WO2000038877A1

WO2000038877A1 - Method of repairing a puncture in a skin of a double-skinned freight container

Info

Publication number: WO2000038877A1
Application number: PCT/GB1999/004403
Authority: WO
Inventors: Eric Mosselar
Original assignee: Ge Seaco Services Ltd.
Priority date: 1998-12-23
Filing date: 1999-12-23
Publication date: 2000-07-06
Also published as: GB9828641D0; AU1988400A; GB2345054A

Abstract

A method of repairing a punctured wall of a double-skinned freight container (1) having foam (4) between an inner (2) and outer skin (3) thereof by removing a portion of punctured skin and foam of one of a number of pre-determined sizes and inserting a patch (20) comprising a skin (21) and attached foam portion (23) of the pre-determined size in the cut-out. Also disclosed is a kit of parts comprising various pre-determined sizes of insert and, preferably, cutting tools for removing the punctured skin and foam. In particular, there is disclosed a corrugated insert for repairing an inner corrugated skin of a punctured wall in a double-skinned freight container, for allowing circulation of air along the corrugation of the container after repair.

Description

METHOD OF REPAIRING A PUNCTURE IN A SKIN OF A DOUBLE -SKINNED FREIGHT CONTAINER

This invention relates to a method of repairing a puncture in a skin of a double-skinned freight container and to a kit of parts for effecting such a repair and to a corrugated insert for repairing a punctured skin of a double-skinned freight container having a corrugation in the vicinity of the puncture.

Known insulated freight containers have walls with an inner and outer skin, the interstitial space between the inner and outer skins being filled with solidified foam to provide thermal insulation between the outside and inside of the container, in particular, so that the inside of the container may be maintained at a lower temperature than the ambient air. The skin of such containers may, for example, be of aluminium, stainless steel or ferrous steel. Both the inner and outer skins of such containers are subject to damage by puncturing of the skin. In a known method of repairing such punctures, an area of skin around the puncture is removed by cutting around the puncture witli an angle grinder and removing foam which was beneath the removed area of skin by chipping, routing or sanding out, leaving a rough surface to the underlying foam. This process of removing the foam tends to release gases such as freon from the foam. The process also produces considerable quantities of discarded foam particles, which may be highly inflammable. Blocks of solid foam are inserted into the chiselled out volume, a patch of skin is cut to be slightly larger than the removed skin and the oversized patch of skin is riveted over the inserted blocks of foam. This method of repair has the disadvantages that the blocks of foam may not fit the volume exactly thus impairing the insulation and a large number of rivets have to be used to fix the over-sized patch of skin in place which is time-consuming and may weaken the wall, and possibly allow the ingress of water. As an alternative, an oversize patch of skin may be fitted over the cut-out and liquid foam injected to solidify under the patch. This has the disadvantage that a repair yard must have available equipment for injecting liquid foam and equipment for cutting the patch to size and must carry a stock of outer skin material. In addition, where air passages are provided by corrugation in the inner skin to allow cooling air to circulate around a load carried in a container, the repair patch may block the air passage.

It is an object of this invention to provide a method of repairing punctures in a skin of a double-skinned freight container which overcomes, at least to some extent, the foregoing disadvantages and also to provide a kit of parts for repairing punctures which at least partially obviates the requirement for repair yards to hold stocks of skin material and foam injection equipment.

According to a first aspect of this invention there is provided a method of repairing a puncture in a wall of a double-skinned freight container, the wall having an interstitial space between an inner skin and an outer skin of the wall filled with foam, the method comprising the steps of: a) removing a portion of punctured skin and foam to form a cut-out of a predetermined size in the foam, b) providing an insert, the insert comprising a skin and attached foam portion of the pre-determined size, c) locating the foam portion of the insert in the cut-out, and d) fixing the insert in place with the foam portion in the cut-out.

Preferably step a) comprises the steps of: cutting a groove to a pre-determined depth around the puncture to mark out a cut-out of the pre-determined size, inserting undercutting means into the groove on one side of the puncture and undercutting the foam with a cut parallel to the wall so that the cut intersects the groove on an opposed side of the puncture from that on which the undercutting means is inserted, and removing the portion of punctured skin and foam.

