CA1105514A - Pipeline sleeve gasket confining structure - Google Patents

Abstract

PIPELINE SLEEVE GASKET CONFINING STRUCTURE Abstract of Disclosure Elastomer seal rings are confined against their leakage or extrusion from a sleeve joining two segments of pipe or from a repair clamp placed at an end of such a sleeve which is leaking liquid from the pipeline by providing, in one embodiment, several segmented, tri-angularly shaped split rings which are overlapped at their ends to fit against and to coact with a beveled face within or at the end of a sleeve to retain packing rings at that end against pressure being exer-ted by a compression ring pressing against the packing from its opposite end. To avoid extrusion of the packing at the compression ring end thereof complementary essentially triangularly shaped split rings are provided or alternately a pair of rectangular split rings are provided one of which is of an internal diameter to fit snugly over the pipeline when snapped thereonto and the other of which has an outside diameter to fit snugly agianst the inner wall of the sleeve or repair clamp. -1-

Description

1~05S~4 PIPELINE SLEEVE GAS~ET CONFINING STRUCTURE
This invention relates to a method and apparatus for preventing leaking or extrusion of packing within a sleeve as on a pipeline connecting two segments of the pipeline. In one of its aspects it relates to a seal-ing mechanism to prevent extrusion of packing rings made of such usual sealing materials as rubber, an elastomer or the like. In another of its aspects the invention relates to confining such packing against extrusion when such packing is maintained under a pressure exerted by a mechanism adapted to compress and to maintain under pressure, even throughout temperature cycles, such packing or sealing material or rings.
In one of its concepts the invention provides a method of preventing extrusion of, say, an elastomeric packing from a sleeve on a pipeline or from a repair clamp attached to such a sleeve on a pipeline when the sleeve has been found to be leaking liquid being transmitted through the pipeline which comprises providing a split, segmented leading ring combination having essentially a triangularly shaped cross-section such that by coaction with a beveled surface of the s]eeve the split, segmented portions, which can be and preferably are overlapped at their ends, will slide against each other at their interface maintaining a tight seal at such interface while at the same time filling the space defined between the beveled surface and the outer surface of the pipe of the pipeline. In another of its aspects the invention provides a seal ring combination essentially consisting of at least two triangularly shaped, complementary portions which can slide against each other the whole forming essentially a rectangularly shaped split combination prior to the application of pressure as by a compression ring adapted to transmit pressure through the combination against the usual elastomer or other seal or packing. In a further concept of the invention the last-described combination can work together with or be replaced by at least ,~

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two rectangularly shaped split rings preferably overlapped at their ends one of which i~ sized to snap and to fit snugly on the pipe while the other i8 slightly larger than the pipe for its internal diameter and very nearly of outside diameter to fit snugly against the inside wall of the sleeve or repair clamp as the case may be. In a further concept of the invention, there is provided a seal-ring combination within the annulus formed by a coupling and a pipe therein, wherein there is also a pressure exerting means adapted immediately to exert a pressure against a follower ring which in turn exerts pressure upon a sealing means and disposed between the pressure exerting means and said following means a resilient means, e.g., a spring or a series of springs adapted to transmit pressure from the pressure exerting means to said follower means so that substan-tially uniform pressure will be upon said follower means and therefore, upon the sealing means, which may be subject to variation due to tempera-ture even as the whole assembly might be albeit such change of tempera-ture is taking place or has taken place.
While the various features of the present invention are appli-cable singly or jointly to effecting the confinement of the usual rubber or elastomer seal or packing material wherever a sleeve or repair clamp may be used it has been devised to effectively overcome an existing problem in the joining of pipeline segments as under the ocean at depths which may attain several hundred feet and at which joining of such seg-ments must necessarily take place. Accordingly, the invention will be described further in connection with such pipeline laying and/or repair.
It is apparent that where a pipeline which may be several hundred miles in length is being laid it may be laid in several sections there being several pipeline laying crews or ships operating simultan-eously. When two of these crews have laid their respective segments of pipeline so that ends of the segments are now in abutting relationship ~lV~

