A SEALI NG DEVI CE FOR A TUBI NG ARRANGEMENT

FIELD OFTHE INVENTION

The present invention relates to a device for providing sealing to a tubing arrangement of the kind having a cable or an inner tube arranged in an interior part thereof. The sealing device of the present invention is very suitable for use in offshore facilities, such as offshore wind turbines or oil rigs. More particularly, the present invention relates to a sealing device which can be removed or replaced, e.g. in order to gain access to the tubing arrangement, e.g. with the purpose of performing maintenance on a cable or an inner tube arranged in the interior part of the tubing arrangement or on the tubing arrangement itself.

BACKGROUND OFTHE INVENTION

In tubing arrangements for offshore facilities it is often desirable to be able to prevent sea water from entering the tubing arrangement, or from passing a specific point in the tubing arrangement. In particular, it may be desirable to prevent rush of sea water into such tubing arrangements. Attempts have previously been made to solve this problem.

US 6,003,873 discloses a method and a device for sealing the entrance of an elongated element into the lower end of an offshore tube. A plug-like device is arranged on the element, a predetermined length of the element is pulled into the tube, and the plug is fixed on the element surface at the bellmouth entrance of the tube. The outer diameter of the plug is somewhat smaller than the inner diameter of the tube. Expandable foam is injected to a space between the outer surface of the plug and the inner surface of the tube in order to substantially fill the space.

The sealing device disclosed in US 6,003,873 can only be mounted at a bellmouth of an offshore tube. Thus, it can not be used for providing sealing in any other position along the tube. Furthermore, it is not possible to remove or replace the sealing device, e.g. in case repair or maintenance of the tube is required. Finally, it is necessary to inject the expandable foam immediately after the elongated element (e.g. a cable) is positioned in the tube. This may be difficult to fulfil when the tubing is positioned at an offshore site.

US 5,765,834 discloses a sealing device for sealing off an elongated body, such as a cable, pipe or umbilical, at its entrance to an aperture of an apparatus, such as an offshore J-tube. The sealing device consists of two substantially identical parts or halves which are hinged together along an axis substantially parallel to the axis of the elongated body, each half comprising a centralizer part, a sealing part and tensioning parts. The tensioning parts are

capable of pressing the sealing parts into sealing contact against the elongated body, against the inner surface of the J-tube and against the centralizing means. The pressure means may consist of tensioning rods with nuts. By tightening the nuts, the seal is compressed and squeezed between the centralizer and the holding device.

The sealing device of US 5,765,834 is relatively complicated. Furthermore, it is necessary to operate the tensioning part after the elongate element has been positioned in the tube. In the case that the tube is arranged at an offshore facility, this has the consequence that the use of divers is required for this task. This adds considerably to the installation costs. Finally, the sealing device of US 5,765,834 can only be positioned at the entrance opening of the tube, since positioning the sealing device in another position would prevent operation of the tensioning parts.

SUMMARY OF THE I NVENTI ON

It is, thus, an object of the invention to provide a sealing device for a tubing arrangement, the sealing device being adapted to be positioned at various positions of the tubing arrangement.

It is a further object of the invention to provide a sealing device for a tubing arrangement, where the sealing device can be removed or replaced without destruction of the tubing arrangement.

It is an even further object of the invention to provide a sealing device for a tubing arrangement, the sealing device being adapted to be arranged on the tubing arrangement substantially without the aid of divers.

It is an even further object of the invention to provide a method of sealing a tubing arrangement for an offshore facility, where the method can be performed substantially without the aid of divers.

According to a first aspect of the invention the above and other objects are fulfilled by providing a sealing device for a tubing arrangement having a cable or an inner tube arranged in an interior part thereof, the sealing device comprising:

- a substantially rigid housing, said housing being mountable on or forming part of the tubing arrangement in such a manner that an interior part of the housing communicates with the interior part of the tubing arrangement, and

- a flexible plug part arranged in the interior part of the housing, said flexible plug part comprising an inlet opening connectable to a grout source,

wherein the flexible plug part is adapted to expand, thereby providing sealing between the housing and a cable or inner tube arranged in the interior part of the tubing arrangement, when grout material is supplied to the flexible plug part via the inlet opening.

In the present context the term 'sealing device' should be interpreted to mean a device which is capable of sealing off the tubing arrangement or part of the tubing arrangement, preferably in such a manner that water is prevented from passing the sealing device.

