FR3096752A1 - Instrumented scraper for the inspection of pipeline pipelines. - Google Patents

Abstract

TITLE. Instrumented scraper for the inspection of pipeline pipelines. The invention relates to an instrumented scraper in which is installed a measuring device making it possible to detect and locate a leak, or an illegal withdrawal of product (active or stopped) in a pipeline. This device is designed to provide in the scraper, a sealed measuring chamber called the reference volume, delimited on the one hand, at the ends of the scraper, by two sealing cups and, on the other hand, by the internal wall of the pipe. , and the central body of the scraper in which the pressure is measured and compared to the reference pressure corresponding to the pressure at which the fluid circulates inside the pipe; a negative pressure variation in this referent volume indicates the presence of a loss of product by leakage or clandestine withdrawal. Other pressure variations, recorded and correlated with the line profile documents (weld book and others), also allow its rapid location. In addition, a positive displacement pump, driven and motorized by the advancement of the scraper, injects and withdraws at a studied rate a calibrated volume of product taken from the tube, inducing an increase and a decrease in pressure in the reference volume. This operation consists in following the measure of the compressibility of the referent volume. When the scraper arrives at a non-active clandestine nozzle, the pressure delta will be lower. In fact, the referent volume has, in line with the stitching, increased in volume by the contribution of the pirate volume and therefore increased the compressibility of the referent volume. This device helps address the online product theft issues facing pipeline operators today.

Description

Instrumented scraper for pipeline pipe inspection.

The present invention relates to the field of the transport of hydrocarbons, and more particularly the transport of these products through pipelines, generally called pipelines in the case of the transport of oil or other liquid hydrocarbons.

More specifically, the invention relates to an instrumented scraper for detecting and locating a product leak and non-active clandestine tappings circulating in pipelines, in particular oil pipelines.

In general, a pipeline consists of a means allowing the transport of fluid materials, for example hydrocarbons, natural gas, chemicals, from one point to another, over greater or lesser distances via conduits or pipes arranged in a network, these can be buried.

Indeed, burying pipelines in the ground is often favored for reasons of safety and aesthetics in particular, by allowing greater discretion and a reduced impact on the external environment, in particular on fauna and flora.

Generally, a pipeline is composed, in addition to pipe segments, of a length varying from 5 to 12 m, butted and welded together, of the following elements:

- a head pumping station, for example located in an oil port or in a production field, constituting the entry point for the product to be transported on the network;

- a plurality of relay pumping stations for liquids, or compression stations, for gases, regularly distributed over the network to ensure the continuity of the flow of the product within said network;

- intermediate and end delivery terminals, to supply regional depots.

In order to ensure the proper functioning of the installations, and to guarantee that the product will be correctly transported along the pipelines, it is necessary to periodically check all the constituent elements of this transport system, whether the pipes , taps, pumps, etc.

As far as pipelines are concerned, they are likely to be subject to various hazards. This may include damage caused by third parties, due to agricultural work or undeclared earthworks in the municipalities crossed, damage linked to the corrosive circulating product, defects in the cathodic protection used to protect the structures corrosion.

It may also be necessary to locate fraudulent actions organized by third parties and, in particular, clandestine tapping intended to carry out product withdrawal.

When the control operations reveal an anomaly, rapid intervention may prove necessary in order to remedy the malfunction identified and ensure the delivery of the products in optimal conditions.

However, such inspection operations can be tedious, especially when it comes to examining the inside of the pipes, and all the more so when these pipes are buried.

To this end, it is known, in the state of the art, to implement special devices specially adapted for the internal inspection of pipes.

Such devices are called "scrapers" or "pistons", and are generally qualified as "instrumented" when they include means for measuring and recording certain physical quantities concerning the tube.

Ordinary scrapers in common use, not having such particular measuring or recording equipment, are also known in the state of the art. These scrapers are generally used for pipe cleaning operations and, with this in mind, are equipped with suitable brushes, often metallic.

Regardless of the type of scrapers implemented in the main lines, these are autonomous. They are driven, inside and along the pipes, by means of the fluid they transport, or else by water.

Generally, the inspection of pipes by instrumented pigs can be carried out without stopping production, in a line in operation whose flow rate has been adapted for the needs of the inspection.

The implementation of scrapers, instrumented or not, implies that the pipeline to be checked is equipped, at each end, at least temporarily, with "scraper stations", which consist of a kind of airlock. Thus, the scraper is introduced at the head of the line at the level of a departure station then is extracted, from this same line, at the end of the inspection, at the level of an arrival station.

The distances between these stations vary, depending on the network, between a few hundred meters and several hundred kilometers. During its journey, the instrumented pig, generally made up of several modules, is logically equipped with an electromagnetic tracking means, or other, to be spotted from the outside in various places of the pipeline by the agents responsible for its launch.