it becomes necessary to join these segments. It is evident that lifting the segments to the surface of the ocean is impractical for a number of reasons one of which is that there would have to be lifted to a point of joining the ends of two segments of pipe which would be an expensive, difficult operation to perform. The angles involved make it apparent that the operation would not be simple and that there would have to be involved lengths of pipe which then would have to be snaked out on the sea floor which would involve still further difficulty and added cost, not to mention the additional bending of the pipe-line which may introduce difficulties in its operation and cleaning as when a cleaning instrument is pumped therethrDugh.
The current practice involves using a frame on the sea floor onto which are lifted, but only a few feet, the abutting ends of the pipeline segments. At this time there is applied a sleeve or coupling, the structure of which in some cases is quite sophisticated.
The following patents deal with pipe joints, sleeves, couplings or connectors for tubular members and the like. U. S. Patents 2,017,994 issued October 22, 1935, F. J. Spang; 3,393,926 issued July 23, 1968, J. F.
Arnold; 3,598,429 issued June 15, 1971, James F. Arnold; 3,704,033 issued November 28, 1972, James F. Arnold; 3,709,260 issued January 9, 1973, Tom J. Windle; 3,744,822 issued July 10, 1973, James F. Arnold; 3,784,234 issued January 8, 1974, Harvey 0. Mohr; 3,830,526 issued August 20, 1974, Mohr; and 3,933,202 issued January 20, 1976, Arthur ~. Ahlstone.
As can be seen from the disclosures of the foregoing patents various means have been provided to actuate packing means in response to a hydraulic pressure as in patent 3,704,033. In that patent packer rings 26 are arranged to be deformed radially inward into sealing engagement with pipe 11 responsive to an axial actuation of force transmitted through packer compression ring 27. In the patent please see column 3 lines 23-33 and Figure 1.

The present invention is directed to solve the problem of leakage owing primarily to the extrusion of packing resulting from the pressure applied by the compression ring.
Pipes to which couplings, sleeves or repair clamps are to be applied can vary in diameter and can be quite large. Such pipes can be from about 8 inches up to about 36 inches or more in diameter. To effect a seal which will hold at joints of such pipes is known to be fraught with difficulty.
Yet, when a 20-inch coupling failed in the North Sea, this caused a loss of about 200,000 barrels per day of oil production at a cost of approximately 2 1/2 million dollars. Thus, continued operation without leakage of couplings is of tremendous importance.
A problem which has been encountered appears to spring from the fact that the couplings are subject to considerable changes in temperature from time to time. Thus, under operating conditions flow of warm oil through the pipeline and coupling and its component parts will warm the coupling, the pipe and said parts. When flow is interrupted for a time the pipe and coupling are cooled to the temperature of the surrounding sea water. This has caused leakage at the packing of the couplings. It appears that the packing is extruded into the space at the ends of the packing zone so that when cooling occurs the packing shrinks somewhat and allows leakage therethrough.
It should be borne in mind that dealing with such large dimensions close fits are not always possible. The fit between the sleeve on the one hand and the pipe or a repair clamp attached to such sleeve and the pipe will be such as to provide an annulus between the sleeve and the pipe or between the clamp and the pipe of irregular or non-circular cross-section.
It is for the reason that such fits are difficult to seal and to maintain sealed, especially through temperature cycles, that there is applied by use of compression rings a pressure which constantly urges the packing to seal against flow of liquid at all times.

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The present invention is intended to prevent leakage through the packing by closing off the areas where or into which extrusion can occur while at the same time maintaining constant pressure on the packing during any temperature cycle.
It is an object of this invention to provide a pipeline sleeve gasket or seal confining structure. It is also an object of this inven-tion to provide a method for sealing a sleeve connecting abutting ends of a pipeline or tubular means. It is a further object of this invention to provide a method and means for preventing extrusion of packing material such as a rubber or elastomer seal material into an annulus existing between pipe and sleeve joining abutting ends of pipe. It is still another object of the invention to provide a lead seal which will prevent effectively the flow of seal or packing material into the irregular annulus formed between a segment of pipe and a sleeve there-around. It is another object of the invention to provide a seal effective to prevent extrusion or flow of elastomer or other sealing material past a compression ring used to apply constantly a pressure to such material.
Other aspects, concepts, objects and the several advantages of the invention are apparent from a study of this disclosure, the drawing and the appended claims.
According to the present invention there is provided an extru-sion proof seal disposed within an annulus formed between a pipe and a coupling or sleeve or clamp member comprising a one ring leading seal of nonpressure extrudable material having ring segments preferably having lapped ends, the segments being arranged to present a triangular cross-section taken along a plane passing through the center point or axis of the rings; the segments of the ring being adapted to slidably abut in a plane substantially at a right angle to said axis; at least one 1 ~(3S51~

