Patent Application
20080000172
The invention will be better understood and other objects, details, features and advantages thereof will become more clearly apparent in the course of the following description of a number of particular embodiments of the invention which are given solely by way of non-limiting illustration with reference to the attached drawings. In these drawings:
Each panel 1 comprises a rigid backboard 2, for example made of plywood, and a first layer of thermal insulation 3, for example made of glass fibre reinforced polyurethane foam, which covers the backboard 2. The backboard 2 and the first layer of thermal insulation 3 together form a secondary thermally insulating barrier element. An impervious covering 4 is stuck to the first layer of thermal insulation 3 on the opposite side to the backboard 2. The impervious covering 4 may be rigid or flexible and comprises three layers, namely a sheet of aluminium about 0.1 mm thick, surrounded with fibreglass fabric and constitutes a secondary sealing barrier element. A second layer of thermal insulation 5, for example made of glass fibre-reinforced polyurethane foam, is bonded to the impervious covering 4, and a top board 6, for example made of plywood, covers the second layer of thermal insulation 5. The second layer of thermal insulation 5 and the top board 6 together form a primary thermally insulating barrier element.
In plan view, the backboard 2, the first layer of thermal insulation 3 and the impervious covering 4 have the shape of a first rectangle. The second layer of thermal insulation 5 and the top board 6 have the shape of a second rectangle with the same centre as the first but of a smaller size. Thus, the impervious covering 4 has a peripheral edge which is not covered by the second layer of thermal insulation 5.
The peripheral edge of the impervious covering 4 is covered by a film 8, as can be seen in
In the embodiment depicted, the film 8 consists of a single sheet, for example a sheet of polyethylene or of card material, bonded to the impervious covering 4, and which has precuts 12 dividing the various protective portions 9 and spew portions 11 from one another. In a variant, a reinforcing layer, for example a fibreglass fabric, is provided on the spew portions 11. In another embodiment, the protective portions 9 and the spew portions 11 of the film 8 are made of different materials and/or have different thicknesses.
The adhesive of the film 8 which sticks it to the impervious covering 4 is, for example, an adhesive of the acrylic or rubber type. These types of adhesive have the advantage of leaving no traces on the impervious covering 4 once the film has been removed, or at least of not leaving any traces detrimental to the bonding of the strip of impervious covering 13 described hereinbelow. In addition, this type of adhesive allows the panels 1 to be stored for relatively long periods, for example of several months, without the properties of the adhesive degrading, for example as a result of the action of ultraviolet radiation, temperature or humidity.
By fixing a plurality of rectangular prefabricated panels 1, and possibly panels of a similar structure that are trapezoidal or some other shape, to the bearing structure of a tank, most of the secondary thermally insulating barrier, of the secondary sealing barrier and of the primary thermally insulating barrier of the tank is formed in a single step. Next, the continuity of these barriers between the panels 1 is established and the primary sealing barrier is fitted. The operations of fixing the panels 1 to the bearing structure, establishing the continuity of the secondary and primary thermally insulating barriers, and of positioning the primary sealing barrier can be performed using techniques known to those skilled in the art, for example as described in documents FR-A-2 724 623 mentioned hereinabove and FR-A-2 781 557. The continuity of the secondary sealing barrier can be established using the technique described hereinbelow.
Having fixed the panels 1 to the bearing structure and established the continuity of the secondary thermally insulating barrier, the protective portions 9 which cover two adjacent edges of two adjacent panels 1 between which there is a space 7 are removed. This then uncovers two regions for bonding 10 of the panels 1. At this stage, the other protective portions 9 of the panels 1 are not removed, so as to continue to protect the bonding regions that they cover.
Next, the uncovered regions for bonding 10 are coated with adhesive and a strip of flexible impervious covering 13 with the same three-layer structure as the impervious covering 4 is laid in such a way that the strip 13 is bonded to the two regions for bonding 10 of the two adjacent panels 1, covering the space 7, as shown in
In order to check the quality of the bonding of the strip 13, a spew test is then performed, that is to say that once the adhesive has cured, the spew portions 11 are removed, as depicted in the left-hand part of
In an embodiment that has not been depicted, the film 8 exhibits a test portion that can be detached from the impervious covering 4 independently of the protective portions 9 and the spew portions 11. This test portion consists for example of a tab delimited by a rectangular precut on a spew portion 11. A peel test can then be performed on site, for example just before fixing the panel 1 to the bearing structure, this test consisting in peeling the tab back at 180° in order to remove it, and measuring the force required using scales. If the force required does not fall within a given range, this shows that the surface of the impervious covering 4 has been damaged or contaminated and is unsuitable for bonding. The impervious covering 4 can then be cleaned prior to bonding or the panel 1 can be scrapped.
Although the invention has been described in conjunction with a number of particular embodiments, it is quite clear that it is not in any way restricted thereto and that it comprises all technical equivalents of the means described and combinations thereof provided that these fall within the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 06/05963 | Jun 2006 | FR | national |
