CA1063644A - Pipe couplings - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A pipe coupling comprising a sleeve which is fitted over the adjacent ends of the pipe sections. The sleeve has sealing means for sealing the sleeve against the pipe and gripping means for gripping the pipe. The sealing means com-prises an annular groove which accommodates an annular tire the interior of which communicates with the exterior of the sleeve through a bore in the wall of the sleeve. The gripping means comprises arcuate groove sections on the inside of the sleeve which accommodates a tubular member or members which communicate with the exterior through bores in the wall of the sleeve, and jaw sectors with teeth which bite into the outside of the pipe. The tubular member or members and the annular tire are filled with a hardenable composition and maintained under pressure until set to force the sealing member into seal-ing contact against the outer surface of the pipe and cause the gripping teeth to bite into the outer surface of the pipe.

Description

636~
The present invention relates to a pipe coupling especially a coupling for oil or gas pipelines.
-In U. S. Patent Specification No. 3,860,270 there isdisclosed 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 under pres-sure until set to 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 teeth, sealing members ~' in the grooves behind the jaw sectors and a chamber which '~-communicates with the exterior and can be filled with a harden-i able 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.
~' 20 The sealing member of the sealing means comprises a sealing ring which forms a seal against the sides of the annu-`j; lar groove and 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 ;"~ sealing rings.

The arrangement of U. S. Patent No. 3,860,270 is con-~ sidered to be unsatisfactory in that the sealing rings do not `~` 30 provide satisfactory seals for use at high pressures.

` ~!, It is the object of the present invention to provide `~ a pipe coupling which overcomes the aforementioned disadvantage.
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The invention provides a coupling comprising 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 sleeve, said groove including a plurality of axially spaced generally circumferentially extending groove sections which are joined to form a continuous groove, jaw sectors with gripping teeth accommodated in the arcuate groove sections, a : 10 tube located in the groove sectios behind the jaw sectors and extending along the length of the convoluted groove, and bores ` extending 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 pressure until set to cause the gripping teeth of the jaw sectors to :~ bite into the outer surface of the tubular member.
` The invention also provides a pipe coupling comprising --.
a sleeve for ~itting over the end of a pipe section, the sleeve `
. 20 having means ~or sealing the sleeve against the pipe and means :
: for gripping the pipe, the sealing means comprising an annular groove which accommodates an annular tire the interior of the :~ t.ire communicating through bores in the wall of the sleeve with :
~-. the exterior, the gripping means comprising arcuate groove sec~
tions on the inside of the sleeve which accommodate jaw sectors : with gripping teeth and a tubular member or members located in 1 the groove behind the jaw sectors, 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 tire and the tubular member or members can be filled ` through the bores with a hardenable composition and maintained under pressure until set to force the sealing member into seal-ing contact against the outer ~urface of the pipe and to cause . ' .

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~(~63644 the gripping teeth of the jaw sectors 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. sy pressurizing the hardenable com-position to the working pressure of the pipel that is the pressure of the fluid in the pipe when the pipe is in use, the compression force on the pipe end will be counterbalanced by the tensile hoop stress caused by the pressure of the fluid in the pipe. In applicatio~ where the working pressure is close to the yield strength of the pipe, say 80%, the gripping load will be equal to about 80~ of the yield strength when the pipe is not in use and will be doubled to approximately 160% of the yield strength when the pipe is in use.
The sleeve may be provided with second means for seal-. .. . . .
ing the sleeve to a pipe so that a single sleeve may be used tocouple two pipe ends together. 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 sleeve attached to the end ':'1 ' :
' 20 of another pipe, to form a pipe joint.
Preferably the sealing means include at least two an-nular grooves, each of which accommodates an annu]ar tire, the ~-~ interior of which 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 groov~sso ~ ~-~ that the space between the two annular grooves and the sleeve i'~ and the pipe end may be pressurized and the pressure monitored ::, ` to detect leaks in the seals. ;~

The sleeve may be formed as a single piece encircling the pipe in which case the groove sections of the gripping means : :~ . :.
may be formed by a helical groove and the tubular member may be ~;
a single helical tubular member, the interior of which communi-cates with the exterior of the sleeve through bores at both ends.
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In the case of a sleeve formed in two parts as descri-bed 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 ti 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.
;j Embodiments 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;
t~ 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 cross-section on an enlarged scale of the epoxy composition filling connection;
Figure 4 shows a longitudinal cross-section of a sec-ond 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 , _4_ ... ~ j.

