GB2188999A

GB2188999A - Cable tube sealing device

Info

Publication number: GB2188999A
Application number: GB08708307A
Authority: GB
Inventors: Brigt Lokke Friis
Original assignee: Standard Telefon OG Kabelfabrik AS
Current assignee: Nexans Norway AS
Priority date: 1986-04-11
Filing date: 1987-04-07
Publication date: 1987-10-14
Anticipated expiration: 2007-04-07
Also published as: NO861416L; NO158908B; GB2188999B; NO158908C; GB8708307D0

Abstract

For sealing off an elongated body such as a cable at its entrance into apparatus, in particular at the lower horizontal end of an offshore J-tube, a sealing device is provided which comprises a bellmouth (1) having two or more door members eg (4, 5) which can be closed around the cable and clamped by bolts (13) to compress a gasket (10). At least one door member is hinged and one door member may be fixed. <IMAGE>

Description

SPECIFICATION Cable tube sealing device The -present invention relates to sealing off an elongated body, such as a cable, at its entrance into apparatus, in particular into the lower horizontal portion of an offshore J-tube.

A J-tube is one having a lower horizontal portion to receive the end of a cable on the sea bed, the cable end passing round a curve into the vertical riser part of the tube.

In some cases it is desirable, after a cable has been installed within a J-tube, that the sea water surrounding the cable within the Jtube be deoxydized to prevent or reduce corrosion. In order to neutralize the sea water in the tube inhibiting agents are added to the water. A problem arises, however, due to difficulties in obtaining a full seal between the cable surface and the tube walls. If the seal is poor the external sea water will enter and contaminate the inhibited sea water within the tube.

A main object of this invention is to make an efficient full seal at the entrance of the Jtube.

According to the invention in its broadest aspect there is provided a sealing device for sealing off an elongated body, such as a cable or pipe at its entrance into an aperture of apparatus, such as an offshore J-tube, characterized in that the device comprises at least two members which are arranged to be pressed against each other, against a circumference of the elongated body and against the aperture of the apparatus.

With this invention there is obtained an efficient sealing device which may be installed before entering the cable end into the J-tube.

The device is easily operated to seal off the cable surface against the tube entrance after the cable has been installed.

Embodiments of the invention will now be described by way of example in conjunction with the drawings, wherein: Figure 1 to 3 illustrate three views of a sealing device, and Figure 4 shows details of a swallow-tail gasket.

Fig. 1 gives a horizontal view of a J-tube seal and shows a bellmouth 1 mounted on the flange 2 of a J-tube 3. The bellmouth has two members 4, 5 which are mounted on hinges 6, 7. The two members 4, 5 can be opened like a door made in two halves. This is indicated by the out-swung door half 4. The hinged door halves form part of the bellmouth 1 and will be installed together with the bellmouth prior to the cable laying. These items will be fabricated from corrosion-resistant steel or the like.

Between a flange 8 on the bellmouth and the door flange surfaces there is arranged an O-ring seal 9 or the like. A sealing 10 between the two door halves 4, 5 is a seal (or gasket) which will be installed in a groove of so-called swallow-tail shape. This is shown in Fig. 4.

The sealing 11 against the cable 12 is also shown in Fig. 1. The material of the gasket 15 is of a soft rubber (compatible with sea water and inhibitor). After the two door halves 4, 5 have been closed and tightened with bolts 13 and all the flange bolts 14 are tightened, the gasket 15 is compressed by means of a gland 16 and bolts 17. All bolt heads should be of same dimension to make the installation easy for a diver. This work may also be done by means of a remote controlled vehicle.

Fig. 2 gives a side view and Fig. 3 gives a front view of the device.

The bellmouth 1 can be equipped with a valve (not shown) for injection of the inhibitor.

Pressure tests can be carried out on shore by use of two sets flanged together.

The entrance 18 to the bellmouth 1 is as shown somewhat displaced, so that the cable 12 is free to be moved about during insertion and when finally installed it will rest on the lower wall 19 of the horizontal J-tube.

Fig. 4 shows details of the gasket 10 which provides a seal between the two halves of the door. It is intended that the door 5 having the swallow tail groove 20 with the special gasket should be closed first. Thereafter the door 4 is closed to make a tight fit with the gasket 10. After tightening the bolts 13, Fig. 3, the flange bolts 14 should be tightened. Care must be taken to make a good connection between the gasket 10 and the O-ring 9 arranged in a groove 21.

It should be understood that the number and arrangement of O-ring and/or gaskets may be varied. There may also as an alternative to having two hinged doors, be used only one hinged door while the other is fixed. Still another alternative is to have the bellmouth aperture divided into more than two hinged doors.