. extrudable seal ring within said annulus; said leading seal combination being disposed within said annulus at one side of said extrudable seal s ring and in espousing relationship with a generallly triangular space formed by a beveled portion of said coupling, sleeve or clamp member and said pipe; and to the other side of said extrudable seal ring a two-ring follower seal combination of non-pressure extrudable material having split rings, preferably lapped at their ends, said last mentioned split rings, when together in operative relationship presenting generally a rectangular cross section taken along a plane passing through the center point or axis of said last mentioned rings, said last mentioned rings being adapted to slidably abut in a plane at an angle to said axis; the said extrusion-proof seal being responsive to pressure applied to said follower seal j combination pressing it against said extrudable seal ring to seal the annulus, even against irregularity of said annulus due to the variation in dimensions of said pipe and said coupling, sleeve or clamp member.
Also according to the present invention there is provided in the annulus formed by a coupling or sleeve adapted to hold together, and seal tight and against loss of fluid a sealing means, means to exert a pressure upon said sealing means, the total device comprising in combina-tion, a sealing means, follower means, a pressure exerting means adapted to act immediately upon said follower means and resilient means between said follower means and pressure exerting means to transmit pressure from said pressure exerting means through said follower means and therefore said sealing means, said sealing means being adapted to continue to transmit continuously substantially the same pressure exerted by said pressure exerting means while a total structure of the sleeve and in the annulus is subjected to change of size and/or configuration owing to a temperature change.

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Further, according to the invention, there is interposed between a follower seal combination and a pressure exerting means a resilient means comprising at least ] spring.
The spring can be one continuous spring so to speak, wrapped around the pipe or it may be several substantially longitudinally disposed springs disposed around the pipe, for example one disposed at each hour of a clock face. Such disposition permits the same pressure to be applied or transmitted from the pressure exerting means regardless of the position of the pipe within the sleeve, i.e., regardless of the size or configuration of the annulus at any given point, especially when there is not absolute concentricity of the sleeve or coupling and the pipe within it.
Also according to the present invention, there is provided a device wherein there is provided a spring assembly which accommodates volume changes of the elastomer seal material without exceeding a pre-determined pressure thereon.
Also according to the present invention the follower ring combination is formed of at least two split, segmented rings, preferably lapped at their ends, presenting a diagonally disposed interface such that two rings viewed in cross-section as before present a substantially triangular aspect whereby, responsive to said pressure applied to said follower seal combination, one of its rings will be forced against the pipe and the other against the coupling sleeve or clamp wall.
Further according to the invention thefollower seal combination is formed by at least two split rings, preferably lapped at their ends, each having a substantially rectangular cross section when viewed as before, the angle to the axis at the interface of said rings being a right angle and one of the rings being sized to fit snugly upon the pipe while another is sized to fit snugly against the inner wall of the , coupling, sleeve or clamp whereby when pressure is applied the rings wil] coact to provide a complete seal of the annulus at the place at which they are positioned.
Still further according to the invention there is provided within one or more faces of the non-extrudable seal co~bination rings, a self-lubricating sealing surface, e.g., a lead or solid synthetic having high resistance to pressure-induced flow.
Referring now to the drawings, Figure 1 shows a connection or coupling of abutting ends of two pieces of pipe. Figure 2 shows in like cross-section, fixed to a sleeve a structure embodying a packing arrangement sealed according to the invention disposed within a clamp fixed to the end of a sleeve. Figure 3 shows an isometric view of a lead seal according to the invention and illustrates the segmented rings which are lapped at their ends. Figure 4 is an isometric view of the segmented rings which are lapped at their ends and which form a follower seal combination according to the invention. Figure 5 is like Figure 2 but differs in that it shows the follower seal com-bination of the invention in which the individual rings are split rings and present a substantially square or rectangular cross-section, one ring fitting snugly the pipe wal] while another fits snugly the wall of the coupling sleeve or clamp member. Finally, Figures 6a and 6b show two different views of a clamp into which the leading seal and follower seal combination of the invention can be placed. Figure 6a shows the clamp in open position with a hydraulic piston in telescoped relationship with its cylinder. Figure 6b shows the clamp in closed position around a pipe, with the piston extended from within its cylinder.
Referring now to Figure 1 there is shown a sleeve 1 espousing or joining abutting pipe ends 2 and 2'. ~his sleeve is beveled at 3 and grooved at 4. The beve] at 3 serves to receive a lead seal combination according to the invention. The groove 4 serves to receive and to retain a clamp as shown in Figure 2.