Conveniently step b) includes the steps of: providing an insert having a foam portion of the pre-determined size, the insert having a coating of pressure-sensitive adhesive for fixing the insert in place in the cut-out, the pressure-sensitive adhesive being provided with a protective covering, and removing said protective covering from the insert before locating the foam portion of the insert in the cut-out. Advantageously step b) includes providing an insert having an oversize skin portion larger than the portion of punctured skin removed, and a foam portion to fit the cut-out, and step c) includes fixing said oversized skin portion to a periphery of the cut-out.

According to a second aspect of the invention there is provided a kit of parts comprising a first plurality of predetermined sizes of insert each comprising a skin portion and an attached foam portion for repairing a punctured portion of a skin of a double-skinned freight container.

Conveniently, the foam portions are of a second plurality of predetermined depths.

Conveniently the kit of parts includes cutting means for cutting a groove around the punctured portion to define a cut-away portion of the skin of a container.

Advantageously the kit of parts further includes undercutting means for insertion within the groove for undercutting the punctured poπion of the skin to form the cut-away portion, for insertion therein of one of the inserts.

According to a third aspect of the invention there is provided a corrugated insert for repairing a punctured corrugated wall of a doubled-skin freight container, the insert comprising a skin portion and a foam portion, the skin of the insert having a corrugation for repairing a puncture in a corrugated inner skin of a wall of the container.

The present invention has the advantage of removing a cut-away portion of wall without releasing large quantities of gas from the foam, since the cut-away foam is removed substantially in one piece. The invention also has the advantage of providing a tight-fitting insert to repair a puncture in which no large voids are left in the insulation in the repaired wall because the inserted foam portion is substantially the same size as the foam portion removed. Moreover, because the insert fits snugly within the cut-out, the insert may be adhered in place with adhesive avoiding or reducing the need for blind rivets, and therefore overcoming the problems of water ingress within the cut-out met in the prior art where large numbers of rivets are used around an oversized patch. Moreover, the provision of a kit of parts including a number of standard sizes of insert, to fit predetermined sizes of cut-outs, reduces the stock-holding requirements of repair yards and avoids the need for repair yards to have equipment for injecting foam and for cutting skin patches to size.

In the case of refrigerated containers provided with corrugations on the inner surface to facilitate the circulation of cooling air around a load carried within the container, the use of corrugated inserts of the invention maintains an air passage when an insert is applied to an inner wall in an area including a corrugation. The invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows a punctured portion of a transverse cross-section of a wall to be repaired,

Figure 2 represents cutting of a groove around the punctured portion of Figure 1,

Figure 3 represents insertion of a saw into the groove to undercut the punctured portion of Fig. 1 to form a cut-out, Figure 4 shows an insert of the invention for insertion in the cut-out of

Figure 2,

Figure 5 shows a transverse cross-section of a wall of the insulated container having a corrugation within a wall to act as an air passage,

Figure 6 shows a puncture in the region of the corrugation of Figure 5, and Figure 7 shows a corrugated insert and a cut-out made around the punctured corrugation of Figure 6.

In the figures like reference numerals denote like parts.

A wall 1 of an insulated freight container, as shown in transverse cross- section in Figure 1, has an inner skin 2 and outer skin 3 with an interstitial space between the skins 2,3 filled with a solidified foam 4 to provide thermal insulation between the inner and outer skins 2,3. A puncture 5 to be repaired, as shown in Figure 1 , has a break 6 in an outer skin 3, surrounded by an area 7 in which the skin 3 is indented into the foam 4. It will be understood that the break 6 could equally occur in the inner skin 2.

In order to repair the puncture 5 linear grooves 10,12 are cut, for example with an angle grinder 14 as shown in Figure 2, to a pre-determined depth in a rectangular or square shape of a predetermined size around the puncture 5 through parts of the undamaged skin 11 surrounding the puncture 5 and to a pre-determined depth of the foam 4. A saw 16 is inserted in one of the linear grooves 10, as shown in Figure 3 to cut a saw-cut 15 parallel to the inner skin 2 of the wall 1 from a first groove 10 to an opposite groove 12 to form a cut-away 13 encompassing the puncture 5. Alternatively, particularly where the inner and outer skins are not parallel, the saw cut 15 may be made parallel to the plane of the outer skin 3, preferably by mounting the saw in a clamp (not shown) to maintain the saw-cut 15 at a constant distance from the plane of the outer skin 3.