Whereas it is important to prevent sea water from entering the J-tube, care should be taken to keep the cable itself sealed against longitudinal flow or migration of water in its outer layers, and also within the cable core if it is not fitted with one or more impervious sheaths.

1. A sealing device for sealing off an elongated body, such as a cable or pipe (12), at its entrance into an aperture of apparatus, such as an offshore J-tube (3), characterized in that the device comprises at least two memberts (4, 5) which are arranged to be pressed against each other, against a circumference of the elongated body (12) and against the aperture (8) of the apparatus.

2. A sealing device according to claim 1,

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Cable tube sealing device The -present invention relates to sealing off an elongated body, such as a cable, at its entrance into apparatus, in particular into the lower horizontal portion of an offshore J-tube. A J-tube is one having a lower horizontal portion to receive the end of a cable on the sea bed, the cable end passing round a curve into the vertical riser part of the tube. In some cases it is desirable, after a cable has been installed within a J-tube, that the sea water surrounding the cable within the Jtube be deoxydized to prevent or reduce corrosion. In order to neutralize the sea water in the tube inhibiting agents are added to the water. A problem arises, however, due to difficulties in obtaining a full seal between the cable surface and the tube walls. If the seal is poor the external sea water will enter and contaminate the inhibited sea water within the tube. A main object of this invention is to make an efficient full seal at the entrance of the Jtube. According to the invention in its broadest aspect there is provided a sealing device for sealing off an elongated body, such as a cable or pipe at its entrance into an aperture of apparatus, such as an offshore J-tube, characterized in that the device comprises at least two members which are arranged to be pressed against each other, against a circumference of the elongated body and against the aperture of the apparatus. With this invention there is obtained an efficient sealing device which may be installed before entering the cable end into the J-tube. The device is easily operated to seal off the cable surface against the tube entrance after the cable has been installed. Embodiments of the invention will now be described by way of example in conjunction with the drawings, wherein: Figure 1 to 3 illustrate three views of a sealing device, and Figure 4 shows details of a swallow-tail gasket. Fig. 1 gives a horizontal view of a J-tube seal and shows a bellmouth 1 mounted on the flange 2 of a J-tube 3. The bellmouth has two members 4, 5 which are mounted on hinges 6, 7. The two members 4, 5 can be opened like a door made in two halves. This is indicated by the out-swung door half 4. The hinged door halves form part of the bellmouth 1 and will be installed together with the bellmouth prior to the cable laying. These items will be fabricated from corrosion-resistant steel or the like. Between a flange 8 on the bellmouth and the door flange surfaces there is arranged an O-ring seal 9 or the like. A sealing 10 between the two door halves 4, 5 is a seal (or gasket) which will be installed in a groove of so-called swallow-tail shape. This is shown in Fig. 4. The sealing 11 against the cable 12 is also shown in Fig. 1. The material of the gasket 15 is of a soft rubber (compatible with sea water and inhibitor). After the two door halves 4, 5 have been closed and tightened with bolts 13 and all the flange bolts 14 are tightened, the gasket 15 is compressed by means of a gland 16 and bolts 17. All bolt heads should be of same dimension to make the installation easy for a diver. This work may also be done by means of a remote controlled vehicle. Fig. 2 gives a side view and Fig. 3 gives a front view of the device. The bellmouth 1 can be equipped with a valve (not shown) for injection of the inhibitor. Pressure tests can be carried out on shore by use of two sets flanged together. The entrance 18 to the bellmouth 1 is as shown somewhat displaced, so that the cable 12 is free to be moved about during insertion and when finally installed it will rest on the lower wall 19 of the horizontal J-tube. Fig. 4 shows details of the gasket 10 which provides a seal between the two halves of the door. It is intended that the door 5 having the swallow tail groove 20 with the special gasket should be closed first. Thereafter the door 4 is closed to make a tight fit with the gasket 10. After tightening the bolts 13, Fig. 3, the flange bolts 14 should be tightened. Care must be taken to make a good connection between the gasket 10 and the O-ring 9 arranged in a groove 21. It should be understood that the number and arrangement of O-ring and/or gaskets may be varied. There may also as an alternative to having two hinged doors, be used only one hinged door while the other is fixed. Still another alternative is to have the bellmouth aperture divided into more than two hinged doors. Whereas it is important to prevent sea water from entering the J-tube, care should be taken to keep the cable itself sealed against longitudinal flow or migration of water in its outer layers, and also within the cable core if it is not fitted with one or more impervious sheaths. CLAIMS

2. A sealing device according to claim 1, characterized in that at least one of the sealing members (4, 5) is hinged to the apparatus.

3. A sealing device according to claim 1 or 2, characterized in that the members 4, 5 are provided with gasket means such as O-rings (9), swallow-tail rings (10) or the like.

4. A sealing device substantially as described with reference to the accompanying drawings.