Once the instrumented scraper has been picked up at the station and transferred to the workshop, the data it has collected during its inspection is transferred, for example to a specific computer that is part of the scraper system.

From this moment, the data extraction phase begins on screen and printer, and the data is analyzed in order to determine, depending on the type of scraper used:

- the presence of any corrosion problems,

- abnormal variations in tube geometry,

- the possible presence of cracks, leaks, etc.

Devices of the instrumented scraper type known from the state of the art are generally composed of one or more functionally distinct element(s), or “modules”.

Thus, generally, an instrumented scraper incorporates:

- a first unit, or "head module", has the function of ensuring the traction of the instrumented scraper under the pressure of the fluid transported within the pipeline, by means of cups. This head module generally contains all or part of the on-board energy, in the form of power supply means of the cell or battery type;

- a second scraper module comprises a system for detecting and measuring the defects sought, mainly by magnetic or ultrasonic method;

- a third module containing the memories and the management of the distance counting, for example in the form of "encoder" wheels in contact with the tube, which make it possible to record the distance traveled within the pipe and subsequently position the data collected, especially in the event of default.

All the modules that make up the instrumented scraper device are linked together by gimbals ensuring the maximum flexibility of the said device, necessary for its routing in the curved parts of the pipes.

These types of instrumented scrapers are used with a prevention objective. In other words, we seek to locate the presence of any defects, with a view to being able to carry out repairs before a product leak occurs.

To do this, pipeline companies compare, in real time, incoming product quantities with outgoing product quantities. These comparisons, also called “line balance”, are carried out by a powerful computer system, over time deltas ranging from a minute to a week, or even more.

However, this line balance can only give a trend over the entire network, which is likely to include several lines.

Also, for this reason, each of the lines of a network is periodically inspected by a specific instrumented scraper, the instrumented leak detector scraper.

More particularly, such an instrumented leak detector scraper is monobody and is equipped with a hydrophone. The latter, by means of an acoustic measurement, is suitable for identifying the specific noise produced by a leak of pressurized liquid, which expands in an environment at atmospheric pressure.

In order to be silent in its inspection mission based on listening, its cups are reduced to 75% of the diameter of the tube, so as not to rub. They silently provide the scraper, through the dynamic thrust of the moving fluid, with the energy necessary for its propulsion inside the pipe.

The hydrophone records variations in a specific frequency band and, when the instrumented leak detector scraper passes over a liquid leak, three pieces of information will then be recorded: the acoustic level of the hiss resulting from the expansion of the product, the online pressure, as well as the time.

At the end of the mission, when the instrumented leak detector pig is extracted from the inspected pipe, the data recorded over the entire length of the pipeline is delivered.

Reading this data, several pieces of information emerge:

- a first piece of information consists of a physically organized noise signal, emerging from the background noise, and which probably indicates a leak on this line;

- a second piece of information gives the pressure of the line to the right of this signal;

- a third piece of information stems from the volume pumped up to the time of the detected signal;

- a fourth piece of information indicates the presumed location of the fault read on the line documents associating pumped volume and kilometric point.

However, this scraper being moved by small cups, therefore leaking, the location of a leak will be imprecise, because said scraper will have slipped in relation to the product. The hydraulic thrust force on the scraper is a function of (∆v²/2g), ∆v being the difference in speed between the product and the scraper. This delay will therefore result in an uncertainty of a few tens or hundreds of meters on the location of the leak.

Consequently, in order to obtain a more precise location of the leak, it will be necessary to carry out a second operation of a different nature, limited to the identified area of uncertainty, or to launch the scraper again with this time marking in this same area. Such location operations, in particular the need for a second launch, have the disadvantage of being costly in terms of time, require significant human resources, and inevitably lead to a halt in the transport of product within the pipeline to be checked.

A pipeline line now known to be leaky will necessarily be impounded to perform the follow-up launch. This water will then have to be cleaned up, and decanted in a rented tank, before being discharged into nature.

This second operation, for the precise location of the leak, induces an additional cost, greater than the previous one.

In addition, for some time now, the transport of liquid hydrocarbons, products with high added value, has been faced with a problem of product theft via in-line tapping, an operation consisting of extracting product from a buried pipeline.

Once the hot tapping has been carried out with the installation of a valve in line with the tube, a pipe, of the high pressure flexible type, buried, is connected from this valve to a recovery means located a few hundred meters from the pipeline. . A second tap, at the end of the pipe, allows the product to be withdrawn at will, whatever the state of the line, when it is stopped or in operation.

In this case, in search of a leak, the noise of the trigger at the right of the tube will be reduced because all or part of this trigger will be made at the end valve of the device used by the pirates who recover the product. The place of the relief, in line with the tube or in line with the end valve, will depend on the line pressure, the flow rate of the withdrawal, and the importance of the pressure drop in the high pressure flexible pipe.

