BE1018248A3 - PROCESS FOR REPLACING A TRUNK OF A PIPING AND DEVICE FOR CARRYING OUT SAID METHOD - Google Patents

Abstract

The invention relates to a method for replacing a section of a pipe (1), in which at least one stitching (5) is welded on the pipe (1), the section to be replaced is removed and removed, in the pipeline, on either side of the location of the missing section, at least one inflatable shutter (11, 12), a replacement section (4) is approached, said inflatable shutters (11, 12) are connected between them and with the outside by a cord (15) passing through the section (4) of replacement and by said at least stitching 5, the section 4 is docked, the shutters (11, 12) are inflated, diffused into the space defined by the inflated shutters (11, 12), an inert protective gas, the section (4) is welded and deflated and removed said shutters of the pipework through said at least stitching (5).

Description

Method for replacing a section of a pipe and device for implementing such a method

The present invention relates to a method of replacing a section of a pipe, such as for example a pipe of a hydraulic circuit of a nuclear power plant.

The invention also relates to a device for internal containment of a section to replace a pipe for the implementation of such a replacement method.

Many industrial installations, such as the hydraulic circuits of nuclear power plants or the circuits of petrochemical plants, have large diameter pipes.

After a certain period of use, it turns out that sections of these pipes, for example straight sections or curved sections, become defective and must be replaced.

It may also be useful to replace or add an accessory such as a valve, a valve or an instrumentation on a hydraulic circuit which then requires replacing a section of said circuit with a replacement section thus supporting said accessory or said instrumentation.

For this, the section to replace the pipe is cut, then a replacement section is disposed in the pipe instead of the defective section.

Then, the replacement section is welded to the pipe.

However, in the case of stainless steel piping, for example, or of the INCONEL type, the welding of the replacement section requires protection against, that is to say from inside the piping with an inert gas. , such as for example argon, during the realization of the root pass * of the weld bead as well as during the filling of the first millimeters of said bead.

This protection is intended to prevent oxidation of the weld and surrounding areas.

The confinement of each weld inside the piping can be obtained by placing in this piping, shutters which delimit between them a sealed zone into which the inert gas is injected, which makes it possible to carry out the welding or welding in good conditions.

The difficulty for this type of intervention does not lie in the introduction of the shutters inside the piping before the installation of the replacement section but in the extraction of these shutters after the welding of the replacement section because the more often the ends of the piping are remote and are connected to other equipment so that the shutters are no longer accessible.

The object of the invention is to propose a method of replacing a section of a pipe which makes it possible, by means that are simple to implement and effective, to solve this problem.

The subject of the invention is therefore a method of replacing a section of a pipework with a replacement section, such as for example a pipework of a hydraulic circuit of a nuclear power station, characterized in that: - the pipe is welded close to the section to be replaced or on the replacement section, at least one stitching, - the section to be replaced is cut in the piping and this section is evacuated, - the piping on either side of the of the missing section, at least one inflatable shutter, - the replacement section of the location of the missing section is approached, - said inflatable shutters are connected by a cord passing through the replacement section and by said at least stitching, - docked the replacement section to the piping, - said valves are inflated from outside the piping, - a gas is circulated in the space delimited by said inflated shutters; protection board, - the replacement section is welded to the piping, and - the valves are deflated and removed from the piping by means of the cord through said at least one stitching.

The subject of the invention is also an internal confinement device for a section to be replaced by a pipe for the implementation of the replacement method as previously mentioned, characterized in that it comprises at least two inflatable shutters and one connecting cord, on the one hand, said inflatable shutters together, and secondly, said shutters with the outside of the pipe by at least one nozzle disposed on this pipe near the section to be replaced to inflate said shutters and extracting said at least stitching these shutters after deflation.

According to other characteristics of the invention: the device comprises means for injecting an inert gas between the inflatable shutters, and the connecting cord comprises a connecting cable for ensuring traction on said shutters by said less stitching and at least one flexible conduit for inflating said shutters and injecting the inert gas between these shutters.

Other features and advantages of the invention will appear on reading the following description, given by way of example and with reference to the accompanying drawings, in which: - Figure 1 is a schematic longitudinal sectional view of a portion of a pipe in which a section must be replaced, - Figures 2 and 3 are schematic views in longitudinal section of the portion of the pipe and showing the steps of containment and replacement of the section to be replaced by a section FIG. 4 is a diagrammatic longitudinal sectional view of a first inflatable shutter in the deflated configuration, FIG. 5 is a diagrammatic longitudinal sectional view of a second shutter in the deflated configuration, and FIG. 6 is a schematic longitudinal sectional view of the portion of the pipework showing the extraction of the shutters.

Referring to these figures, we will describe an embodiment, other variants that will be described later, are possible

FIG. 1 diagrammatically shows a portion of a pipework designated as a whole by the reference numeral 1, such as, for example, a pipework of a hydraulic circuit of a nuclear power station.

