WO2000066924A1

WO2000066924A1 - Pipe sealing system

Info

Publication number: WO2000066924A1
Application number: PCT/GB2000/001663
Authority: WO
Inventors: Owen Walmsley
Original assignee: Hydra-Tight Limited
Priority date: 1999-05-01
Filing date: 2000-04-28
Publication date: 2000-11-09
Also published as: AU4422600A; GB9910232D0

Abstract

A pipe repair system comprises a sealing unit (2) for sealing a damaged pipe (12) and a remotely-operable applicator rig (4) which is operably connectable to the sealing unit. In use, the applicator rig effects securement of the sealing unit to an outer cylindrical surface of the damage pipe so as to seal the damage pipe. The applicator rig is recoverable after the pipe has been sealed.

Description

PIPE SEALING SYSTEM

The present invention relates to a system for sealing damaged pipes, particularly but not exclusively, underwater pipes.

Underwater, particularly subsea, pipelines are susceptible to damage requiring repair but may be inherently difficult to access and may lack a freely available pipe end which would facilitate repair by sliding a sleeve member along the pipe to cover the damaged section. One type of repair system, as exemplified in GB 1483141 , comprises a pair of coupling members each having semi-cylindrical inner surfaces, and a pair of flanges along their longitudinal free edges. When the coupling members are assembled around the pipe to be repaired they form a sleeve around the damaged region of pipe. The coupling members are fixed in place by a number of bolts through the flanges and seal around the pipe by means of a multi-part gasket carried by the members. Such a system is disadvantageous in that it is a time consuming task for a diver to fasten a number of bolts in a hostile underwater environment and at deep sea depths the cost of the repair is increased by the requirement for specialist divers and equipment.

It is an object of the present invention to provide an improved pipe sealing system which obviates or mitigates the problems associated with prior art systems, particularly with respect to underwater pipelines.

According to a first aspect of the present invention, there is provided a pipe repair system comprising:- (i) a sealing unit for sealing a damaged pipe; and

(ii) a remotely-operable applicator rig which is operably connectable to the sealing unit, wherein, in use, the applicator rig effects securement of the sealing unit to an outer cylindrical surface of the damaged pipe so as to seal the damaged pipe and wherein, the applicator rig is recoverable after the pipe has been sealed.

Preferably, the sealing unit is capable of adopting an open configuration so as to allow it to be placed around the pipe, and a closed configuration in which it completely surrounds the outer cylindrical surface of the pipe.

Preferably, the sealing unit comprises at least one two-part seal made from, for example, an elastomer, PTFE, or nickel reinforced graphite, and means for retaining the seal in position on the damaged pipe. More preferably, the two-part seal is compressible such that efficient sealing is effected between the two parts of the seal when compressed in use.

In an alternative embodiment, the seal is formed in situ on the damaged pipe from a flowable/molten material which is hardened by curing/cooling. Preferably, means are provided for containing the flowable/molten material within the damaged region of the pipe prior to curing/cooling.

Preferably, the seal retaining means is a two-part sleeve which surrounds the seal when the sealing unit is in the closed configuration. Each part of the two-part sleeve preferably comprises a number of half- annular elements which abut the corresponding elements of the other part of the sleeve to form the same number of annular ring members arranged on a common cylindrical axis when the sealing unit is in the closed configuration. Preferably, each ring member is engaged with each adjacent ring member in a tongue and groove arrangement by means of formations provided on annular end surfaces of each ring member, each pair of adjacent ring members being capable of relative rotation about the common cylindrical axis.

Preferably, the applicator rig is provided with means for moving the sealing unit from its open configuration to its closed configuration.

Preferably, the applicator rig is provided with means which allow the detachable engagement of the applicator rig to each ring member of the sleeve. More preferably, the applicator rig is provided with rotation means which act upon the engagement means so as to cause, in use, relative rotation of each pair of adjacent ring members. Most preferably, one ring member of each pair is rotated (preferably by 90°) while the other is held stationary.

It will be understood that when the ring members are rotated as above, the sleeve can not be separated into its two-part form due to the interlocking of the ring members.

Means may be provided for preventing undesirable rotation of the ring members. In a preferred embodiment in which a compressible seal is used, such rotation is prevented solely by hoop stress generated in the ring members when the seal is compressed. In either case, bolting or welding is not required to prevent the sleeve separating into its two component parts.

