Note: Descriptions are shown in the official language in which they were submitted.
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~he present invention relates to a pipe coupling
especially a coupling for oil or gas pipelines.
BACKGROUND OF THE INVENTION
In U.S. Patent Specification No. 3,860,270 there is
disclosed a coupling comprising a sleeve for fitting over the end of a
pipe. The sleeve has means for sealing the sleeve against the pipe and
means for gripping the pipe. The sealing means comprises an annular
groove containing a sealing member and a chamber which communicates with
the exterior and can be filled with a hardenable composition and maintained
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~ under pressure until set ~gr force the sealing member into sealing contact
against the outer surface of the pipe. The gripping means comprises
annular grooves on the inside of the sleeve which accommodate jaw sectors
, with gripping tee~h, sealing members in the grooves behind the
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~aw sectors and a chamber which communicates with the exterior and can
1 15 be filled with a hardenable composition and maintained under pressure until
set to cause the gripping teeth of the jaw sectors to bite into the outer
surface of the pipe.
The sealing member of the sealing means comprises a
sealing ring which forms a seal against the sides of the annular groove and
l against the pipe and the chamber is formed by the space in the groove behind
,, the sealing ring. Similarly the sealing members of the gripping means
, comprise sealing rings which form seals against the-sides of the annular
grooves and the pressure chambers are the spaces in the grooves behind the
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sealing rings. ~ ~ '
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The arrangement of u.S~ Patent No. 3,860,270 is
considered to be unsatisfactory in that the sealing rings do
not provide satisfactory seals for use at high pressures.
It is the ob~ect of the presen~ invention to provide
a pipe coupling which overcome~ the aforementioned disadvantage.
SUMt~RY OF TEIE INVENTION
$he invention provides a coupling compri~ing a sleeve
for fitting over a tubular member and gripping means associated
with the sleeve for gripping said tubular member, said gripping
means comprising at least one convoluted groove on the inside of
said ~leeve, said groove including a plurality of axially spaced
generally circumferentially extending groove sections which are
~oined to form a continuous groove, ~aw sectors with gripping
teeth accommodated in the arcuate groove sections, a tube
located in the groove sections behind the ~aw sectors and
extending along the length of the convoluted groove, and bores
extendîng through the wall of the sleeve at the ends of the
tube through which the interior of the tube communicates with
the exterior, whereby the tube can be filled through the bores
with a hardenable composition and maintained under pre~sure
until set to cause the gripping teeth of the jaw sector~ to
bite into the outer surface of the tubular member.
The invention also provide~ a pipe coupling comprising
a sleeve for fitting over the end of a pipe section, the sleeve
having means for sealing the sleeve against the pipe and means
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for gripping the pipe, the ~ealing means comprising an annular
groove which accommodates an annular tyre the interior of the
tyre communicating through bores in the wall of the ~leeve with
the exterior, the gripping means oomprising arcuate groove
sections on the in~ide of the sleeve which accommodate jaw
sectors with gripping teeth and a tubular member or member3
located in the groove behind the ~aw ~ectors, the tubular
member or members communicating through bores extending through
the wall of the sleeve with the exterior, the arrangement being
such that the annular tyre and the tubular member or members
can be filled through the bores with 3 hardenable composition
and maintained under pressure until set to force the sealing
member into sealing contact against the outer surfa~e of the
pipe and to cause the gripping teeth of the ~aw sector~ to
bite into the outer surface of the pipe.
An advantage of the present invention is that it
enables a gripping load that is greater than the strength of
the pipe to be achieved~ By pressuri~ing the h ædenable
composition to the working pressure of the pipe, that i8 the
~ 20 pressure of the fluid in the pipe when the pipe is in use, the
: compres~ion force on the pipe end will be counterbalanced by the
: tensile hoop stress caused by the pre~ure of the fluid in the
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pipe. In applications where the working pressure i~ close to
the yield strength of the pipe, ~ay 80%, the gripping load will
be egual to about 8Q% of the yield strength when the pipe is not
in use and will be doubled to approximately 160% of the
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yield strength when the pipe ls in use.
~he sleeYe may be provided with second means for sealing the sleeve
to a pipe so that a single sleeve may be used to couple two pipe ends
togethex. Alternatively the sleeve may have an external flange at one
end so that it can be bolted or clamped to the flange of a similar
~leeve attached to the end of another pipe, to form a pipe joint.
Preferably the sealing means include at least two annular grooves,
; - each of which accommodates an annular tyre, the interior of wh~ch
communicates with the exterior through bores in the wall of the sleeve.