Consequently, because part or all of this expansion is transferred outside the right-of-way of the pipeline, it will no longer be audible by the current tracking system, namely the hydrophone positioned on the instrumented pig.

To deal with these various difficulties, oil companies are now looking for a solution.

It is within the framework of an inventive approach that the inventors have developed an instrumented scraper which, on the one hand, is capable of detecting such leaks which are now less noisy and therefore more difficult to detect by systems. and on the other hand, this new system considerably improves the precision of the location of the leak by allowing immediate and very precise identification of the location of the fault: leak with or without tapping.

To this end, the present invention relates to an instrumented scraper for detecting and locating a fluid leak from the inside of a pipeline pipe, said pipe consisting of a plurality of tubes joined two by two by one. butt weld characterized in that it comprises at least one upstream sealing cup and one downstream sealing cup, taking into account the direction of movement of said instrumented scraper in the pipe, said two cups being interconnected at the means of a central body, said two sealing cups, defining, moreover, with said central body and the internal wall of the pipe, a sealed reference volume, peripheral to said central body, in which the pressure is measured and recorded periodically .

This is carried out by means for measuring and recording the pressure, the latter being capable of detecting at least one negative pressure variation within said reference volume at the level of said fluid leak, with respect to a reference pressure at the within the reference volume in the absence of a leak corresponding to the pressure at which the fluid circulates inside the pipe.

Advantageously, the present invention makes it possible to locate tappings in line and thus to better cope with the new phenomenon of hydrocarbon theft in pipelines.

According to another characteristic, the present invention allows, by a finer localization than by the existing methods, the precise localization of a leak or of a clandestine withdrawal, and thus avoids a costly additional launch of a classic operation of search for leaks.

According to other additional advantageous and optional characteristics of the instrumented scraper according to the invention:

- the referent volume is optimized and between 6 and 77 liters for lines whose diameters are between 8" and 20";

- the means for measuring and recording the pressure is able to measure and record during a leak, a pressure drop of 0.01 to several bars in the referent volume;

- the measuring and recording means is capable of detecting pressure variations of the order of 10 to 300 mbar in the reference volume induced by the weld beads in the reference volume;

- the measuring and recording means is capable of detecting changes in pressure, of the order of 50 to 800 mbar in the reference volume induced by changes in the thickness of the tubes.

The invention also relates to an instrumented scraper for detecting and locating a non-active pirate tapping, from inside a pipeline pipe, said pipe being made up of a plurality of tubes butted two by two by a butt weld characterized in that it comprises at least one upstream sealing cup and one downstream sealing cup, taking into account the direction of movement of said instrumented scraper in the pipe, said two cups being interconnected by means of a central body, to which is attached a device containing a volumetric pump injecting and withdrawing alternately a calibrated and constant quantity of product in the reference volume, reference volume in which the pressure is measured and recorded periodically by a measuring means and for recording the pressure, the latter being capable of detecting smaller pressure differences generated by the presence of a pirate volume added to the referent volume with respect to a reference pressure within this same referent volume.

Other characteristics and advantages of the invention will emerge from the detailed description which will follow of the non-limiting embodiments of the invention, with reference to the appended figures in which:

schematically represents a view in longitudinal section of a buried pipeline pipe inside which runs an instrumented scraper according to a particular embodiment of the present invention, in which a sealed reference volume is arranged between a cup upstream seal and a downstream seal cup connected to each other by means of a central body, said reference volume being framed, in addition to said two cups, by said central body of the scraper and by the internal wall of the pipe, said central body housing a pressure recording sensor installed in a sealed container connected by a hose to the pressure tap of the referent volume;

represents, schematically, a cross-sectional view of a pipe, in which there is an instrumented scraper according to a particular embodiment of the invention;

shows, schematically, an embodiment of a detail of the instrumented scraper device according to the invention, in this case the lips of a cup which seal the volume referring even to the passage of a weld bead connecting two adjacent tubes of a pipeline to each other or during thickness variations;

schematically illustrates the comparison between a sequence corresponding to the welds between the butt-jointed tubes of a pipeline pipe installed at the time of construction of said pipeline and a sequence of delta P pressure variations collected by the scraper instrumented according to the invention during its journey within said pipe, the comparison between said two sequences allowing the precise location of the product leak out of the pipe;

schematically illustrates a clandestine on-line pick-up;

schematically illustrates a scraper detecting non-active or inert leaks and clandestine tappings, in which a volumetric pump is coupled to the scraper and whose mode of operation will be described further;

consists of a graphical representation illustrating, according to the theory, the measurements made by an instrumented scraper device detecting inert taps and leaks.

With reference to the figures of the accompanying drawings, in particular figures 1 and 2, the present invention relates to an instrumented scraper device 1 intended to allow the detection of a leak 2 of fluid, in particular of liquid, which is normally conveyed, from a starting point to a point of arrival, by means of a line 3 of a pipeline 4.

