METHOD OF MANUFACTURING A FORM STABLE HEAT INSULATING BOWL

Abstract: In a method for manufacturing a form stable heat insulating and diffusionproof bowl, a diffusionproof sheet (9) is first placed against a first part (6) of a mould, and then a second part (8) of the mould is so positioned in relation to the first part as to provide a cavity between the second part (8) and the sheet (9), following which curable plastics is foamed in said cavity.

Description: Method of manufacturing a form stable heat insul atinq bowl The invention concerns a method of manu acturing a form stable heat insulating bowl adapted to be mounted around a pipe installation to be insulated. Insulating bowls are known e.g. from the DK Patent Application 150 392, which concerns bowls hich, however, are not diffusionproof so that they cannot be used for insulating cooling installations. Further, in connection ith heating installations, they are not suitable for insulating pipes hich are subjected to temperatures in excess of about 120 D C. Insulation of fittings in cooling circuits have till now been effected by placing an aluminium jacket around the fitting, and then curable plastics is foamed in the gap between the fitting and the aluminium jacket. This has the drawback that the insulation is to be destroyed completely if the fitting is to be serviced, following which the relatively time-consuming insulating process is to be repeated. The object of the invention is to provide a method by which it is possible to manufacture partly diffusionproof insulating bowls and partly heat insulating bowls capable of withstanding very high temperatures, where these types of bowls can be mounted and disassembled repeatedly. This object is achieved in that the insulating bowl is manufactured as stated in the characterizing portion of claim 1, which has the ad antage in terms of manufacture that the pressure of the plastics mass during the foaming process urges the loosely pre-arranged layer of material into tight engagement with one of the mould parts. In connection ith cooling installations, the layer of material may typically be an aluminium sheet and may e.g. be a ceramic fibre material in connection with thermal insulation, and this layer of material is applied so loosely over the respective mould part that ample material will be present; it will be appreciated that the mould part adjoining the layer of material should not have any sharp edges. When the plastics has cured, the outer surface of the bo l may be subsequently treated in various ays, depend¬ ing upon the actual use. However, it is an advantage to make the outer surface of the bowl from an impact- resistant weatherproof material, and in this case it is particularly expedient to perform the method as stated in claim 5, wherein an impact-resistant and weatherproof shell of plastics is used as one of the mould parts. The invention will be explained more fully by the follow- ing description of some embodiments with reference to the drawing, in which fig. 1 schematically shows a pair of known insulation halves for a pipeline fitting, figs. 2 and 3 show mould halves for manufacturing an insulating bowl according to the invention, figs. 4 and 5 show examples of insulating bowls in a manufacturing phase according to the invention, in which various layers of various types of materials are used, fig. 6 shows a section through an insulation around a cooling installation, using an insulation bowl manu- factured according to the invention. Fig. 1 shows two identical insulating bowls 1 and 2 as known from the Danish patent specification previously mentioned. The bowls are moulded in polyurethane foam and shaped to fit around a pipeline fitting 3, it being possible to secure the bowls around the fitting by applying clamping bands in the shown grooves 4 and 5. These insulating bowls result in rationalization of the insulation of heating pipes. Howe er, e.g. in the petro-chemistry, there is an in¬ creasing need for insulation of cooling pipes where the well-kno n condensation and ice formation phenomenon occurs. To prevent formation of ice, the insulation around a cooling pipe must comprise a vapourproof membrane at the warm surface of the insulation, so that no water vapour can diffuse into the cold pipes where the vapour condenses and freezes. This form of insulation has till now been effected in the manner described in the beginning of the description. With reference to figs. 2 and 3, a pair of embodiments of the method of the invention will be explained. The figures show a first mould half 6 and a second mould half 7 whose underside has a mould projection 8 adapted to be received in a trough-shaped depression in the mould half 6 so as to define a cavity between the two mould halves. Such mould halves can in principle be used for moulding insulating bowls of the type shown in fig. 1 by filling the cavity between the mould halves with polyurethane foam, In a first embodiment of the invention, a vapourproof sheet 9 (e.g. an aluminium sheet) is placed in the first mould half 6, said sheet being shown transparent in fiq. 3 for clarity. In fig. 3, the sheet is shown in a position where it has been pressed loosely do n into the cavity of the mould half 6 manually or automatically, so that the sheet 9 is creased somewhat and is far from being tightly engaged with the internal surface of the mould half. Then the mould halves 6 and 7 are assembled, and e.g. polyurethane foam is injected through the holes 10 shown in fig. 2. The special effect of the method of the invention is then that the pressure applied by the foaming material to the sheet causes the sheet to be