METHOD AND ASSEMBLY FOR COVERING AN OBJECT

Abstract: A resilient girdle is used for holding a wraparound recoverable sleeve around the object. The girdle is provided with separating means for separating overlying layers of the wraparound sleeve, and the girdle is positioned so that the separating means separates the overlying layers.

Description: Method and Assembly for Covering an Object The present invention relates to a method and assembly for covering an object, the assembly comprising a wraparound sleeve, particularly a sleeve that is dimensionally recoverable, and a girdle for holding the sleeve in its wrapped configuration. The present invention also provides a new girdle for holding a wraparound sleeve closed. A dimensionally recoverable article is one whose dimensional configuration may be made to change when subjected to an appropriate treatment. Usually such articles recover towards an original shape from which they have previously been deformed but the term "recoverable", as used herein, is also applicable to an article which, on recovery, adopts a new configuration even if it has not previously been deformed. It is preferred to use sleeves that are recoverable by the action of heat. In their most common form, heat-recoverable sleeves comprise polymeric material exhibiting the property of elastic or plastic memory, as described in US 2027962, US 3086242, and US 3597372, for example. As is made clear in US 2027962, for example, the original dimensionally heat stable form may be a transient form in a continuous process in which, for example, an extruded tube is expanded while hot to a dimensionally heat-unstable form but, in other applications, a preferred dimensionally heat-unstable article is deformed to a dimensionally heat-unstable form in a separate state. Heat-recoverable articles based on fabrics are also known, and are described in GB A 2133639, GB A 2133740, GB A 2134334, GB A 2135632, GB a 2135836 and GB A 2139142, the disclosures of these documents are incorporated herein by reference. The method and assembly of the present invention may employ a fabric recoverable sleeve. Wraparound recoverable sleeves have the advantage over tubular sleeves that they can be installed around an object without having to gain access to an end of the object Known closures for wraparound sleeves include adhesives coated patches such as that disclosed in US 4200676, and the so called "rail and channel closure" disclosed in GB 1155470. It is also known from EP-A-0239377 (B126A EPC) to use a resilient girdle to maintain a wraparound recoverable sleeve in its wrapped configuration during recovery. That patent publication describes an assembly for covering an object the assembly comprising a wraparound recoverable sleeve and being characterised in that it also comprises a resilient girdle provided with means for fastening opposite edge regions thereof together, thereby enabling the girdle to hold the sleeve in its wrapped configuration during recovery. The girdle may remain in place after recovery. Alternatively, for example, where the recoverable sleeve, as is typical, is lined with an adhesive, eg a hot melt adhesive, which is activated on recovery and bonds and seals the sleeve to the object, the girdle may be removed after recovery. The present invention provides a modification to the invention described in EP-A-0239377 (B126A EPC), the entire disclosure of which is incorporated herein by reference. The present invention has significant advantages in particular applications. A first aspect of the present invention provides a method of covering an elongate object which comprises: (a) wrapping a wraparound recoverable sleeve around the object such that the outer longitudinal edge of the sleeve overlaps at least part of the underlying layer of the recoverable sleeve; and (b) wrapping a resilient girdle around the recoverable sleeve and fastening the girdle to itself to hold the recoverable sleeve in its wrapped configuration when the sleeve is recovered; characterised in that the girdle is provided with separating means for separating overlying layers of the wraparound recoverable sleeve, and the method comprises positioning said separating means relative to the recoverable sheet to separate the said overlying layers. A second aspect of the invention provides an assembly for covering an elongate object comprising: (a) a wraparound recoverable sleeve and (b) a resilient girdle which can be wrapped around the recoverable sleeve and fastened to itself to hold the recoverable sleeve in its wrapped configuration during recovery of the recoverable sleeve, characterised in that the girdle is provided with separating means for separating overlying layers of the wraparound recoverable sleeve. A third aspect of the invention provides a resilient girdle which can be wrapped around a wraparound recoverable sleeve and fastened to itself to hold the recoverable sleeve in its wrapped configuration during recovery of the sleeve, characterised in that the girdle is provided with separating means for separating overlying layers of the wraparound recoverable sleeve.. The present invention is particularly advantageous where it is desirable to separate adjacent layers of the recoverable sleeve around at least part of the circumference of the sleeve. One example where this occurs, according to a preferred embodiment according to the invention is an embodiment in which the sleeve itself is intrinsically heatable, rather than needing to be heated from an external heat source such as a gas torch, eg where the sleeve has an in built electrical heater, for example of the type described in EP-B-0245067 (B129 EPC). In such situations overlapping of the sleeve edges may result in overheating. For example, in the embodiments described in EP-B-0245067 (B129 EPC) a sleeve may be arranged to be multi- wrapped around an elongate object, and the heater may be designed, say to give the desired heat output for a two layer wrap of the recoverable