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It will be understood by one skilled in the art in possession of this disclosure having studied the same that the structure or structures -9a-of the invention, as earlier noted, can be encompassed within a sleeve in which event the beveled portion 3 will be moved to a location within the sleeve.
Referring now to Figure 2 there is shown a clamp lip 26 which is engaged in groove 4 of a sleeve. Fitting tightly within the triangular space formed between the sleeve and pipe wall S is a lead seal 6 according to the invention. It will be noted that this seal is wedged up against bevel 3 which when pressure is applied from left to right urges the triangular ring downwardly against the pipe. Referring to Figures 2 and 3 it will be seen that responsive to the urging of bevel 3 the various segments of the triangular cross-section ring 6 will be indivi-dually urged against the pipe whiie there is constant seal at S of Figure 3. Referring to Figure 2, rings 7 are pressure extrudable seal rings. ~ight is a follower seal combination according to the invention showing that embodiment in which the rings in cross-section present a triangular or substantially triangular configuration. To the left of seal combination 8 there is provided a compression ring 9 to the left of which there is provided a serpentine spring 10. To the left of spring 10 there is provided another compression ring and the usual or conventional pressure piston assembly as shown at 11.
When the clamp has been pl~ced upon the pipe and sleeve and pressure has been applied and the desired seal effect has been obtained, the piston position is fixed by flowing a hardenable fluid or plastic in behind the pressure piston. It will be seen that at all times there is a constant pressure being applied to the compression ring and that as the overall seal assembly tends to expand or to contract during a temperature cycle and therefore to work the extrudable packing rings 7 are constantly retained fully sealed against flow by the working components of the lead and follower seal combinations of the invention.

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In Figure 2 there is shown at 13 a self-lubricating insert providing a surface which will move readily over the pipe wall surface during the temperature cycle and, of course, as the initial pressuri~ing of the compression ring assembly is effected.
In Figure 4 the segmented ring combination seal is shown to have the preferred overlapped ends as at 14.
Obviously, because the annulus may vary at any place along the pipe from about 0 to about even 1/2 inch or more the use of split rings which are segmented and overlapped at the ends of the segments according to the invention is beneficial to attain a tight seal thus to prevent extrusion of the rubber or elastomer or other pressure extrudable seal as during a warmup period in a temperature cycle.
The various rings or segments according to the invention in its now preferred form are formed of a metal suitable to withstand the pressures and the working during the temperature cycle. Any metal commonly used for seal ring purposes where temperature cycles are encountered can be used.
In Figure 5 split rings 16 and 17 which generally have a square or rectangular cross-section are shown to have interface 18. Ring 17 is snapped onto the pipe and as earlier noted is machined or made to fit snugly aga nst the pipe wall. This ring is not segmented but is over-lapped at the split. Ring 16 is machined to espouse snugly the largest diameter of the coupling, sleeve or clamp. This ring also is split and lapped at its ends.
It is within the scope of the invention for certain uses to supply ring 16 or 17 as more than one piece. The mechanical engineer studying this disclosure will understand that such segmenting of the ring may not always be preferred. Thus, much will depend upon the si~e and configurations of the portion or portions of the annulus into which such segments would be placed.

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Generally, in the matter of assembling the various rings, these can be held in place by temporary adhesive or otherwise as will be apparent to one skilled in the art.
Referring now to Figure 6 there is shown a clamp-on device or repair clamp like unto that shown in Figure 2. Figure 6a and 6b show the clamp in two different views. In operation of the invention, as earlier noted, it is often necessary to work below surface of water, indeed on the ocean floor. Whether a sleeve or coupling is being installed or a repair clamp as shown in Figure 6 the general approach will be about the same. The workers must be on the ocean floor, they must have means for bringing together the ends of the pipe segments and means for installing the coupling, sleeve or repair clamp. Each working crew will no doubt have its own carefully worked out procedure as to just what step is taken and when in the order of steps taken it will be taken.
Generally speaking, the various segments or ring portions will be installed on a sufficiently permanent basis to permit installation of the sleeve or clamp or other coupling. However, care must be taken that when the pistons are subjected to pressure that the various portions which are to move and which are to be compressed will move and be compressed as desired.
Specific Example:
A 20-inch repair clamp incorporating the non-extrudable lead seal and follower seal combination of the invention is assembled on board a barge prior to lowering on a line to the site of a sea floor coupling in a pipeline.
The pipeline is uncovered for easy access by jetting away cover and fill material thereon. This allows access to the coupling for application of the repair clamp or clamps.

