GB2085385A - Marine tether anchoring device - Google Patents

Abstract

A marine tether 1 has a hollow segmented spring collet 2 that may be expanded to engage a shoulder 4 on the inner surface of a sleeve 5 by raising a plug 6 from a release position 8 to a locking position 7. The sleeve 5 is held at its upper end in an anchoring chamber 9 by latching arms 10 that engage grooves 11 in the upper surface of chamber 9 to prevent the sleeve 5 from being pulled out. Bags 12 of reinforced rubber material when full of water urge the arms 10 into the locking position but when evacuated draw the arms 10 away from the grooves 11 to provide a secondary release for the marine tether which may be withdrawn with the sleeve 5 from the anchoring chamber 9. <IMAGE>

Description

SPECIFICATION Marine tether anchoring device The invention relates to marine tether anchoring devices.

Various methods are known for fixing tethers of drilling platforms, and the like, in position and it is an object of the present invention to provide an improved marine tether anchoring device which can be released and re-established if necessary and as require.

In U.K. Application 8029947 there has been described a releasable marine tether connection in which a plug 7 is moved between two positions for providing a primary connection by expanding a segmented collet against the inside surface of an anchoring chamber. In Figure 4 slidable sleeves 21 and 24 provide a secondary connection for use if there is a mal-function and the primary connection becomes jammed. The present invention relates to a tether connection where a single sleeve provides a secondary connection.

According to the invention there is provided a marine tether anchoring device in which there is provided a sleeve for extending into an anchoring chamber to provide a tether anchoring connection there within, in which, there is arranged a releasable connection between the sleeve and the anchoring chamber adjacent the uppermost end of the chamber.

A marine tether connection will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a sectional view of the connection; and Figures 2 and 3 are sectional views of part of the connection.

Referring to the drawings, in Figure 1 a marine tether 1 is provided with a hollow segmented spring collet 2 which extends from the tether 1 with its outer surface adjacent its extreme end extending at 3 to engage a shoulder 4 on the inner surface of a sleeve 5. A locking plug 6 movable upwards and downwards within the collet 2 between positions shown at 7 or 8 to secure or release respectively the collet 2 within the sleeve 5. The sleeve 5 extends upwards to adjacent the uppermost end of an anchoring chamber 9 and has attached thereto twelve latching arms 10 (two of which are shown). The arms 10 engage grooves 11 in the upper surface of the chamber 9 to prevent the sleeve 5 from being pulled out of the chamber 9.

In Figure 2, the latching arms 10 are shown in a locked position and are held in or urged into that position by inflating bags 12 with fluid under pressure. In Figure 3 the latching arms 10 are shown in their released position and are held or urged there by evacuating the bags 12. The bags 12 are made of reinforced rubber material and conveniently one bag is provided for each latching arm.

In Figure 3, a hydraulic jack 13 is shown which may be used if any bag is punctured or becomes detached from its respective arm 10. The jack 13 can then be used to force the arm 10 into the released position.

In use, the tether connection 1 and sleeve 5 are lowered into the anchoring chamber 9 with the plug 6 in position 8. The bags 12 may be inflated at least to some extent during insertion or inflated once the arms 10 are below the grooves 11 to thereafter prevent the sleeve 5 being pulled out of the anchoring chamber 9. The plug 6 is then raised, by hydraulic or other means, to position 7 so that the collet 2 expands to urge the surface 3 against the surface 4. The tether connection is then fully secured to the anchoring chamber 9.

As a primary releasing action, tension is removed from the tether connection and the plug removed to position 8. Reapplication of tension to the tether connection forces the collet 2 out of the sleeve 5. If this fails to release the tether connection due to mal-function of the plug 6 or the collet 2 otherwise remains locked in the sleeve 5, the tension is again removed and the bags evacuated to draw the arms 10 away from the grooves 11. This releases the sleeve 5, as a secondary release action, from the chamber 9 to allow the tether to be withdrawn, with the sleeve 5, from the chamber 9.

Thus, the described connection provides two connections to ensure release of the tether even if one connection fails to be released or mal-functions.

It will be noted that the bags 12 may be filled with water before the tether connection is lowered towards and into the anchoring chamber 9. Normally, this provides sufficient biassing of the arms towards the grooves 11 during insertion into the anchoring chamber 9 to cause the arms 10 to lock into the grooves 11. In other words no extra inflation of the bags 12 is required once the tether connection has been prepared, at the quay side for example, for lowering towards the anchoring chamber 9.

1. A marine tether anchoring device in which there is provided a sleeve for extending into an anchoring chamber to provide a tether anchoring connection there within, in which there is arranged a releasable connection between the sleeve and the anchoring chamber adjacent the uppermost end of the chamber.

