US3457987A

US3457987A - Orifice sealing devices

Info

Publication number: US3457987A
Application number: US686060A
Authority: US
Inventors: Harry G Lampe
Original assignee: Gulf Oil Corp
Current assignee: Chevron USA Inc
Priority date: 1967-11-28
Filing date: 1967-11-28
Publication date: 1969-07-29
Anticipated expiration: 1986-07-29

Description

July 29, 1969 H. G. LAMPE 3,457,987

ORIFICE SEALING DEVICES Filed Nov. 28, 1967 (PR/0R ART) INVENTOR HARE Y 6. LAMPE United States Patent 3,457,987 ORIFICE SEALING DEVICES Harry G. Lampe, Springfield Township, Delaware County, Pa., assignor to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Nov. 28, 1967, Ser. No. 686,060 Int. Cl. F161? 1/34; F28f 19/00, 7/00 US. Cl. 165-71 16 Claims ABSTRACT OF THE DISCLOSURE Sealing devices comprising two plugs, the first of which is an expandable hollowed out shell and the second of which is a generally conically shaped plug so tailored that it will fit, small end first, into the hollowed out cavity or shell of the first plug, are disclosed along with their method of use. The second plug is loosely placed into the cavity of the first plug and assembled, first plug first, into the orifice to be sealed. By providing a backup or stop plate in contact with the first plug on one side of the orifice and applying a force against the larger end of the conically shaped plug on the other side of the orifice sufficient to wedge or force the conical plug into the cavity of the first plug and thereby cause the cavity walls to expand tightly against the orifice, a very tight seal of the orifice can be obtained. The invention is especially applicable when used in plugging heat exchanger tubes in a floating head type heat exchanger, wherein the floating head cover is used as the stop plate, since the invention eliminates the need to dismantle the floating head end in order to plug the tubes.

Background of the invention This invention relates to orifice plugging devices. More specifically this invention relates to forming tight seals in tubes with novel devices.

For many years the problem of forming tight inexpen-.

sive seals in orifices generally, and various types of tubes more specifically, has been presented to the art.

This problem has been noticeably acute in the heat exchanger art, especially when a leaky heat exchanger tube in a floating head type heat exchanger must be plugged to prevent the various fluids from intermingling. Previous solu ions for this especially acute problem in the heat exchanger art have consisted of plugging devices which either require the uneconomical dismantling of the floating head end of the heat exchanger to permit access to the end of the leaky tube or form defective, temporary, uneconomical, and otherwise undesirable plugs. For example, one known way of plugging these tubes is to insert a ball of steel wool into the end of the leaking tube. The nonpermanency of such a solution is readily apparent.

Another known way of plugging these tubes is to dismantle the floating head end of the heat exchanger to permit open access to the tubes so that a conventionally welded permanent plug may be inserted therein. This involves removing the back shell cover and floating head cover (sometimes referred to as the floating tube sheet cover) of the exchanger, erecting scaffolding to be used as a working platform while a standard permanent plug is inserted or welded into the end of the tube, and then reassernbiing the apparatus. In most every instance, reassembly also necessitates pressure testing the reassembled floating head cover to check for leaks. The lack of economy due to shutdown time and labor costs makes this procedure undesirable indeed.

Two recent patents, US Patent No. 2,856,963 to I. J. Hoerter and U8. Patent No. 2,937,666 to O. Maisch, exemplify another known approach to this problem.

Basically this approach comprises a relatively elaborate mechanism for wedging a conical plug into an expandable hollow shell by pulling the conical plug downwardly into the shell and into the tube, thereby expanding the shell 5 Wall against the tube to form a seal. The relatively elaborate nature of the mechanism required, the special materials needed, and the dual seal developed, i.e., the first seal being between the tube and the expanded plug and the second seal being between the expanded plug and the conical plug, and thus the dual risk of leakage, all serve to leave room for further improvements in this area.

It is therefore an object of this invention to provide a novel and improved plug device for sealing orifices.

It is a further object of this invention to provide a plug device which seals tubes and especially tubes of a floating head type heat exchanger.

It is a further object of this invention to provide a device for plugging an orifice including both novel and conventional stop means and a means to apply an expanding force.

Summary of the invention The present invention, though basically a double plug approach, serves to overcome the above problems in a novel and nonobvious way as evidenced by its strikingly nonelaborate mechanism which results in economy, eliminates the need for dismantling of the floating head end of a floating head type heat exchanger, and, at least in one embodiment, presents only a single seal, i.e., a seal between the expandable plug and the orifice or tube.