Preferably, the instrumented scraper 1 of the invention is intended to allow the internal inspection of a pipe 3 in which a liquid hydrocarbon is conveyed.

The pipe 3 in which the leak 2, symbolized by a solid arrow in FIG. 1 occurs, is, for example, an underground pipe, positioned under the surface of the ground 41, as is also illustrated in this figure.

However, it is also possible that the pipe 3 which must be inspected is a non-underground pipe, and therefore arranged above the surface of the ground 41.

Such a pipe 3 is usually formed of a plurality of tubes butted in pairs and connected together by means of a butt weld 31, such a weld 31 being visible in particular in Figure 3.

The instrumented scraper 1 object of the present invention comprises at least, essentially, two sealing cups 5 and 6, namely, more particularly, an upstream cup 5 and a downstream cup 6, taking into account the direction of movement 7 of said instrumented scraper 1 in pipe 3, this direction of movement 7 being symbolized by an arrow in FIG. 1.

The two cups upstream 5 and downstream 6 of the instrumented scraper 1 are interconnected by means of a central body 8.

This central body 8, in equal pressure, consists, preferably, but not limited to, of a cylinder, and is advantageously made from a metallic material, preferably from steel. It ensures, in particular, the rigidity and the overall structure of the entire scraper device 1, between the two cups 5, 6.

For this, at each of its ends, an upstream 51 and downstream 61 flange is welded to allow fixing in a sandwich, with the addition of two circular flanges upstream 19 and downstream 17 of the upstream 5 and downstream 6 sealing cups. he set of flanges, cups, and flanges is locked at each end, by a distributed set of braked bolts.

The upstream flange 19 is perforated to allow access to the interior of the central body 8 where the container assembly 12 is arranged, comprising a lid 20, and pressure recording sensor 11, a bulkhead crossing 15 and its hose 14 of connection with the referent volume 10. The downstream flange 17 is full. It contributes, in the same way as the sealing cups 5 and 6, to the propulsion of the scraper 1 under the effect of the pumping pressure. These two flanges 17, 19 can also serve as a support for fixing the anchoring means 16, and for the electromagnetic tracking system 18.

Outside the central body 8 of the instrumented scraper 1, is defined a reference volume 10, sealed with respect to the rest of the pipe 3, the latter being delimited, in addition to said central body 8, on the one hand, by the upstream 5 and downstream 6 cups at the two ends of the instrumented scraper 1, and on the other hand, by the internal wall 9 of said pipe 3.

In other words, on the periphery of the cylindrical central body 8, the upstream 5 and downstream 6 sealing cups, positioned on either side of said central body 8, make it possible to isolate such a reference volume 10 from the rest of the pipe 3 in which the circulation of the product to be transported continues even when said pipe is inspected by means of the instrumented scraper 1 of the invention, the latter being moreover driven by the product moving within the pipe 3.

The referent volume 10 is therefore deliberately isolated from the pipe 3 while being mobile and sealed.

With a view to guaranteeing the tightness of the referent volume 10, the upstream 5 and downstream 6 cups have a high inertia, and are for example, but not limited to, made from polyurethane, while having a significant thickness, in particular of the order of 25 mm, and profiled lips preferably conical as illustrated in figure 3.

Said upstream 5 and downstream 6 cups frame the referent volume 10.

In a preferred embodiment, the value of the reference volume 10 for each scraper diameter is preferably between 6 and 77 liters, for the diameters of lines 3 ranging from 8 to 20".

This referent volume 10 must be as small as possible to increase the detection sensitivity of the scraper 1, is optimized within the limit of the capacity of the latter 1 to cross the line hangers 3, the minimum radius of curvature of which can be 1.5D.

The maximum optimized distance between the upstream 5 and downstream 6 sealing cups of the scraper 1 will therefore be substantially equal to 1.10 times the diameter of the line 3, and the ratio between the diameter of the line 3 and the diameter of the body 8 of 1.7.

The sensitivity of the scraper 1 is all the greater as the diameter of the line 3 is small. Therefore, a leak of 100 litres/hour will induce a pressure drop in the referent volume 10 of 3 bar for a line 3 with a diameter of 20", and of 16 bar for a line 3 with a diameter of 8".

Is arranged, inside this central body 8, a sealed container 12 in which is housed a pressure recording sensor 11. This sensor 11 is hydraulically connected via a partition crossing 15 in the container, and of a hose 14, to a pressure tap 13, in the referent volume.

The recording sensor 11 of the pressure in the referent volume 10 is advantageously provided with a power supply means to guarantee its correct operation all along the path of the instrumented scraper 1 inside the pipe 3, in the form , for example, batteries or cells.

