Field of the invention

This invention relates to a clamp assembly for external reinforcement and/or repair of a tubular element, such as a pipe.

Background of the invention

Pipelines are subjected to internal and external corrosion, excessive ground forces and other factors in their surrounding environment which can result in holes, cracks and other structural damage through which leakage of contents can occur. Repair clamps are commonly provided for assembly around the outside circumference of a damaged pipe. Typically, when applied, the clamp forms a fully circumferential envelope enclosing the damaged area of pipe. This envelope may be formed either from a rigid body comprising perimeter sealing elements, or a flexible, typically metal body such as in stainless steel, mild steel, or a malleable iron.

For high-pressure applications, e.g. on pipes for transport of hydrocarbons (petroleum, natural gas, etc.) a commonly known repair clamp comprises two clamp halves of a cast metal, clamped together by bolts and having sealing elements at both ends. As these clamps are exposed to a corrosive environment, materials having a corresponding corrosion-resistant properties are required. Due to the high pressures these clamps must be able to withstand, the clamp halves must be of a material having a sufficient strength and rigidity. Therefore, clamps of this type are heavy and require substantial manpower and/or other support structures during assembly and disassembly. Furthermore, due to their size and weight, these known clamps require a large area to be cleared around the damaged pipe in order to expose the damaged area and allow freedom of movement for the operator to clean the pipe surface and assemble the clamp. There is also a considerable lead time on the delivery of these cast clamp halves. Such delay will increase the cost of a repair operation if it becomes necessary to fit clamp halves of a different dimension than that initially envisaged, which is not uncommon. It may even be necessary to reduce or shut down production until the damaged pipe has been repaired.

The present invention aims to provide a repair clamp which will substantially overcome the aforementioned problems and allow more convenient fitting of a repair clamp whilst not compromising on structural or sealing integrity. Summary of the invention

The invention is set forth and characterized in the independent claim 1 , while the dependent claims describe other characteristics of the invention. 10 000009

One purpose of the invention is to provide a clamp assembly which is more versatile and easier to use than the known pipe clamps. The invented clamp assembly allows fabrication using standard elements, thereby making it versatile and adaptive to several clamp configurations. It is a modular construction, having individually replaceable elements, and the various elements may provide different materials properties.

The invention comprises a clamp assembly for external reinforcement and/or repair of a tubular element, comprising first and second modular clamping elements configured for connection around the tubular element and, when in use, together enveloping an outer circumferential surface of a portion of the tubular element; said clamping elements being releasably interconnected by securing and tightening means, characterised by each clamping element further comprising a respective plurality of support elements connected to respective housing sections, each said housing section configured for connection around a circumferential segment of the tubular element and, when in use, together enveloping an outer circumferential surface of a portion of the tubular element.

In one embodiment of the invention, the support elements within each clamping element are juxtaposed to each other in a tubular element longitudinal direction. Spacers may be arranged between juxtaposed support elements. Preferably, the support elements within each clamping element are interconnected by support element connectors, preferably extending through the support elements in a tubular element longitudinal direction.

In one embodiment, the securing and tightening means comprise a plurality of tensioning bolts extending between the clamping elements and being releasably secured to the clamping elements by means of connection elements, preferably configured as longitudinal elements having openings for the tensioning bolts and being arranged in a tubular element longitudinal direction.

In one embodiment, the support elements within each clamping element are juxtaposed to each other with an interval in a tubular element longitudinal direction which is greater than the width of the securing and tightening means extending between the clamping elements. The securing and tightening means are preferably arranged between juxtaposed support elements and preferably extend in a direction substantially transverse to the tubular element longitudinal direction. The plurality of support elements may be connected to their respective housing sections by means of fasteners.

Seals are arranged in the region of both ends of the housing sections, between the housing sections and portions of said outer circumferential surface of the tubular element, whereby the region enclosed by the housing sections, the seals and the tubular element is sealed off. Also, longitudinal seals may be provided between the adjoining housing sections. In one embodiment, each support element has a plate shape and a recessed portion of a shape which matches an outside shape of the housing section to which it is connected.

In one embodiment, each support element is connected to the respective housing section in an orientation which is substantially perpendicular to the tubular element longitudinal direction.

The support elements material may comprise ordinary steel or alloyed steel.

The housing sections may comprise an oxidation and corrosion resistant material which retains its strength over a wide temperature range material, such as Inconel . In one embodiment, the support element connectors extend through the spacers.

The invention also comprises an arrangement of clamps for external reinforcement and/or repair of a tubular element, where a plurality of clamp assemblies according to the invention are connected in an end-to-end relationship along a length of the tubular element, preferably by connecting respective abutting ends of housing sections.

