RU2268435C1 - Mode of making a current insulating insertion for a pipeline - Google Patents

Abstract

FIELD: the invention refers to the field of the pipeline transport and may be used for electric disconnection of pipelines and/or their sections particularly at protecting them from corrosion.

SUBSTANCE: dielectric insertions are placed between adjacent butt-ends of two sockets fulfilled out of the material of the pipeline and between the sockets and the exterior muff connecting them. The interior surface of the sockets in the zone of location of the muff is provided with ring lugs with the height exceeding the thickness of the dielectric insertions between the sockets and the muff and radial distribution of sockets is carried out as a minimum until elimination of gaps between the sockets and the muff along the entire length of their coupling. The ring lug on the interior surface of the sockets are made by way of fixing of packing rings inside the sockets. As dielectric insertions between the sockets and the muff an exterior plastic covering of the sockets may be used. In case of transporting along the pipeline of electrically conducting fluid the inner surface of current insulating insertion is provided with dielectric covering.

EFFECT: reduces labor-intensiveness of manufacturing.

4 cl, 3 dwg

Description

The invention relates to pipeline transport and can be used for electrical separation of pipelines and / or their sections.

A known method of manufacturing a current-insulating connection for a pipeline, including the inner groove of the adjacent ends of two nozzles, placement and attachment in the grooves of a common dielectric coil, and in the gap between the ends of the nozzles - a dielectric ring and the formation on the outer surface of the adjacent ends of the nozzles of the fiberglass winding (US Pat. RF No. 2174638 C. F 16 L 25/03, publ. 10.10.01).

The disadvantage of this method is the high complexity of manufacturing and low strength of the resulting compounds in bending and tensile loads.

The closest in technical essence to the proposed one is a method of manufacturing a current-insulating insert, comprising an integral coupling connection of two pipe sections made of the same material as the pipeline, with preliminary placement of dielectric spacers between the surfaces of the pipe sections and the coupling and between adjacent ends of the pipe sections. According to the description of the invention, an integral coupling connection is performed by radially crimping a coupling having annular protrusions at the ends (US Pat. RF No. 2131949, class C 23 F 13/00, publ. 20.06.99).

The disadvantage of this method is the high complexity of manufacturing, due to the need to use bulky and energy-intensive equipment for radial crimping of the coupling.

The objective of the invention is to reduce the complexity of manufacturing a current-insulating insert.

The problem is solved in that in the method of manufacturing a current-insulating insert for a pipeline, comprising placing between adjacent ends of two nozzles made of pipeline material, and between the nozzles and the external coupling of the dielectric gaskets connecting them and the integral connection of the pipes by the joint by joint radial deformation of the pipes and the coupling, according to the invention, the inner surface of the nozzles in the area of the coupling is provided with annular protrusions of a height exceeding the thickness of the dielectric their gaskets between the nozzles and the coupling, and radially distribute the nozzles, at least until the clearances between the nozzles and the coupling along the entire length of their joint are removed.

Annular protrusions on the inner surface of the nozzles can be created by fixing inside the nozzles of the washer rings.

As dielectric gaskets between the nozzles and the coupling, an external polymer coating of the nozzles can be used.

In addition, the inner surface of the insulating insert is provided with a dielectric coating.

The method is illustrated by drawings, which shows longitudinal sections of the assembly of a current-insulating insert before distributing the nozzles (Fig. 1), after distributing them with a mandrel (Fig. 2) and a current-insulating insert with an internal dielectric coating (Fig. 3).

The method is as follows.

Pipes 1 are made (see Fig. 1) from a pipe material having an external polymer insulation 2. Inside the nozzles in the area of the coupling 3 installation, the underlay rings 4 are installed and fixed by welding, with a thickness exceeding the thickness of the outer insulation of the nozzles. A dielectric spacer 5 is placed between adjacent ends of the nozzles and an assembly of a current-insulating insert is assembled, as shown in FIG. Distribute the nozzles along their entire length with a turning device, at least until the radial clearance between the coupling and the nozzles is eliminated. At the same time, in the locations of the washer rings, the nozzles are pressed into the coupling, forming a lockable one-piece connection of the nozzles by the coupling (see Fig. 2). The deformations of the nozzles and the coupling, in addition to the plastic one, contain an elastic component, which ensures constant contact pressure over the entire contact surface of the coupling with the nozzles and, therefore, the tightness of the connection, since the outer polymer coating of the nozzles plays the role of not only an electrical insulator, but also a sealing gasket. The presence of the coupling and locks provides high strength joints with respect to tensile and bending loads.