When a compressible two-part seal is used, the applicator rig is preferably provided with compression means for effecting compression of the two- part seal whereby to form an efficient seal.

Preferably, at least one of (and more preferably each of) the moving means, ring-member engagement means and compression means of the appl icator comprise at least one hydraulic ram.

According to a second aspect of the present invention, there is provided a two-part tubular sleeve for use in a pipe sealing repair system, each part of said two-part sleeve comprising a number of interlocking half-annular elements which are capable of abutting the corresponding elements of the other part of the sleeve to form the same number of annular ring members arranged on a common cylindrical axis, each pair of adjacent ring members being capable of relative rotation about the common cylindrical axis such that the two parts of the sleeve can not be separated.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:-

Figure 1 is a part sectioned view of a sealing system in position on a pipe; Figure 2 shows a detail of Figure 1 ;

Figures 3 and 4 are simplified perspective views of part of the sealing unit of Figure 1 ;

Figure 5 is an end-on view of an applicator rig for the sealing unit of Figures 3 and 4;

Figure 6 is a side view of the applicator rig of Figure 5;

Figure 7 shows one stage in the deployment of the sealing system of Figure 1 ; and

Figure 8 shows the part of Figure 3 in its locked position.

Figure 9 is a part-sectioned view of part of the applicator rig and sealing unit of Figure 1.

Referring first to Figure 1 , a pipeline repair system basically comprises a sealing unit 2 and an applicator rig 4. The sealing unit 2 comprises a primary tubular seal 6, a secondary annular seal 8 and a tubular sleeve 10, all of circular cross-section. The primary and secondary seals 6,8 are formed in nickel reinforced graphite (in other embodiments, not shown, the seals are formed in an elastomer or PTFE). The primary seal 6 takes the form of an elongate cylinder of significantly greater axial length than the seal 8, and is provided with a metal liner (not shown) which contacts, in use, the outer cylindrical surface of a pipe 12 under repair. The primary and secondary seals 6,8 are spaced apart by a pair of oppositely directed wedge rings 14. The primary seal 6 consists of two semi- cylindrical seal members which form the tubular primary seal 6 when pressed together along their longitudinal free edges. Similarly, the secondary seal 8 and rings 14 consist of two half-annular seal members and ring members respectively. Each primary and secondary seal member and ring member is carried on an inner part-cylindrical surface of a different one of a pair of clamp portions 16 (described in more detail below) which constitute the tubular sleeve 10.

Referring to Figures 2, 3 and 4, each of the clamp portions 16 comprises a number of interlocking semi-cylindrical ring segments 18 (seven in the embodiment illustrated) disposed between first and second semi- cylindrical end pieces 20,22. When the clamp portions 16 are juxtaposed in a closed position (Figure 3), each ring segment 18 and each end piece 20,22 of one clamp portion 16 abuts a corresponding segment 18 or end piece 20,22 of the other clamp portion 16 so as to define an annular ring member 24 and first and second annular end pieces 26,27 respectively.

Each ring segment 18 has an inner face 28 and an outer face 30 and first and second end faces 32,34. The first end face 32 has a part-annular channel 36 formed between coaxial, longitudinally extending inner and outer flanges 38,40, the outer flange 40 being of greater axial length than the inner flange 38. An outer part-cylindrical surface of the flange 40 has chamfered part-annular edges 41 (Figure 2). The second end face 34 is provided with a third flange 42 the radius of which corresponds to the radius of the channel 36. The channel 36 in the first end face 32 accommodates the third flange 42 of an adjacent ring segment 18 in a tongue and groove arrangement, whereby the ring segments are interlocked radially. In the closed position (Figure 3) each adjacent pair of ring members 24 is mutually rotatable about their common cylindrical axis.

A radially inner part-cylindrical surface of each outer flange 40 is provided with a number of part-annular ribs 43 (in this embodiment 6, Figure 2) which interlock with a corresponding number of part-annular ribs 44 on a radially outer part-cylindrical surface of the third flange 42 of the adjacent ring segment 18. As an alternative (not shown), the ribs 43, 44 are in the form of part-threads.