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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 em-bodiment 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;
; Figure 9 shows a coupling collar of Figure 7 being lowered into position;
Figure 10 shows an enlarged fragmentary longitudinal section of the coupling collar on the coupling sleeve; , ~-~
Figure 11 shows an enlarged fragmentary cross-section of the coupling collar on the coupling sleeve; -~
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"~ Figure 12 shows a cross-section of a fourth 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 Figure 14 shows how the sleeve of Figures 12 and 13 ' may be used to connect two parallel pipes out of alignment.

Referring to Figures 1 to 3, this shows the ends o ;
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two abutting pipes 11 and 12 coupled together by a sleeve of steel. Two pairs of annular 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 annular grooves 16 are provided in the inside surface of the sleeve 13 near the two .~ . . .
i ends of the sleeve. An annular tire 17 is accommodated in each ~ of the grooves 14, 15 and 16 and the interior of each tire com-i : . . .
' 30 municates with the exterior through two bores 18 and 19 in the ~< wall of the slee~e. The bores 18 at the bottom of khe sleeve constitute inlet ports for injection of an epoxy resin composi-tion and are provided with a filling pipe 20 which i5 connected . , , .

' ~063644 to a manifold 21. The bores 19 at the top of the sleeve consti-tute exhaust ports for air and are provided with air bleed valves 22. .:
In use thP tires in the grooves 14, 15 and 16 are filled with epoxy resin through the manifold 21, the filling pipe 20 and the bores 17. The epoxy resin composition fills the tires 18, displacing the air in them and exhausting it from the tires through the air bleed valves 2~ in the bores lY. 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 tires 17 is raised to the pressure at which it is delive- :
: .
red from the pump (a pressure exceeding 2,0~0 psi) under the :
pressure of the resin in the tires 17; the tires which are of .~.
nitrile rubber are deformed and pressed tightly against the .~ .
outside of the pipes ll and l2 ~o form a seal. The epoxy resin composition is maintained under 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 -;: ',1, ~
steel are accommodated in the grooves ~3. The jaw sectors 24 are a close fit in the grooves and abut against each other with a half millimetre clearance. The jaw sectors have a series of circumferential knife or saw-tooth shaped gripping edges which bite into the outer surface of the pipe. In each 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 communi-cates with the exterior through a bore 26. The bore 26 is fit-' 1!: , ted with an air bleed valve 27.: s.
, 30 At khe.inner end of the kube 25 at the lower side of ;~i : the sleeve 13 the interior of the tube communicates with the exterior khrough a bore 28. The bore is fitted with a filling :.

pipe~29 connected to the manifold 21. The helical tubes 25 are ~ 6- :

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filled with epoxy resin composition in a similar manner to the tires 17. Epoxy resin composition is introduced into the tubes 25 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 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 saw-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 lI and 12 i5 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 is provided for conne~ting to one end of one pipe 12 ;
and includes a circumferential outwardly projecting bolting flange 130 for connecting the coupling sleeve 113 to a similar coupling sleeve mounted on the end of another pipe. The coup- -20~ ling flange 130 is provided with bolt holes 131 for receiving the bolts (not shown). ~ recess 132 in the end face of the sleeve at the end that bears the flange 130 accommodates a nie trile rubber tire 133. The nitrile rubber tire 133 communicate~
through a bore 134 in the flange with the exterior. Once the ., two similar coupling sleeves have been bolted together by means of their flanges 130 the tire 133 can be filled with epoxy resin in the usual way and maintained under pressure until set to form a permanent face seal.
The sleeve 113 is divided longitudinally along a plane through the axiB of the sleeve. The two halves of the . ~...................................................................... . .
,7. sleeve 113 can be secured together by means of hydraulic jackiny ,1 ,~ bolts 135 whiah pass through holes in bolting flanges 136.

On the inside of the sleeve 113 are provided annular ~7 . . .

