GB2207483A

GB2207483A - Clamp for pipe or tube

Info

Publication number: GB2207483A
Application number: GB08817193A
Authority: GB
Inventors: Ian Edward Tebbett
Original assignee: WIMPEY GROUP SERVICES Ltd
Current assignee: WIMPEY GROUP SERVICES Ltd
Priority date: 1987-07-23
Filing date: 1988-07-19
Publication date: 1989-02-01
Anticipated expiration: 2008-07-19
Also published as: GB8717423D0; GB2207483B; GB8817193D0

Abstract

A clamp, for use in the repair and/or strengthening of a member or members or other structural component(s), comprise two rigid parts (41,42) each having engaging portions (43,44) at its free edges so that abutting engaging portions of the two parts inter-engage to form a collar (45) to surround the member or members or other structural components to be repaired and/or strengthened with an annular space (49) there-between. The arrangement is such that material filling the annular space sets, cures or solidifies thereby to prevent the parts of the collar from being dis-engaged. <IMAGE>

Description

A CLAMP AND A METHOD OF USING TEE SAME FOR REPAIRING AND/OR STRENGTEENING A MEMBER OR MEMBERS OR OTHER STRUCTURAL COMPONENTS This invention relates to clamps and to methods of using the same for repairing and/or strengthening members or other structural components.

Offshore steel platforms, for example those used in the North Sea for oil exploration and recovery, and pipelines and conductors associated therewith, on occasions need repair. One way of effecting repair in the past has been to use a bolted clamp such as that illustrated in Figure 1(a). This bolted clamp consists of two identical half-cylindrical parts 10,11 each having flanges 12,13 on their axially directed edges.

The two parts 10,11 are placed around, for example, a pipe 14 to be repaired with the flanges 12,13 abutting.

The abutting flanges 12,13 are then bolted together (the bolts are not shown in Figure 1(a)) so that the parts 10,11 form a unitary collar surrounding the pipe 14 but spaced therefrom by an annular space 15. Grout 16 is then inserted into the annular space 15 to complete the repair. In the context of the specification the term "grout" means any material capable of flowing into the available space and which subsequently sets, cures or solidifies into a contiguous solid form. The disadvantage of this type of clamp is that, because the parts 10,11 must first to be bolted together to form the unitary collar, no stressing of the grout 16 by the clamp is possible.

In an attempt to overcome this problem, a stressed clamp, as illustrated in Figure 1(b) has been developed.

This stressed clamp consists of two half cylindrical parts 20,21 which are separated by flexible seals 22,23 to form a cylindrical collar which is spaced from, for example, a pipe 24 to be repaired, by an annular space 25. Two saddles 26,27 are located on diametrically opposite sides of the collar~and connected together by bolts 28 (only part of one of which is shown in Figure 1(b)). Grout 29 is inserted into the annular space 25 and, after the grout has cured, the bolts 28 are then tightened to stress the grout and effect the repair of the pipe. This type of clamp has the disadvantage that it is relatively heavy and, when used under water, attracts significant extra hydrodynamic forces because of its non-streamline configuration.

To reduce the hydrodynamic forces generated by this type of clamp a welded clamp as shown in Figure 1(c) has been used. This consists of two half cylindrical parts 30,31 which are welded together leaving an annular space 32 between the resulting collar and, for example, a pipe 33 to be repaired. The welding usually takes place above the water level and so that when the repair is to be effected underwater the collar must be slid down the pipe to the position where the repair is to be effected and then grout 34 is inserted in the annular space 32. The resulting collar is relatively lightweight and has a smooth exterior profile to minimise extra hydrodynamic forces on the pipe, but has the disadvantage that fabrication above the water level is inconvenient and may not be practical in view of, for example, other members connected to the pipe to be repaired.Alternatively, sub-sea welding could be used. This is extremely expensive to effect and quality of welding may be poor.

The present invention, therefore, seeks to provide a clamp which (a) does not require fixing bolts, (b) is relatively lightweight, (c) does not increase significantly hydrodynamic forces or waveloads on the part to be repaired and, (d) eliminates in situ welding.