If an electrically conductive liquid is transported through the pipeline (water, flooded oil, etc.), then to reduce the flow of electric current through the liquid in the pipeline, the inner surface of the current-insulating insert is provided with a dielectric coating 6 (see Fig. 3). If the pipeline also has an internal coating, then to prevent burnout of the coating in the weld zone, the ends of the current-insulating insert are equipped with tips 7 made of corrosion-resistant steel. The welded ends of the pipeline are supplied with the same tips. If the pipeline does not have an internal coating, then the tips 7 are not installed; it is enough to apply an adhesive coating that does not require a high temperature to cure it.

In the described method of manufacturing a current-insulating insert, small-sized durning equipment (horizontal hydraulic press with a mandrel) of low power is used, since the force during distribution is 1.5-2 times lower than the force during external crimping of the coupling. All this reduces the complexity of manufacturing a current-insulating insert.

An example of a specific implementation.

From a steel pipe in accordance with GOST 8732-78 with a diameter of 273 mm and a wall thickness of 9 mm, having a two-layer extrusion polyethylene outer coating with a thickness of 3 mm, 2 pipes with a length of 750 mm were made. At the inconsistent ends of the nozzles at a distance of 100 mm from the ends, the outer coating was removed and the bevel for butt welding was removed. Inside the nozzles at a distance of 200 mm from the butt ends, by welding with an intermittent seam (to avoid thermal damage to the outer coating), steel rings were fixed with an outer diameter of 254 mm, a wall thickness of 6 mm and a width of 100 mm. From a steel pipe according to GOST 8732-78 with an outer diameter of 299 mm and a wall thickness of 9 mm, a sleeve 800 mm long was made. We placed the connected ends of the nozzles in the coupling with the installation of a 20 mm thick polyethylene gasket between the ends of the nozzles. Using a horizontal hydraulic press, which develops a force of up to 50 tons, and a mandrel with a diameter of 258 mm, pipes were distributed along their entire length. A polyethylene pipe with a diameter of 257 mm, a wall thickness of 6 mm and a length of 1100 mm was inserted inside the current-insulating insert and its ends were fixed with a tip made of corrosion-resistant steel grade 08X18H10T by distributing it using the same turning equipment. A current-insulating insert with such an inner coating is recommended for use in pipelines made of pipes lined with polyethylene pipes, the ends of which are also fixed with 08Kh18N10T steel lugs. Electrical and hydraulic tests showed that the obtained insulating insert in a non-conductive medium has an almost infinite electrical resistance between the ends and is sealed at a pressure of up to 15 MPa (usually the working pressure of a pipeline with a diameter of 273 mm does not exceed 10 MPa).

Claims (4)

1. A method of manufacturing a current-insulating insert for a pipeline, comprising placing between adjacent ends of two nozzles made of pipeline material, and between the nozzles and the external coupling of the dielectric spacers connecting them and the integral connection of the pipes by a joint by joint radial deformation of the pipes and couplings, characterized in that the internal the surface of the nozzles in the area of the coupling is provided with annular projections with a height exceeding the thickness of the dielectric gaskets between the nozzles and the coupling, and radially distribute the nozzles, at least until the clearances between the nozzles and the coupling are eliminated along the entire length of their joint. 2. The method according to claim 1, characterized in that the annular protrusions on the inner surface of the nozzles are created by fixing inside the nozzles of the washer rings. 3. The method according to claim 1 or 2, characterized in that as the dielectric spacers between the nozzles and the coupling, an external polymer coating of the nozzles is used. 4. The method according to claim 1 or 2, characterized in that the inner surface of the insulating insert is provided with a dielectric coating.

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