Brief description of the drawings FIG. 1 is a sectional view of a well known floating head type heat exchanger, for which the plug of the present invention is particularly adapted; and

FIG. 2 is a partial sectional view of one form of the loosely assembled unexpanded device inserted in the floating head end of a floating head type heat exchanger tube along with the rod which was used to insert it.

FIG. 3 is partial sectional view of another form of loosely assembled unexpanded plug device.

FIG. 4 is a schematic 3 dimensional view of the device in FIG. 3 before it is assembled.

Detailed description of the invention Basically, the invention comprises a double plug device having a first plug capable of being inserted into the orifice to be plugged and having in one end thereof a longitudinally extending cavity, or hollowed out portion, defining a totally surrounding cavity wall, or shell, of sufficient thickness and flexibility to expand upon the application of force to form a seal with the orifice. The second plug is of a generally tapered shape and is tailored such that the smaller end of the taper is of such a size that it may be inserted into the cavity, or shell portion, of the first plug and such that the larger end of the taper is of sufficient size so that when the second plug is driven, wedged, or forced into the first plug cavity, it will cause the cavity to expand sufliciently far to bring the cavity walls into sealing contact with the orifice.

The first plug may be of many diflerent forms and shapes. Generally, of course, its cross-sectional shape will be basically that of the orifice to be filled or of such a shape that it may be expanded into the cross-sectional shape of the orifice to be filled. The cavity of the first plug may or may not extend through the entire length .of the plug. If it does, the first plug may be a piece of expandable tubing. However, in its preferred form, the cavity of this first plug does not extend all the way through the plug, but rather terminates intermediate the two ends of the plug and thus defines a first plug which has an open and a closed end. As is readily seen, this provides a system which when in expanded form, has but one sealing interface.

As will be shown more thoroughly later, this plug may be of any desirable and operative length. For example, when it is used to plug the floating head end of a floating head type heat exchanger tube, its thickness is such that it can be inserted and pushed freely through the tube when in unexpanded form and its length is suflicient such that, when its leading end contacts the floating head cover (acting as the stop means), at least a portion of the expandable part of the plug is within the confines of the tube. In an especially preferred form, the diameter of this tube is only slightly less than that of the orifice to be plugged.

The second plug may also have various forms, shapes and sizes. Generally, it may be stated that its cross sectional shape at the point of sealing contact is basically the cross-sectional shape of the orifice to be plugged. This plug may be tapered only at one end or throughout its length and may be conical in shape. It may also be solid, but in a preferred form it is provided with a hole extending longitudinally through its entire length. This hole serves to release air pressure in the cavity that would otherwise build up when the second plug is forced into the first plug, thus helping to form a more secure seal. In this respect, it is seen that if the air pressure were not released from the cavity, application of heat, for example, during a heat exchange process, would cause the air to expand and force the conical plug out of the cavity. Of course, it is clear that if the orifices to be sealed are tubes, the dimensions of this plug may be such that it is capable of insertion into and through the tube.

The plug assembly contemplated herein may be used in a wide variety of environments. For example, it may be used as an emergency measure to plug holes developing in various types of tanks. It may be used to plug drain orifices at the bottom of liquid containing tanks or containers. It may also be used to seal the spouts of containers used in various environments or to plug orifice plates so as to achieve a given design. The most preferred environment, however, is in its use as a plug to seal inaccessible ends of leaky heat exchanger tubes and especially heat exchanger tubes in a floating head type heat exchanger.

In combination with this plug assembly, another feature of this invention contemplates the use of a stop means located, preferably but not necessarily, on the side of the orifice opposite that side to which the expansion causing force is applied to the second plug. This stop means serves to stop the plug assembly from being inserted too far into or through the orifice, as well as serving to brace the assembly against longitudinal movement during the application of force. It is readily apparent that this stop means should be positioned such that the plug assembly, after full insertion, is held so that at least part of the expandable cavity wall of the first plug will be within the confines of the orifice or tube to be sealed. As is obvious to the skilled artisan, if the stop means is provided for by the structure holding the orifice to be sealed, the plug assembly will be dimensioned so as to fulfill the above requirement.

In a preferred form, this stop means comprises the floating head cover (floating tube sheet cover) of a floating head type heat exchanger which is in spaced relation from the heat exchanger tubes.