Advantageously, such a means for measuring and recording the pressure 11 allows the detection of a pressure drop or negative pressure variation, within the reference volume 10 as defined above, in particular when the instrumented scraper 1 of the invention passes in line with a fluid leak 2.

Such a drop in pressure is detected by comparison with a reference pressure measured within the referent volume 10 in the absence of leak 2, and substantially corresponding to the pressure at which the fluid circulates inside the pipe 3.

Thus, during an inspection of pipe 3 of pipeline 4 by means of an instrumented scraper 1 according to the invention, in the event that a degradation in the wall of said pipe 3 leads to a leak of the fluid which is transported therein , said scraper 1 will be capable of measuring and recording a drop in pressure, associated with such a leak 2, in the referent volume 10.

It should be noted that, by means of the importance of the negative delta P measured, it will be possible, using suitable calculation means, to deduce an order of magnitude from the flow rate of the leak or the pirate withdrawal, for example in litre/hour notably.

In a preferred exemplary embodiment, for example the recording sensor 11 is capable of performing continuous measurements and recordings of the pressure in the referent volume 10, at the rate of a sampling of at least five measurements per second, the pressure measured by said sensor 11 at a given location being substantially equal to the pressure of the pipe 3 at this location.

Even more preferably, the recording sensor 11 can take ten pressure measurements per second, which allows it, at its speed of 1 m/s, to perform at least 4 measurements in a line 3 with a diameter of 8" (219 mm) and 7 measures in a row 3 in diameter 20" (508 mm).

With a view to allowing such measurements, the pressure recording sensor 11 must, by way of example but not limited to, present the following performances:

- measured pressure scale: 0 - 100 bar;

- sampling: 10 measurements/second;

- precision: 0.025% of the measured pressure;

- resolution: 1 mbar;

- memory capacity: 1000000.

A leak 2 of product out of the pipe 3, whether due to malicious withdrawal or localized degradation of said pipe 3, will result in a large drop in pressure in the referent volume 10 of the instrumented scraper. This will be measured by the pressure recording sensor 11, substantially lower, from 0.01 to several bars, than the pressure measured in the rest of the pipe 3, where there is no leak 2 of product.

This relatively large negative pressure variation in the referent volume 10, which can be detected by means of the instrumented scraper 1 according to the invention, results from the combination of various factors which are, in particular, the presence of a liquid leak in pipe 3, the provision of a reference volume 10 where the pressure is measured which is both sealed and of optimized dimensions, the low compressibility of the liquids circulating inside the pipe and finally, the frequency measurements (10 measurements per second).

Interestingly, and specific to the present invention, the instrumented scraper 1 developed, in addition to the fact of making it possible to detect, with certainty, a leak 2 of product which is more difficult to detect by traditional scrapers equipped with hydrophones, due to its original design, facilitates the precise location of said leak 2.

Indeed, the pipes 3 of a pipeline 4 generally consist of a plurality of tubes butted together in pairs by a butt weld 31, said tubes having a length generally comprised between five and twelve meters.

Whatever the thickness of the walls of the tubes constituting the pipe 3, each weld bead 31 connecting two tubes causes the formation of an emergence, or emergent bead, at the level of the internal 9 and external wall of the pipe 3, under the form of an extra thickness, between 0.5 and 1.5 mm, 10 mm wide inside and outside this pipe 3.

Such an internal emergence at the level of the weld bead 31 is more particularly visible in FIG. 3 attached.

When the instrumented scraper 1 passes over each of the weld beads 31 present along the pipe 3, the pressure measuring and recording means 11, in the form of a recording sensor 11, will detect a relatively small pressure variation, positive this time, with respect to the reference pressure of the pipe 3, and which corresponds to the additional force necessarily provided by an additional pressure to the instrumented scraper 1, and in particular by the cups upstream 5 and downstream 6, at the time of crossing each of said weld beads 31.

Generally, such a pressure variation detected by the recording sensor 11 at the time of passage of the instrumented scraper 1 of the invention at the level of a weld bead 31, and due to the change in thickness of the pipe 3 at this location , is greater than 50 mbar and generally depending on the diameter of the lines, and the qualities of the welds, between 50 and 300 mbar.

In other words, when the pipe 3 does not have any extra thickness due to a weld bead 31, and in the absence of a leak 2, the recording sensor 11 will measure a reference pressure within the referent volume 10. When of the passage of a weld bead 31 through the scraper 1, in particular through the upstream cup 5 thereof, a low positive delta P will be measured and the measured pressure will then be slightly higher than the reference pressure. Then, once the weld bead 31 has been crossed by the downstream cup 6, a new delta P is recorded, negative this time, to return to the reference pressure.

These low delta P measured by the recording sensor 11, due to the weld beads 31 will make it possible to facilitate the location of the leaking tube.