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1~6364~
gooves 14, 15 and 16 with annular tires 17 similar to the grooves and tires of the embodiment of Fiyure 1. The area be- -~
tween the grooves 14 and 16 on the inside oE 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 sec-10 tors is a continuous hollow nitrile rubber tube 139 which fol-lows a sinuous path in the groove and communicates with the ex-terior at opposite ends through bores 26 and 28 fitted with air bleed valves and filling pipes as the bores 26 and 28 of Figures 1 to 3.
To form a pipe joint two coupling sleeves 113 are fitted on the ends of the two pipes to be jolned, the two parts of each sleeve 113 being bolted together by the bolts 135 and y~ the two flanges 130 being bolted together. The tires 17, the i ~ ~ tube 139 and the tire 133 are all filled with epoxy resin com-~;~ 20 ~ position and maintained under pressure untll set. The tires 17 form seals against the pipes, the tube 139 forces the jaw sectors 24 into gripping engagement with the pipes and the tire 133 seals the joint between 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 re-gard to the arrangement of sealing and gripping means but has a joint which is scared or inclined to the pipe axis for acces-;
sibility and ease of fitting. At least two stub flanges 230 are held together by two hinged segments of a coLlar 231 which ,, l; ~ 30 is closed around the flanges 230 and held in the closed positlon -~ by a tapered plug 232 which is inserted through holes ~33 in the two interleaving dogs 234.
Figure 9 shows how the t wo hinged segmenks of the '~i ' ;'; .:
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~0636~4 collar 231 may be closed around the flanges 230 of the sleeve 213 either by a hydraulic actuator 235 or by gravity using the sling 236. ;
As can ~e seen in Flgure 8 the tapered plug 232 in-cludes a number of load cells 237 which are connected together within the pin by bores Z38. After the plug 232 has been in-serted the load cells may be pressurized using epoxy resin ; composition 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 togéther. The hinge pin 239 may be of simllar construction to the plug 232 and its load cells may be pressurized in a similar way so as to draw the two halves of t~e x~ collar together on opposite sides of the sleeve. -As can be seen from Figure 10 the abutting faces of the flanges 230 include a face seal similar to the face seal shown in Figure 4.
Figures 12 and 13 show yet another coupling according to the inventlon. 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 and the abutting ends of the sleeves .~ ~
have stub flanges 330 which are held together by two segments 331 of the collar. The segments have bolting flanges 333~which . : ~ . .
; are secured together using hydraulic bolts. ~ -i ~ To accommodate malalignment between pipe ends thè
scarfed faces can be rotated relative to one another~ ~o assist in producing this relative rotation, the edge of one flange is ; machined with worm teeth 334 to engage a pair of worms 335 car- -s~ ried by the collar. The worms 335 may be driven by air or hy-~ 30~ draulic motors. The other flange of the pair is pinned to the ,:
collar by a pin 336.

As can be seen in Fiyure 14 a displacement of the - -.
, axis of the pipes 11 and 12 can he accommodated by the use of a :., . : ,:
bobbin tube 337 and two collars.
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Prior to assembly of the pipe couplings described above each coupling should be tested. The coupling sleeves are threaded over a test pipe at the works and the following test ; procedure is carried out just before despatch to the site where the coupling is to be used. The annular tires 17 are pressur-ized with oil to 2,000 psi which centralizes 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 the bore 402. If a leak - ;~
is shown up the cause will most probably be sand or other foreign ~-.
~ matter lodged under the seals. The following pressure test pro-:
cedure will show which of the three seals is leaking. If pres-sure is applied at the ~ore 40Z and it is not held but it drops ~' and shows no pressure rise at bore 401 then the seal in groove 16 is leaking. By pressurizing through bore 401, if the pressure ~`~ at bore 402 increases then this conirms that the seal in groove .j ~; 14 is leaking. If however there~is no pressure rise at bore 402 i then it is the seal in groove 15 that is leaking.
Before the seals are dismantled to see if ~hey are 20 faulty the pressure in the tires 17 should be reduced to 100 psi and clean sea water or solvent is injected through the bores 401 and 402. The pressure test is then repeated and if it is still leaking the~seal must be moved 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 defective seal replaced by a new seal. If care is taken that the surface of ~-P,~ the pipe is satisfactory and clean sea water is injected through the bores 401 and 402 to wash out any sand collected in these spaces during assembly it is mo=t unlikely that there will ~e any difficulty when the pipe joint is assembled. The second sleeve is then slid onto the test pipe and the coupling rotated to match up ~ith the flange of the first coupling. Pressuriza-tion and air testing o the second sleeve on the pipe is carried ~-, ' . .' -10~
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~ut in the same way as with the first sleeve. The pres~ure is then redu¢ed 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 23~ is pressurized to close the clamp ring and caus~ the interleaving dogs 234 to engage enabling the taper plug 232 to be inserted and rotated into the correct position by passing over a locating dowel pin 404. Both the tapered plug and the hinge pin 239 are pressurized with oil at 2,000 psi causing the collar to engage the stub flanges 230 firmly. Iso-lating valves are used to lock in the pressure. The face seal provided by the tire 1~3 is now tested. The tire 133 is pres- ~
surized to 2,000 psi through the bore 134 and air at 100 psi is ;
applied through a bore 405 to the face opposite the tire 133.
No air leakage should occur if the face s al is new and undam-aged. The air and oil pressures are then returned to atmosphe-.. . .
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As a final test the tapered plug 232 and the hinge , pin Z39 are pressurized to 1,000 psi and the tires 17 and 1~3 are pressurized to 2,000 psi. The air tests at 401, 402 and 405 ., .
are then repeated.

