WO1983003132A1

WO1983003132A1 - Method of insulating pipe details

Info

Publication number: WO1983003132A1
Application number: PCT/FI1983/000020
Authority: WO
Inventors: Suomen Muovitehdas - Finska Plastfabriken Ab Oy
Original assignee: Jansson, Bertel; HAGSTRÖM, Erik; HAGSTRÖM, Nils
Priority date: 1982-03-05
Filing date: 1983-03-04
Publication date: 1983-09-15
Also published as: AT388429B; AU549722B2; JPS59500330A; GB2134034B; GB2134034A; ATA904083A; AU1337483A; CA1217913A; GB8406702D0

Abstract

Method of insulating pipe details, such as pipe branches. A continous insulating layer is obtained around the pipe branch by enclosing the pipe branch (15, 16) in a mould which sealingly surrounds the branching point and contains a thermoplastic material, whereafter the mould is rotated so that the thermoplastic material forms a continous layer (17, 18) around the branching point. The closed space between this layer and the pipes (15, 16) is finally filled with an insulating material, for example, a foam plastic.

Description

Method of insulating pipe details

The present invention relates to a method of insulating pipe details, such as pipe branches and bends.

Thermally insulated pipe joints are presently manufactured, for example, in the manner illustrated in Figure 1. A main pipe 1 usually made of metal is at the branching point surrounded by a thermal insulation layer 2 comprising usually a rigid outer layer and a softer inner layer of foam plastics. Thereafter a hole is made in the sheath ^"surface of the insulation layer 2. A branch pipe 3 is inserted through said hole and welded to the edges of an opening in the main pipe 1. Hereafter insulation layer lengths 4, 5 and 6 are pushed onto the branch pipe and joined to each other and to^* the insulation layer 2 by means butt welding, manual welding using a wire or adding a plasticized material to the seams. This entire operation is very time-consuming, and often the seams will not be quite tight due to which moisture may later penetrate into the foam plastic layer. In addition, the foam plastic is entirely unprotected at the end of the insulation layer wherefore it may be damaged during transport. The object of the present invention is to provide a method of insulating pipe branches and pipe bends by means of which the work can be carried out quickly and be easily automatized and which results in a water¬ proof product. The method is characterized in that the pipe detail is enclosed in a mould whose inner surfaces are located at a distance from the outer walls of the pipe detail and whose ends are by means of an element which is transverse with respect to the pipe detail sealed against the pipe detail, that a thermoplastic material is fed into the mould which is heated and put in motion so that the thermoplastic material forms a continuous layer along the inner surfaces of the mould, that the mould upon solidification of the continuous thermoplastic layer is removed and the space between said layer and the pipe detail is filled with an in¬ sulating material. In this way the pipe detail, for example, a pipe branch, is provided with an insulation layer consisting of a continuous rigid surface covering also the ends of the layer and of an inner foam plastic layer. The method can for the main part be carried out in an automatic casting machine, and as a result an insulation is obtained in which water cannot penetrate into the foam plastic, not even during transport of the detail, and in which the foam plastic will neither be damaged during the transport.

According to one preferred embodiment of the method according to the invention the sealing elements located at the ends of the mould comprise end gables of the mould provided with a central opening for the pipe detail. Because the end gables are made integral with the mould, the space between the mould and the pipe detail need not be sealed with any separate means. According to a second preferred embodiment of the invention the insulating material preferably com¬ prising a liquid foaming material is fed into the space between the solidified thermoplastic layer and the pipe detail through a hole made in the sheath surface of the layer. Also this step can be easily automatized which involves additional cost savings.

It is often desirable, for example, in view of strength requirements to make the insulating material adhere to the part to be insulated, in other words, in this case to the metal pipe. This can be made possib¬ le by cooling the pipe detail during the formation of the thermoplastic layer whereby the thermoplastic does not adhere to the metal pipe during heating of the mould. The cooling can be produced, for example, by feeding a cooling medium into the pipe detail. One preferred embodiment of the method according to the invention will be described in more detail in the following with reference to the accompanying draw¬ ing, in which Figure 1 illustrates a previously known insula¬ ting method,

Figure 2 is a side view of a mould to be used in the method according to the invention,

Figure 3 is a plane view of the mould, Figure 4 illustrates an insulated pipe branch manufactured by means of the method according to the invention,

Figure 5 is a cross-section of the pipe branch along the line V-V in Figure 4, Figure 6 illustrates the area B in Figure 5 on an enlarged scale, and

Figure 7 illustrates a pipe bend manufactured by means of the method according to the present invention.

