GB2210135A - A method of connecting to, repairing and/or strengthening a structural component - Google Patents

Abstract

A method of connecting to, repairing and/or strengthening a structural component (30) includes the steps of: rigidly connecting, for example, collars (31) in contact with the structural component (30) by welding studs (33) (Fig. 4 not shown) to the collars (31) and the structural component (30); forming a space (35) between, for example, a sleeve (34) and the collars (31); and inserting into the space (35) a material which subsequently sets, cures or solidifies. <IMAGE>

Description

A METHOD OF CONNECTING TO, REPAIRING AND/OR STRENGTHENING A STRUCTURAL COMPONENT This invention relates to methods of connecting to, repairing and/or strengthening 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 occasion need in situ repair and/or strengthening and/or additional attachments must be provided for the connection of structural or other components. One way of effecting connection to, repair and/or strengthening of components has been to use a grouted sleeve such as that illustrated in Figure 1. A pipe 11 may be an existing part of a structure, pipeline or conductor or may be a new component forming part of a repair and/or strengthening system. A sleeve 12 surrounds the pipe 11 with an annular space 13 therebetween.The surface of the sleeve 1 2 opposed to the pipe 11 and/or the pipe 11 may have welded shear connectors arranged as axially spaced apart hoops 10,14 in the form of steel bars attached by welding to the sleeve or pipe, or in the form of beads formed by weld deposition. Alternatively the hoops 10 and/or 14 of bar or weld deposit may be arranged in helical formation on either the pipe 11 and/or sleeve 12.

The sleeve may be composed of more than one segment, joined together in-situ by bolted flange(s) 15.

The ability to separate the sleeve into a plurality of site assembled components eases the installation of the sleeve, particularly around existing structural members.

Grout (not shown) is inserted in the annular space 13 to complete the repair.

In the context of this specification the term "grout" means any material capable of flowing into the available space and which sets, cures or solidifies into a contiguous solid form. The grout may, for example, be cementitious or an epoxy resin material.

The purpose of the hoops 10,14 is to increase the load transfer capacity per unit contact area between the grout and each of the pipe 11 and the sleeve 13.

The disadvantage of the type of grouted sleeve shown in Figure 1 is that the welding necessary to attach the hoops or weld beads is technically and economically impractical when the part of the pipe 11 to be repaired or strengthened is underwater.

In an attempt to overcome this disadvantage, a stressed clamp as illustrated in Figure 2 has in the past been adopted. This stressed clamp consists of two saddles 20,21 which have half-cylindrical parts 22,23 respectively facing a structural component, such as a cylindrical pipe 24 to be connected to, repaired or strengthened. The saddles 20,21 are assembled around the pipe 24 by means of a plurality of bolts 25 leaving an annular space 26 between the pipe and the parts 22,23. This annular space is then filled with grout (not shown) which, wen set, cured or solidified, is stressed by tightening the bolts 25. The stress thus placed on the grout increases the load transfer capacity per unit area between the grout and each of the pipe 2 and the saddles 20,21.Alternatively the grout may be omitted and the clamp relies on steel to steel, or other pre-arranged surface contact, plus the additional external bolt ioads to increase the load carrying capacity of the interface between the saddles 20,21 of the clamp and the pipe 24.

This type of stressed clamp has the disadvantage that the bolts 25 have to be inspected periodically and this is a time consuming and consequently expensive operation when the stressed clamp is located underwater.

Moreover, there is the disadvantage that the stressed clamp is relatively heavy and, when used underwater, attracts significant extra hydrodynamic forces because of its non-streamline configuration.

The present invention, therefore, seeks to provide a method of connecting to, repairing and/or strengthening a structural component which does not require the use of relatively expensive welding techniques or maintenance subsequent to installation.

Although the present invention is primarily directed to any 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 method of connecting to, repairing and/or strengthening a structural component including the steps of: rigidly connecting load transmitting means to the structural component to be connected to, repaired and/or strengthened by welding or otherwise attaching a plurality of studs to the load transmitting means and the structural component; forming a space between a connecting, repairing and/or strengthening ember and the load transmitting means; and inserting in said space a material which subsequently sets, cures or solidifies.

In one embodiment the load transmitting means comprises a plurality of spaced apart elongate members.

The structural component may be cylindrical and each elongate member may be arranged to extend circumferentially or axially.

In another embodiment the structural component may be flat or very slightly curved, and the load transmitting means may comprise a mesh.