Brief description of the drawings

Figure 1 is a perspective view of an embodiment of the clamp assembly according to the invention, in an assembled state;

Figure 2 is a perspective view of the clamp assembly illustrated by figure 1, in an assembled state on a pipe;

Figure3 is a perspective view of the clamp assembly illustrated by figures 1 and 2, partly assembled into two clamp sections, e.g. in a configuration prior to installation on a pipe;

Figure 4 is a partly exploded perspective view of the clamp assembly illustrated by figures 1 to 3.

Detailed description of an embodiment

Referring first to figure 3, the illustrated embodiment of the clamp according to the invention comprises first and second clamp sections 1 , 2, which essentially are similar. As shown in the other figures, the clamp sections I ₅ 2 are releasably connected to each other by a plurality of tensioning bolts 6 extending through holes 16, 26 in clamping bars 14, 24 connected to respective clamp sections.

In operation, in order to repair a damaged portion of a pipe, the clamp sections are positioned opposite each other in the desired location on the pipe, seals 42a,b are fitted within and in the region of both ends of the clamp liner sections 10, 20, as is illustrated in figure 3. In the illustrated embodiment, longitudinal seals 49 are provided in suitable grooves in each of the liner sections, as shown in figure 3. The region within the between the packers within the liner sections is thus sealed off when the clamp sections are assembled onto a pipe.

The first clamp section 1 comprises a first semi-circular liner section 10 which is configured for assembly onto the pipe and fitted with first packer sections 42a and first end covers 44a at both ends. The second clamp section 2 comprises a second semi-circular liner section 20 which is configured for assembly onto the pipe and fitted with second packer sections 42b and second end covers 44b at both ends. Inside each liner section, ridges 46 may be provided as support elements for the packers 42a,b. Each clamp section I ₅ 2 furthermore comprise a plurality of support cradles 12, 22 connected to respective liner sections 10, 20. For example, in the illustrated embodiment, five first support cradles 12 in the first clamp section 1 are connected to the first liner section 10, for example by means of screws 7 through holes 8 in the liner section 10 and into threaded holes 9 in each of the first cradles 12. Also, five second support cradles 22 in the second clamp section 2 are connected to the second liner section 20 in a similar manner.

The cradles 12, 22 are connected to the respective liner section 10, 20 in a juxtaposed configuration, transversely to the pipe longitudinal axis and at an interval determined by spacers 5. In each clamp section, the cradles 12, 22 are interconnected by means of connection bolts 4, extending through suitable holes 25 in the cradles, and also through the spacers 5. Figure 4, which is a partly exploded view, shows the spacers 5 assembled onto the connection bolts 4.

As illustrated by figures 3 and 4, the cradles 12, 22 are preferably plate elements and have a shape facing the respective liner sections 10, 20 which is complementary to an outside shape of the liner section 10, 20. In this way, when the tensioning bolts 6 are tightened against the clamping bars 14, 24, the compression loads are transferred to the liner sections in a uniform and controlled manner.

In general, the support cradles 12, 22 are arranged substantially perpendicular to the respective liner section 10, 20, i.e. substantially perpendicular to a longitudinal axis A (see figure 2), generally coincident with a pipe longitudinal axis. Also, the tensioning bolts 6 are arranged generally transverse of the longitudinal axis A, while the connection bolts 4 extend generally parallel with the longitudinal axis A.

The support cradles 12, 22 within each clamp section 1, 2 are juxtaposed to each other with an interval in a direction along the axis A which is greater than the width of the tensioning bolts 6 extending between the clamp sections.

Referring now to figure 1 and figure 2, showing the clamp in an assembled state, by itself (figure 1) and fitted on a pipe (figure 2), it is clear how the tensioning bolts 6 each have a length which at least exceeding the outside diameter of the pipe. In the illustrated embodiment, the lengths of the tensioning bolts exceed the distance constituted by two opposing support cradles 12, 22. Specifically, the tensioning bolts extend through the elongate clamping bars 14, 24 on the outside of each clamp section, and each clamping bar spans all the support cradles 12, 22 on the respective connection element. Thus, when the tensioning bolts 6 are tightened against the clamping bars 14, 24, the compression loads are transferred to the liner sections via the support cradles in a uniform and controlled manner.

One advantage with the present invention is the versatility during operation. For example, only the first and second liner sections 10, 20 need to be of an oxidation and corrosion resistant material which retains its strength over a wide temperature range material. The support cradles 12, 22 need no such stringent material specifications, as they are not exposed to the harsh environment as are the liner sections (For example if the clamp assembly is used on a pipe containing H ₂ S). Therefore, while the liner sections may be made of an oxidation and corrosion resistant material (e.g. Inconel ^® ), the support cradles may be made of virtually any material readily available (e.g. ordinary steel or alloyed steel), as long as that material fulfils the requirements for compressive strength and rigidity.

With the clamp assembly according to the invention, in-field modifications may easily be made. Also multiple clamp assemblies may be joined in an end-to-end relationship along an extended length of the tubular element.