GB1569104A

GB1569104A - Pipe couplings

Info

Publication number: GB1569104A
Application number: GB3028275A
Authority: GB
Original assignee: Pilgrim Engineering Developments Ltd
Current assignee: Pilgrim Engineering Developments Ltd
Priority date: 1976-10-18
Filing date: 1976-10-18
Publication date: 1980-06-11

Description

(54) IMPROVEMENTS TN PIPE COUPLINGS (71) We, PILGRIM ENGINEERING DE VELOPMENTS LIMITED, a British Company, of Beaufort House, St. Botoiph Street, London EC3A 7DX (formerly of One Aldgate, London EC3N 1 PT), do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to pipe couplings, especially pipe couplings for use in oil or gas pipelines.

According to the present invention 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 for gripping the pipe, the sealing means comprising an annular groove which accommodates an annular tube the interior of the tube communicating through first bores in the wall of the sleeve with the exterior of the sleeve, the gripping means comprising a series of axially-spaced circumferentially-extending groove sections on the inside of the sleeve which accommodate jaw sectors with gripping edges, the groove sections being joined together to form one or more continuous channels and a tubular member or members located in the channel or channels behind the jaw sectors, the tubular member or members communicating through second bores extending through the wall of the sleeve with the exterior, the arrangement being such that the annular tube can be filled through said first bores with a hardenable composition and maintained under pressure until set to force sealing means into sealing contact against the outer surface of the pipe and the tubular member or members can be filled through the second bores with a hardenable composition and maintained under pressure until set to cause the grip ping edges 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 pressure that is greater than the yield pressure of the pipe to be achieved. By pressurising the hardenable composition to the working pressure of the pipe, that is the pressure of the fluid in the pipe when the pipe is in use, the compression on the pipe end will be counterbalanced by the pressure of the fluid in the pipe. In applications where the working pressure is such that the pipe is operating close to its failure pressure, say 80% thereof, the gripping pressure will be equal to about 80% of the failure pressure when the pipe is not in use and will be doubled to approximately 160% of the failure pressure when the pipe is in use.

The sleeve may be provided with second means for sealing the sleeve to a pipe so that a single sleeve may be used to coupIe 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 of another pipe, to form a pipe joint.

Preferably the sealing means include at least two annular grooves, each of which accommodates an annular tube 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 grooves so that the space bounded by the two annular grooves, the sleeve and the pipe end may be pressurised 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 communicates with the exterior of the sleeve through bores at both ends of the sleeve.

Alternatively, the sleeve may be formed in two halves separated from one another along a longitudinal plane through the axis of the sleeve. Two halves may be coupled to one another along their longitudinal pairs of edges by bolts which pass through flanges disposed along the longitudinal edges. This arrangement may facilitate the placing of the sleeve in position under difficult conditions such as for example when repairing a pipeline on the sea bed.

In the case of a sleeve formed in two half sleeves as described above the groove sections of the gripping means may be joined to form two continuous sinuous channels, one in each half-sleeve and the tubular members may be formed as a continuous tube in each half sleeve.

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; Figure 2 shows a cross-section on an enlarged scale of air bleed valves of the coupling of Figure 1; Figure 3 shows a cross-section on an enlarged scale of an epoxy composition filling connecting of the coupling of Figure 1; 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 is a detailed view from the interior of the coupling of Figures 4 and 5 on an enlarged scale; Figure 7 shows on a reduced scale 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; Figure 9 shows the 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: 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 Figure 1, this shows the ends of two abutting pipes 11 and 12 coupled together by a sleeve of steel. Sealing means comprising two pairs of annular grooves 4 and 15 are provided in the inner surface of the sleeve 13 opposite the respective end portions of the pipes 11 and 12. Two further sealing means comprising annular grooves 16 are provided in the inside surface of the sleeve 13 near the two ends of the sleeve. An annular tube or tyre 17 is accommodated in each of the grooves 14, 15 and 16 and the interior of each tyre communicates with the exterior of the sleeve 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 each provided with a filling pipe 20 (Fig. 3) which is connected to a manifold 21. The bores 19 at the top of the sleeve constitute exhaust ports for air and are provided with air bleed valves 22 (Fig.

2).

In use the tyres in the grooves 14, 15 and 16 are filled with a hardenable composition, for example an epoxy resin composition, through the manifold 21, the filling pipe 20 and the bores 18. The epoxy resin composition fills the tyres 17, displacing the air in them and exhausting it from the tyres through 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 composition and the pressure of the epoxy resin composition 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 composition in the tyres 17 the tyres which are of nitrile rubber are deformed are pressed tightly against the outside of the pipes 11 and 12 to form a seal.

The epoxy resin composition is maintained under pressure until set.

