Sealing apparatus

An apparatus for sealing a pipe having a defect or penetration comprises a housing coupled to the pipe by a clamp member. A piston is mounted in the housing and the piston and housing define a chamber. The piston further comprises a port for providing fluid communication between the pipe and the chamber. A seal member is provided between the piston and the pipe and, in use, the apparatus is located over and/or around the defect or penetration in the pipe such that the seal member engages the pipe. The piston is urged towards the pipe by a fluid pressure force generated by fluid in the pipe thereby maintain sealing engagement between the seal member and the pipe and to prevent leakage of fluid through the penetration.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to United Kingdom Patent Application No. GB 0714294.6 which was filed on 21 Jul. 2007.

FIELD OF THE INVENTION

This invention relates to an apparatus for use in providing a sealing engagement with a pipe and, in particular, but not exclusively, to an apparatus for use in sealing a defect or penetration in a pipe, tube, conduit, pipeline or the like.

BACKGROUND OF THE INVENTION

In many industries, pipes or pipelines are utilized to transport fluid over distance. For example, in the oil and gas industry, there is a need to transport fluid over great distances and often over or through largely inaccessible terrain or deep water.

Of course, it will be recognized that it is important where a defect or penetration occurs in a pipe that the pipe is sealed to obviate or mitigate loss of fluid. Alternatively, it may be required to provide a sealed intervention into a pipe, for example, where a nozzle is to be added for the fitting of a branch or tee connection to a live pipeline containing fluid at pressure, typically termed “hot tapping.”

At present, one method of sealing a pipe is to use a saddle clamp to cover the defect or penetration in the pipe. The saddle typically seals on a pad or, alternatively, on a ring seal encircling the defect or penetration to prevent escape of fluid from the pipe. In such an arrangement, energization of the seal is attained by pre-loading the seal on installation of the clamp, the pre-load being of a force in excess of the load generated by internal pressure within the pipe during operation. In this way, the penetration or defect may be isolated to prevent escape of fluid from the pipe.

The use of a clamp arrangement such as that described above operates sufficiently well for low pressure systems. However, the pre-load necessary to maintain the required sealing force is significant in relatively high pressure systems. There is also a need for the load to be evenly distributed over the seal. This can be problematic where, for example, the clamp is fitted to a de-pressurized pipe, as the pre-load may be sufficient to deform the pipe resulting in further defects or deformation to the pipe. This is particularly prevalent where the pre-load is applied to a thin walled pipe with low internal pressure.

Furthermore, it is known that the internal pressure in a pipe produces a radial force which resists external forces applied to the pipe. Thus, where the internal pressure within the pipe increases, an extrusion gap can form in the seal resulting in a reduction in operational effectiveness or failure of the seal.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an apparatus for use in sealing a defect or penetration in a pipe the apparatus comprising:

a body adapted to be coupled to a pipe;

a piston mounted in the body, a first face of the piston defining an actuating area of a first area and adapted for fluid communication with the pipe; and

a seal member for isolating the defect or penetration, the seal member being operatively associated with the piston and defining a sealing area of a second area, the piston being adapted to be urged to maintain the seal member in sealing engagement with the pipe.

In a preferred embodiment, the piston comprises a bore or port for providing fluid communication between the pipe and the first piston face defining the actuating area. The bore may extend through the piston between the sealing area and the first piston face. The bore may extend axially through the piston.

Thus, in use, the invention may provide a pressure energized seal, the retained fluid pressure in the pipe being directed to the first face of the piston to urge or, where required, translate the piston relative the body. The piston urges the seal member to maintain sealing engagement with the pipe, this assisting in the prevention of fluid loss from the defect or penetration in the pipe.

It will be understood that reference to the term pipe includes any elongate construction including, for example, but not exclusively, an oil or gas pipeline, whether subsea, above or below ground, down hole tubing, or indeed any other conduit suitable for transport or storage of fluids. It will be further recognized that the present invention may be used on any cross sectional shape of pipe.

It will be recognized that fluid pressure within the pipe and being communicated through the defect or penetration provides a force acting against seal energization, this force corresponding to the pipe pressure multiplied by the sealing area. It will be further recognized that, due to fluid communication between the pipe and the first piston face, the same pressure acts on the actuating area. In a preferred embodiment, the first area is larger than the second, sealing area. Thus, as the actuating area is larger than the sealing area, the force urging sealing engagement of the seal member will be greater than the force acting against energization of the seal member. Thus, the retained pressure in the pipe will urge and/or translate the piston to provide or maintain sealing engagement between the seal member and the pipe.

The piston may house or provide mounting for the seal member. Alternatively, the seal member may be provided separately from the piston such that, in use, the piston may be urged and/or translated into engagement with the seal member or otherwise transmit a sealing force to the seal member.