The means chosen to apply an expanding force to the second plug can be one of many well known and applicable devices. However, in applying the force, it is most desirous to apply it to the larger end of the tapered plug from a direction which will drive the tapered plug firmly and swiftly into the cavity of the first plug. A hammer blow is one example of such a force. In a preferred form, and especially when plugging inaccessible ends of heat exchanger tubes, a rod sufiiciently long to extend beyond the non-plugged end of the tube when it is inserted into abutting contact with the larger end of the tapered plug,

is used to transfer the application of force, such as by hammer blow, etc., from a point outside of the tube to the tapered plug.

The invention also contemplates within its scope the method of inserting and expanding the plugs in an orifice. This method basically consists of first loosely inserting the tapered plug in the cavity, or shell hole, of the first plug, inserting this assembly through the orifice far enough so that at least a portion of the expandable shell or cavity wall is located within the confines of the orifice. This latter step may be achieved by positioning a stop plate or device on the side of the orifice opposite to that side on which the expanding force is to be applied. Finally, force is applied to the tapered plug, as by hammering, etc., to drive, wedge, or force this plug toward the stop means into the cavity and thereby expand the cavity walls into sealing contact with the orifice. As was alluded to hereinabove, when the orifice to be plugged is an inaccessible end of a tube, it is very convenient to use a rod as the force delivery means. Such method of plugging is then modified to first include inserting the loosely assembled plugs into the accessible end of the tube to be plugged, then inserting the rod behind the assembled plugs, and pushing the plugs through the pipe until the first plug contacts the stop means. Since the rod, because of its length, extends out of the accessible end of the tube and at the same time abuttingly contacts the larger end of the tapered plug, the final step comprises the application of force to the rod as by a hammer or other convenient means until the seal is effected, after which the rod may be withdrawn.

Of course, it is understood that this basic procedure may be followed with all tubes even though both ends are accessible. In fact, this latter renders it unnecessary to insert the tube from the far end. Rather, the plugs may be inserted directly into the end to be sealed and the rod then used solely as a force delivery means. This may, in certain instances, necessitate the use of a movable stop means.

It is also understood that various types and shapes of stop means or back-up braces can be used, many of which are well known and conventional in the art. It is further noted that the stop means need not be on the side of the orifice opposite to the application of force side, but rather may be present on the same side as the application of force.

Preferred embodiments Although the following discussion sets forth some preferred embodiments and the best mode contemplated for carrying out the invention, it will be readily apparent that the scope of the invention presented herein is not so limited, but rather has applicability for orifice and tube systems generally, as hereinbefore shown.

Referring now to the drawings, FIG. 1 depicts a well known floating head type heat exchanger having a floating head end 1, a heat exchange portion 2, and a stationary head end 3. The floating head end 1 is made up essentially of a shell cover 4, a floating head cover, 5 (sometimes called a floating tube sheet cover), a floating tube sheet 6 which, as shown best in FIG. 2, houses one end of heat exchanger tube 7. Of course it is realized that in actuality there exists a plurality of these heat exchange tubes, but only one such tube is illustrated here for the sake of clarity. The heat exchange portion 2 includes a bank of tubes 7, as suggested above, a shell 8, a shell nozzle 9, and an instrument connection 10. The stationary head end 3 includes a stationary tube sheet 11 which houses the stationary head end of the exchanger tube 7, a channel or stationary head 12, a channel nozzle 13 and an instrument connection 14.

As hereinbefore stated, reference to the above description points out the great waste of time and labor which occurs if the floating head end of the exchanger must be disassembled, and why a nonelaborate but effective sealing device is so needed in the art. The invention disclosed herein and now to be illustrated and described presents the art with just such a device.

Referring to FIG. 2, there is illustrated in accordance with one embodiment of the invention, a first plug having an outside diameter slightly less than the inside diameter of heat exchanger tube 7 and being provided with a longitudinally extending cavity, or hollowed out portion 16. This cavity defines a totally surrounding cavity wall 17 having a bottom 18 intermediate the ends of plug 15, thus providing a plug having an open end 19 and a closed end 20. This plug may be made of any suitable material which when hollowed out will provide the necessary malleability to the cavity wall 17 so that it may be expanded into sealing contact with the inner wall of tube 7. Examples of such materials are tempered steel and alloys thereof.

Referring to FIGS. 34, and in accordance with another embodiment of the invention, first plug 15 consists of two sections, front section 32 and rearward section 33. Front section 32 and rearward section 33 are connected by dowel portion 34 extendingfrom rearward section 33 and being so dimensioned as to press fit into hollow cavity 35 in the rearward end of front section 32. Of course it is realized that this connection in practice may be of many forms and types, from mere abutting relationships to elaborate interlocking connections. For convenience, only the preferred form is depicted in these drawings.