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After cleaning the end of the coupling and the pipe wall adjacent the coupling, the repair clamp is guided into place by a diver to engage groove 4 in the coupling end. The repair clamp will be fully open as shown in Figure 6a.
Application of hydraulic pressure communicated from the barge to hydraulic cylinder 20 shown on Figure 6a closes the repair clamp around the pipeline and coupling end. The split ends of seal rings 7, lead seal ring 6 and follower seal 8 join each other to make complete rings around the pipe. Split ends of compression rings 9 and serpentine spring 10 also join each other. Repair clamp bolt-studs 18 are inserted and made up on both sides of repair clamp.
The final step is to apply through connection 24 a predetermined pressure to pistons 28 arranged around the periphery of repair clamp by introduction of hardenable fluid, such as epoxy resin. Serpentine spring 10 is thereby partially compressed and continues to apply pressure to compression ring 9 and to packing rings 7 to maintain a tight seal against pipeline 5 at all times. Expansion and contraction of packing rings 7 with change in temperature is thereby accommodated.
When the invention is used in a pipe coupling, the coupling is slid over the end of one section of pipeline, then back over the end of the other section of pipeline before tightening in place to make a leak-proof joint.

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Reasonable variation and modification are possible within the scope of the foregoing disclosure, drawings and the appended claims to the invention the essence of which is that non-extrudable working split ring seals which can be segmented and overlapped at the ends at the splits and/or of the segments in configurations as described to encompass and thus to retain against pressure extrusion the conventional rubber or elastomer or other seal ring material during temperature cycles in a pressurized assembly in which a lead seal combination of generally triangular cross section as described and a follower seal combination also as described; and a spring assembly which accommodates vo]ume changes of the elastomer seal material without exceeding a predetermined allowable pressure range, all as described, have been provided.

Claims (8)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An extrusion-proof seal comprising a ring of extrudable material disposed within an annulus formed between a pipe and a coupling or sleeve or clamp member said seal being retained in said annulus in an extrusion-proof manner, said annulus comprising a leading seal of non-pressure extrudable material having ring segments so constructed and arranged as to present a triangular cross-section taken along a plane passing through the center point or axis of the ring, the ring's segments being adapted to slidably abut in a plane substantially at a right angle to said axis; said seal ring of extrudable material within said annulus having said leading seal being disposed within said annulus at one side of said seal ring of extrudable material and being in espousing relationship within a generally triangular space formed by a beveled portion of said coupling, sleeve or clamp member and said pipe; and to the other side of said seal ring of extrudable material a two-ring follower seal combination of non-pressure extrudable material having split rings, said last mentioned split rings, when together in operative relationship presenting generally a rectangular cross-section taken along a plane passing through the center point or axis of said last mentioned rings, said last mentioned rings being adapted to slidably abut in a plane at an angle to said axis; the extrusion-proof seal being responsive to pressure applied to said follower seal combination pressing it against said seal ring of extrudable material to seal the annulus, even against irregularity of said annulus due to the variation in dimension of said pipe and said coupling, sleeve or clamp member.

2. An extrusion-proof seal according to claim 1 wherein the two-ring follower seal combination is formed of at least two split rings, presenting a diagonally disposed interface such that each of the two split rings viewed in cross-section as before presents substantially a triangular aspect whereby to move responsive to said pressure applied to said follower seal combination in a manner that one of its rings will be forced against the pipe wall and the other against the coupling, sleeve or clamp inner wall.

3. A seal combination according to claim 1 wherein the follower seal combination is formed by at least two split rings each having a substantially rectangular cross-section when viewed as before the angle to the axis being a right angle and one of the rings being sized to fit snugly upon the pipe while another is sized to fit snugly against the inner wall of the coupling, sleeve or clamp.

4. A seal according to claim 1 wherein the ends of the two-ring follower seal comprised of split rings are overlapped in a manner to permit reducing the overall diameter of the installed rings and increasing said diameter as during a complete temperature cycle while at all times maintaining an extrusion-proof seal which will prevent extrusion of extrudable seal or packing material.

5. A seal according to claim 2 wherein the ends of the two-ring follower seal comprised of split rings are overlapped in a manner to permit reducing the overall diameter of the installed rings and increasing said diameter as during a complete temperature cycle while at all times maintaining an extrusion-proof seal which will prevent extrusion of extrudable seal or packing material.

6. A seal according to claim 3 wherein the ends of the two-ring follower seal comprised of split rings are overlapped in a manner to permit reducing the overall diameter of the installed rings and increasing said diameter as during a complete temperature cycle while at all times maintaining an extrusion-proof seal which will prevent extrusion of extrudable seal or packing material.

7. A seal according to claim 1 wherein there is provided a self-lubricating surface upon at least one of said follower seal ring and said leading seal to permit ready motion of the said ring and/or seal while held tightly against the wall with which it coacts to maintain a seal during a temperature cycle.

8. A device according to claim 1 wherein there is provided a spring assembly which accommodates volume changes of the elastomer seal material without exceeding a predetermined pressure.