A further bore may be provided through the wall of the sleeve between
the annular grooves so that the space between the two annular grooves
and the sleeve and the pipe end may be pressurised and the pressure
monitored to detect leaks in the seals.
m e sleeve may be formed as a single piece encircling the pipe ~`
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~5 in which case the groove sections of the gripping means may be formed
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by a helical groove~and the tubular member may be a single helical
tubular member, the interior of which communicates with the exterior of
; the sleeve through bores at both ends. Alternatively, the sleeve may
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be formed in two parts separated from one another along a longltudinal
plane through the axis of ~he sleeve. The two parts may be coupled to
one another along their ~ongitudinal pair of edges by bolts which pass
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.through flangës along the lo~gitudinal edges. This
arrangement may facilitate the placing of the sleeve in position under
~; difficult conditions such as fox example when repairing a pipeline on ~he
25~ eea bed.
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In the case of a sleeve formed in two parts as described above
the groove sections of the gripping means may be in the form of a
continuous sinuous groove with groove sections extending from one
longitudinal edge to the other, the groove sections being connected
alternately at opposite edges by semi-circular sections and the
tubular member may be in the form of a separate single tubular
member for each part of the sleeve, the interior of the tubular
members communicating with the exterior through bores in the wall
of the pipe at both ends.
Embodiment~ of the invention will now be described, by way of
example, with reference to the accompanying drawings, of which: -
Figure 1 shows a longitudinal cross-section of a coupling
sleeve according to the invention joinIng two pipe ends;
Figure 2 shows a cross-section on an enlarged scale of the air
bleed valves of the coupling of Figure l;
Figure 3 shows a cros~-section on an enlarged scale of the
epoxy composition filling connection;
Figure 4 shows a longitudinal cross-section of a second
embodiment of coupling sleeve according to the invention joined to
one pipe end;
Figure 5 is an end view of a coupling sleeve of Figure 4:
Figure 6 which is on the same sheet of drawings as Figure 4
is a detailed view from the interior of the coupling of Figures 4
and 5 on an enlarged scale:
Figure 7 shows a longitudinal section of a third embodiment of
coupling sleeve according to the invention joining two pipe ends;
Figure 8 shows an enlarged detail of a hydraulic valve for
holding together the ends of the coupling collar of the coupling
sleeve of Figure 7;
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Figure 9 shows a coupling collar of Figure 7 being lowered
into pos~tion;
' Figure 10 shows an enlarged fragmentary longitudinal sectionof the coupling collar on the coupling sleeve;
Figure 11 shows an enlarged fragmentary cross-section of the
coupling collar on the coupling sleeve;
' ~igure 12 shows a cross-section of a fouxth embodiment of coupling
sleeve according to the invention joining the ends of two pipes;
Figure 13 shows the coupling sleeve of Figure 12 with the parts
,of the sleeve rotated relative to one another; and
Flgure 14 shows how the sleeve of Figures 12 and 13 may be used
to connect twp parallel pipes out of alignment.
'I ~ ` Referring to Figures l~ this shows the ends of two abutting pipes
, 11 and 12 coupled together by a sleeve of steel. Two pairs of annular
,I 15 grooves 14 and 15 are provided in the'inner surface of the sleeve 13
"' ' opposite'the respective ends of the pipes 11 and 12. Two further
,'1 annular grooves 16 are provided in the-inside surface of the sleeve 13
,.! near the two ends of the sleeve. An annular tyre 17 is accommodated
ln each of the grooves 14, 15 and 16 and the interior of each tyre
' 20 communicates with the exterior through two bores 18 and 19 in the wall of
' the sleeve. The bores 18 at the bottom of the sleeve constitute inlet
' ports for injection of an epoxy resin composition and are provided with
,l ~ a filling pipe 20 which is connected to a manifold 21. The bores 19
' at the top of the sleeve constitute exhaust ports for air and are provided
w~th air bleed valves '22.
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In use the tyres in the grooves 14, 15 and 16 are illed with
epoxy resin through the manifold 21, ~le filling pipe 20 and the
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bores ~. The epoxy resin composition fills the tyres 17,
Y displacing the air in them and exhausting it from the tyres through
5 ' the air bleed valves 22 in the bores 19. When the epoxy resin
reaches the valves 22 they are automatically closed by the epoxy
resin and the pressure of the epoxy resin in the tyres 17 is raised
to the pressure at which it is delivered from the pump (a pressure
exceeding 2,000 psi) under the pressure of the resin in the tyres 17;
the tyres which are of nitrile rubber are deformed and pressed tightly
against the outside of the pipes 11 and 12 to form a seal. The epoxy
xesin composition is maintained undër pressure until set.