sleeve. However this means that either the sleeve must be specifically selected for the size of the object to be enclosed, or, if the sleeve is not exactly the correct size, over at least part of the circumference of the wrapped object, there will be a single or a triple wrap of recoverable sleeve. This may lead to under- or over-heating. The present invention which provides means for separating layers of the sleeve can thus be used to provide that the desired number of wraps (say a double wrap,) of sleeve are adjacent each other arounα me entire circumference of the object enclosed, and any excess sleeve over that double wrap is separated from the adjacent wraps by the separating means on the girdle. For this application, at least the separating means of the girdle, and preferably the entire girdle, is formed from heat resistant material. Similar constructions can be used to produce any number of layers or part layers inside and outside of the separating means of the girdle. Preferably the separating means of the girdle is an opening in the girdle, through which the ends of the outer layer of the wrapped wraparound sleeve can be inserted. Thus the outer end of the wrapped sleeve can be inserted through the opening and thereby separated by the girdle from the underlying wrapped sleeve. The opening may be appropriately positioned for the desired recoverable sleeve and object to be used. Thus for inventory purposes a single size sleeve can be used to cover a variety of different sized objects by using a girdle in which the opening is appropriately positioned. One or more openings may be provided in the girdle. The opening in the girdle is preferably a rectangular slit extending generally parallel to the elongate object when the girdle is in its wrapped configuration. Alternatively, or in addition, the separating means of the girdle may comprise a flap extending, in the wrapped configuration within the sleeve. This is positioned in the method according to the invention beneath the outer end of the wrapped recoverable sleeve. The flap may be selected to be the appropriate length to underlie any excess outer wrapped length of sleeve which it is desired to separate from the inner sleeve wraps. Alternatively the flap may be cut to length in the field. In a particularly preferred embodiment the girdle comprises both an opening in the girdle and a separating flap, wherein the opening is provided towards one end of the girdle, and the flap is secured to the inner side of the girdle in the wrapped configuration at a position on the side of the opening opposite to the end of the girdle, and wherein the flap extends from that secured position beyond that said end of the girdle. In this case during installation the outer end of the wrapped sleeve is preferably inserted and extenαs tnrough the opening of the girdle, and the flap extends beneatn me window in a direction counter ratationary (in the wrapped configuration) to that of the outer end of the sleeve. In this way, the very end part of the outer end of the sleeve is separated from the inner wraps by having passed through the opening in the girdle, and a part of the sleeve further from the end of the sleeve is separated by the flap on the girdle. This embodiment is especially preferred since it enables two variables (the position of the opening and the flap length) to be adjusted to achieve the desired separation of layers. The recoverable sleeve is preferably provided on its inner surface with bonding means, eg an adhesive such as a hot melt adhesive, to bond it to the elongate object or in the case of multi-wrap to underlying layers of the wrapped sleeve. Thus after recovery of the sleeve, the girdle may be removed. Also, after recovery, the outer end of the sleeve which was separated from the other layers of the sleeve by the separating means of the girdle, may also be removed, for example by cutting. Preferably the girdle is provided with cooperating means so that it can be fastened to itself, the girdle may be fastened to itself by securing overlapping edges of it together by mating velcro strips. Other mechanical or adhesive means may also be used. The recoverable sleeve and /or the girdle may be provided with additional securing means whereby the girdle and recoverable sleeve are secured to each other before being wrapped around the elongate object. The invention is particularly advantageous since it means that different sizes of elongate objects can be covered with the same sleeve product. Also the length of the sleeve product is less critical. The present invention may be used for covering a variety of elongate objects, for example pipes and cables and pipe-joints and cable-joints. In one application it may be used to cover a joint between district heating pipes. Such pipes typically comprise an inner metal pipe and an outer thick insulation. Typically the insulation is removed to form a welded joint between the inner metal pipes, and then an oversize casing positioned around the joint, extending between the insulation on either side of the cut- Dack region. The recoverable sleeve of the present invention may be used to bridge the seed, between the oversize casing and the pipes on either side of the oversize casing. An embodiment of the invention will now be described wherein: Figure 1 is a schematic cross-sectional view of a prior art assembly for covering a pipe. Figure 2a and 2b are plan and side views of a girdle as used in an assembly according to the invention; and Figure 3 shows the girdle of Figure 2 used in an assembly according to the invention. Referring to the drawings, Figure 1 shows a prior art assembly according to EP 0245061 in which a heat recoverable sleeve 2 containing its own electrical heater (not shown), is multiply wrapped around a district heating pipe 4 comprising an inner steel pipe 6 and an insulating polyethylene foam 8. The sleeve is lined with hot melt adhesive (not shown). A resilient girdle 10 is wrapped around the wrapped