GB2349414A

GB2349414A - Clamped assembly for sub-sea use

Info

Publication number: GB2349414A
Application number: GB9910149A
Authority: GB
Inventors: Ewan George Lawrence Reid
Original assignee: Balmoral Group Ltd
Current assignee: Balmoral Group Ltd
Priority date: 1999-04-30
Filing date: 1999-04-30
Publication date: 2000-11-01
Also published as: GB9910149D0

Abstract

A clamped assembly for sub-sea use comprising a plurality of buoyant, negatively buoyant or insulating items 2,3 abutting at at least one joint face 10, the items being urged together by a plurality of tensioned clips extending over the joint, the clips comprising shoes received in steps 11 of the items. A tensioned strap 13a extends around the assembly over the clips.

Description

CLAMP, CLAMPED OBJECT AND METHOD OF CLAMPING This invention relates to a clamp, clamped object and method of clamping. More especially but not exclusively this relates to clamps for clamping buoyant or negatively buoyant objects onto other objects.

By way of example the invention may be used to clamp sinkers on to horizontal extending pipes or distributed buoyancy on flowlines rising through water. The invention may also be useful for clamping thermal insulation on to flowlines.

A problem with sub-sea engineering in general is the difficulty of access to installed systems which are of long life time for servicing.

Buoyancy is often clamped on to assemblies. The clamping components and those clamped undergo creep. Creep is a slow movement of the object in response to load. Thus a strap under load will be subject to an irreversible lengthening with time. Part of the problem can be overcome by selection of materials and pre-treatment but it can not be eliminated.

As a result of creep a clamp has to be designed to have adequate clamping force at the end of its service life. This can only be achieved by having a larger force exerted during earlier stages of the service life.

Large forces require, generally, heavy and/or expensive apparatus.

The invention seeks to provide a clamping arrangement less subject to or affecte by creep than hitherto.

According to the invention there is provided a clamped assembly comprising a plurality of items abutting it at least one joint face the items being urged together by a plurality of tensioned clips extending over the joint, the clips comprising shoes received in steps of the items.

According to the invention there is furie provided a method of clamping for sub-sea use, the method comprising the steps of a) providing a plurality of items to be clamped the items having steps formed in the periphery thereof, b) abutting the plurality of items together at a joint face, c) engaging a plurality of clips having shoes in the steps the clips extending over the joint face so as to urge the items together.

According to the invention there is further provided a clamp for clamping items use comprising a clip having a pair of shoes receivable in steps of the item.

Embodiments of the invention will be desired by way of nonlimiting example by reference to the accompanying figures of which: Figure 1 is a cross-section of an embodiment of the invention ; and Figure 2 is side elevation of a strap for use in the embodiment of Figure 1.

In Figure 1 the strap is shown fitted only to the right side of the module for clarity. Furthermore the steps, to be described hereinafter, on the left hand side are shown as a different shape to those on the right. This is optional and may not be preferred.

Buoyancy module 1 may comprise syntactic foam. It comprises in the illustrated embodiment first and second halves or shells 2,3 which may be identical. Recesses 4 of a half receive projections 5 of the other half. Cavities 6,7,8 are provided for flow lines and control lines. Close to the joint faces 9,10 of the half shells 2,3 are provided steps 11,12.

Straps 13 comprises a generally lightly constructed member 14 which may conveniently be of a corrosion resistant alloy such as a stainless steel, of titanium, or of Kevlar.

Buckles 15 can be provided with a spring tensioning arrangement 16 for example comprising disc springs. This spring tensioning arrangement maintains a low tension in a major portion 13a of the strap. This tension accommodates changes in size of the shells which may be caused by one or more of hydrostatic pressure creep and thermal expansion or contraction or other factors. Minor portion 13b of the strap is provided with a clip having shoes 17. The clip extends over the join line. Shoes 17 are in the illustrated embodiment received in the steps 11. Operative face 18 of the shoes 17 abuts a face 19 of the steps 12. When urged together by the strap tension the shoes urge faces of steps 12 together thereby urging the halves together. In some embodiments of the invention the faces are provided with co-operating dog-toothed portions.