The reference pressure will also change when the instrumented scraper 1, traveling within a pipe 3, encounters a reinforced 62 or reduced 62 section of pipe. The pressure variation delta P generated in this case will be constant throughout the crossing of this section, reinforced 62 or diminished.

For the instrumented scraper 1, an increase in the thickness of the wall 62 of the pipe 3 reduces its passage section and therefore increases the tightening of the upstream 5 and downstream 6 cupels and vice versa, as illustrated in figure 3.

These positive or negative, brief or continuous delta P pressure variations will be of great use in locating a leak 2.

Indeed, the examination of the data collected by the recording sensor 11 of the instrumented scraper 1 of the invention will allow the identification of the sequence of tubes framing the leaky tube 2, which will be compared with the sequence of tubes put in place at the time of the construction of the pipeline 4 seen on the weld book.

Figure 4 illustrates, in the upper part, the sequence S1 of the weld book between the butted tubes 21, 22, 23, 24, 25 of a pipe 3, the weld beads 31 being represented by vertical lines. In the lower part of FIG. 4 is represented the sequence S2 of pressure variations delta P of the scraper, the direction of movement of which is symbolized by the dotted arrow. On this sequence S2, it is the pressure variations delta P which are represented by vertical lines.

The examination of this sequence S2 coming from the data collected by the recording sensor of the instrumented scraper 1, and the comparison of this sequence S2 with the sequence S1 of the original welding notebook makes it possible to position the leak 2 of product, in the occurrence at the level of the tube 23 of the pipe, and this without requiring a second intervention in the pipe 3.

Advantageously, the present instrumented scraper 1 also incorporates an electromagnetic tracking means 18 for locating said scraper 1 in the event, for example, of fortuitous immobilization of the latter within the pipe 3.

This electromagnetic locating means 18 can advantageously be secured to one of the solid fixing flanges 19 with which the instrumented scraper 1 is provided.

In a preferred embodiment, the instrumented scraper 1 object of the invention further comprises an anchoring means 16 facilitating the handling of said scraper 1, in particular during its insertion into the pipe 3 at the launching station of the pipeline 4 or else during of the exit.

The example below also illustrates the interest of the instrumented scraper 1 object of the present invention, with reference to table 1 on the following page.

Theoretical example 1: Detection of a negative pressure variation in the referent volume of the instrumented scraper of the invention at the level of a liquid leak in a pipe.

Under the initial conditions, the pipeline line in which the instrumented scraper 1 of the invention was implemented rotates at 275 m3/h at a pressure of 25.50 bar (height H of 300 m). The product in line is diesel with a density of 866 kg/m3, the compressibility coefficient of which: (∆v/V/∆p) is 7.30.E-5.

As for the line to be inspected, it has an outside diameter of 12" (323.8 mm), a maximum thickness of 8.74 mm and a minimum thickness of 6.35 mm. The minimum inside diameter is 306.32 mm and the maximum inside diameter is 311.1 mm.

The sealing cups upstream 5 and downstream 6 of scraper 1 have a diameter of 320 mm and a thickness of 25 mm, the space between cups 5 and 6 is 350 mm. The diameter of the central body 8 is 168 mm, and the referent volume 10 between the upstream 5 and downstream 6 cups is 18.8 L.

The speed of passage of scraper 1 within the pipe is 1m/s, the volume per bar of the reference volume is 1.37 cm3, the duration of the withdrawal is 0.35 seconds (time of passage of the reference volume to the right of withdrawal or leakage).

With regard to the withdrawal, or the leak, the diameter of the tapping is 1mm, and its section 0.785 mm², the nozzle coefficient K is equal to 0.65, the withdrawal speed is 76.7 m/s corresponding to a flow of 0.04 l/s (litres/second).

The table below illustrates the theoretical data collected by the instrumented scraper 1 during passage to the right of the leak and the resulting calculated data.

It emerges from Table 1 above that the instrumented scraper 1 of the invention makes it possible to detect, in a particularly advantageous manner, a drop in pressure in the referent volume 10 of this scraper 1, in this case a little more of 16 bar, corresponding to a defect in the pipeline pipe, due either to a leak or to pirate tapping. The data collected also makes it possible to deduce, in particular, data such as the leak rate, the volume withdrawn per period of time, in this case 0.1 second, the cumulative volume withdrawn, etc.

In this theoretical example, applied to a pipe with a diameter of 12", the passage time of the volume referring to the right of the leak will be 0.35 seconds, and will result in five pressure measurements of 0.1 seconds each, i.e.: 25 .50; 19.30; 13.93; 09.40; 25.50 bar.

These five measures break down as follows:

- 25.50 bar: line pressure;

- 19.30......9.40 bar: pressure drop through the leak in the referent volume;

- 25.50 bar: return to line pressure.