The pipe joint is then assembled as follo~s. If 1:
~ there is a leak or rupture in a sub sea pipeline, the faulty .~ .
section which may be 10' on either side of the damaged part is aut out using standard scarf or inclined cuts and the damaged piece is removed after measurements of the spring and the cuts . . , : .
,7~ ~ have been made. The damaged piece plus the gap measurements .: ~ ... ..
~ are used to manufacture the replacement pipe. The sleeves are ~ .,, 3 threaded over the upstream and downstream open ends of the 30 pipeline. The replacement section of pipe complete with the sleeves sIipped over its ends is lowered into position and }ined up so that the pipe edges are paralleI and the gap split between both ends. If there is some spring or lack of alignment ,.:: :
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between the upstream and downstream ends of the pipes -then the necessary rotational adjustment must be made to bring the coup-ling faces true and fair. The hinged collar is then lowered into place and secured with the tapered plug. The dowel is then pressurized to 2,000 psi and the insolating valves are closed.
The face seal provided by tire 133 is then pressurized to 2,000 psi and the joint between the flanges is air te~ted by applying air at 100 psi through the bore 405. The coupling sleeves are similarly pressurized with oil and the seals air tested as be-10 fore. All pressures are then bled away. The assembly is now ~ -ready for permanent setting.
The hydraulic taper plug 232 and the hinge~pin 239 are pressurized to 2,000 psi with epoxy resin composition and ~ . .
- the pressure is locked in using a valve. The pressure seals pro-vided by the tires 17 and the tire 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 to the bore 134 which ~; is injected with epoxy compound, air being bled off and the tire 133 b~ng pressurized to 2,000 psi for 10 minutes before the bore :.:.
~ 20 134 is closed. Epoxy resin compound is injected into the tires ~, 17 and the helical tube 25 through the manifold 21, the air be-ing bled off through the air bleed valves and the pressure being raised to 2,000 psi for 10 minutes before the inlet bores are closed. Finally the helical space between the jaw sectors is injected with epoxy resin, air being bled off and pressurlzed ;~ , . : .
to 5,000 psi to seal off the interface. ;~ ~
Air tests at 401, 402 and 405 are finally applied to ~ -check that everything is in order.
;,. : . .:
If it is acceptable that the epoxy metering, mixing and pressure injection pump may be clamped to each coupling sleeve - i.e. he 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 controls to do the .

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~063644 , pressurization with oil for the proving tests with oil before -~
final pressurization with epoxy compound. It could be that experience will determine that this precaution is not necessary and that air tests carried out after the pressurization with epoxy compound will always show a satisfactory end result.
The pump will operate on a 100 psi air 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.
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The joint is designed as a permnent fixture. Where a demountable connection is required between coupling halves a . , bolted connection may be used. If due to damage or displacement, the face seal providsd by tire 133 reauires renewal, arrangements have been made in the design to enable the hinged clamp ring to be quickly removed by breaking 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 ~ould have been damaged beyond~repair and the complete joint would require to be~remad'e with a new ma~e-up section o~ pipe~

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Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A coupling comprising;
a sleeve for fitting over a tubular member;
gripping means associated with the sleeve for grip-ping said tubular member, said gripping means comprising at least one convoluted groove on the inside of said sleeve, said groove including a plurality of axially spaced generally cir-cumferentially extending groove sections which are joined to form a continuous groove, jaw sectors with gripping teeth accom-modated in the arcuate groove sections, a tube located in the groove sections behind the jaw sectors and extending along the length of the convoluted groove, and bores extending 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 pressure until set to cause the gripping teeth of the jaw sectors to bite into the outer surface of the tubular member.

2. A coupling according to Claim 1, wherein the arcuate groove sections are joined to form a continuous helical groove.

3. A coupling according to Claim 1, wherein the sleeve is divided diametrically to form two half sleeves and the groove sections are joined to form two continuous sinuous grooves, one in each half sleeve.