Between the annular grooves 14 and 16 opposite the ends of the
pipes 11 and 12 are two helical grooves 23 in the inside surface of the
sleeve 13. Many jaw sectors 24 of tough steel are accommodated in
the grooves 23. The jaw sectors 24 are a close fit in the grooves
and abut against each other with a half millimetre clearance. The
~aw sectors have a series of circumferential ~nife or saw-tooth shaped
gripping edges which bite into the outer surface of the pipe. In each
~0 groove 23 behind the jaw sectors 24 is a nitrile rubber helical tube 25
which forms a load cell. At the outer end of the helical tube at the
top of the sleeve the interior of the tube 25 communicates with the
exterior through a bore 26. The bore 26 is fitted with an air bleed
valve 27.
At the inner end of the tube ~ at the lower side of the sleeve 13
the interior of the tube communicates with the exterior through a bore
28. The bore is fitted with a`filling pipe 29 connected to the manifold
21. The hclical tubes ~ are filled with epoxy resin c0mposition in a
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simllar manner t the tyres 17. Epoxy resin composition is introduced
lnto the tubes ~6 at the lower side of the sleeve and works its way around
the helical tube displacing the air in front of it until the epoxy resin
reaches the air bleed valve 27. When it reaches the air bleed valve
S the epoxy resin closes the valve and the epoxy resin in the tube is raised
to the pressure at which it is delivered from the pump. The pressure of
the epoxy resin causes the tube to expand forcing the jaw sectors 24
to bite into the outer surface of the pipe. The circumferential knife or
~aw-tooth edges to the jaws grip the pipe. The epoxy resin is maintained
under pressure until set so that the gripping load of the jaw sectors 24
against the ends of the pipes 11 and 12 is maintained.
Referring to Figures 4 to 6 these show a modification of the design
of pipe coupling of Figures 1 to 3. A coupling sleeve 113~for connecting
to one end of one pipe 12 a~d~h~b~ a circumferential outwardly projecting
lS bolting flange 130 for connecting the coupling sleeve 113 to a similar
coupling sleeve mounted on the end of another pipe. The coupling flange
130 is provided with bolt holes 131 for receiving the bolts (not shown).
A recess 132 in the end face of the sleeve at the end that bears the flange
.~ 130 accommodates a nitrile rubber tyre 133. The nitrile rubber tyre 133
communicates through a bore 134 in the flange with the exterior. Once the
two similar coupling sleeves have been bolted together by means of their
1anges 130 the tyre 133 can be f;lled with epoxy resin in the usual way and
maintained under pressure ~ntil set to form a permanent face seal.
` ~he sleeve 113 is divided longitudinally along a plane through the
; 25 axis of the sleeve. The two halves of the sleeve 113 can be secured together
' by means of hydraulic jacking bolts I35 which pass through holes in bolting
flanges 136.
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on the inside of the sleeve 113 are provided annular grooves
14, 15 and 16 with annular tyres 17 sLmilar to the grooves and tyres
of the embodiment of Figure 1. The area between the grooves 14 and
16 on the inside of the sleeve each sleeve part is provided with a
series of semi-circular groove sections 137. Adjacent groove
sections are joined at alternate ends by semi-circular sections 138.
Thus the sections 137 and 138 form in each sleeve part a groove
which is continuous from one end to the other. Located in the
groove in each sleeve part are arcuate jaw sectors 24. In the
groove behind the jaw sectors is a continuous hollow nitrile rubber
tube 139 which follows a sinuous path in the groove and communi-
cates with the exterior at opposite ends through bores 26 and 28
fitted with air bleed valves and filling pipes as the bores 26 and
28 of Figures~l to 3.
To form a pipe joint two coupling sleeves 113 are fitted on
the ends of the two pipes to be joined, the two parts of each sleeve
113 being bolted together by the bolts 135 and the two flanges 130
being bolted together. The tyres 17, the tube 139 and the tyre 133
are all filled with epoxy resin composition and maintained under
pressure until cet. The tyres 17 form seals a0ainst the pipes, the
tube 139 forces the jaw sectors 24 into gripping engagement with
the pipes and the tyre 133 ~eals the joint be~ween the two sleeves
113.