In the embodiment shown in this figure, this portion of the pipe 1 comprises two rectilinear sections 2 between which is interposed a curved section 3 forming a bend which must be replaced.

The replacement of the section 3 is carried out as follows.

Firstly, it welds on the pipe 1 near the section 3 to be replaced, a tapping 5 which opens inside the pipe 1 in a rectilinear portion 2.

Then, in the pipe 1, the section 3 to be replaced according to two cutting planes, respectively A and B, is cut and after cutting the section 3, this section 3 is evacuated.

As shown in Figure 2, an internal containment device designated by the general reference 10 is disposed in the pipe 1 to isolate the section 3 of the pipe 1 to be replaced, as will be seen later.

This containment device comprises two inflatable shutters, respectively a first inflatable shutter 11 and a second inflatable shutter 12.

The first inflatable shutter 11 is placed in the rectilinear portion 2 near the stitch 5 and the second inflatable shutter 12 is placed in the other straight portion 2 on the other side of the portion of the pipe 1 cut.

Alternatively, each inflatable shutter, respectively 11 and 12, may be composed of a group of shutters comprising one or more shutters 11 or 12 identical mounted in series or different combined with each other.

As shown in Figure 2, a replacement section designated by the reference 4 is approaching replacement of the missing section of the pipe 1 and the two inflatable shutters, respectively 11 and 12, are interconnected by a bead 15 passing through the section replacement 4 and the stitching 5. A pre-inflating of the shutters 11 and 12 can be performed so as to facilitate their introduction into the pipe 1.

Then, the replacement section 4 is approached at each rectilinear portion 2 to reform the pipe 1, as shown in Figure 3.

At rest, the inflatable shutters, respectively 11 and 12, are deflated and are in the configuration shown in Figure 2.

Referring now to FIG. 4, the inflatable shutter 11 will be described. This inflatable shutter 11 comprises a flexible envelope 20 in the form of a tube, one end edge of which is fixed on a head cap 21 and the other end of which end edge is attached to a tail cap 22.

The head cap 21 comprises a first longitudinal orifice 21a and a second longitudinal orifice 21b parallel to each other.

The tail cap 22 has a longitudinal orifice 22a and a second longitudinal orifice 22b extend parallel to the first longitudinal orifice 22a.

The longitudinal orifice 21a of the head cap 21 is connected to the longitudinal orifice 22a of the tail cap 22 via a hose 23 and the longitudinal orifice 21b of the head cap 21 opens inside the flexible envelope 20. The longitudinal orifice 22b of the tail cap 22 opens on one side into the space formed inside the flexible envelope 20 and the other side in the space provided inside the replacement section between the two shutters, respectively 11 and 12.

The second inflatable obturator 12 shown in FIG. 5 is also formed by a flexible tube-shaped envelope 30 of which one end edge is fixed on a head cap 31 and whose other end edge is fixed on a stopper. tail 32.

The head cap 31 has a longitudinal orifice 31a and the tail cap 32 is provided with a small diameter longitudinal orifice 32a forming a controlled leakage system.

Preferably and for the purpose of facilitating the manufacture of the shutters 11 and 12, the respectively head cap 21 and 31 and tail 22 and 32, are identical and each have two longitudinal holes to allow inflation and permanent diffusion of the gas inert in the area between the shutters 11 and 12. In this case, one of the longitudinal holes of the tail cap 32 of the shutter 12 is closed while the other is open to form the controlled leakage system.

The connecting cord 15 has a first portion 15a which connects the head cap 21 of the first inflatable shutter 11 with the outside and a second portion 15b which connects the tail cap 22 of the first shutter 11 with the head cap 31 of the second shutter 12.

The first portion 15a of the connecting cord 15 comprises a flexible conduit 16 which is connected, on the one hand, to unrepresented means for injecting an inert gas under pressure and, on the other hand, to the longitudinal orifices, respectively 21a and 21b.

The second portion 15b of the connecting cord 15 also comprises an inflation duct 16, one end of which is connected to the longitudinal orifice 22a of the tail cap 22 of the first inflatable shutter 11 and whose other end is connected to the longitudinal orifice. 31a of the head cap 31 of the second inflatable obturator 12.

The connecting cord 15 also comprises a connecting cable 17 extending along the first portion 15a and along the second portion 15b of said connecting cord 15.

The connecting cable 17 of the first portion 15a connects the head cap 21 of the first shutter 11 with the outside through the stitching 5 and the connecting cable 17 of the second portion 15b connects the tail cap 22 of the first shutter 11 with the head cap 31 of the second shutter 12.