The punctured cut-away 13 is removed to leave a cut-out 22 (see Figure 4) and an insert 20 is provided comprising a skin 21 of sufficient size to overlap the edge of the cut-out 22 and a solidified foam portion 23 of the pre-determined size and depth. To complete the repair, the foam portion 23 of the insert 20 is inserted into the cut-out 22 of pre-determined size and depth and an overlapping portion 24 of the skin 21 of the insert 20 is adhered by adhesive to the skin 3 surrounding the cut-out 22. Alternatively, or in addition, the overlapping skin 24 may be riveted with blind rivets to the surrounding skin 3. In addition or alternatively, the foam portion 23 of the insert 20 may be adhered by adhesive to the foam 4 surrounding the cut-out 22. The insert 20 may be provided with a coating of adhesive, protected by a protective layer which is removed before inserting the insert 20 into the cut-out 22.

Where a flush-fitting patch is required, a peripheral area of skin 3 may be removed around the cut-out 22 to accommodate the overlapping portion 24 of the skin of the insert so that when the insert 20 is inserted into the cut-out 22 the skin 21 of the insert 20 is in the same plane as the skin 3 of the repaired wall 1. As shown in Figures 5-7 in the case of a puncture 30 in the region of a corrugation 31 provided in a wall 32 for the purpose for circulating cooling air around goods to be carried within the container, an insert 33 may be provided having a corrugation 34 in the skin portion 35 of the insert 33, so that the air passage 31 is not impeded in the repair.

Claims

1. A method of repairing a puncture in a wall of a double-skinned freight container, the wall having an interstitial space between an inner skin and an outer skin of the wall filled with foam, the method comprising the steps of: a) removing a portion of punctured skin and foam to form a cut-out of a predetermined size in the foam, b) providing an insert, the insert comprising a skin and an attached foam portion of the predetermined size, c) locating the foam portion of the insert in the cut-out, and d) fixing the insert in place with the foam portion in the cut-out.

2. A method as claimed in claim 1, wherein step a) comprises the steps of: cutting a groove to a pre-determined depth around the puncture to mark out a cut-out of the pre-determined size, inserting undercutting means into the groove on one side of the puncture and undercutting the foam with a cut parallel to the wall so that the cut intersects the groove on an opposed side of the puncture from that on which the undercutting means is inserted, and removing the portion of punctured skin and foam.

3. The method of claims 1 or 2 wherein step b) includes the steps of: providing an insert having a foam portion of the pre-determined size, the insert having a coating of pressure-sensitive adhesive for fixing the insert in place in the cut-out, the pressure-sensitive adhesive being provided with a protective covering, and removing said protective covering from the insert before locating the foam portion of the insert in the cut-out.

4. The method as claimed in claim 1 wherein step b) includes providing an insert having an oversize skin portion larger than the portion of punctured skin removed, and a foam portion to fit the cut-out, and step c) includes fixing said oversized skin portion to a periphery of the cut-out.

5. A kit of parts comprising a first plurality of predetermined sizes of insert each comprising a skin portion and an attached foam portion for repairing a punctured portion of a skin of a double-skinned freight container.

6. A kit of parts as claimed in claim 5, wherein the foam portions are of a second plurality of predetermined depths.

7. A kit of parts as claimed in claims 5 or 6, including cutting means for cutting a groove around the punctured portion to define a cut-away portion of the skin of a container.

8. A kit of parts as claimed in claim 7, further including undercutting means for insertion within the groove for undercutting the punctured portion of the skin to form the cut-away poπion, for insertion therein of one of the inserts.

9. A corrugated insert for repairing a punctured corrugated wall of a doubled- skin freight container, the insert comprising a skin portion and an attached foam portion, the skin of the insert having a corrugation, for repairing a puncture in a corrugated inner skin of a wall of the container.