Figures 7 and 8 show another form of pipe coupling which is
similar to the arrangement of Figures 1 and 4 with regard to the
arrangement of sealing and gripping means but has a joint which i8
scarfed or inclined to the pipe axis for accessibility and ease of
fitting. At least two stub flanges 230 are held together by two
hinged segments of a collar 231 which is closed around the flanges
230 and held in the ~losed position by a tapered plug 232 which is
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inserted through holes 233 in the two interleaving dogs 234.
Figure 9 shows how the two hinged segments of the collar 231
may be g
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~losed around the flanges 230 of the sleeve 213 either by a hydrauli¢
a~tuator 235 or by gravity using the sling 236.
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As can be seen in Figure 8 the tapered plug 232 includes a number
of load cells 237 which are connected together withln the pin by bores
; S 238. After the plug 232 has been inserted the load cells may be
pressurised using epoxy resin compositLon at a pressure of 2,000 psi.
The load cells act on opposed parts of the interleaved dogs drawing
; the segments of the collar forcibly together. The hinge pin 239 may
, be of similar construction to the plug 232 and its load cells may be
pressurised in a similar way so as to draw the two halves of the collar
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together on opposite sides of the sleeve.
; As can be' seen from Figure 10 the abutting faces of the flanges
; ~ 23D include a face seal similar to the face seal shown in Figure 4.
. 1~
Figures 12 and 13 show yet another coupling according to the
lnvention. The arrangement for sealing and gripping each sleeve 313
; to the ends of the pipes 11 and 12 is similar to that shown in connection
with Figures 1 and 4. The joint between the two sleeves 313 is scarfed
~'J~ - and the abutting ends of the sleeves have stub flanges 330 which are
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held~together by two segments 331 of the collar. The segments have
bolting 1anges 333 which are secured together using hydraulic bolts.
To accommodate malalignment between pipe ends the scarfed faces
can be rotated relative to one another. To assist in producing this
relative rotation, the edge of one flange is machined with worm teeth
34 to engage a pair o worms 335 carried by the collar. The worms
~25 ~ 335 may~be dsiven by air or hydraulic,motors. The other flange of the
7~ pair i8 pinned to the collar by a pin 336.
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As can be seen in ~ rFs 14 a displacement of the axis of the
p~pes 11 and 12 can be accom~odated by the use of a bobbin tube 337
and two collars.
, Prior to assembly of the pipe couplings described above each
'5 coupling should be tested. The coupling sleeves are threaded over
a test pipe at the works and the following test procedure is carried
out iust before despatch to the site where the coupling is to be
: used. The a~nular tyres 17 are pressurised with oil to 2,000 psi
which centralises the coupling sleeve on the pipe. A 100 psi air
test is applied to the test space 400 between the grooves 14 and 15
through the bore 401 and spaced between the grooves 14 and 16 through
c ~re
the bore 402. If a leaX is shown up the ~ will most probably
be sand or other foreign matter lodged under the seals. The following
~ pressure test procedure will show which of the 'three seals is leaking.
If pressure is applied at the bore 402 and it is not held but it drops
s'~/
and shows no pressure rise at bore ~e~ then the seal in groove 16 is
' leaXing. By pressu,rising through bore 401, if the pressure at bore
'402 increases then this confirms that the seal in groove 14 is leaXing.
If however there is no pressure rise at bore 402 then it is the seal
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~0 ln groove 15 that is leaking.
Before the seals are,dismantled to see if they are faulty the
', pressure in the tyres 17 should be reduced to 100 psi and clean sea water
or solvent is in~ected through the bores 401 and 402. ~he pressure
~, ' t`est is then repeated and if it is still leaking the seal must be moved
,~ 25 axially so that the location of the seal on the pipe surface can be
,- inspected. If nothing is found then the seal must be removed and the
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defectlve seal seplaced by a new seal. If care is taken that the
surface of the pipe is satisfactory and clean sea water ls injected
through the bores 401 and 402 to wash out any sand collected in these
~paces during assembly it is most unlikely that there will be any
difficulty when the pipe ~oint is assembled. The second sleeve is
then slid onto the test pipe and the coupling rotated to match up with
the flange of the first coupllng. Pressurisation and air testing
of the second sleeve on the pipe is carried out in the same way as
wlth the first sleeve. The pressure is then reduced to atmosphere.