After placing the two shutters 11 and 12 inside the rectilinear sections 2 of the pipe 1 and connected these two shutters 11 and 12 by the connecting cord 15 and also connected the shutter 11 with the outside of the pipe 1 through stitching 5, as shown in Figure 2, the replacement section 4 is approached to the pipe 1, as shown in Figure 3.

Before setting up the shutters 11 and 12 in the pipe 1, pre-inflating of these shutters 11 and 12 can be performed to ensure their proper placement.

Then, the two shutters 11 and 12 are inflated by injecting an inert gas under pressure through the hose 16 of the connecting cord 15. The inert gas enters the flexible envelope 20 of the first shutter 11 through the longitudinal orifice 21b. This inert gas also passes through the longitudinal orifice 21a, the hose 23, the longitudinal orifice 22a, the flexible conduit 16 of the portion 15a of the cord 15, and then inflates the flexible envelope 30 of the second shutter 12 through the orifice longitudinal 31a. This inert gas is also injected into the space defined between the two shutters 11 and 12.

Indeed, the pressurized inert gas passes through the longitudinal orifice 21b of the head cap 21 of the shutter 11, then passes into the flexible envelope 20 of the shutter 11 and passes through the longitudinal orifice 22b of the tail cap 22 to diffuse inside the internal space delimited by the two shutters 11 and 12 inflated.

The replacement section 4 is then welded between the two straight sections 2 of the pipe 1 and, during this welding, an inert gas protection, such as argon, is maintained inside the replacement section 4, This makes it possible to perform the two welds in good conditions and to avoid the oxidation of each of these welds and the surrounding areas, in particular during the realization of the root pass and the first millimeters of filling of each weld.

The two shutters, respectively 11 and 12, are then deflated, then removed from the pipe 1 through the stitching 5 as shown in FIG. 6. For this, a traction is performed on the connecting cable 17 from outside the piping 1 and when each shutter 11 or 12 passes into the nozzle 5, its corresponding flexible envelope retracts, as shown in Figure 6.

For example, the internal diameter of the pipe 1 is of the order of 300 mm and the tapping 5 has an internal diameter of about 50 mm.

The flow rate of inert gas is of the order of 5 to 10 l / min and the second shutter 12 has via the longitudinal orifice 32a, a controlled leakage system to avoid pressure build the delimited chamber by the envelope 30 of this second shutter 12.

The two shutters 11 and 12 can be inflated simultaneously or successively and, in this case, each shutter can have its own flexible inflating conduit.

Several variants are possible for the arrangement of the stitching 5 without departing from the scope of the invention.

According to a first variant, one or more taps 5 may be welded to the replacement section 4.

According to a second variant, one or more taps 5 may be welded on the pipe 1 and on the replacement section 4.

According to a third variant, two taps 5 may be arranged on either side of the section 4 to be replaced to the extent that this section 4 is of great length. In this case, two shutters can be arranged on either side of the left weld and two shutters can be arranged on either side of the right weld.

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Claims (4)

1.- Method for replacing a section of a pipe (1) with a replacement section (4), such as for example a pipework of a hydraulic circuit of a nuclear power station, characterized in that: - one soda on the pipe (1) near the section (3) to be replaced or on the replacement section (4), at least one stitching (5) - is cut in the pipe (1) the section (3) to be replaced and this section (3) is evacuated, - at least one inflatable shutter (11, 12) is arranged in the pipework (1) on either side of the location of the missing section, - the section (4) is approached replacing the location of the missing section, - connecting said inflatable shutters (11, 12) to each other and to the outside of the pipework (1) by a bead (15) passing through the replacement section (4) and by at least said stitching (5), - the replacement section (4) is docked to the pipe (1), - it is inflated from outside the yauterie (1), said shutters (11.12), - an inert shielding gas is diffused in the space delimited by said inflated shutters (11, 12), - the replacement section (4) is welded to the pipework ( 1), and - deflates and removes said shutters (11, 12) of the pipe (1) by means of the cord (15) through said at least stitching (5). 2. Device for internal containment of a section to replace a pipe (1) for implementing the replacement method according to claim 1, characterized in that it comprises at least two inflatable shutters (11, 12). and a bead (15) connecting, on the one hand, said inflatable shutters (11, 12) to each other and, on the other hand, said shutters (11, 12) with the outside of the piping (1) by at least one stitching (5) disposed on this pipe (1) close to the section (3) to be replaced to inflate said shutters (11, 12) and extracting said at least stitching (5) these shutters (11, 12) after their deflation, 3. Device according to claim 2, characterized in that it comprises means for injecting an inert gas between said inflatable shutters (11,12). 4, - Device according to claim 2 or 3, characterized in that the connecting cord (15) comprises a cable (17) connecting to ensure traction on said shutters (11, 12) by said at least stitching (5) and at least one flexible conduit (16) for inflating said shutters (11, 12) and injecting the inert gas between said shutters (11, 12).