The mould 7 shown in the Figures 2 and 3 comprises two symmetrical halves 8 and 9 which are pivotally connected to each other by means of two hinges 10. The mould consists of an elongated cylindrical portion for the main pipe and a bent portion for the branch pipe extending laterally from the first-mentioned portion. Both portions have such a configuration that their inner surface is located at a constant distance from the outer surfaces of the main and the branch pipes of the pipe branch. The ends of the mould are provided with gables 11, 12 which, in the closed position of the mould, form a continuous disc-shaped ring around the main and branch pipe. In order to permit the pipes to extend through the gables said gables are provided with recesses 13. The branch pipe portion is provided with a locking means 14 for locking the mould. The Figures 4 to 6 illustrate a pipe branch insulated according to the invention and comprising

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LA a main pipe 15 and a transverse branch pipe 16 welded to said main pipe. The pipe branch is ^'surrounded by a substantially, rigid sintered layer 17 of a thermoplas¬ tic material. The thermoplastic layer is provided also with end surfaces 18.which extend from the sheath sur¬ face to the outer surface of the pipes.15, 16, see Figure 6. The space between the outer surface of the pipes 15, 16 and the inner surface of the thermoplas¬ tic layer is filled with an insulating material 19, preferably- comprising foam plastic, which is inserted in this closed space through a hole 20 in the thermo¬ plastic layer.

The pipe branch according to Figures 4 to 6 is insulated according to the invention in the following manner. After the branch pipe 16 has been welded to a lateral opening in the main pipe 15, the pipe branch is positioned in the mould according to Figures 2 and 3 in which a suitable quantity of a preferably particular thermoplastic material is disposed. When the mould is closed, the pipes are fixed in the mould so that they are located along the central longitudinal axes of the mould parts. Hereafter the mould is heated while rota¬ ting it both around horizontal and vertical axes by means of means (not shown) for such a long time that the thermoplastic material is sintered along the inner surfaces of the mould. In order to prevent sintering of the material also on the pipe surfaces the pipes are cooled by feeding a cooling medium into them. Hereafter the mould 7 is cooled, and the pipe branch together with the continuous surrounding ,thermoplastic layer 17 can be removed from the mould. Because material is also sintered on the inside of the gables 11, 12 of the mould, the thermoplastic layer has end surfaces 18 which keep the pipes in position along the centre lines of the thermoplastic layer. Hereafter a hole 20 is made in the sheath surface of the thermoplastic layer, and the closed space between the pipes and the thermoplas¬ tic layer is filled with a liquid foaming insulating material 19 through the hole 20 whereafter the insulat¬ ed pipe branch is ready. The insulated pipe bend shown in Figure 7 is made in the same way but the mould must of course have the same shape as the pipe bend.

If desired, the cooling of the pipes can be omitted in which case the thermoplastic material is sintered also on the outer surface of the pipes. The gables 11, 12 of the mould can be replaced by sealing plugs which are pressed in between the pipe and the sheath surface of the mould.

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Claims

Claims :

1. A method of insulating pipe details, such as pipe branches and bends, c h a r a c t e r i z e d in that the pipe detail .^'(15, 16) is enclosed in a mould (7) whose inner surfaces are located at a distance from the outer walls of the pipe detail and whose ends are by means of a sealing element (11, 12) sealed against the pipe detail (15, 16), that a thermoplastic o material is fed into the mould which is heated and put in motion so that the thermoplastic material forms a continuous layer (17. 18) along the inner surfaces of the mould, that the mould upon solidification of the continuous thermoplastic layer is removed and the space 5 between said layer (17, 18) and the pipe detail (15, 16) is filled with an insulating material (19).

2. A method according to claim 1, c h a r a c ¬ t e r i z e d in that the sealing elements located in the ends of the moulds comprise end gables (11, 12) 0 of the mould provided with recesses (13) for the pipe detail (15, 16).

3. A method according to claim 1, c h a r a c ¬ t e r i z e d in that the insulating material (19) is fed to the space between the solidified thermoplastic 5 layer (17, 18) and the pipe detail (15, 16) through a hole (20) made in the sheath surface of said layer.

4. A method according to claim 3, c h a r a c ¬ t e r i z e d in that the insulating material (19) comprises a liquid foaming material. 0

5. A method according to claim 1, c h a r a c ¬ t e r i z e d in that the pipe detail (15, 16) is cooled during formation of the thermoplastic layer.

6. A method according to claim 5, c h a r a c ¬ t e r i z e d in that a cooling medium is fed into the 5 pipe detail.