Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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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
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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.
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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
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. 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
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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
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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.
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