In the case of the embodiment of Figure 7 the collar 231 is
then lowered into position over the flanges 230. The hydraulic
actuator 235 is pressurised to close the clamp ring and cause the
- - lnterleaving dogs 234 to engage enabling the taper plug 232 to be
.inserted and rotated into the correct position b~ passing over a
; 15 locating dowel pin 404. ~oth the tapered plug and the hinge pin 239
are pressurised with oil at 2,000 psi causing the collar to engage the
stub flanges 230 firmly., Isolating valves are used to lock in the
i pressure. Ihe face seal provided by the tyre 133 is now tested. The
tyre 133 is pressurised to 2,ooo p9i through the bore 134 and air at
~- 100 psi is appll;ed through a bore 405 to the face opposlte the tyre
133. No air leakage should occur if the face seal is new and undamaged.
~he air and oil pressures are then returned to atmospheric.
~, As a final test the tapered plug 232 and the hinge pin ~5T are
pressurised to 1,000 psi and the tyres 17 and 133 are pressurised to 2,000
; 25 psi.^ The air tests at 401, 402 and 405 are then repeated.
The pipe join~ is then assembled as follows. If there is a leak
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105~549
or rupture in a sub sea pipeline, the faulty sect1on which may ~e
10' on either side of the damaged part is cut out using standard
scarf or inc'ined cuts and the damaged piece is removed after
' measurements of the spring and the cuts have been made. The damaged
piece plus the gap measurements are used to manufacture the replacement
pipe. The sleeves are threaded over the upstream and downstream open
ends of the pipeline. The replacement section of pipe complete with
the sleeves slipped over its ends is lowered into position and lined
up so that the pipe edges are parallel and the gap split between both
ends. If there is some spring or lack of alignment between the
upstream and downstream ends of the pipes then'the necessary rotational
' adjustment must be,made to bring the coupling faces true and fair.
m e hinged collar is then lowered into place and secured with the
,tapered plug. The dowel is then pressurised to 2,000 psi and the
isolating valves are closed. The face seal provided by tyre 133
18 then pressurised, to 2,000 psi and'the joint between the flanges
is air tested by applying ai,r at 100 psi through the bore 405. The
coupling sleeves are similarly pressurised with oil and the seals air
, tested as before. All pressures are then bled away. The assembly
', 20 is now ready for permanent settlng.
' The hydraulic taper plug 232 and the hinge pin 239 are pressurised,
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' to 2,000 psi with epoxy resin composition and the pressure is locked
" ' in using a valve. The pressure seals provided by the tyres 17 and
the tyre 133 are bled off and the oil is blown down by air. A metering
mixing and pressure delivery pump for epoxy resin compound is connected
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to the bore 134 which i9 injected with epoxy compound, air being
bled off and the tyre 133 being pressurised to 2,000 psi for 10
rlnutes before the bore 134 is closed. Epoxy resin compound is
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~i ~n~ected into the tyres 17 and the helical tube ~ through the
S manifold 21, the air being bled off through the air bleed valves
' and the pressure being raised to 2,00~ psi for '1~ minutes before
- the inlet bores are closed. Finally the helical space between the
' ~aw sectors is injected wLth epoxy resin, air being bled off and
pressurised to 5,000 psi to seal off the interface.
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,, 10 Air tests at 401, 402 a~d 405 are finally applied to check that'
~' '' everything is in order. ~ '
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'' If it is acceptable that the epoxy metering, mixing and pressure
injection pump ma,y be clamped to each coupling sleeve - i.e. be a part
of the coupling sleeve then it is a practical matter to fully automate`
the epoxy injection procedure. The same pump will be used with local
, c~ntrols to do the pressurisation with oil for the proving tests with
oil beiore final pressurisat'ion with epoxy compound. It could be that
, experience will determine that this precaution is not necessary and
~'~ ' that air tests c,arried out after the pressurisation with epoxy compound
will always show a satisfactory end result.
~he pump will operate on a 100 psi alr supply which could be
an air bottle and regulator
,' A supply of epoxy resin and hardner and oil - where required would
be secured to the top or alongside the pump unit.
The joint is designed as a permanent fixture. Where a
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connection may be used. If due to damage or displacement, the face
~eal provided by tyre 133 requires renewal, arrangements have been
rade in the design to enable the hingcd clamp ring to be quicXly
removed by brea~ing it away using a weak explosive. A screwed
connection for the "gun" is shown as 410 in Figure 10 and Figure 11
where the section of hinged clamp ring has been reduced to
enforce a sudden break at this point. If the damage is serious,
the pipe - which is the weaker member would have been damaged beyond
repair and the complete joint would require to be remade with a new
.
maXe-up section of pi.pe.
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