Device for local compression pipelines

 

(57) Abstract:

The invention relates to the field of power engineering and chemical industry, in particular to a device for creating a favorable compressive stresses in welded joints of pipelines to prevent corrosion cracking under tension during operation. The principle of the proposed device is based on the effect of changes in water density at the transition from a liquid to a solid state of aggregation. The device is made in the form of a split sleeve, equipped with a cooling system and has a working chamber in the form of an annular cavity, covering the pipeline. The compression is due to the hydrostatic water pressure in the working chamber when the cooling device. Simplified design and reduced energy costs. 4 C.p. f-crystals, 3 ill.

The invention relates to the field of power engineering and chemical industry, in particular to a device for creating a favorable compressive stresses in welded joints of pipelines to prevent corrosion cracking under tension during operation.

There is a method of creating a compressive mnogosloinoi hardfacing weld and the area thermocline (see Century Century Rumyantsev. Piping at nuclear power plants: improved reliability and durability. Nuclear technology abroad, 1993, 3, S. 3-8). This technology is used for operating nuclear power plants in the United States. The disadvantage of this method is its high complexity.

Also known a method of creating a favorable residual stresses in the weld seam area, providing local compression of the pipeline in the immediate vicinity of the welded connection using devices made in the form of a split sleeve with replaceable core inserts and hydraulic drive (see J. S. Porowski, W. J. O'donnell, M. L. Badlani and E. J. Hampton. Use of the mechanical stress improvement process to mitigate stress corrosion in BWR piping systems. Nuclear Engineering and Desing. 124 (1990), p. 91-100). These devices are the closest to the claimed device, and adopted for the prototype. Their disadvantage is the high structural complexity and necessity of using a powerful hydraulic drive.

An object of the invention is to simplify the design and reduce energy consumption.

A device for the local compression of pipes made in the form of a split sleeve, equipped with a cooling system, and said sleeve has a built-in heat exchanger and the working chamber in the form of covering the pipeline EOM in the working chamber is placed at least one insert, allows you to vary the volume of the chamber.

The device is provided with extensometry located in the zone of compression, and decompression of the working chamber and / or heating system.

System depressurization of the working chamber is made in the form of two intersecting channels, located in the split sleeve, rolling stock and explosives with a detonator placed in one of the channels, while the working chamber is connected with the atmosphere by another channel, blocked by the said rod.

Heating system made in the form of the current-carrying tires mounted on split sleeve or alimama pipe section, and a current source.

The principle of the proposed device is based on the effect of changes in water density at the transition from a liquid to a solid state of aggregation. The use of water as the working environment for local compression of the pipeline allows the use of structurally simple and less energy consuming device that has no moving force elements. The compression is due to the hydrostatic water pressure in the closed volume of the working chamber.

The claimed device by Fig. 2 - system depressurization of the working chamber, Fig. 3 - heating system.

As can be seen from Fig. 1, the device is made in the form of a split sleeve 1 with the working chamber 2, covering the perimeter of the pipeline 3. Split nut 1 is tightened mounting bolts 4. The device is equipped with a low-temperature cooling system, including the Dewar vessel 5 is filled with liquid nitrogen 6, the evaporator 7, the supply hose 8 and the heat exchanger 9, built-in detachable sleeve 1. The device may contain a removable insert 10 is placed in the working chamber 2. The temperature control is carried out using thermocouples 11. In the split sleeve 1 set extensometry 12.

In Fig. 2 shows a variant of embodiment of the system depressurization of the working chamber. In the split sleeve 1 is made of two intersecting canal 13 and 14. Channel 13 connects the working chamber 2 with the atmosphere and covered by a movable shaft 15, mounted in the channel 14. The latter has the cover 16, between which and the piston rod 15 is placed explosive charge 17 with the detonator wires 18 and 19 connecting the detonator to the source of supply 20.

Variant of embodiment of the heating system shown in Fig. 3. She Gropovod 3, and current source 20.

Compression of the pipeline using the proposed device is as follows.

Split sleeve 1 is installed on the pipeline 3 and tighten the mounting bolts 4. The working chamber 2 is filled with water. Connect the supply hose 8 cooling system to the heat exchanger 9. Include the evaporator 7 and passed a pair of liquid nitrogen through the heat exchanger 9. When cooled split sleeve 1 water in the working chamber 2 turns to ice. The pressure in the chamber 2 increases, occurs radial compression of the pipeline.

Depending on the structural design of the device the water in the working chamber, in whole or in part, into the ice. In the first case you use the device in the working chamber which is placed an insert, allowing you to vary the volume of the chamber, see Fig. 1. The second device with extensometry and system depressurization of the working chamber or the heating system, see Fig.2 and Fig.3

When the compression pipeline for the second process variant, providing partial transformation of water into ice, the process is controlled by extensometers. When the desired deformation producing the traveler through them current and melting ice, and stop the process of compression.

Depressurization of the working chamber is made as follows, see Fig. 2. When the desired deformation of the pipeline 3 undermine the explosive charge 17 using the detonator 18. The rod 15 is moved in the channel 14, the opening of the channel 13. Is the depressurization of the chamber 2, the pressure therein decreases, the compression process is terminated.

Thus, the proposed device provides the possibility of local compression of the pipelines due to hydrostatic water pressure in the closed volume of the working chamber. The device contains no moving force elements, different constructive simplicity and does not require large energy consumption for compression.

1. A device for the local compression of pipes made in the form of a split sleeve, characterized in that it is provided with a cooling system, and said sleeve has a built-in heat exchanger and the working chamber in the form of covering the pipeline annular cavity for filling with water.

2. The device under item 1, characterized in that it is provided with at least one insert placed in the chamber.

3. The device under item 1, characterized in that anistemi heating.

4. The device according to p. 3, characterized in that the system depressurization of the working chamber is made in the form of two intersecting channels, located in the split sleeve, rolling stock and explosives with a detonator placed in one of the channels, while the working chamber is connected with the atmosphere by another channel, blocked by the said rod.

5. The device according to p. 3, characterized in that the heating system is made in the form secured to the split sleeve or alimama pipe section current trunks and current source.

 

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