The seal member may comprise an elastomeric seal. Alternatively, the seal member may comprise a graphite seal, or any other suitable seal member. Further, the seal member may comprise a compression seal, for example, but not exclusively, a face seal, ring seal or the like. Thus, in use, the piston may be urged and/or translated to compress the seal member to provide or maintain sealing engagement between the seal member and the pipe.

Alternatively, the seal member may comprise a lip seal, or any other suitable seal.

The seal member may be adapted to be compliant to the pipe surface, such that seal integrity may be maintained where the surface of the pipe is irregular or has been subject to damage, for example as a result of the penetration.

The seal member may be of any shape including, for example, an ‘O’ ring, ‘D’ seal, elastomer sheet or the like.

The apparatus may comprise a plurality of seal members operatively associated with the piston. Thus, the piston may be adapted to be urged to maintain one or more seal member in sealing engagement with the pipe.

At least one seal member may be uni-directional. Alternatively, or in addition, at least one seal member may be bi-directional. Thus, a bi-directional seal permits a seal to be retained when the seal member is exposed to pressure on either side of the seal.

Where two or more seal members are provided, the seal members may define an annulus therebetween.

The piston may further comprise a test port for providing fluid communication between the annulus and a corresponding port in the body. Pressure may be applied to the annulus, for example, via the test port, to permit testing or monitoring of the seals. The provision of a plurality of seal members further provides for retention of sealing engagement with the pipe should failure of one seal occur.

The apparatus may further comprise one or more sliding seal elements located between the piston and the body for sealing therebetween. A sliding seal element may define the actuating area. The provision of two or more sliding seal elements may permit pressure to be applied to the annulus, for example, via the test port, to permit testing of the seal elements.

The piston and the body may together define a chamber for receiving fluid from the pipe. Thus, fluid entering the chamber will act on the actuating area to urge the piston to maintain sealing engagement between the seal member and the pipe.

Further, the body and/or the piston may define or provide mounting for a boss or stand-off. A standoff permits fluid to enter the chamber and to permit the retained fluid pressure to act on the actuating area.

The apparatus may further comprise a clamp member for coupling the body to the pipe.

The clamp member may be configured to permit application of a pre-load to the body and thus the piston and seal member to provide initial energization of the seal member. The provision of a pressure energized seal will require the pre-load to be sufficient only to generate the initial seal, simplifying construction and/or installation of the apparatus. Furthermore, a reduction in the load to be applied to the pipe may obviate or mitigate deformation of the pipe by the pre-load force, for example assisting in preventing damage to a low pressure or de-pressurized pipe.

In addition, a reduction in the load applied facilitates provision of a relatively lightweight apparatus. This would be particularly beneficial where, for example, the pipe penetration is to be found in a remote or inaccessible location.

The clamp member may be integral to the body. Alternatively, the clamp member may comprise one or more separate components coupled to or providing mounting for the body.

The clamp member may, for example, but not exclusively, comprise a strap, cable, split sleeve clamp or any other suitable restraint on the pipe or vessel.

The clamp member may be constructed from a metallic material, for example, steel, though it will be understood that any material may be utilized, where appropriate.

Where the clamp member comprises more than one separate component or portion, the clamp portions may be removably coupled together, for example, but not exclusively, via one or more pin, bolt, screw or by another suitable fastener.

Alternatively, the clamp portions may be permanently coupled together, for example, but not exclusively, by welding, riveting or by another suitable means.

The clamp member may be adapted to be coupled to the body by a fastener. The body may further comprise one or more bore adapted to permit the clamp member or fastener to be inserted therethrough to secure the body to the pipe via the clamp member. At least a portion of the clamp member may be adapted to be orientated tangentially to the pipe, the fastener being orientated in line with the clamp member. This assists in a reduction in bending forces and permits the use of a smaller, lighter clamp member.

Furthermore, as the retained pipe pressure is utilized to provide the contact pressure on the seal member, the pressure differential across the pipe is minimized, minimizing deformation of the pipe, which deformation may otherwise result in the formation of an extrusion gap between the seal member and the pipe.

Also, the bearing load applied by the apparatus to maintain seal energization will increase in concert with any increase in pipe pressure such that the maximum bearing load impinging on the pipe applies where there is matching pipe pressure to support the pipe.

According to a second aspect of the present invention there is provided a method of sealing a defect or penetration in a pipe, the method comprising:

providing a body and coupling the body to a pipe;

providing a piston in the body, a first face of the piston defining an actuating area of a first area; and

providing a seal member for isolating the defect or penetration, the seal member being operatively associated with the piston and defining a sealing area of a second area;

urging the piston to maintain the seal member in sealing engagement with the pipe.

Further aspects of the present invention are set forth in the independent claims. Further features are described in the dependent claims below.