The sectioning of first plug 15 into a plurality of sections is intended for use in handling special situations that arise in plugging different types of systems. For example, when heat exchange-r tubes 7 or orifice systems generally are made of soft and puncturable metal such as copper, the sectioning of first plug 15 enables rearward section 33 to be made of a soft metal such as copper, brass, or annealed steel, thus decreasing the probability of injury to the soft metal exchanger tubes 7 upon plugging with second plug 21 hereinafter described. At the same time, from section 32 of first plug 15 may be made of a hard metal such as a drill rod or cold rolled steel, thus serving to furnish a stronger material for support against the stop means. Rearward section 33, of course, does not have to be made entirely of the softer metal, but need only be made of the softer metal at the point of expanded contact with the puncturable orifice.

The sealing devices of this invention as illustrated in FIGS. 24, also include a tapered second plug 21 being of a generally conical shape and being so tailored that its smaller end 22' has a diameter less than the diameter of the cavity opening 19, whereby it is capable of insertion into cavity opening 19. The larger end 23 of this plug is of a size sufiicient such that when this plug is forcibly inserted, small end 22 first, into the cavity opening 19, the gradually increasing diameter or taper of plug 21 will, at some given distance of insertion, part way along its length, force cavity, or shell, wall 17 outwardly and into sealing contact with the wall of tube 7.

Tapered plug 21 preferably is provided with a hole or cavity 24 longitudinally extending through its entire length. This hole or cavity, as heretofore discussed, serves to relieve back-up pressure caused by air which might otherwise be compressed in cavity 18 in advance of plug 21 as it is being inserted.

The length of first plug 15 is seen to be sufiicient such that when its forward end contacts floating head cover 5, at least a portion of its expandable end generally defined by walls 17 is within the confines of tube 7.

A preferred example of the method of using these plugs is as follows:

In operation, heat exchangers of the type shown in FIG. 1 are tested for leaks by any one of many well known methods. One of these methods convenient for use in this invention, is to first remove the channel or stationary head 12, thus exposing the stationary tube sheet 11 and the stationary head ends of heat exchanger tubes 7. Next hydrostatic pressure is applied to the shell side of the tubes in heat exchange portion 2 by flooding shell 8 with a fluid through shell nozzle 9. The leaky tubes then readily exhibit themselves when the fluid runs out of their exposed ends.

Once it is determined that a tube 7 is leaking, hydrostatic pressure is withdrawn and the stationary head ends of the tubes are left exposed. Plug 21 is then loosely placed, end 22 first, into cavity 16 of first plug 15. This loose assembly is then placed, end 20 of plug 15 first, into the stationary head end of leaky tube 7. Rod 25 is then inserted behind the assembly of plugs and into tube 7. This rod is then pushed into and through tube 7 carrying with it the plug assembly until end 20 of plug 15 contacts the floating head cover 5 and end 26 of the rod abuts larger end 23 of plug 21. As shown in FIG. 2, rod 25 is of such a length that when the above abutting-contacting condition exists, it extends beyond the exposed end of tube 7. A force, such as a hammer blow, is then applied to end 27 of rod 25 which forces or wedges plug 21 into cavity 16, thereby forcing cavity walls 17 into sealing contact with tube 7. Rod 25 is then withdrawn from tube 7 and a conventional, permanent plug is placed in the exposed end of tube 7. With the replacement of channel 12 and the start-up of the exchanger, it can be seen that the leaky tube has been permanently and economically plugged, without the need for dismantling the floating head section, and with a plug having only a single seal interface.

This method, of course, is broadly applicable to many different types of tubes and heat exchanger tubes. It is apparent, however, that an even more simplified method exists when plugging simple orifices. In such a case the plug assembly is inserted until at least a portion of the expandible part of the first plug is within the confines of the orifice, the plug being held against further movement by any suitable stop means. Force in the nature of a hammer blow may then be delivered directly to the second plug, without the need for a rod, until the first plug is expanded into sealing contact with the orifice.

Many other features, modifications, and embodiments of this invention are obvious to one skilled in the art and thus are included within its scope.

What I claim as my invention is:

1. An orifice sealing device comprising:

(a) a first plug capable of being inserted into the orifice and having in one end thereof a longitudinally extending cavity defining a totally surrounding cavity wall of sufiicient thickness and flexibility to expand upon the application of force into sealing contact with said orifice, said cavity having a bottom intermediate the ends of said plug to thereby define an open end and a closed end of said plug, and

(b) a tapered second plug, the smaller end of which is of such a size as to enable it to be inserted into the longitudinally extending cavity of said first plug and the larger end of which is of a size sufficient such that when said second plug is forcibly inserted, small end first, into the cavity of said first plug, said tapered second plug will expand said cavity walls into sealing contact with the orifice.

