A method is shown for installing a heat tube on a section of pre-insulated piping. A metal carrier pipe is covered with a first layer of foam insulation. Next, a wire brush is used to cut a longitudinal slot along the length of the pipe so that the pipe exterior surface is exposed from the insulation. A heat tube is then installed within the longitudinal slot, whereby the heat tube contacts the exterior surface of the metal carrier pipe. A second layer of foam insulation is then sprayed onto the exterior of the metal carrier pipe, covering the previously formed longitudinal slot and installed heat tube. A polyolefin coating is then applied over the insulation to form a protective outer jacket for the insulated pipe.

Disclosed is a method for preparing graphite film, comprising steps as follows: 1) winding; 2) carbonizing at a low temperature; 3) graphitizing at a high temperature; 4) unwinding and feeding, winding up the electrographite film semi-finished product and flexible graphite paper separately; 5) calendaring to press the electrographite film semi-finished product against release film or protective film; 6) winding up and packaging. The winding process comprises steps as follows: a. winding high temperature resistant elastic material around the graphite cylinder core; b. bonding macromolecular film to flexible graphite paper, and then winding around the graphite cylinder core based on step a; c. when the macromolecular film and flexible graphite paper wound in step b reach the predetermined thickness, securing with carbon cord.

A composite strip which extends in a main direction between first and second ends and which comprises a main strip comprising first fibres embedded in a matrix. The first fibres are made of carbon, an electrically conducting material, and the matrix is made up of at least one polymer. The composite strip further comprises a junction layer formed of an electrically conducting junction material. The junction layer is placed on the main strip.

A composite strip which extends in a main direction between first and second ends and which comprises a main strip comprising first fibres embedded in a matrix. The first fibres are made of carbon, an electrically conducting material, and the matrix is made up of at least one polymer. The composite strip further comprises a junction layer formed of an electrically conducting junction material. The junction layer is placed on the main strip.

A length of a main pipe is provided. The main pipe has an internal surface and an external surface. A plurality of channels, tubes or conduits is attached to the external surface of the main pipe and spaced about a circumference thereof. A spray foam insulation is applied to the external surface of the main pipe. Prior to curing the spray foam insulation, a compressive force is applied against an exposed outer surface of the spray foam insulation to prevent a bulge from forming over the channels, tubes or conduits so that the outer surface of the insulation has a uniform radius.

A length of a main pipe is provided. The main pipe has an internal surface and an external surface. A plurality of channels, tubes or conduits is attached to the external surface of the main pipe and spaced about a circumference thereof. A spray foam insulation is applied to the external surface of the main pipe. Prior to curing the spray foam insulation, a compressive force is applied against an exposed outer surface of the spray foam insulation to prevent a bulge from forming over the channels, tubes or conduits so that the outer surface of the insulation has a uniform radius.