sleeve 2 and opposite longitudinal edges of the girdle held together by mechanical means 12. The girdle 10 holds the sleeve 2 tightly around the pipe 4. Thus when the sleeve 2 is recovered by powering it electrically the girdle 10 urges the sleeve 2 downwardly onto the pipe 4 so ensuring a void free recovered sleeve 2. Over most of the circumference of the pipe 4 there is a double layer of wrapped sleeve 2. However over an arc "A" of the pipe there is a triple layer. This may cause overheating in that region. This is particularly disadvantageous in the case of covering district heating pipes, as shown, since the overheating may damage the polyurethane foam 8. While this could be avoided simply by correct selection of the length of sleeve 2, this means large inventories, especially where the sleeve 2 is electrically heated with its own electrical heater, the sleeve can not simply be cut to length in the field. Figures 2a and 2b show in plan and side view a girdle 14 which can be used according to the present invention in place of the plain girdle 10 of Figure 1. The girdle 14 comprises a heat resistant silicone resilient sheet 16 containing an opening in the form of a rectangular slit 18 extending across the girdle 14 in a position towards one end 20 of the girdle 14. A flap 22 comprising the same material as the girdle 14 is secured along a line 24 to one face of the girdle (the underside in the wrapped configuration). The securing line 24 extends parallel to slit 18, adjacent thereto, and on the opposite side of the slit 18 from end 20 of the girdle 14. The flap 22 extends beyond the end 20 of the girdle 14. Velcro strips 26 and 28 are provided on opposite ends of the girdle 14 to secure overlapping ends of the girdle 14 in the wrapped configuration. Figure 3 shows the girdle 14 of Figure 2 installed in place of the girdle 10 of Figure 1 around the pipe 4. The free end 30 of the sleeve 2 extends through the slit 18, and the flap 22 extends between part of the outer layer of wrapped sleeve 2 and the underlying layer. Thus over the arc of the circumference A, as over the remainder of the circumference of the pipe, there is only a double wrap of sleeve 2. Using this embodiment after recovery of sleeve 2, the girdle 14 can be removed and the part of the sleeve 2 from point marked B to the free end of the sleeve can be cut off.

Claims: CLAIMS 1. A method of covering an elongate object which comprises: (a) wrapping a wraparound recoverable sleeve around the object such that the outer longitudinal edge of the sleeve overlaps at least part of the underlying layer of the recoverable sleeve; and (b) wrapping a resilient girdle around the recoverable sleeve and fastening the girdle to itself to hold the recoverable sleeve in its wrapped configuration when the sleeve is recovered; characterised in that the girdle is provided with separating means for separating overlying layers of the wraparound recoverable sleeve, and the method comprises positioning said separated means relative to the recoverable sheet to separate the said overlying layers. 2. An assembly for covering an elongate object comprising: (a) a wraparound recoverable sleeve and (b) a resilient girdle which can be wrapped around the recoverable sleeve and fastened to itself to hold the recoverable sleeve in its wrapped configuration during recovery of the recoverable sleeve, characterised in that the girdle is provided with separating means for separating overlying layers of the wraparound recoverable sleeve. 3. A resilient girdle which can be wrapped around a wraparound recoverable sleeve and fastened to itself to hold the recoverable sleeve in its wrapped configuration during recovery of the sleeve, characterised in that the girdle is provided with separating means for separating overlying layers of the wraparound recoverable sleeve. -4. A method, assembly or girdle according to claim 1 or 3, wherein the said separating means of the girdle is an opening in the girdle, through wmcn the end of the outer layer of the wrapped wraparound sleeve can be inserted 5. A method, assembly or girdle according to any preceding claim, wherein the separating means of the girdle comprises a flap extending, in the wrapped configuration within the sleeve. 6. A method, assembly or girdle according to claim 4 or 5 wherein the girdle comprises both an opening in the girdle and a separating flap, wherein the opening is provided towards one end of the girdle, and the flap is secured to the inner face of the girdle in the wrapped configuration at a position on the side of the opening opposite to the end of the girdle, and wherein the flap extends from that secured position beyond that said end of the girdle. 7. A method, assembly or girdle according to any preceding claim in which the sleeve is heat recoverable and at least the separating means on the girdle and preferably the entire girdle is formed from a heat resistant material. 8. A method, assembly or girdle according to any preceding claim, wherein the sleeve has an in-built electrical heater. 9. A method, assembly or girdle according to any preceding claim, wherein the girdle is provided with cooperating means so that it can be fastened to itself. 10. A method, assembly or girdle according to any preceding claim, wherein the girdle is fastened to itself by securing its overlapping edges together. 11. A method, assembly or girdle according to claim 10, wherein the overlapped edges of the girdle are secured by mating Velcro strips. 12. A method or assembly according to any preceding claim, wherein the recoverable sleeve and /or the girdle are provided with additional securing means whereby the girdle and recoverable sleeve are secured to each other before being wrapped around the elongate object.

Inventors: VAN BEERSEL JOZEF, VAN ESCH WILLY, VAN BEERSEL, JOZEF, VAN ESCH, WILLY
Applicants: RAYCHEM LTD, RAYCHEM SA NV, N.V. RAYCHEM S.A., RAYCHEM LIMITED
Application year: 1992
Main classification: B29C63
IPC codes: B29C61