The first end piece 26 has a first end face which corresponds in shape to the first end face 32 of the ring members 24 (and includes ribs 45 which interlock with the ribs 44 of the third flange 42 of the adjacent ring segment 18) and which receives the third flange 42 of the adjacent ring member 24. A plane second end face 46 of the first end piece 26 forms an end face at the first end of the sleeve 10. The second end piece 27 has a first end face which corresponds in shape to the second end face 34 of the ring members 24 (and includes ribs which interlock with the ribs 43 of the outer flange 40 of the adjacent ring segment 18) and which is received in the channel 36 of the adjacent ring member 24. A plane second end face 50 of the second end piece 27 forms an end face at the second end of the sleeve 10. A radially outer part-cylindrical surface of each end piece 26,27 has chamfered part-annular edges 26a (not shown for end piece 27). A pair of spaced annular sealing ribs 52 extend radially inwardly from the second end piece 27 (Figure 1 ).

The geometry of the ring members 24 is such that when they are interengaged axially their the inner faces 28 define an inner cylindrical surface 54 of the sleeve 10. An exposed part of each outer face 30 of the ring members 24 and the end pieces 26,27 forms an outer surface of the sleeve 10, which outer surface has cylindrical sections 56 of a first diameter interposed between cylindrical sections 58 of a second, smaller diameter. Each end piece 26,27 and each alternate ring member 24 is provided with a recess 60 in its exposed outer face 30. Each remaining (alternate) ring member 24 is provided with a circumferential groove 62 in its exposed outer face 30 (Figure 8). It will be appreciated that because of the interlocking rib arrangement, once assembled, the ring segments 18 and end pieces 26,27 of each clamp portion 16 cannot be moved axially relative to each other.

Referring to Figures 1 , 5 and 6, the applicator rig 4 has a support frame 70 which comprises a pair of semi-cylindrical support portions 72 each of which comprises a series of half-annular ring segments 74a,74n which are interlocked in a similar manner to the ring segments 24 of the sleeve 10. An arm 76 extends from one end region of each segment 74a of each alternate (anchored) pair of segments 74a, the arms 76 being pivoted at their free ends on an axially extending metal rod 78. This arrangement allows the support frame 70 to be pivoted from an open position (Figure 5) in which each segment 74a,74n is spaced from the opposite segment 74a,74n of the pair, to a closed position in which each segment 74a,74n abuts its opposite segment 74a,74n of the pair to form a ring.

The inner surface of the support frame 70 substantially corresponds in shape to the outer surface of the sleeve 10 so that each constituent clamp portion 16 of the sleeve 10 can be accommodated in a respective one of the support portions 72 of the support frame 70. Two sacrificial bolts 80 attached to hydraulic cylinders (not shown) are provided through each support portion 72. The bolts are attached to the metal liner of the respective clamp portions 16 of the sleeve 10 so as to hold the latter in the support frame 70 during deployment.

A drive pin (not shown) extends inwardly from one ring segment 74a of each pair of anchored ring segments 74a of the support frame 70 and is located in the corresponding recess 60 provided in the alternate ring members 24 or end pieces 26,27 of the sleeve 10. A drive pin also extends inwardly from one ring segment 74n of each pair of non-anchored ring segments 74n and is located in the corresponding groove 62 provided in the remaining ring members 24.

The arms 76 of each anchored ring segment 74a of each portion 72 of the support frame 70 are interconnected by a respective axially extending cross member 82. A pair of hydraulic rams 84 disposed at opposite end regions of the cross members 82 are arranged to act upon the cross members 82 to effect movement of the support frame 70 between its open and closed positions, and thus in use can be actuated to close the two halves of the associated sealing unit around the damaged region of the pipe 12.

One non-anchored segment 74n of each pair of non-anchored segments 74n is releasably attached to a respective locking hydraulic rams 86. Each locking ram 86 is pivotal ly mounted on a rod 88 which extends between outward extensions 90 on the arm 76 of one segment 74a of the anchored pair of segments 74a at each end of the support frame 70. The pivot axis of the rod 88 is parallel to the metal rod 78 about which the two support portions 72 of the support frame 70 pivot. Each locking ram 86 is arranged to rotate the respective non-anchored segment 74n about its cylindrical axis.

