Double pipe system with a primary pipeline conducting a medium and a secondary pipeline which is arranged around the primary pipeline for protection, containing pipes and fittings of the primary pipeline, wherein the pipes and fittings of the primary pipeline are connected together, and pipes and fittings of the surrounding secondary pipeline, wherein the pipes are configured as one-piece plastics pipes and the fittings are configured as half-shells, wherein the half-shells of the fittings and the adjoining pipes of the secondary pipeline are connected together by means of electric welding sleeves, or in that the half-shells of the fittings and the adjoining fittings consisting of half-shells are connected together by means of electric welding sleeves.

An apparatus for thermally joining thermoplastic fiber composite components includes a pressurization arrangement for jointly covering, at least in a region of a joining zone, thermoplastic fiber composite components to be joined and applying pressure to the thermoplastic fiber composite components to press the thermoplastic fiber composite components against one another, at least in the joining zone, the pressurization arrangement being flexible, at least in some section or sections. A welding device is configured for welding the fiber composite components in the joining zone during pressurization. The pressurization arrangement and welding device are configured to weld the thermoplastic fiber composite components in a pressurized state in the joining zone. The pressurization arrangement is configured to maintain pressurization independently of the welding device until the joining zone solidifies. A cover is also disclosed for a pressurization device for thermally joining thermoplastic fiber composite components.

The invention relates to a method for connecting a thermoplastic line element (3) to a connecting element (2). The method comprises the steps of: providing the at least one thermoplastic line element (3); providing the connecting element (2) having a thermoplastic body (4 wherein a heating element (6 is embedded in the body (4 for generating heat in a welding region (5 for welding the body (4 to the at least one line element; joining the connecting element (2) to the at least one thermoplastic line element (3; providing a welding device (10) for welding the connecting element (2 to the at least one thermoplastic line element (3); welding the connecting element (2 at least one thermoplastic line element (3 by generating heat in the welding region (5 by means of the welding device (10).

The welding of the connecting element (2) to the at least one thermoplastic line element (3) is stopped by the welding device (10) before the end of the planned welding duration if an error criterion is met.

A method of manufacturing a heat exchanger array that includes stacking a plurality of heat exchanger units in an aligned configuration with respective first ports of the plurality of heat exchanger units aligned. The method can further include generating heat in the first coupling elements at the same time and at a temperature sufficient to generate a first plurality of respective couplings between adjacent sheets of adjacent heat exchanger units about adjacent first ports and without a coupling being generated between the first and second sheets of a given heat exchanger unit.

An electrofusion fiting (20) comprises a fitting body (24) and an electrofusion collar (26). The fitting body (24) has an exterior surface (30), an interior surface (32), and a terminal portion (44) extending to a rim (34). The collar (26) has: an inner wall (42) having a heating element (60); a segmented outer wall (40) spaced radially apart from the inner wall; and a linking portion (46) linking the outer wall and inner wall. The fitting body terminal portion is between the inner wall and the outer wall. The collar and fitting body have interfitting features (150, 152) axially retaining the collar against extraction from the fitting body while permitting relative rotation of the collar and the fitting body.

A method keeps a voltage or a current constant during a welding process of an electrofusion fitting. The method includes: connecting an extension cable between a connection cable of a welding power supply and the electrofusion fitting to be welded; detecting the extension cable by the welding power supply; detecting and recording the electrofusion fitting to be welded and its data by the welding power supply; autonomously supplying the current or the voltage with the welding power supply; and autonomously regulating the current or the voltage based upon the detection of the connected extension cable and a resulting resistance due to the connected extension cable. The current or the voltage is adjusted such that the current or the voltage remains constant during the welding of the electrofusion fitting.

Disclosed is a method of resistance welding between composite articles. A conductive element is provided between faying surfaces, having a plurality of lower resistivity electrode portions spaced apart along the length of the contact area between the composite articles. The electrode portions can be used to spot weld across the electrode portions, and along a longitudinal portion of the conductive element between the electrode portions by application of an electrical current. Also disclosed are apparatus for use in the resistance welding methods and composite articles and structures and elements incorporating the conductive element.

The invention relates to a weldable connecting element 2 for connecting or joining thermo-plastic line elements 3. The connecting element 2 comprises: a thermoplastic body 4; at least one heating element 6, which is embedded in the body 4, wherein the heating element 6 serves to generate heat in a welding area 5 for welding the body 4 to the at least one line element 3. Furthermore, a joining control 12 is provided, which is configured to prohibit the welding operation and/or to interrupt the welding operation if the body 4 and the line element 3 are not joined correctly.

A method of joining a non-metallic pipe to a metallic pipe. The pipe may be wrapped with one or more sheets of reinforcement material (e.g., pre-impregnated fiberglass, carbon fiber, or aramid fiber) and then fitted with an adapter or fitting that is connectable to a metallic pipe. The reinforcement material may be heated using a heating apparatus which allows the material to bond to the pipe to strengthen the joint.

A system for coupling pipes includes a first pipe having a tapered, spigot end; a second pipe having a tapered, spigot end; and a coupler having two tapered socket ends adapted to internally receive the respective tapered, spigot ends of the first pipe and the second pipe. The first pipe and the second pipe are made from a reinforced thermosetting resin (RTR). The coupler comprising a resistive element implanted therein and connected to electrodes extending to an exterior of the coupler. A thermoplastic material is disposed between an exterior of the first pipe and an interior of the coupler. A thermoplastic material is disposed between an exterior of the second pipe and the interior of the coupler. Upon application of electricity to the electrodes, the resistive elements are heated sufficiently to melt the thermoplastic material such that, when the heat is removed, the hardened thermoplastic material seals the first pipe and the second pipe to the coupler. A method of coupling pipes includes disposing a thermoplastic material between an exterior of a first pipe and an interior of a coupler; disposing a thermoplastic material between an exterior of a second pipe and the interior of the coupler; inserting the first pipe and the second pipe into the coupler; and applying of electricity to electrodes of the coupler such that resistive elements of the coupler heat sufficiently to melt the thermoplastic material such that, when the heat is removed, the hardened thermoplastic material seals the first pipe and the second pipe to the coupler.