The method may include the step of temporarily attaching the load transmitting means to the structural component prior to rigidly connecting the load transmitting means thereto.

Preferably the surface of the connecting, repairing and/or strengthening member opposed to the load transmitting means has one or more upstanding projections.

According to another non-restrictive aspect of the present invention there is provided a structural component when connected to, repaired and/or strengthened by a method according to the present invention.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which: Figure 1 illustrates one known form of grouted sleeve for connecting to, repairing and/or strengthening a structural component; Figure 2 illustrates a known stressed clamp used for connecting to, repairing and/or strengthening a structural component; Figure 3 illustrates one embodiment of a method according to the present invention for connecting to, repairing and/or strengthening a structural component; Figure 4 is a cross-section taken on the line 3-3 of part of the structural component shown in Figure 3; and Figures 5 and 6 illustrate other embodiments of methods according to the present invention for connecting to, repairing and/or strengthening a structural component.

Referring first to Figures 3 and 4 there is illustrated one embodiment of a method according to the present invention for connecting to, repairing and/or strengthening a structural component, such as, for example, a pipe 30. Initially elongate bars made of metal, e.g. steel, aluminium, or a plastics material, e.g. a high density polymer formed into a plurality of collars 31 are located on the pipe 30 at axially spaced apart intervals. Each of the collars has a plurality of spaced apart apertures 32 around its circumference. The collars are located by temporary locating means (not shown), e.g. self-lockino belts.A stud 33 (Figure 4) is located in each aperture and is then welded, by friction welding, drawn arc welding or other welding or joining technique both to the walls of the aperture and to the pipe 30 thereby rigidly connecting the collars 31 to the pipe. The welding to the walls of the aperture ensures satisfactory load transfer between the stud and the collar, and may be replaced by a close tolerance fit of the stud in the aperture. The temporary locating means may then be removed.

Next, a sleeve 34 which may be similar to the sleeve 12 of Figure 1, is placed to surround the pipe 30 with an annular space 35 therebetween. The surface of the sleeve 34 opposed to the pipe has a plurality of axially spaced apart hoops 36 welded thereto. These hoops may be similar to the hoops 14 of the grouted sleeve illustrated in Figure 1. As an alternative to the hoops 36, the opposed surface of the sleeve 34 may have other projections, e.g. an upstanding helical band welded thereto or upstanding annular or helical weld bead or beads.

Grout (not shown) is then inserted in the annular space 35. The collars 31, and to a lesser extent the studs 33 rigidly fixed to the pipe, together with the hoops 36 rigidly fixed to the sleeve 34, cooperate with the grout when set, cured or solidified so as to increase axially directed load transfer capacity per unit contact area between the grout and each of the pipe 30 and the sleeve 34.

Figure 5 illustrates another method according to the present invention for connecting to, repairing and/or strengthening a structural member. Like parts in Figures 3, 4 and 5 have been designated by the same reference numerals and will not be further described.

The structure of Figure 5 is designed to increase the load transfer capacity per unit contact area between the grout and each of the pipe 30 and the sleeve 34 in a predominantly circumferential plane. A flexible mesh consists of a plurality of spaced apart parallel relatively thin ties 40 and a plurality of substantially parallel relatively thick bars 41 and is placed around the pipe 30 so that the ties 40 extend circumferentially and the bars 41 extend axially. The ties are then joined by suitable means (not shown) to retain temporarily the mesh in place. The ties 40 can be of metal spot welded or rivetted to the bars 41 or of plastics material fixed by adhesive. Each of the bars has a plurality of apertures along its length, these apertures being similar to the apertures 32 of Figure 3.

Studs 33 are then welded by a suitable method such as disclosed in relation to Figures 3 and 4 to the walls of respective apertures and, through the ties 40, to the pipe 30. Thus the bars 41 are rigidly connected to the pipe by the studs. The ties 40, which have acted as temporary locating and securing means, then serve no significant purpose. Under certain circumstances, the ties 40 may be dispensed with, the bars 41 being welded directly to the pipe 30 by means of the studs 33.

Once the bars 41 have been fixed to the pipe by means of the studs 33, the sleeve 34 is put in place and grout (not shown) inserted into the annular space 35, as described in relation to Figures 3 and 4. The bars 41 may be made of metal, e.g. steel or aluminium.