One end of the applicator rig 4 is provided with a series of spaced energising hydraulic rams 92 which are orientated parallel to the longitudinal axis of the support frame 70 and which are secured to one end thereof. The energising rams 92 are releasably connected to, and arranged to act upon, a tubular compressing member 94 (which forms a part of the sealing unit 2, Figure 1 ) which is formed in two semi- cylindrical parts. The compressing member 94 is seated on the inner surface 54 of the sleeve 10 and has a wedge shaped end region which abuts the primary seal 6. Sliding movement of the compressing member 94 relative to the sleeve 10 is restricted by a ratchet mechanism (not shown) which allows movement of the compressing member 94 towards but not away from the primary seal 6. Referring to Figures 7 and 8, in use, the sealing unit 2 is fitted to the applicator rig 4 and is releasably secured thereto by the sacrificial bolts 80. Hydraulic power to the rams 84,86,92 is provided by a remotely operated vehicle (ROV) 96. The rig 4 (attached to a clump weight 98 and a buoyancy tank 100) and the ROV 96 are lowered from a surface vessel 102 by means of a heave compensation winch 104. The heave compensation winch 104 allows the applicator rig 4 to be accurately positioned relative to a damaged section of pipe 12 to be repaired. When positioned around the pipe 12, the closing hydraulic rams 84 are activated to move the support frame 70 to its closed position. A small load is maintained on the closing rams 84 to ensure that this position is maintained until locking of the sealing unit 2 has occurred. Prior to locking, the integrity of the sealing unit can be tested by applying pressure between the primary and secondary seals 6,8. Locking is effected by activating the locking rams 86 which cause the non-anchored ring segments 74n of the support frame 70 to rotate by 90°. As the non- anchored segments 74n rotate, each drive pin attached thereto engages with one end of the respective groove 62 in the ring members 24, causing the latter to rotate. The drive pin which extends from each anchored segment 74a and which is located in the recess 60 of the corresponding ring member 24 prevents rotation of that ring member 24. Thus after locking, each ring member 24 is angularly displaced by 90° relative to the adjacent ring member(s) 24. In this position (Figure 8), it is no longer possible to separate the two clamp portions 16 of the sleeve 10 by virtue of the interlocking tongue and groove arrangement of the ring members 24. Sealing is effected by activation of the energising rams 92 which act on the compressing member 94 to compress the primary seal 6 against the wedge rings 14 which in turn slide axially compressing the seal 8 against a wedge shaped abutment surface within the end piece 27. The wedge forms acting on the seals 6,8 serve to urge the seals against the outer surface of the pipe 12.

The compression causes the primary seal 6 to completely fill the void between the outer surface of the pipe 12 and the inner surface 54 of the sleeve 10. The seal 6 is compressed until a predetermined seal stress has been obtained. At this stress, the two seal members of the seal 6 are pressed so firmly together that there is no leakage through the longitudinal split lines between the two seal members. Under extreme compression, the two seal members may in fact merge to form a unitary seal. The ratchet mechanism holds the compressing member 94 in place to maintain the desired seal stress and prevents extrusion of seal material axially of the sleeve 10 at its first end. The sealing surfaces 52 of the second end piece 27 prevent extrusion of seal material axially of the sleeve 10 at the second end of the sleeve 10, and the metal liner of the seal 6 prevents extrusion of seal material through any holes in the damaged pipe 12. After pressure testing, the sacrificial bolts 80 holding the sealing unit 2 to the applicator rig 4 are broken by activation of the hydraulic cylinders (not shown).

The sealing unit 2 is then hydraulically released from the applicator rig 4 by reversing the rotation of the non-anchored segments 74n. Each drive pin attached to the non-anchored segments 74n moves within the corresponding groove 62 without causing rotation of the latter until the non-anchored segments 74n are aligned with the anchored segments 74a. After the support frame 70 is returned to its open position the hydraulic rams 84,86,92 are deactivated and the rig 4 and ROV 96 are recovered to the surface.

In this embodiment, unwanted rotation of the ring members 24 of the sleeve 10 is prevented after separation of the applicator rig 4 by the hoop stress induced in the ring members 24 by compression of the primary seal 6.

Referring also to Figure 9, a drive pin 1 10 and part of a ring member 24 are shown. The groove 62 of the ring member 24 is provided with a recess 1 12 at a first end. In the position shown, the drive pin 1 10 sits within the groove 62, above the recess 112. For locking of the ring members 24, rotation of the (alternate) ring members 24 is effected by application of a force to the drive pin 1 10 against the first end of the groove 62 (arrow A). Application of a force in the opposite direction (arrow B) effects removal of the applicator rig 4 without rotation of the ring members 24, since the drive pin 1 10 moves along the groove 62 without resistance. However, it may be necessary to remove the sealing unit 2 from the pipe 12, for example if the sealing unit 2 is used as a temporary repair. Such removal is effected by urging the drive pin 1 10 towards the ring member 24 so that it locates in the recess 1 12 in the groove 62. When the drive pin 1 10 is now subjected to a force in direction B, its movement along the groove 62 is prevented by a wall of the recess 1 12. Such force therefore causes the ring member 24 to rotate towards its unlocked position. The system may be constructed for use with any particular nominal pipe diameter. However, the system can accommodate small variations from this nominal diameter, due to the nature of the seal energisation.