The tubing arrangement may advantageously be of a kind which is suitable for use in an offshore facility, such as an offshore wind turbine or an oil rig. However, the sealing device of the invention may also be used in other kinds of tubing arrangements for use on shore.

The sealing device comprises a substantially rigid housing. This should be interpreted to mean that one or more outer walls delimit the sealing device, thereby forming a housing. The housing is preferably substantially closed. Furthermore, the walls of the housing are substantially rigid, i.e. they are capable of maintaining their shape, or at least capable of restoring their shape if the shape is changed as a consequence of a force being applied.

The sealing device comprises a flexible plug part arranged in an interior part of the housing. In the present context the term 'flexible' should be interpreted to mean that the plug part comprises one or more walls being capable of changing shape, preferably being expandable. The one or more walls may, e.g., be made from a resilient material, such as a rubber material. As an alternative, the flexible plug could be made from another suitable material, such as canvas, a resilient type of plastic material, cloth, etc.

The flexible plug part comprises an inlet opening connected to a grout source. Accordingly, grout material can be supplied to the flexible plug part via the inlet opening. Due to the flexibility of the flexible plug part, supplying grout material in this manner will cause the flexible plug part to expand, or at least adopt the shape of the interior part of the housing. This will be explained further below. The grout material preferably comprises cement and/or concrete. It could, e.g., be a cement/bentonite mixture, such as a mixture made from approximately 50 kg cement, 10 litres of bentonite and 50 litres of water. However, other types of cement, concrete, mortar or mixtures thereof could be used. As an alternative, a curable plastic material may be used. In this case the plastic material should be adapted to cure when positioned under water. Preferably, the grout material is of a kind which cures sufficiently slow to allow the flexible plug part to expand and adopt the shape of the interior

parts of the housing and the tubing arrangement, and sufficiently fast to ensure a sealing effect within a reasonable time interval.

The housing is mounted on or forms part of the tubing arrangement in such a manner that an interior part of the housing communicates with the interior part of the tubing arrangement. Thus, at least one passage exists between the interior part of the housing and the interior part of the tubing arrangement. Accordingly, when grout material is supplied to the flexible plug part, and the flexible plug part thereby expands as described above, it is allowed to expand into the interior part of the tubing arrangement. Due to the flexibility of the flexible plug part it will expand in such a manner that it adapts to outer walls of the housing and/or of the tubing arrangement in the vicinity of the flexible plug part, as well as to a cable or an inner tube arranged in the interior part of the tubing arrangement. Thus, when the supplying of grout material to the flexible plug part has been completed, the flexible plug part abuts firmly against such walls and the cable/inner tube, preferably filling out the entire space between outer walls and the cable/inner tube. Accordingly, water can not pass the position of the sealing device inside the tubing arrangement, and a sealing effect is thereby obtained.

The housing may form part of the tubing arrangement. In this case it may simply be a part of the tube where the flexible plug part is arranged. The housing may define an increased cross sectional diameter of the tube. As an alternative, the housing may be a separate part which can be mounted on the tubing arrangement in a detachable or non-detachable manner. In this case, the housing may comprise two flange parts attached to the tubing arrangement and a detachable intermediate part, e.g. formed by two or more subparts, arranged between and attached to the flange parts.

As described above, the sealing effect is obtained in a very easy manner. Furthermore, the sealing device may be positioned at any desired position along the tubing arrangement, i.e. it is not limited to being positioned at an opening. It should be noted, however, that the tubing arrangement must be designed to have the sealing device arranged at a desired position, since the tubing arrangement should be shaped in such a manner that the sealing device fits into the tubing arrangement at the desired position.

A further advantage of the sealing device of the present invention is that the grout source may be positioned in any suitable position, such as above the water level if the tubing arrangement is installed on an offshore facility. Accordingly, the grout material can be supplied, and the sealing effect thereby obtained, without the requirement of divers. It is even possible to mount the sealing device on the tubing arrangement before the tubing arrangement is mounted on the offshore facility, preferably during manufacture of the tubing arrangement on shore. The tubing arrangement, along with the sealing device, is then

transported to the site of the offshore facility and mounted thereon. At a later point in time, preferably after a cable or inner tube has been positioned in the interior part of the tubing arrangement, the grout material can be supplied, and the sealing effect thereby obtained. During the procedure described above, use of divers is only necessary to the extent that it is necessary for mounting the tubing arrangement on the offshore facility, i.e. to the extent that it would be necessary if a sealing device was not present. Furthermore, it is not necessary to supply the grout material immediately after the sealing device has been mounted at the offshore site, possibly along with the entire tubing arrangement. Thereby this can be done whenever the weather allows so, and when other circumstances are appropriate.

