RU1809908C - Method for insulating pipeline section - Google Patents

Abstract

SUMMARY OF THE INVENTION: Insulating material is applied to the outer surface of the pipeline and heated. Before applying the material to the site, a nozzle is installed, which is deformed during heating of the material. The material is heated in the direction from the middle of the insulated area to its ends. 1 s.p. f-ly, 3 ill.

Description

FIELD OF THE INVENTION This invention relates to pipeline transport, and more particularly to the application of external insulation to a limited section of a pipeline, and can be used in the construction of pipelines.

The purpose of the invention is to improve the quality of insulation and strength properties of the pipeline section by installing a pipe on the insulated section of the pipeline before applying the insulating material and deforming it during heating of the insulating material.

In FIG. 1 shows a simplified illustration of the arrangement of the external insulation elements of a pipeline section in its initial state; Fig. 2 - external insulation of a pipeline section with an additional pipe installed; in FIG. 3 - section of the pipeline with an installed additional pipe in the process of deformation of the pipe.

The method is carried out as follows.

On the surface of the insulated section of the pipeline 1, for example in the zone of the weld 2, a concentric additional pipe 3 is installed with a surface prepared in advance under optimal (workshop) conditions. An insulating material is applied to the prepared surface of the installed pipe and the adjacent insulated zone of the pipeline. A strong casing 5 is laid on the insulated section of the pipeline with a layer 4 of insulating material and a pipe placed on it, the walls of which are tightly adjacent to them. The casing is heated in its middle part. In this case, the portion of the layer of insulating material adjacent to the inner surface of the casing is heated primarily because of its low thermal conductivity. The end sections of the casing and the insulated section of the pipeline are removed from the heating zone and remain cold relative to its middle. Inside the casing, between its wall heated in the middle part and the wall of the additional nozzle, a closed chamber 6 is formed with excess pressure, filled with thermally expanding molten insulating material. Overpressure, image00

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contained in the chamber acts on the walls of the casing and pipe. The nozzle under the action of excessive pressure in the chamber is plastically deformed, decreases in diameter and tightly pressed against the pipe wall, forming with it an elastically stressed connection with guaranteed tension (connection of concentrically arranged cylindrical parts). In this case, the molten insulating material is firmly bonded to the crimped additional pipe. After warming up the middle part of the casing, its ends are warmed up, and the remains of the insulating material in the insulated section of the pipeline are melted. As a result of this, a monolithic insulating shell is formed on the outer surface of the pipeline, reinforced by an additional pipe.

Example. The prepared ends of the pipes 1 (see Fig. 1) with a diameter of 325 mm and a wall thickness of 8 mm were welded together with a seam 2, A coil of pipe 3 with a length of 700 mm was spirally wound to a bare part of the pipeline 1 with a wire of 5 mm diameter from steel 3. The coils were welded together with an intermittent seam 7 with an arbitrary step and the elastic spiral was transformed into a rigid pipe. The surface of the wire was previously cleaned and degreased. A tape 100 mm wide and 0.4 mm thick insulating material of sevilen grade 11306-075 according to TU 6-05-1636-78 was wound on pipe 3 and layers 4 of adjacent external insulation sections 150 mm long. Layer thickness 0.8 mm. Then, on top, they were applied in the form of a tape 100 mm wide and 1 mm thick polyethylene P VD grade 10204003 according to GOST 16337-77. Layer thickness 5 mm. The length of the insulated portion is 1 m. After each layer was applied, the insulating material was heated to a softening temperature to increase the winding plane. After applying the insulating layer, the insulated section of the pipeline was wrapped with three layers of profiled Z-shaped metal tape with a width of 40 mm and a thickness of 1.8 mm. The extreme turns of the spiral formed were welded together by an intermittent seam 7, The length of the thus formed strong casing 5 of steel

30 was 1100 mm and overlapped a superimposed layer of insulating material 50 mm from each end. After placing the casing on the pipeline, its middle part

heated to 220 ° C. The temperature of its ends increased by 8: 10 ° С from the initial one. .

When the casing walls were heated, the adjacent layers of insulating material melted. Under it, a closed chamber 6 was formed with an excess pressure of 70 - 75 kg / cm, filled with molten, thermally expanding insulating material (Fig. 3). Under the influence of this overpressure, the additional pipe 3 radially deformed by 3 mm and pressed tightly against the surface of the pipe 1. A concentric cylindrical part was formed with a guaranteed tension of 0.1 mm. The strength of the two-layer wall of the pipeline in this section increased by 35% (experimentally determined). After 10 minutes of exposure at 220 ° C, the wall of the casing was heated in the rest from the middle to the ends for 5 minutes until there were signs of melt flow of the insulating material from under the casing. Heating was stopped and the casing was cooled under natural conditions, while at the same time isolating the adjacent exposed section of the pipeline. After cooling the casing to ambient temperature, it was removed. A monolithic shell formed on the insulated area, firmly

bonded to the surface of the pipeline (see, FIG. 2). .

Claims (2)

1. The method of isolating a section of the pipeline, which consists in applying an insulating material to its outer surface and then heating it, characterized in that before applying the insulating material to the insulated section of the pipeline, a pipe is installed that is deformed during heating of the insulator tion material. 2. Method pop, 1, characterized in that the heating of the insulating material is carried out in the direction from the middle of the insulated area to its ends. FIG. 7 Fia. 2. Fie.-W