Creep in the major portion of the strap is not of great significance. The tension in the portion intermediate the operative forces governs the clamping force. Because this distance is small the amount of load induced creep is small. Furthermore because the distance is small heavily built components of expensive materials can be used with relatively small weight and cost. For example a 54"riser has a circumference of about 4.32m. In accordance with the invention the faces may be about 5cm from the joint face. Since two clips are provided creep is experienced over about 20 cm (i. e. 5 cm for each of four locations) which is less than 5% of the distance subject to creep in prior art arrangements.

Generally speaking the shoes are attached to the strap but this is not essential. Where present the strap can be provided outside the shoes. The illustrated embodiment shows the strap passing through the shoe. This can be desirable because undesirable bending forces are less likely to be imposed on the shoe. It is not, however, essential. If desired the steps can be generally parallel. However in some embodiment of the inventionthe face can taper together toward the edge of the items. In this arrangement driving the clip onto the items urges the faces together. In some embodiments of the invention the steps can taper away from each other toward the edge of the items. This provides a degree of self locking. Where a strap (or straps) is provided the clip (or clips) may be secured to it. In some embodiments the clips are slidably movable in a first direction but not in a second direction. This allows for easy assembly. While described by reference to two segment items it will be apparent to the skilled that the invention has application to items with more components.

Claims

Claims 1. A clamped assembly for sub-sea use comprising a plurality bf buoyant, negatively buoyant or insulating items abutting at at least one joint face, the items being urged together by a plurality of tension clips extending over the joint, the clips comprising shoes received in steps of the items.
2. A clamped assembly as claimed in claim 1 wherein a strap overlies the clips.
3. A clamped assembly as claimed in claim 2 wherein the strap is secured to the clips.
4. A clamped assembly as claimed in claim 2 or claim 3 wherein the strap is provided with a tensioning device.
5. A clamped assembly substantially as described herein.
6. A method of clamping buoyant, negatively buoyant or insulating items for sub-sea use, the method comprising the steps of a) providing a plurality of items to be clamped the items having steps formed in the periphery thereof, b) abutting the plurality of items together at a joint face, c) engaging a plurality of clips having shoes in the steps the clips extending over the joint face so as to urge the items together.
7. A method as claimed in claim 6 further comprising the step of d) overlying the clips with a strap.
8. A method as claimed in claim 6 wherein the clips are secured to a strap.
9. A method as claimed in claim 7 or claim 8 wherein the strap is provided with a tensioning device.
10. An insert retainer substantially as herein described and illustrated in the accompanying drawings.

10. A method as claimed in claim 9 wherein the tension device comprises a screw threaded fastener provided with disc washers.

11. A method of clamping substantially as described herein.

12. A clamp for clamping buoyant, negatively buoyant or insulating items for sub-sea use comprising a clip having a pair of shoes receivable in steps of the item.

13. A clamp as claimed in claim 12 carried on a strap.

14. A clamp as claimed in claim 13 wherein a plurality of clips are provided on the strap. 15. A clamp as claimed in claim 13 or claim 14 wherein means for adjusting the length of the strap are provided.

16. A clamp substantially as described herein.

Amendments to the claims have been filed as follows CLAIMS

1. A means of retaining one or more inserts plus loose documents inside a diary or other book comprising a stick-on container with two or more compartments each closed at two or three edges which can be attache inside a cover or to an internal page.

2. An insert retainer as claimed in Claim 1 which is approximately 7.5 x 15cm to fit in typical pocket diaries.

3. An insert retainer as claimed in Claim 1 made from a clear material such as plastic.

4. An insert retainer as claimed in Claim 1 where one or more compartments are subdivided to accommodate smaller items.

5. An insert retainer as claimed in Claim 1 where one or more compartments are closed at a third edge to ease access and to reduce the chance of items falling out 6. An insert retainer as claimed in Claim 5 where one or more compartments are closed at a third edge on alternate sides.

7. An insert retainer as claimed in Claim 1 where one surface is covered with adhesive protected by backing paper to prevent the container sticking to a surface before it is needed.

8. An insert retainer as claimed in Claim 7 where the backing paper is in two sections to allow one section to be presented and located first.

9. An insert retainer as claimed in Claim 7 where the adhesive allows the pocket to be detached and re-located.