urged into tight engagement with the internal surface of the mould so that the foaming process ensures that the sheet and thus the external surface of the insulating bowl have the desired shape. This method is typically used in connection with the making of insulating bowls for cooling installations. For insulating bowls adapted for heating installations the structure of the bowls is slightly different, but the method is in principle the same as for the cooling jackets. Apart from the aluminium sheet being replaced, of course, by a decidedly heat insulating, thin layer of material (e.g. a ceramic fibre material), the method is changed in that, in contrast to the aluminium sheet, the layer of material is to be provided so that it defines the internal surface of the finished, heat insulating bowl. This just involves the difference that the layer of material is applied loosely on the second mould half 7 so that the foaming material is injected behind the ceramic fibre material so to speak. Figs. 4 and 5 show a pair of insulating bowls 11 and 26 after removal from the mould halves. It will be seen in connection with fig. 4 that the sheet 9 has still not been cut along the rim of the insulation bowl. The external surface of the insulation bowl will therefore have a desired, well-defined contour, but although the sheet will be folded and have creases at several points, it will be unbroken so that the sheet is vapourproof. As mentioned, the internal surface of the insulating bowl 11 consists of polyurethane foam and is quite smooth. In this embodiment, i.e. serving as a cooling jacket, it will particularly be desirable to subsequently treat the external surface of the insulating bowl, e.g. with a plastics cover which is impact-resistant and weatherproof. In a preferred embodiment of this method of the invention, a plastics shell is first provided, which is then used as a mould half 6, an adhesive being then applied between the plastics shell and the sheet 9. This provides an insulating shell which comprises on the outside an impact- resistant and weatherproof plastics shell, then a vapour¬ proof membrane and finally an insulating layer of poly¬ urethane foam. Such an insulating bowl is likewise shown in section in fig. 6. Fig. 5 shows the method adapted for manufacturing a heat insulating jacket 26, wherein the layer of material, now heat insulating, is to be positioned directly against the valve 14. This just means that the foaming polyurethane is to be sprayed to the other side of the layer of material, seen in relation to the production of the cooling jacket, so that the layer of material, which may be a ceramic fibre material as mentioned, will be shaped entirely according to the contour of the second mould half 7. In fig. 6, the broken line 28 indicates the position of the heat insulating layer of material in contrast to the vapour barrier sheet 21. Fig. 6 also shows a pair of cooling pipes 12 and 13, between which a fitting 14 with a pindle 15 is placed. The pipes 12 and 13 are pre-provided with insulating webs 16 and 17, and also the spindle is provided with in¬ sulation 18. Then an insulating bowl manufactured by the method of the invention may be applied. The insulating bowl 19 comprises an outermost layer of impact-resistant and weatherproof plastics 20, and then, depending upon the purpose, a vapourproof membrane 21 and an innermost insulation layer 22, on the exterior of which a ceramic fibre material 28 may be arranged in replacement of the membrane 21. Apart from the shape shown in fig. 6, the bowl 19 may advantageously be given a rectangular contour, so that the assembled jacket is easy to clean, but can also advantageously be used for packaging the valve. For example a clamping band of a known type is used for the attachment, and when the insulating bowls are assembled, additional insulating webs 23, 24 and 25 are placed around the insulation previously described and tightly against the insulating bo l 19. Very rational insulation of cooling as well as heating installations may be obtained in the manner described, the assembly being almost as simple as that known from the Danish patent and considerably more simple than the known insulating method. The prerequisite for the assembly known per se with pre-manufactured insulating bowls is that it is possible to manufacture very in¬ expensive insulating bowls by the method of the invention which comprise either a vapour barrier or a heat in¬ sulati g layer.

Claims: AMENDED CLAIMS [received by the International Bureau on 18 April 1988 (18.04.88); original claims 1 and 5 combined as amended claim 1; claims 2 and 3 unchanged; claim 4 cancelled (1 page)] 1. A method of manufacturing a form stable heat in¬ sulating bowl adapted to be mounted around a pipe in- stallation to be insulated by providing a relatively thin layer of mouldable material against the inner side of a part of a mould so as to provide a substantially closed cavity between the layer of material and an opposite part of the mould, following which curable plastics is foamed in said cavity, c h a r a c ¬ t e r i z e d by using a pre-manufactured plastics shell as one part of the mould, and applying an adhesive to the inner side of said shell prior to said foaming operation. 2. A method according to claim 1, c h a r a c t e r ¬ i z e d by using a vapourproof sheet as said layer of material. 3. A method according to claim 1, c h a r a c t e r ¬ i z e d by using a ceramic fibre material as said layer of material.

Inventors: JENSEN BOERGE, JENSEN, BOERGE
Applicants: TOPO CAP UNIT AS
Application year: 1987
Main classification: F16L59
IPC codes: B29C44, F16L59