Although the present invention is primarily directed to vny novel integer or step, or combination of integers or steps, herein disclosed and/or as shown in the accompanying drawings, nevertheless, according to one particular aspect of the present invention to which, however, the invention is in no way restricted, there is provided a clamp for use in the repair and/or strengthening of a member or members or other structural component(s) comprising two rigid parts each having engaging portions at its free edges so that abutting engaging portions of the two parts inter-engage to form a collar to surround the member or members or other structural components to be repaired and/or strengthened with an annular space therebetween, the arrangement being such that material filling the annular space sets, cures or solidifies thereby to prevent the parts of the collar from being disengaged.

The clamp may include means adjacent the engaging portions to reduce or prevent separation of said parts due to induced bending moments in the clamp when in use.

Said means may comprise a bolted, strapped or interlocking extension of the engaging portions.

Preferably the engaging portions of each part comprise a tooth at one end and a detent at the other end, the tooth of one part inter-engaging with the detent of the other part.

Means may be provided preventing the parts of the collar from being dis-engaged before the annular space is filled with said material. Said means may comprise at least one bolt passing through one of the parts adjacent to the inter-engaging portions and screwed in the other of the parts.

In the preferred embodiment each of the parts is a half cylinder. Thus the length of the collar may exceed its diameter.

According to another non-restrictive aspect of the present invention there is provided a method of repairing and/or strengthening a member or members or other structural component(s) comprising placing around the member or members or other structural component(s) two parts each having engaging portions at its free edges so that abutting adjacent portions of the two parts inter-engage to form a collar, there being an annular space between the collar and the member or members or other structural component(s) to be repaired and/or strengthened, and filling said annular space with material which when set, cured or solidified prevents the parts of the collar from being dis-engaged.

The method may include preventing the parts of the collar from being dis-engaged before the annular space is filled with said material.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which: Figure 1, consisting of Figures 1(a), 1(b) and 1(c), illustrates three known clamps used for the repair of offshore steel platforms; Figure 2 shows, in cross section, a clamp according to the present invention in situ; Figure 3 shows, on an enlarged scale, part of the clamp of Figure 2; Figure 4, consisting of Figures 4(a), 4(b), and 4(c) illustrates the use of the clamp of Figure 2 for effecting repair and/or strengthening of a conductor or pipe or tubular member; and Figure 5 is similar to Figure 2 showing a modification of the clamp of Figure 2.

Referring first to Figures 1 and 2 there is shown a clamp 40 according to the present invention consisting of two elongate half-cylindrical parts 41,42. At one axially directed free edge of each part 41,42 is a tooth 43 and at the other free edge there is a detent 44.

When the parts 41,42 are placed together they form a cylindrical collar 45, the teeth 43 and the detents 44 inter-engage, the tooth of one part engaging with the detent of the other part and vice versa. Temporary holding bolts 46 are then passed through holes 47 (Figure 4) in the end of each part 41,42 adjacent a tooth 43 and screwed into tapped blind holes 48 adjacent the detent 44 in each of the parts. An annular space 49 is thus formed between the collar 45 and a pipe or conductor or tubular member 50 to be repaired and/or strengthened. Grout 51 is then inserted into the annular space 49 to effect the repair and/or strengthening.

The use of the clamp 40 for effecting repair of the pipe or conductor 50 will be described in greater detail with reference to Figure 4. As shown in Figure 4(a) the part 41 is positioned so that the end adjacent the detent 45 touches the pipe or conductor or tubular member 50. The part 42 is then moved towards the portion 41 (Figure 4(b)) so that the detent 44 passes through the gap between the pipe or conductor or tubular member 50 and the tooth 43 of the part 41. Respective teeth and detents of the parts 41,42 are then moved towards each other so that they inter-engage and the bolts 46 are then put in place to maintain this relationship of the parts 41,42. This completes the collar 45 so that the grout 51 can then be inserted into the annular space 49.Once the grout has set the bolts may be removed since the grout prevents relative movement between the parts 41,42 and maintains the collar 45 unitary.