The housing may comprise at least two detachable housing parts. Thereby the sealing device can easily be mounted on the tubing arrangement. Furthermore, in the case that it is necessary to perform maintenance on the tubing arrangement or to a cable or inner tube arranged in the interior thereof, including replacement of one or more parts, it is easy to dismantle the sealing device from the tubing arrangement, since it is merely necessary to detach the housing parts from each other and remove the flexible plug part along with the grout material. Thus, the sealing device can, in this case, be dismantled from the tubing arrangement regardless of its position along the tubing arrangement. When the required maintenance has been performed, the sealing device can be replaced by another, substantially identical, sealing device, and the sealing effect is, thus, re-established. It may even be possible to refit the original sealing device. However, this would probably require a replacement of the flexible plug part, since the grout material previously supplied has most likely cured. In order to ensure that the tubing arrangement is not discontinued at the position of the sealing device during a replacement as described above, part of the sealing device may remain on the tubing arrangement. Such a part of the sealing device may, e.g., be in the form of one or more stiffening ribs or the like, and/or it may form an integral part of the tubing arrangement. It should, however, be ensured that the flexible plug part of a replacement sealing device is allowed to expand as described previously in order to ensure that a proper sealing effect is obtained.

The housing may comprise exactly two detachable housing parts. Alternatively, it may comprise more than two detachable housing parts, such as three, four, five, six, etc. detachable housing parts. The housing parts may have at least substantially identical size and/or shape, or the size and/or shape of the housing parts may vary.

The flexible plug part may comprise at least one hollow diaphragm, e.g. made from a rubber material, such as a natural rubber material, e.g. natural latex rubber, or a synthetic rubber material, e.g. butyl rubber. As mentioned above, canvas, plastic materials or cloth could be used instead of rubber. As an alternative, the flexible plug part may be in the form of at least

one bag or the like being able to expand/'inflate' when grout material is supplied as described above. The flexible plug part may comprise exactly one hollow diaphragm, or it may comprise two or more hollow diaphragms. This will be explained further below.

The tubing arrangement may be or comprise a J-tube. A J-tube is a tube having substantially the shape of a 'J', i.e. with a substantially straight part connected to a curved part, preferably arranged near an end of the tube. J-tubes are often used at offshore facilities, such as offshore wind turbines or oil rigs. The tubes may be used for guiding wires, cables or supply tubes to/from the offshore facility. For instance, cables may be used for supplying power to the offshore facility and/or for leading power produced by an offshore wind turbine to a site on shore.

Thus, the tubing arrangement may preferably be adapted to be applied in an offshore facility. However, the tubing arrangement may, alternatively, be applied in a facility positioned on shore.

The flexible plug part may comprise at least two detachable plug portions. The detachable plug portions may advantageously be in the form of hollow diaphragms. According to this embodiment it is very easy to remove or replace the sealing device, since the plug portions can readily be removed when the housing has been removed, regardless of the position of the sealing device along the tubing arrangement. Furthermore, a new sealing device can easily be mounted on the tubing arrangement. It should be noted that it will normally be necessary to provide a grout connection to each of the plug portions. When grout material is supplied to the plug portions, these will expand in such a manner that sealing is further provided between the plug portions.

The flexible plug part may comprise exactly two detachable plug portions. Alternatively, it may comprise more than two detachable plug portions, such as three, four, five, six, etc. detachable plug portions. The plug portions may have at least substantially identical size and/or shape, or the size and/or shape of the plug portions may vary. Preferably, the housing as well as the flexible plug part is formed by detachable parts, and in this case each of the plug portions may advantageously be sized and shaped in accordance with the size and shape of a corresponding housing part.

According to a second aspect of the invention the above and other objects are fulfilled by providing a tubing arrangement comprising a sealing device according to the first aspect of the invention. As mentioned above, the tubing arrangement may be or comprise a J-tube.

According to a third aspect of the invention the above and other objects are fulfilled by providing a method of sealing a tubing arrangement, the method comprising the steps of:

- providing a sealing device according to the first aspect of the invention,

- mounting the sealing device on the tubing arrangement, and

- supplying grout material to the flexible plug part of the sealing device.

