Method of making compound pipes for conveying various fluids and pipe obtained by this method

DETAILED DESCRIPTION The object of the present invention is in particular to remove the above-mentioned inconvenience by providing a tube which may be made in a continuous fashion very quickly and at a low cost price, which exhibits high mechanical characteristics at any point and thoughout its length and which may be used not only as a tube for internally lining damaged ducts or pipelines but also as a conventional rigid tube like the presently prefabricated tubes to carry various materials or fluids.
For this purpose, the subject matter of the invention is a method of making tubes of any cross-section for conveying fluids also of any kind, comprising covering a mandrel with a layer of plastics material, effecting a continuous circular weaving of several concentric tubular layers onto said plastic layer, then impregnating by means of a resin the whole of said tubular layers and causing the polymerization of this resin through a heating integrated into the tubular layers.
According to another characterizing feature of this method, at least one metal layer reinforcing or strengthening the tube and also serving as a heating resistor means for polymerizing the resin is inserted between the aforesaid tubular layers.
According to still another characterizing feature of this method, the heating temperature of the resin is detected or sensed so as to control or adjust the supply of electric current to said metal layer.
It should also be pointed out that after leaving the mandrel and subsequent impregnation with the resin, the tube is shaped through inflation or expansion preferably prior to heating.
The invention is also directed to a tube or pipe for conveying any fluids, obtained through the method according to either one of the foregoing characterizing features and of the kind comprising at least one layer of glass fibers impregnated with a resin, this tube being characterized by comprising at least one assembly of successive concentric layers, namely from the inside towards the outside : a layer of impervious plastics material, a first layer of glass fibers made fast with the aforesaid layer, a layer of electrically conducting material such for instance as a metal and a second layer of glass fibers, the three lastly cited layers being impregnated with resin