(c) said tapered second plug being provided with a longitudinal hole extending through its entire length.

2. A device according to claim 1 wherein said tapered plug is of a generally conical shape.

3. A device according to claim 1 including a first plug stop means located on the side of the orifice opposite to the application of expansion causing force side, to stop said first plug when it is inserted into and beyond said orifice and brace it against further longitudinal movement by said force.

4. A device according to claim 3 wherein the orifice is a tube passage and said tapered plug is of dimensions such that it is capable of insertion into the tube.

5. A device according to claim 4 wherein the orifice to be plugged is an inaccessible tube end in a heat exchanger.

6. A device according to claim 5 wherein the heat exchanger is a floating head type heat exchanger, the tube end to be plugged is at the floating head end of the exchanger, and the stop means is the floating head cover.

7. A device in accordance with claim 5 wherein said second plug is a conical shell.

8. A device according to claim 1 wherein said first plug is comprised of a rearward section and a detachable front section.

9. A device for plugging an orifice comprising:

(a) a first plug having an outside diameter which is less than the inside diameter of the orifice and is capable of insertion into said orifice, said plug having in one end thereof a longitudinally extending cavity defining a totally surrounding cavity wall of sufiicient thickness and flexibility to expand upon the application of force into sealing contact with said orifice,

(b) a tapered second plug, the smaller end of which is of such a size as to be insertable into the longitudinally extending cavity of said first plug and the larger end of which is of a size suflicient such that when said second plug is forcibly inserted, small end first, into the cavity of said first plug, said tapered second plug will expand said cavity wall into sealing contact with the orifice,

(c) said second tapered plug having a longitudinal hole extending through its entire length,

(d) a first plug stop means located on the side of the orifice opposite that side of the orifice whereon the expansion causing force is applied, to stop said first plug when it is inserted into and beyond said orifice and brace it against further longitudinal movement by said force, and

(e) means for applying a force to said second plug in an amount suflicient to force said second plug into the cavity of said first plug and cause the cavity walls to expand into sealing contact with the orifice.

10. A device according to claim 9 wherein said tapered plug is of a generally conical shape.

11. A device according to claim 9 wherein the orifice is a heat exchanger tube located in a heat exchanger, the means for applying the force to the large end of said second plug is located at the opposite end of the tube from the end to be plugged, and the stop means is located at and beyond the end of the tube that is to be plugged.

12. A device according to claim 11 wherein the heat exchanger is a floating head type heat exchanger, the tube passage to be plugged is at the floating head end of the Exchanger, the stop means is the floating head cover, and the means for applying a force to the larger end of said second plug comprises a rod extending from the stationary head end of the heat exchanger through the tube and into abutting contact with the larger end of the second plug and means to apply a longitudinal force to the rod at the stationary head end.

13. A device according to claim 12 wherein the cavity of said first plug has a bottom which is intermediate the ends of the plug to thereby define an open end and a closed end of said plug.

14. An orifice sealing device comprising:

(a) a first plug capable of being inserted into the orifice and having in one end thereof a longitudinally extending cavity defining a totally surrounding cavity wall of suflicient thickness and flexibility to expand upon the application of force into sealing contact with said orifice, said cavity having a bottom intermediate the ends of said plug to thereby define an open end and a closed end of said plug, and

(b) a tapered second plug, the smaller end of which is of such a size as to enable it to be inserted into the longitudinally extending cavity of said first plug and the larger end of which is of a size sufficient such that when said second plug is forcibly inserted, small end first, into the cavity of said first plug, said tapered second plug will expand said cavity walls into sealing contact with the orifice,

(c) said first plug being comprised of a rearward section and a detachable front section, said rearward section consisting essentially of that portion of said first plug which contains that portion of said cavity walls which are expandable into sealing contact with the orifice, said detachable front section being harder than at least that portion of said cavity walls of said rearward section which are expandable into sealing contact with the orifice.

15. An orifice sealing device according to claim 14 wherein said rearward section and said detachable front section are connected by dowel means extending therebetween.

16. An orifice sealing device according to claim 14 wherein said second plug is provided with a longitudinal hole extending through its entire length.

References Cited UNITED STATES PATENTS 3,203,479 8/1965 Hindm'an 165-134 ROBERT A. OLEARY, Primary Examiner C. SUKALO, Assistant Examiner US. Cl. X.R. l76, 134