The essential principle of this scraper 1 is based, on the one hand, on the creation of a referent volume 10 in the scraper, and, on the other hand, on a "fleeting vision of the leak": indeed, in a situation inspection of a line, the scraper 1, and therefore the referent volume 10, only sees the leak 2 for a fraction of a second; the response time of the cups 5 and 6 with high inertia to react to this sudden drop in pressure is longer than the escape time 2 seen by the reference volume 10 . Moreover, if the cups undergo a bending (and are not perfectly sealed) in this time, it means that the pressure has dropped in the referent volume 10.

The sensor 11 will have correctly noted this fall. Whatever the value of the pressure drop recorded, if there is a pressure drop, this implies a product leak 2.

In another embodiment, now described with reference to Figures 5 to 7, the instrumented scraper 1 according to the invention is implemented to detect and locate a clandestine tapping which is not permanently active.

Indeed, since modern pipelines for transporting refined products are multi-products, hackers seek to select only consumer products such as premium fuels and diesel.

Thus, the instrumented scraper device 1 according to the invention can advantageously present a functionality complementary to what has been presented above and allow the location of an inactive clandestine tapping, that is to say closed at its end. and allowing the withdrawal of the specific product chosen.

Figure 5 illustrates the configuration of a clandestine tapping.

Referring to the upper part of Figure 5, it is composed of a valve 2 welded to the pipe 3 and whose presence is only necessary when creating the hot tapping; buried and integral with the pipeline 3, it remains constantly open (denoted 2 in the figure because it can thus be assimilated to a leak). Only the end tap 50 is open (withdrawal) or closed (stopped), as will be explained below.

The second element of a clandestine tapping consists of a flexible or rigid connection 51, buried, between the pipeline 3 and the discreet and remote withdrawal location.

Referring now to the lower part of Figure 5, the third element of such a clandestine tapping is a withdrawal valve 50 accessible from the outside, and generally positioned in a discreet place and away from the pipeline 3, said valve 50 being able to be opened (active withdrawal of the product), as illustrated in figure 5, or closed (no withdrawal, or clandestine tapping inactive).

The installation of this inactive clandestine tapping creates a pirate volume 48 complementary to the referent volume 10.

Referring now to Figure 6, the instrumented scraper 1 according to the present invention is advantageously equipped with a volumetric pump 47 comprising a motor type connecting rod (crankshaft, connecting rod, piston, sleeve) connected to a drive wheel 40. This wheel motor 40 is also supported on the inner lower wall of the pipe 3.

The circumference of wheel 40 ensures a rate of injections, and therefore of measurements, corresponding to the length of the referent volume.

The volumetric pump 47 and drive wheel 40 assembly is coupled by two arms 45 to a support shaft 44 fixed to the upstream flange 17. These two arms 45 ensure the stability of the assembly, reinforced by two springs 42 imparting good adhesion between drive wheel 40 and line 3.

A suction mouth 46 and a discharge hose 43 provide the functional connection between the pump 47 and the reference volume 10 of the scraper 1.

The assembly - instrumented scraper 1, coupled device volumetric pump 47 and driving wheel 40 - is dimensioned in such a way as to allow the crossing of the bends of the pipes 3 whose minimum radius of curvature is 1.5 D.

The implementation of this embodiment of the invention is as follows:

When withdrawal is active, the location of the product leak 2 is recorded by the pressure drop in the reference volume 10 of the instrumented scraper 1, as explained in the first part of the description, with reference to Figures 1 to 4.

When the withdrawal is inactive, closed at its end by the valve 50 visible in Figures 5 and 6, the pirate connection increases, by its pirate volume 48, the referent volume 10 of the instrumented scraper 1, and modifies by increasing it, its compressibility.

The existence of this pirate volume 48 complementary to the referent volume 10 will be identified by the implementation of the volumetric pump 47.

A constant quantity of product is alternately injected, and withdrawn by the pump 47, from the referent volume 10. In reality, it performs a continuous back and forth movement through the scraper 1 in line.

In a healthy tube 3, that is to say free of leaks or active tappings, the action of the pump induces pressure variations in the reference volume 10 of the instrumented scraper 1. These are constant, and recorded at the rate of 10 measurements per second.

During the passage of the instrumented scraper 1 to the right of the inactive tapping, configuration visible at the bottom of FIG. 5, the action of the pump 47 also induces pressure variations in the referent volume 10 of the scraper 1 but the height of these pressure variations will be less than previously in the ratio (referent volume 10) / (referent volume 10 + pirate volume 48).

With reference to FIG. 7, the graphic representation illustrates the pressure variations of the referent volume 10 induced by the alternating action of the volumetric pump 47.

