facilitate re-u pairs the `tube sheets have been made removable and renewable, se that if either sheet should crack or become otherwise impaired it may be removed rnerely by releasing the bolts 3 or I2. To facilitate 'accessibility for cleaning, inspection .35 and so on, removable heads B and C are provided. These are secured in place by bolts il and wing nuts I 5, and. hinges may' also be provided, about which the heads may be swung. but they are not disclosed in the present instance as 40 they form no part of the invention. The inner surface of the head B is provided with a transverse rib or partition wall I6, which divides the head into two chambers II and Il. The head C is provided with two cross-ribsl thereby forming 45 three chambers I9, 20 and 2|. The liquid to be heated or otherwise treated enters the chambers I9 through an elbow connection 22. It flows through the tubes 23 and 24 in the direction of the arrows into chamber i'i, then through tube 50 25 into chamber 20, then through tube 26 into chamber I8, and nally through tubes 21 and 28 into chamber 2i, and out through an elbow 29. In actual practice considerable difficulty has been experienced in maintaining a tight seat besi chamber to another unless tight seats are maintained. Plainly speaking, if the liquid to be cir culated and heated can leak or flow from one chamber to another without passing -through the heat exchanging tubes, the proper temperature will not be obtained. In most instances, the liquid to be circulated and heated is maintained under considerable pressure, for instance, 80 lbs. gauge or more, and obviously the higher the pressure the greater the leakage.

In the structure here shown, a gasket or pask-` ing strip 30 is employed which is self-seating and `which is held against the seat by the pressure maintained on the liquid. This is accomplished as follows:

Referring to the drawings. andvparticularly to Fig. 3, it will be noted that each cross-rib ls provided with a side bar 3|-, and that eachhside bar is maintained in spaced relation to its cross-rib by spacer lugs 32 welded or otherwise secured to the respective members. 'Ihe inner face 33 of each rib and side bar is machined or finished to clear the adjacent tube sheet by, for instance. of an inch, when the heads B and C are closed and tightened into place against ltheir gaskets 40. The gaskets or packing strips Il maybe made of rubber or any suitable material. They are placed between each cross-rib and cooperating side bar, and are frictionally held in place between them. They may project beyond the faces 33 when in place, and as such they will engage the adjacent faces of the tube sheets when the heads are applied and tightened, but such engagement can not be depended upon, as the tube sheets andthe heads proper are subject to variations in both temperature and pressure, and a uniform seating surface can therefore not be relied upon. The moment liquid is introduced under pressure, and starts circulating, each insured, regardless of any irregularity in the seating surface. I

In an apparatus of this character the liquid to be heated is usually maintained in continuous n circulation and under pressure by means of a pump, not here shown. 'I'hat is, the pump is pr0 vided with a discharge pipe which connects with the elbow 22, and the suction side of the pump is connected with the elbow 2Q. Thus there is tendency for differential pressure, the pr being highest in the chamber i Q and lowest in the chamber 2i. This pressure variation increases the tendency for the liquid to by-pass from one chamber to another without passing through the tubes, but such a tendency is entirely overcome by maintaining the gaskets or packing strips in the manner here disclosed.

The principle of maintaining a packing gasket in engagement with its seat by means of fluid pressure is not limited to the specific application shown in Figs. 1 and 2, as it is equally applicable to the type of gasket shown at 40 in Fig. l. For instance, in Fig. 4, the gasket 40a is shown as dls\ posed adjacent the inner annular face 4i of the f head B', and is retained in that position by a retainer ring k42 and lugs 43. In this position one face of the gasket will engage thetube sheet, while the opposite iacewill be exposed to the iluld under pressure, and as such will be forced against the tube sheet with sufllcient pressure to prevent leakage between head B' and the tube sheet.

While certain features of my invention have been more or less specifically described and illustrated, I nevertheless wish `it understood that changes` may be resorted to within the scope of the appended claim, and that the materials and finish of th'e various parts employed may be such as the manufacturer desires, or various conditions of use demand.

Having thus described my invention, what I claim and desire to secure by Letters Patent is- In a heat exchanger of the character described,

a body member, a tube sheet secured at one end thereof, a plurality of heat-'exchanging tubes securedln the. tube-sheet, through which a fluid under pressure is circulated, a removable head cooperating with the tube sheet, said head having a partition wall which divides the head into two chambers, rsaid chambers diverting and causing a back-and-forth flow of the uid through the tubes, and means for preventing leakage under theA partition wall fromone chamber to the other, said means comprising a bar disposed parallel to the wall and spaced therefrom, and a packing gasket disposed between the wall and the bar, said gasket having one face positioned to engage the tube sheet and the opposite face exposed to the fluid under pressure, so that the pressure exerted thereon will force the gasket against the seat.

EDWARD M. ODONNEIL.

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