Between the each adjacent pair of annular grooves 14 and 16 opposite the ends of the pipes 11 and 12 is a respective helical groove or channel 23 in the inside surface of the sleeve 13. The helical grooves provide a series of axially-spaced circumferentially-extending groove sections. 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 jaw sectors have a series of circumferential knife or saw-tooth shaped grip ping edges which bite into the outer surface of the pipe. In each groove 23 behind the jaw sectors 24 is a tubular member in the form of a nitrile rubber helical tube 25 which forms a load cell. At the outer end of each helical tube at the top of the sleeve the interior of the tube 25 communicates with the exterior of the sleeve through a bore 26. The bore 26 is fitted with an air bleed valve 27.

At the inner end of each tube 25 at the lower side of the sleeve 13 the interior of the tube communicates with the exterior of the sleeve through a bore 28. The bore is fitted with a filling pipe 29 (Fig. 3) connected to the manifold 21. The helical tubes 25 are filled with a hardenable composition, for example and epoxy resin composition in a similar manner to the tyres 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 gripping 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 coupling sleeve 113 for connecting to one end of one pipe 12 and having a circumferential radially outwardly projecting 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 of the sleeve. Once the two similar coupling sleeves have been bolted together by means of their flanges 130 the tyre 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 axis of the sleeve. The two halves of the sleeve 113 can be secured together by means of hydraulic jacking bolts 135 which pass through holes in bolting flanges 136.

On the inside of the sleeve 113 are pr vided annular grooves 14, 15 and 16 with annular tyres 17 similar to the grooves and tyres of the embodiment of Figure 1. Between the grooves 14 and 16 on the inside of the sleeve each half sleeve is provided with gripping means including a series of axially spaced circumferentially-extending half-annular groove sections 137. Adjacent groove sections are joined at alternate ends by halfannular sections 138. Thus the sections 137 and 138 form in each sleeve half a channel which is continuous from one end to the other. Located in the channel in each sleeve half is a hollow nitrile rubber tube 139 which communicates 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 Figure 1. Arcuate jaw sectors are fitted in the groove sections in front of the tube 139 as in the embodiment 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 joined, the two halves 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 face seal 133 are all filled with epoxy resin composition and maintained under pressure until set.

Figure 7 shows another form of pipe coupling which is similar to the arrangements of Figures 1 and 4 with regard to the arrangement of sealing and gripping means but has a joint which is 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 closed position by a tapered plug 232 which is inserted through holes 233 in the two interleaving dogs 234.

Figure 9 shows how the two hinged segments of the 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 be seen in Figure 8 the tapered plug 232 includes a number of load cells 237 which are connected together within the pin by bores 238. After the plug 232 has been inserted the load cells may be pressurised 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 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 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 invention. The arangement 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.

To accommodate malalignment between pipe ends the scarfed races can be rotated relative to one another. To assist in producing this relative rotation, the edge of one flange is machined with worm teeth 334 to engage a pair of worms 335 carried by the collar. The worms 335 may be driven by air or hydraulic motors. The other flange of the pair is pinned to the collar by a pin 336.

As can be seen in Figures 14 a displacement of the axis of the pipes 11 and 12 can be accommodated by the use of a bobbin tube 337 and two collars.

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 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 16 through the bore 401 and spaced between the grooves 14 and 16 through the bore 402.

If a leak is shown up the cores 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 and shows no pressure rise at bore 401 then the seal in groove 16 is leaking. By pressurising through bore 401, if the pressure at bore 402 increases then this confirms that the seal in groove 14 is leaking. If however there is no pressure rise at bore 402 then it is the seal in 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 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 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 most unlikely that there will be 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 with the flange of the first coupling. Pressurisation and air testing of the second sleeve on the pipe is carried out in the same way as with the first sleeve. The pressure is then reduced to atmospheric.

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 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 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 pressure. The face seal provided by the tyre 133 is now tested.

The tyre 133 is presusrised to 2,000 psi through the bore 134 and air at 100 psi is applied through a bore 405 to the face opposite the tyre 133. No air leakage should occur if the face seal is new and undamaged. The air and oil pressures are then returned to atmospheric.

As a final test the tapered plug 232 and the hinge pin 237 are pressurised to 1,000 psi and the tyres 17 and 133 are pressurised to 2,000 psi. The air tests at 401, 402 and 405 are then repeated.

The pipe joint is then assembled as follows. If there is a leak or rupture in a sub sea pipeline, the faulty section which may be 10 feet on either side of the damaged part is cut out using standard scarf or inclined 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. The 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 is then pressurised to 2,000 psi and the joint between the flanges is air tested by applying air 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 is now ready for permanent setting.

The hydraulic taper plug 232 and the hinge pin 239 are presurised 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 to the bore 134 which is injected with epoxy compound, air being bled off and the tyre 133 being pressurised to 2,000 psi for 10 minutes before the bore 134 is closed. Epoxy resin compound is injected into the tyres 17 and the helical tube 25 through the manifold 21, the air being 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 pressurised 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 inject on pump may 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 controls to do the pressurisation with oil for the proving tests with oil before final pressurisation with epoxy compound. It could be that experience will determine that this precaution is not necessary and that air tests carried out after the pressurisation 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 hardener and of oil-where required would be secured to the top or alongside the pump unit.