Figure 6 illustrates another method according to the present invention for connecting to, repairing and/or strengthening a structural member 50 which may, for example, be flat or have a relatively large radius of curvature. A fabric or mesh 51 has apertures therein for receiving studs 52. These studs are welded or attached by other suitable means to the structural member 50 rigidly connecting the mesh thereto. A repair plate 53 is then located by suitable means so that there is a space between itself and the mesh 51. Grout 54 is then inserted into this space.

It will be appreciated that the mesh 51 will increase the load transfer capacity per unit contact area between the grout and each of the member 50 and the repair plate 53 in more than one direction. The mesh 51 may be made of, for example, metal, e.g. steel or aluminiums or plastics material, e.g. a high density polymer, as long as it can be welded or attached by other suitable means to the studs 52.

The methods according to the present invention and described above have the advantage that they can be performed rapidly underwater by non-specialist divers.

Without restricting or limiting the use of other methods of welding or attachment, the most suitable method of attaching the studs to the collars, bars or mesh fabric is regarded to be friction welding. Friction welding underwater is easier to perform, less expensive and does not require such a high degree of expertise on the part of the operator as, for example, other forms of welding.

The technique is not affected by underwater pressure and the metallurgical properties of the structural member are not significantly affected. Whilst primarily intended for underwater application it will be appreciated that methods according to the present invention are applicable above water e.g. on land especially in situations where welding must be minimised or avoided.

It has also been found that instead of using friction welding to connect the studs to the structural member drawn arc welding could also be employed to achieve the same advantages. Drawn arc welding would offer a faster method of attaching studs, at the cost of some losses in metallurgical properties in the parent structural component. Other welding or attachment techniques either currently available or possible future developments will provide alternative methods of attachment of studs, collars, bars and/or mesh fabric to the structural components.

Claims (9)

LA

1. A method of connecting to, repairing and/or strengthening a structural component including the steps of: rigidly connecting load transmitting means to the structural component to be connected to, repaired and/or strengthened by welding or otherwise attaching a plurality of studs to the load transmitting means and the structural component; forming a space between a connecting, repairing and/or strengthening member and the load transmitting means; and inserting in said space a material which subsequently sets, cures or solidifies.

2. A method as claimed in claim 1 in which the load transmitting means comprises a plurality of spaced apart elongate members.

3. A method as claimed in claim 2 in which the structural component is cylindrical and each elongate member is arranged to extend circumferentially or axially.

4. A method as claimed in claim 1 in which the structural component is flat or very slightly curved, and the load transmitting means comprises a mesh.

5. A method as claimed in any preceding claim including temporarily attaching the load transmitting means to the structural component prior to connecting rigidly the load transmitting means thereto.

6. A method as claimed in any preceding claim in which the surface of the connecting, repairing and/or strengthening member opposed to the load transmitting means has one or more upstanding projections.

7. A method as claimed in any preceding claim in which the studs are frictionally welded to the load transmitting means.

8. A method of connecting to, repairing and/or strengthening a structural component substantially as herein described with reference to Figures 3 to 6 of the accompanying drawings.

9. A structural component when connected to, repaired and/or strengthened by a method as claimed in any preceding claim.

9. A structural component when connected to, repaired and/or strengthened by a method as claimed in any preceding claim.

10. 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.

Amendments to the claims have been filed as follows Cubs 1. A method of connecting to, repairing and/or strengthening a structural component including the steps of: rigidly connecting load transmitting means in contact with a structural component to be connected to, repaired and/or strengthened by welding a plurality of studs to the load transmitting means and the structural component; forming a space between a connecting, repairing and/or strengthening member and the load transmitting means; and inserting in said space a material which subsequently sets, cures or solidifies.

2. A method as claimed in claim 1 in which the load transmitting means comprises a plurality of spaced apart elongate members.

3. A method as claimed in claim 2 in which the structural component is cylindrical and each elongate member is arranged to extend circumferentially or axially.

4. A method as claimed in claim 1 in which the structural component is flat or very slightly curved, and the load transmitting means comprises a mesh.

5. A method as claimed in any preceding claim including temporarily attaching the load transmitting means to the structural component prior to connecting rigidly the load transmitting means thereto.

6. -A method as claimed in any preceding claim in which the surface of the connecting, repairing and/or strengthening member opposed to the load transmitting means has one or more upstanding projections.

7. A method as claimed in any preceding claim in which the studs are frictionally welded to the load transmitting means.

8. A method of connecting to, repairing and/or strengthening a structural component substantially as herein described with reference to Figures 3 to 6 of the accompanying drawings.