The above system has been described for remote undersea use. However, the system may also be used on more easily accessible pipes, e.g. on land. In these cases, the applicator rig is not necessary, and the sealing unit 2 can be manually positioned around the pipe and locked into position using a suitable lever tool.

Modifications (not shown) of the above embodiment include one or more of the following features:-

(i) The ROV is omitted, hydraulic power to the rig being supplied by lines from the surface vessel.

(ii) The ROV is provided with means to guide the applicator into position on the damaged pipe.

(iii) A latch mechanism is provided on the sleeve to prevent any rotation of the ring members after deployment.

(iv) A second set of seal energising rams are provided at the opposite end of the sleeve to ensure that the primary seal is evenly stressed.

In an alternative embodiment (not shown), the tubular sleeve 10 is provided with end faces which grip the pipe 12 such that the sleeve 10 forms an enclosure around the pipe 12. The seal 6 is formed by injecting a molten or curable resin into the space between the pipe 12 and the sleeve 10 and cooling or curing the resin in situ around the pipe.

Claims

1. A pipe repair system comprising:

(i) a sealing unit for sealing a damaged pipe; and

2. A pipe repair system as claimed in claim 1 , wherein the sealing unit is capable of adopting an open configuration so as to allow it to be placed around the pipe, and a closed configuration in which it completely surrounds the outer cylindrical surface of the pipe.

3. A pipe repair system as claimed in claim 1 or 2, wherein the sealing unit comprises at least one two-part seal and means for retaining the seal in position on the damaged pipe.

4. A pipe repair system as claimed in claim 3, wherein the two-part seal is compressible such that efficient sealing is effected between the two parts of the seal when compressed.

5. A pipe repair system as claimed in claim 4, wherein the applicator rig is provided with compression means for compressing the two-part seal.

6. A pipe repair system as claimed in claim 1 or 2, wherein the sealing unit comprises a seal which is formed in situ on the damaged pipe from a flowable or molten material which is hardened by curing or cooling.

7. A pipe repair system as claimed in any preceding claim, wherein the seal retaining means is a two-part sleeve which surrounds the seal when the sealing unit is in the closed configuration.

8. A pipe repair system as claimed in any preceding claim, wherein each part of the two-part sleeve comprises a number of half-annular elements which abut the corresponding elements of the other part of the sleeve to form the same number of annular ring members arranged on a common cylindrical axis when the sealing unit is in the closed configuration.

9. A pipe repair system as claimed in claim 8, wherein each ring member is engaged with each adjacent ring member in a tongue and groove arrangement by means of formations provided on annular end surfaces of each ring member, each pair of adjacent ring members being capable of relative rotation about the common cylindrical axis.

10. A pipe repair system as claimed in any preceding claim, wherein the applicator rig is provided with means for moving the sealing unit from its open configuration to its closed configuration.

1 1. A pipe repair system as claimed in any one of claims 8 to 10, wherein the applicator rig is provided with means which allow the detachable engagement of the applicator rig to each ring member of the sleeve.

12. A pipe repair system as claimed in claim 11 , wherein the applicator rig is provided with rotation means which act upon the engagement means so as to cause, in use, relative rotation of each pair of adjacent ring members.

13. A pipe repair system as claimed in any one of claims 8 to 12, wherein means are provided for preventing undesirable rotation of the ring members.

14. A pipe repair system as claimed in any one of claims 10 to 13, wherein at least one of the moving means, ring-member engagement means and compression means of the applicator comprise at least one hydraulic ram.

15. A two-part tubular sleeve for use in a pipe sealing repair system, each part of said two-part sleeve comprising a number of interlocking half- annular elements which are capable of abutting the corresponding elements of the other part of the sleeve to form the same number of annular ring members arranged on a common cylindrical axis, each pair of adjacent ring members being capable of relative rotation about the common cylindrical axis such that the two parts of the sleeve can not be separated.