The joint is designed as a permanent 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 provided by tyre 133 requires 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 clams 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 make-up section of pipe.

WHAT WE CLAIM IS:- 1. 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 for grip ping the pipe, the sealing means comprising an annular groove which accommodates an annular tube the interior of the tube communicating through first bores in the wall of the sleeve with the exterior of the sleeve, the gripping means comprising a series of axially-spaced circumferentially-extending groove sections on the inside of the sleeve which accommodate jaw sectors with grip- ping edges the groove sections being joined together to form one or more continuous channels and a tubular member or members located in the channel or channels behind the jaw sectors, the tubular member or members communicating through second bores extending through the wall of the sleeve with the exterior, the arrangement being such that the annular tube can be filled through said first bores with a hardenable composition and maintained under pressure until set to force the sealing means into sealing contact against the outer surface of the pipe and the tubular member or members can be filled through the second bores with a hardenable composition and maintained under pressure until set to cause the gripping edges of the jaw sectors to bite into the outer surface of the pipe.

2. A pipe coupling according to claim 1 in which the sleeve has second means for sealing the sleeve against a second pipe, being spaced axially from the first mentioned sealing means and including an annular groove which accommodates an annular tube, bores communicating with the interior of the tube extending through the wall of the sleeve to the exterior of the sleeve.

3. A pipe coupling according to claim 1 in which the sleeve has an external flange at one end so that it can be bolted or clamped to a similar sleeve attached to the end of another pipe, to form a pipe joint.

4. A pipe coupling according to claim 3 in which two sleeves with flanges are coupled together by a collar which encircles the flanges.

5. A pipe coupling according to claim 1 or 2 in which the or each sealing means includes at least two annular grooves, each of which accommodates a respective annular tube with bores communicating with the interiors of the said tubes extending through the sleeve to the exterior of the sleeve.

6. A pipe coupling according to claim 5 in which a filling hole is provided through the wall of the sleeve between the two annular grooves of the or each sealing means.

7. A pipe coupling according to any one of claims 1 to 6 in which the or each sleeve is formed as a single piece encircling the pipe and the groove sections of the grip

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. 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 to the bore 134 which is injected with epoxy compound, air being bled off and the tyre 133 being pressurised to 2,000 psi for 10 minutes before the bore 134 is closed. Epoxy resin compound is injected into the tyres 17 and the helical tube 25 through the manifold 21, the air being 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 pressurised 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 inject on pump may 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 controls to do the pressurisation with oil for the proving tests with oil before final pressurisation with epoxy compound. It could be that experience will determine that this precaution is not necessary and that air tests carried out after the pressurisation 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 hardener and of oil-where required would be secured to the top or alongside the pump unit. The joint is designed as a permanent 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 provided by tyre 133 requires 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 clams 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 make-up section of pipe. WHAT WE CLAIM IS:-

1. 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 for grip ping the pipe, the sealing means comprising an annular groove which accommodates an annular tube the interior of the tube communicating through first bores in the wall of the sleeve with the exterior of the sleeve, the gripping means comprising a series of axially-spaced circumferentially-extending groove sections on the inside of the sleeve which accommodate jaw sectors with grip- ping edges the groove sections being joined together to form one or more continuous channels and a tubular member or members located in the channel or channels behind the jaw sectors, the tubular member or members communicating through second bores extending through the wall of the sleeve with the exterior, the arrangement being such that the annular tube can be filled through said first bores with a hardenable composition and maintained under pressure until set to force the sealing means into sealing contact against the outer surface of the pipe and the tubular member or members can be filled through the second bores with a hardenable composition and maintained under pressure until set to cause the gripping edges of the jaw sectors to bite into the outer surface of the pipe.

ping means of the or each sleeve are formed by a helical groove, the tubular member being a helical tube.

8. A pipe coupling according to claim 7 in which the said second bores through which helical tube communicates with the exterior of the or each sleeve are at both ends of the or cach sleeve.

9. A pipe coupling according to any one of claims 1 to 6 in which the or each sleeve is formed in two halves separated along a longitudinal plane through the axis of the sleeve, means being provided for securing the two halves together.

10. A pipe coupling according to claim 9 in which the groove sections of the gripping means are joined to form two continuous sinuous channels, one in each half sleeve and the tubular members being formed as a continuous tube in each half sleeve.

11. A pipe coupling substantially as described hereinbefore with reference to Figures 1 to 3 of the accompanying draw lungs.

12. A pipe coupling substantially as described hereinbefore with reference to Figures 4 to 6 of the accompanying drawings.

13. A pipe coupling substantially as described hereinbefore with reference to Figures 7 to 11 of the accompanying drawings.

14. A pipe coupling substantially as described hereinbefore with reference to Figures 12, 13 and 14 of the accompanying drawings.