It should be noted that a skilled person would readily recognise that any feature described in combination with the first aspect of the invention could also be combined with the second and third aspects of the invention, any feature described in combination with the second aspect of the invention could also be combined with the first and third aspects of the invention, and any feature described in combination with the third aspect of the invention could also be combined with the first and second aspects of the invention.

As described above, the step of mounting the sealing device on the tubing arrangement is performed in such a manner that it is ensured that an interior part of the housing of the sealing part communicates with an interior part of the tubing arrangement. Thus, when grout material is supplied to the flexible plug part, the flexible plug part expands as described above, thereby providing a sealing effect.

As mentioned above, the step of mounting the sealing device on the tubing arrangement and the step of supplying grout material to the flexible plug part may be temporally spaced apart, thereby providing the possibility of supplying the grout material at a time where weather conditions etc. are favourable, and providing the possibility of mounting the sealing device prior to transporting the tubing arrangement to an offshore site.

The method may further comprise the step of replacing the sealing device by another at least substantially identical sealing device. This may, e.g., be desirable in the case that maintenance of the tubing arrangement and/or of a cable or inner tube arranged in the interior part of the tubing arrangement is required. This has already been described above. Alternatively, the sealing device itself may be broken or faulty, a replacement thereby being necessary.

As described above, a substantial time interval may be allowed to lapse between performing the step of mounting the sealing device and performing the step of supplying grout material.

BRI EF DESCRI PTI ON OF THE DRAWI NGS

The invention will now be described in further detail with reference to the accompanying drawings in which

Figs. 1a and 1b are cross sectional views in two perpendicular directions of a sealing device according to an embodiment of the invention, prior to supplying grout material, and

Figs.2a and 2b are cross sectional views of the sealing device of Figs. 1a and 1b after grout material has been supplied.

DETAILED DESCRIPTION OFTHE DRAWINGS

Figs. 1 a and 1 b are cross sectional views of a sealing device 1 according to an embodiment of the invention. The sealing device 1 is mounted on a tubing arrangement 2 having a cable 3 arranged in an interior part thereof. In Fig. 1a the cross section is taken in a direction which is substantially perpendicular to a lengthwise direction of the tubing arrangement 2. In Fig. 1 b the cross section is along line B-B shown in Fig. 1 a.

The sealing device 1 comprises a housing 4 and a flexible plug part 5 arranged in an interior part of the housing 4. It is clear from Fig. 1b that the interior part of the housing 4 communicates with the interior part of the tubing arrangement 2, and that it is therefore possible for the flexible plug part 5 to expand into the interior part of the tubing arrangement 2. This will be explained further below with reference to Figs. 2a and 2b. I n Figs. 1 a and 1 b the flexible plug part 5 is empty. Therefore it does not extend beyond the interior part of the housing 4, and a passage 6 is defined between the flexible plug part 5 and the cable 3. This passage 6 allows the cable 3 to move along the lengthwise direction of the tubing arrangement 2. This is, e.g., necessary during installation of the cable 3 in the tubing arrangement 2, where the cable 3 is typically pulled through the tubing arrangement 2.

The flexible plug part 5 is connected to a grout source (not shown) via an inlet opening (not shown). When the cable 3 has been properly installed in the interior part of the tubing arrangement 2, grout material can be supplied to the flexible plug part 5 from the grout source, via the inlet opening. The flexible plug part 5 is made from a flexible or resilient material, and supplying grout material in this manner therefore causes the flexible plug part 5 to expand.

Figs.2a and 2b are cross sectional views of the sealing device 1 of Figs. 1a and 1b, and illustrating this situation. Fig.2a corresponds to Fig. 1a and Fig.2b corresponds to Fig. 1b.

Thus, in Figs.2a and 2b grout material 7 has been supplied to the flexible plug part 5, and this has caused the flexible plug part 5 to expand into the interior part of the tubing arrangement 2. It can be seen that the flexible plug part 5 abuts the cable 3, and that the passage shown in Figs. 1a and 1b is no longer present. Once the grout material 7 has been allowed to cure, the flexible plug part 5 will stay in this position. Accordingly, it is not possible for water to pass the position of the sealing device 1 , and a sealing effect has thereby been provided. Furthermore, the fact that the flexible plug part 5 abuts the cable 3 provides the possibility of using the sealing device 1 for reducing load caused by a freely hanging cable 3, thereby reducing wear on the cable 3 as well as on parts carrying the cable 3.