RU2217311C2 - Method for connection of plastic reinforced pipes - Google Patents

Abstract

FIELD: construction of pipe- lines of plastic, for example, polyethylene pipes. SUBSTANCE: the method consists in butt welding of pipe end faces and welding of the zone of the butt weld with the reinforced plastic coupling. Annular grooves are preliminarily made in the pipe end faces for picking the reinforcing layer, or the pipe end faces are encapsulated coating them with a layer of plastic. Besides, the pipes are welded by an electric spiral between each other and with the coupling, which is installed in the coupling or in the pipes, or in intermediate thin-walled sleeve positioned between the pipes and the coupling. Tread rings in the form of a fixed winding of reinforcing belt are installed on the coupling. EFFECT: provided sealed connection of the pipes and prevented destruction of the reinforcing layer of pipes in the point of their connection. 3 cl, 14 dwg

Description

 The invention relates to the field of construction of pipelines made of plastic, for example polyethylene pipes.

 A known method of connecting plastic reinforced pipes using metal screw couplings and o-rings installed between the ends of the pipes [1. French Patent 2728049, MKI 7 F 16 L 15/08, 1995].

 The method does not provide reliable sealing of the ends of the pipes, which leads to the delamination of the reinforcing layer from plastic and, as a result, to the violation of the tightness of the pipelines.

 A known method of connecting plastic reinforced pipes using reinforced plastic couplings that are embedded with an electric heating element (electric coil) is welded with each of the pipes connected into the lash [2. Certificate of the Russian Federation 13078, MKI 7 F 16 L 47/00, 1999].

 This method also does not provide sealing of the ends of the pipes. At high pressure in the pipeline, the pipes inflate somewhat, while the ends of the pipes entering the coupling bend and the seal loses its tightness. A leak in the coupling joint occurs when the pipes bend.

 Closest to the claimed technical solution is a method of connecting reinforced pipes of thermoplastics. The method involves butt welding of pipes with the displacement of the reinforcing layers outside. After butt welding, in place of the obtained seam, a sleeve with an electric coil is installed and welded with pipes [3. RF patent 2115057, MKI 6 F 16 L 47/02, B 29 C 65/20, 1994].

 Partial or complete displacement of the reinforcing layer outward weakens the joint of the pipes. In addition, a possible violation of the tightness of the welded joint of the pipes with the coupling, for example, along an electric spiral, will lead to depressurization of the outgoing reinforcing layer.

 The technical challenge facing the invention is to ensure the tightness of the connection of the pipes and to prevent the possibility of destruction of the reinforcing layer of pipes at the place of their connection.

 The problem is solved in that when connecting plastic reinforced pipes by butt welding of pipe ends and welding of the butt weld zone with a reinforced plastic sleeve, annular grooves are performed at the pipe ends to select the reinforcing layer or the pipe ends are encapsulated by covering with a plastic layer.

 Pipes between each other and with the coupling are welded with an electric spiral installed in the coupling, or in pipes, or in an intermediate thin-walled plastic sleeve placed between the pipes and the coupling.

 To increase the strength of the connection, retaining rings are installed on the coupling, for example, in the form of a fixed winding from a reinforcing tape.

 The invention is illustrated by drawings, where figure 1-14 shows the options for connecting plastic reinforced pipes by welding according to the proposed method.

 According to the proposed method, you can connect plastic, for example polyethylene pipes, reinforced with high-strength polyamide, aramid and other fibers.

 Various options for connecting pipes by simultaneously welding them with a sleeve and butt are provided.

 The simplest option for welding reinforced pipes (Fig. 1, 1a) is that pipes 1 and 2 are welded using the well-known technology for welding polyethylene pipes with a sleeve 3, into which an electric spiral 4 is wound, but an electric spiral is also installed between the ends of the pipes to be connected, embedded in a flat polyethylene ring 5. After preparing and installing the pipes and in the welding machine, the spirals are connected to the power source while pressing the ends of the pipes. After heating the contact zones to the melting temperature, the power is turned off, and the connection is maintained until it is cooled to a predetermined temperature, which ensures reliability and tightness of the connection. The electric spiral can be wound not on the inner surface of the coupling, but on the ends of the pipes (figure 2).

 Options for simultaneous welding of pipes with a sleeve and butt can be as follows.

 Option 1. Using heating tools - a mandrel and sleeves [2] heat the contact surfaces of the coupling and pipes, at the same time heat the ends of the pipes. Pipes are inserted into the coupling, pressed against each other and held until a reliable weld is obtained.

 Option 2. An electric-spiral coupling is put on one of the pipes, after which the ends of the pipes are heated and quickly brought together, they immediately push the coupling to the joint, press the pipes together and connect the electric spiral of the coupling to the power source.

 Option 3. Previously, at the ends of the pipes make annular grooves 6, while choosing a reinforcing layer 7 (Fig.1, 2 and 3). During welding, polyethylene flows into the ring sample and increases the tightness of the reinforcing layer of the connected pipes.

 Option 4. The ends of the pipes are pre-encapsulated (FIGS. 4 and 5), covered with a layer of plastic 8, which increases the tightness of the reinforcing layer of the connected pipes.

 Welding can be carried out not only with the use of electric coils 4 located on the inner surface of the coupling (Fig. 1, 3 and 6) or on the outer surface of the pipes and their ends (Fig. 7 and 8), as well as using spirals walled in intermediate thin-walled plastic bushings (rings) 5, installed between the pipes and the coupling (Fig.9, 10, 11, 12 and 13).

 To increase the contact surface, the ends of the pipes are stepped and overlap them (Fig. 13).

 At the end of welding, retaining rings can be installed on the coupling, for example, in the form of a fixed winding from a reinforcing tape 9 (Fig. 14).

Claims (3)

1. A method of joining plastic reinforced pipes, including butt welding of pipe ends and welding of a butt weld zone with a reinforced plastic sleeve, characterized in that annular grooves are made at the pipe ends to select the reinforcing layer or the pipe ends are encapsulated by coating with a plastic layer. 2. The method according to claim 1, characterized in that the pipes are welded together and with a sleeve by an electric coil installed in the sleeve, or in pipes, or in an intermediate thin-walled plastic sleeve placed between the pipes and the sleeve. 3. The method according to claim 1 or 2, characterized in that the bandage rings are mounted on the coupling in the form of a fixed winding of reinforcing tape.

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