DETAILED DESCRIPTION OF THE DRAWINGS

In reference initially toFIGS. 1 and 2of the drawings, there is shown a sectional view of an apparatus10for sealing a pipe12in accordance with a first embodiment of the present invention. The pipe12is used to transport fluid14under pressure, the pipe pressure being indicated by P. The pipe12includes a defect or penetration16through which fluid14under pressure can exit.

As shown in the figures, the apparatus10including a body in the form of a housing18coupled to the pipe12by a clamp member or strap20. The strap20is constructed from a steel cable and includes a split clamp, the clamp portions22,24being coupled around the pipe12and secured to the housing18by bolts26. The housing18further includes countersunk bores28which permit the ends of the clamp portions22,24to be inserted therethrough and secured to the housing18by the bolts26. As shown inFIG. 1, the clamp portions22,24are orientated such that they are tangential to the pipe12. This assists in reducing bending forces and permitting a smaller, lighter clamp20to be utilized. The bolts26are orientated such that they are in line with the clamp portions22,24. The portions22,24are secured to each other below the pipe12via a bolted connector29.

As shown most clearly inFIG. 2, the apparatus10further includes a piston30mounted in the housing18, the piston30engaging an offset31provided in the housing18such that the piston30and housing18define a chamber32. The piston30further includes an axial port34for providing fluid communication between the pipe12and the chamber32. The piston30has a first face36defining an actuating area A1and a second face38.

A seal member40in the form of a compression face seal is provided between the second face38of the piston30and the pipe12and is located over and/or around the defect or penetration16in the pipe12. The seal member40defines a second, sealed area A2on the second face38. Furthermore, a circumferential sliding seal element42is provided between the piston30and housing18to prevent loss of fluid14therearound.

In use, fluid14is directed from the pipe12through the axial port34to the chamber32, the pipe pressure P acting on the actuating area A1of the piston30resulting in a force F1on the piston30. The retained fluid pressure P within the pipe12provides a force F2acting against seal energization, this force F2corresponding to the pressure P within the pipe20multiplied by the area A2. As the actuating area A1of the first face36is greater than the second, sealed area A2, the force F1maintaining energization of the seal member40will be greater than the force F2acting against energization of the seal member40.

It will be recognized that the net fluid pressure force on the piston will be substantially equivalent to the pipe pressure P multiplied by a factor equal to A2/A1. Thus, the piston30is adapted to be urged or translated relative to the housing18to urge the seal member40to maintain sealing engagement with the pipe12. As such, fluid loss from the defect or penetration16may be reduced or eliminated.

Referring now toFIGS. 3 and 4of the drawings, there is shown sectional views of an apparatus110for sealing a pipe112in accordance with a second embodiment of the present invention, in which like components are indicated by like numerals incremented by 100.

In reference toFIG. 3, the apparatus110includes a branch or tee connection144coupled to a housing118. The connection144also includes a bore or port146which, when coupled to the housing118sees the same fluid pressure P as fluid114in the pipe112.

The apparatus110includes two seal members, a first seal member140and a secondary seal member148. The first seal member140is a bi-directional seal, the seal member140permitting a seal to be retained when the seal member140is exposed to pressure on either side of the seal. The second seal member148is also a bi-directional seal, though a uni-directional seal may be used. The first and second seal members140,148define an annulus150therebetween, the annulus being in fluid communication with a test port152provided in the piston130. The provision of the second seal member148and test port152permits pressure to be inserted into the annulus150to test the integrity of the seal or seals. The provision of a second seal member148also provides a fallback should the first seal member140fail.

The piston130is further provided with circumferential first and second sliding seal elements142,154on an outer face of the piston130in order to provide sealing around the test port152. Insertion of pressure through the test port152will also permit monitoring of the seal elements142,154.

In reference now toFIG. 4of the drawings, operation of the apparatus110is described.

Fluid114from the pipe112is transported through the piston130via the axial port134to the chamber132. The retained pipe pressure P acts on the actuating area A1of the piston130resulting in a force F1(shown by the downward arrows inFIG. 4). The pipe pressure P also results in a force F2on the second, sealed area A2, (shown by the upward arrows inFIG. 4).

As described above in respect of the first embodiment, the area A1is greater than the area A2such that the net force acting on the piston130urges and/or translates the piston130relative to the housing118to urge one or both of the seal members140,148to maintain sealing engagement with the pipe112.

As shown inFIG. 4, the housing118includes a port156which can be used to access the test port152of the housing118such that the pressure integrity between the first and second seal members140,148can be monitored, where necessary. The seal elements142,154are spaced so as to always encompass the housing port156over the stroke of the piston130.

It will be clear to those of skill in the art that various modifications and improvements may be made to the above-described embodiment without departing from the present invention.

For example, the apparatus may be utilized where there is an existing penetration in a pipe and the apparatus is utilized to seal the penetration. Alternatively, or in addition, the apparatus may be utilized to provide sealing engagement prior to an intervention into the pipe through a connection, for example, to permit a branch or tee connection to be coupled to the pipe.