- The first three pressure measurements induced by the pump, changing from 10 to 13.42 bar, are the image of the pressure delta of 3.42 bar recorded in the referent volume 10 in a healthy tube 3;

- The fourth measurement induced by the action of the pump, changing from 10 to 12.61 bar, indicates that scraper 1 "saw" a non-active pirate tapping; the difference with the previous ones is 0.81 bar;

- The following two variations indicate the return of the scraper to a healthy tube 3;

- The following variation indicates an active pirate withdrawal or a product leak 2 due to an injury to the tube (corrosions, cracks, etc.);

- Then, return of pressure variations in a healthy tube 3.

According to other advantageous and optional additional characteristics according to the invention, the instrumented scraper 1 is able to circulate in pipes 3 with diameters greater than 20". For diameters of 32" for example, the referent volume will be established according to the present invention to 260 liters. In this situation, the detection of the leak 2 or of the tapping will be less easy due to the importance of the referent volume 10 with respect to the loss of product to be identified; the circulation speed of the instrumented scraper 1 in the pipe 3 will then be adapted in order to increase the <perception duration> of the leak 2 or of the tapping in line with the referent volume 10 .

In a particularly interesting manner, the value of the quantity injected by the volumetric pump 47 into the referent volume 10 is optimized so that when the instrumented scraper 1 completes its pump 47 and impeller 40 device passes in front of an inactive tapping, the variations pressure recorded by the pressure measurement and recording means 11 are relatively large.

It should be noted that the quantity of product to be injected by means of the positive-displacement pump 47 depends in particular, but not exclusively, on the internal diameter of the pipe 3 inspected, and therefore on the reference volume 10 and on the coefficient of compressibility of the product in which the scraper instrumented 1 circulates; those skilled in the art will be able to adapt the value of these alternative injections according to such parameters in order to optimize the detection of a negative pressure variation.

As an example for a 16'' diameter line in which diesel fuel circulates and whose compressibility coefficient is 7.3.E-5, for a referent volume of 40000 cm³ in which 10 cm³ is injected, the variation pressure induced by the pump is 3.42 bar.

In the case of an added pirate volume of 12400 cm³, i.e. 100 meters away from the pipe and with an internal diameter of 12.5 mm and all other things being equal, the pressure variation induced by the pump is only 2.61 bar.

Claims (8)

Instrumented scraper (1) for detecting and locating product leaks (2) and non-active clandestine tappings from inside a pipeline (3) of a pipeline (4), said pipeline (3) with a diameter between 8'' and 32'', consisting of a plurality of tubes joined together in pairs by a butt weld (31) characterized in that it comprises at least one upstream sealing cup (5) and a downstream sealing cup (6), taking into account the direction of movement (7) of said instrumented scraper (1) in the pipe (3), said two cups (5, 6) being interconnected by means of a body (8), said two cups (5, 6) defining, moreover, with said central body (8) and the internal wall (9) of the pipe (3), a sealed reference volume (10), peripheral to said body central unit (8) optimized and comprised between 6 and 260 litres, further characterized in that it comprises, coupled to the central body (8) by means of two arms (45), a volumetric pump (47) driven by a wheel (40) resting on the internal wall of the pipe (3), volumetric pump (47) functionally connected to the referent volume (10) by a suction mouth (46) and a discharge pipe (43), by means of which a constant volume of product is continuously injected and withdrawn from said reference volume (10) and in which the pressure is measured and recorded periodically, by means of measuring and recording the pressure (11), the latter being capable of detect either a pressure drop or a lower pressure variation within said reference volume (10), compared to the constant pressure variation generated by the injection of a constant volume of product into the reference volume (10) at the clandestine tapping depending on whether it is open (leakage 2 ) or closed. Instrumented scraper (1) according to the preceding claim, characterized in that the reference volume (10) is optimized and between 6 and 260 liters for lines whose diameters are between 8" and 32". Instrumented scraper assembly (1) and coupled device consisting of the volumetric pump (47) and the wheel (40) according to any one of the preceding claims, characterized in that it is dimensioned in such a way as to allow the crossing of the bends of the pipe (3) whose radius of curvature is at least 1.5D. Instrumented scraper (1) according to any one of the preceding claims, characterized in that the means for measuring and recording the pressure (11) is able to measure and record at the level of a leak (2), or at the right of an inactive tapping a pressure variation of 0.01 to several bars in the referent volume (10). Instrumented scraper (1) according to any one of the preceding claims, characterized in that the pressure measurement and recording means (11) is able to perform at least 10 measurements per second. Instrumented scraper (1) according to any one of the preceding claims, characterized in that the measuring and recording means (11) is capable of detecting pressure variations of the order of 10 to 300 mbar in the reference volume (10) induced by the weld beads (31). Instrumented scraper (1) according to any one of the preceding claims, characterized in that the means for measuring and recording the pressure (11) is able to differentiate the tubes according to their thickness. Instrumented scraper (1) according to any one of the preceding claims, characterized in that the means for measuring and recording the pressure (11) is capable of identifying and locating the tubes with the contribution of the weld book of the 'work.