It will be appreciated that a clamp according to the present invention and illustrated in Figures 2 to 4, has the advantage of a smooth exterior profile with the result that hydrodynamic forces caused by wave action on the pipe or conductor or tubular member 50 that has been repaired and/or strengthened are minimised. In the completed clamp there are no bolts to increase the wave action and the absence of bolts or saddles as in clamp of Figure 1(b) reduces weight. Moreover, the two parts 41,42 of the collar are maintained together by the grout 51 and so no in situ welding is required. As shown in Figure 3, the teeth 43 and detents 44 are welded to the remainder of the parts 41,42, but that welding takes place during manufacture of the parts not in situ.

It will be appreciated that whilst the parts 41,42 are shown as half cylindrical, they may have any desired cross section which preferably is complimentary to that of the member or members or other structural component(s) to be repaired and/or strengthened.

It is not essential to have two bolts 46 for temporarily holding the parts 41,42 together since one bolt may be sufficient in certain circumstances.

Moreover, other means of temporarily holding the parts 41,42 together may be used, e.g. a strap or straps surrounding the collar 45 or saddles bolted together as in the clamp shown in Figure 1(b). The collar preferably has an axial length that exceeds its diameter. If the collar has a relatively long axial length then the bolts 46 or other means of temporarily holding the parts 41,42 together may be provided at axially spaced apart points along the length of the collar.

Figure 5 shows a modification of the clamp shown in Figures 1 and 2. In Figure 5, the tooth 43 of each part 41,42 is provided with a hook 60 which engages with a projection 61 on the other part. The inter-locking of the hooks 60 with the projections 61 reduces or prevents separation of the teeth 43 and detents 44 due to induced bending moments within the clamp during use.

In another modification (not shown) in place of the inter-locking hooks 60 and projections 61, an extension of the tooth 43 of each part 41,42 is bolted to the other part. In a yet further modification, two straps (not shown) are connected, e.g by bolts between the parts 41, 42 shown in Figure 3, with each strap extending over a respective one of the teeth 43.

Claims

1. A clamp for use in the repair and/or strengthening of a member or members or other structural component(s) comprising two rigid parts each having engaging portions at its free edges so that abutting engaging portions of the two parts inter-engage to form a collar to surround the member or members or other structural components to be repaired and/or strengthened with an annular space therebetween, the arrangement being such that material filling the annular space sets, cures or solidifies thereby to prevent the parts of the collar from being dis-engaged.

2. A clamp as claimed in claim 1 in which the engaging portions of each part comprise a tooth at one end and a detent at the other end, the tooth of one part inter-engaging with the detent of the other part.

3. A clamp as claimed in claim 1 or 2 in which means are provided for preventing the parts of the collar from being dis-engaged before the annular space is filled with said material.

4. A clamp as claimed in claim 3 in which said means comprises at least one bolt passing through one of the parts adjacent to the inter-engaging portions and screwed in the other of the parts.

5. A clamp as claimed in any preceding claim including means adjacent the engaging portions to reduce or prevent separation of said parts due to induced bending moments in the clamp when in use.

6. A clamp as claimed in claim 5 in which said means comprise a bolted, strapped or inter-locking extension of the engaging portions.

7. A clamp as claimed in any preceding claim in which each of the parts is a half cylinder.

8. A clamp as claimed in claim 7 in which the length of the collar exceeds its diameter.

9. A clamp for use in the repair and/or strengthening of a member or members or other structural component(s) substantially as herein described with reference to and as shown in Figures 2 to 4 of the accompanying drawings.

10. A method of repairing and/or strengthening a member or members or other structural component(s) comprising placing around the member or members or other structural component(s) two rigid parts each having engaging portions at its free edges so that abutting adjacent portions of the two parts interengage to form a collar, there being an annular space between the collar and the member or members or other structural component(s) to be repaired and/or strengthened, and filling said annular space with material which when set, cured or solidified prevents the parts of the collar from being dis-engaged.

11. A method as claimed in claim 10 including preventing the parts of the collar from being disengaged before the annular space is filled with said material.

12. A method as claimed in claim 10 and substantially as herein described with reference to Figures 2 to 4 of the accompanying drawings.

13. Any novel integer or step, or combination of integers or steps, hereinbefore described and/or as shown in the accompanying drawings, irrespective of whether the present claim is within the scope of or relates to the same, or a different, invention from that of the preceding claims.