2. A marine tether according to Claim 1, in which said releasable connection comprises latching means operated by inflating or deflating resilient bag means connected to the latching means.

3. A marine tether according to Claim 2, in which there are a plurality of latching means distributed around said sleeve each being provided with respective bag means.

4. A marine tether according to Claim 2 or 3, in which said latching means is arranged to be operable by mechanical jacking means.

5. A marine tether substantially as herein described with reference to the accompanying drawings.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Marine tether anchoring device The invention relates to marine tether anchoring devices. Various methods are known for fixing tethers of drilling platforms, and the like, in position and it is an object of the present invention to provide an improved marine tether anchoring device which can be released and re-established if necessary and as require. In U.K. Application 8029947 there has been described a releasable marine tether connection in which a plug 7 is moved between two positions for providing a primary connection by expanding a segmented collet against the inside surface of an anchoring chamber. In Figure 4 slidable sleeves 21 and 24 provide a secondary connection for use if there is a mal-function and the primary connection becomes jammed. The present invention relates to a tether connection where a single sleeve provides a secondary connection. According to the invention there is provided a marine tether anchoring device in which there is provided a sleeve for extending into an anchoring chamber to provide a tether anchoring connection there within, in which, there is arranged a releasable connection between the sleeve and the anchoring chamber adjacent the uppermost end of the chamber. A marine tether connection will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a sectional view of the connection; and Figures 2 and 3 are sectional views of part of the connection. Referring to the drawings, in Figure 1 a marine tether 1 is provided with a hollow segmented spring collet 2 which extends from the tether 1 with its outer surface adjacent its extreme end extending at 3 to engage a shoulder 4 on the inner surface of a sleeve 5. A locking plug 6 movable upwards and downwards within the collet 2 between positions shown at 7 or 8 to secure or release respectively the collet 2 within the sleeve 5. The sleeve 5 extends upwards to adjacent the uppermost end of an anchoring chamber 9 and has attached thereto twelve latching arms 10 (two of which are shown). The arms 10 engage grooves 11 in the upper surface of the chamber 9 to prevent the sleeve 5 from being pulled out of the chamber 9. In Figure 2, the latching arms 10 are shown in a locked position and are held in or urged into that position by inflating bags 12 with fluid under pressure. In Figure 3 the latching arms 10 are shown in their released position and are held or urged there by evacuating the bags 12. The bags 12 are made of reinforced rubber material and conveniently one bag is provided for each latching arm. In Figure 3, a hydraulic jack 13 is shown which may be used if any bag is punctured or becomes detached from its respective arm 10. The jack 13 can then be used to force the arm 10 into the released position. In use, the tether connection 1 and sleeve 5 are lowered into the anchoring chamber 9 with the plug 6 in position 8. The bags 12 may be inflated at least to some extent during insertion or inflated once the arms 10 are below the grooves 11 to thereafter prevent the sleeve 5 being pulled out of the anchoring chamber 9. The plug 6 is then raised, by hydraulic or other means, to position 7 so that the collet 2 expands to urge the surface 3 against the surface 4. The tether connection is then fully secured to the anchoring chamber 9. As a primary releasing action, tension is removed from the tether connection and the plug removed to position 8. Reapplication of tension to the tether connection forces the collet 2 out of the sleeve 5. If this fails to release the tether connection due to mal-function of the plug 6 or the collet 2 otherwise remains locked in the sleeve 5, the tension is again removed and the bags evacuated to draw the arms 10 away from the grooves 11. This releases the sleeve 5, as a secondary release action, from the chamber 9 to allow the tether to be withdrawn, with the sleeve 5, from the chamber 9. Thus, the described connection provides two connections to ensure release of the tether even if one connection fails to be released or mal-functions. It will be noted that the bags 12 may be filled with water before the tether connection is lowered towards and into the anchoring chamber 9. Normally, this provides sufficient biassing of the arms towards the grooves 11 during insertion into the anchoring chamber 9 to cause the arms 10 to lock into the grooves 11. In other words no extra inflation of the bags 12 is required once the tether connection has been prepared, at the quay side for example, for lowering towards the anchoring chamber 9. CLAIMS

1. A marine tether anchoring device in which there is provided a sleeve for extending into an anchoring chamber to provide a tether anchoring connection there within, in which there is arranged a releasable connection between the sleeve and the anchoring chamber adjacent the uppermost end of the chamber.

2. A marine tether according to Claim 1, in which said releasable connection comprises latching means operated by inflating or deflating resilient bag means connected to the latching means.

3. A marine tether according to Claim 2, in which there are a plurality of latching means distributed around said sleeve each being provided with respective bag means.

4. A marine tether according to Claim 2 or 3, in which said latching means is arranged to be operable by mechanical jacking means.

5. A marine tether substantially as herein described with reference to the accompanying drawings.