FR2490818A1 - METHOD OF LOCATING DEFECTS IN A NETWORK OF CHARGING PIPES - Google Patents

Abstract

THE INVENTION CONCERNS THE CONTROL OF PIPING SYSTEMS. THE PROCESS, SUBJECT OF THE INVENTION, IS CHARACTERIZED IN PARTICULAR IN THAT SENSORS ARE PLACED IN AT LEAST THREE CONTROL POINTS 3, 9, 18 OF THE PIPE NETWORK, SEPARATED FROM ONE ANOTHER BY MAXIMUM DISTANCES, MEASURED ALONG THE PIPES, FOR WHICH, FOR A GIVEN MINIMUM LEAK VALUE, THE PRESSURE DROP WAVE OCCURRING AT ANY CONTROL POINT WILL HAVE, AT THE TWO NEIGHBORING CONTROL POINTS, SUFFICIENT AMPLITUDE TO OPERATE THEM PLACES AT THESE TWO POINTS. THE INVENTION IN PARTICULAR MAKES IT SIMPLIFY THE IMPLEMENTATION OF THE PROCESS UNDER THE CONDITIONS OF A COMPLEX BRANCHED AND LOOP DUCT NETWORK AND TO INCREASE ITS RELIABILITY.

Description

 The present invention relates to the technique of controlling piping systems, and particularly relates to a method of locating the degradation of pipes in a network load.

 A method for locating a defect in the piping is known (see the USSR N0% o9o9 author's certificate published in 1973) by measurement, on the surface of the pipe layout, acoustic oscillations originating at the location of the pipe. degradation and spreading in the soil. According to this method, on the surface of the ground, above the degraded piping, are found two stationary wave maximums, preferably the nearest ones, having equal amplitudes, and the coordinate of the site of degradation is determined by dividing by two the distance measured between said maximums.

 The cited method does not allow the search of the place of the defect during the day because of the disturbances produced by the means of transport and various industrial installations. On the other hand, even in the relative absence of disturbances, the application of this method for locating the defect in complex branched piping systems is time-consuming since the route must be determined. piping and visit its entire length with a measuring device.

 There is also known a method of locating the location of damage to a pipe (see U.S.A.

 No. 3691819 published in 1972), also based on the measurement of acoustic oscillations, but in this case the measuring device is introduced inside the piping to be controlled, where it is moved by the product conveyed in the piping. This process generally requires pumping of the product for the introduction of the measuring device into the pipework, which is difficult to achieve under the conditions of a branched branch pipe network.

 There is also known a method of locating a degradation in a pipe under load (see USSR author's certificate No. 327425 published in 1972), consisting in placing at the ends of the pipe to be controlled sensors responsive to pressure pulsations of the product in the audible frequency range, pulsations that are caused by the oscillations of a jet escaping through the hole resulting from the damage of a pipe, and determining the location of the degradation according to the importance of phase shift pulsations acting on sensors.

 The latter method requires the use of a transmission path between the sensors and the measuring device; moreover, it is of insufficient precision in the evaluation of the angle of phase shift, which results in a significant error in the localization of the defect. In addition, when this method is applied to complex branched networks, it is necessary to significantly complicate the means to implement it.

 There is also known a method for locating a defect in a pipework without resorting to a special transmission path, in which, instead of said transmission channel, the liquid conveyed in the pipework is used, and the information carrier function is filled by an artificial disturbance wave produced by an electromagnetic valve placed at a known distance from the measuring device (see article by AB

Shturmin and others "Automatic detection of places of deterioration of pipelines without the use of a special transmission channel", in the collection edited by TSINIS Gosstroia USSR, "Study of water supply projects and sewers, Series IV, booklet 2/71, Moscow, 1971) The valve opens under the action of a pressure drop wave which reaches it from the fault location, simulating a leak at the location of the valve. determines the location of the fault according to the time difference between the arrival times on a device for measuring two different waves of pressure drop.

 This method is practically difficult to apply to complex piping systems and requires the use of complicated apparatus, therefore. which has a relatively low reliability.

 Another method of locating a defect in pipe systems is known (see USSR author's certificate No. 403920 published in 1973), according to which, on the basis of a prior study of a particular network of pipes, a pressure sensor interrogation sequence is defined and the permissible pressure drop speeds are measured, the pressure in the monitored parts is measured, the rate of variation of the pressure in each part is calculated during the time interval between the pressures. measurements, and is compared to said allowable pressure variation speed. By detecting the part in which the speed of variation of the pressure exceeds the admissible value, one observes the existence of a degradation of the network. To locate the defect, one chooses, among all the parts under control, two adjacent parts characterized by maximum speeds of variation of the pressure, these parts limiting the damaged portion.

 This method does not allow to locate precisely the location of the defect and only delimits the area where the fault is.

As a prototype of the present invention, was retained the method of locating defects in a network of pipes in charge, described in the author's certificate
USSR No. 191284 published in 1967. According to this method, sensors at the opposite ends of the portion to be tested of the pipework are sensitized to the action of a pressure drop wave originating at the location of the defect and propagating through the product channeled through the piping, and the location of the defect is determined from the time difference between the operating times of the sensors.

 By applying the prototype method to locate a damaged location in a branched and looped network of pipes, it is necessary to control virtually every portion of such a network that can be imagined as a mainline with a minimal number of taps. However, in a complex network, there can be a very large number of such portions, making it essential to place at the ends of each portion of the sensors which will lead to a transmission path leading to the device implementing said method. As a result, the control system becomes cumbersome, difficult to achieve and unprofitable; in addition, because of the large number of transmission paths and recording devices (sensors) to be used, the reliability of the control system is substantially lowered.

 The object of the present invention is in particular to allow the implementation of a method for the location of defects in a network of charging conduits designed so that the sensors detecting the existence of a degradation are arranged so as to simplify the implementation of the process under the conditions of a branched and looped complex network of pipes and to increase its reliability.

 The objective is achieved thanks to the fact that in a method of locating defects in a network of pipes in charge, consisting in placing, on portions of the network, sensors sensitive to the action of a pressure drop wave. originating at the location of the fault and propagating through the product conveyed in the network deconduites, and to determine the location of the fault by using the time difference between the operating times of the sensors, according to the invention is placed said sensors at least three control points of the pipe network separated from each other by a maximum distance, measured along the pipes, for which, and for a given value of the minimum leak, the pressure drop wave occurring at any control point present, at the two nearest control points, a sufficient amplitude to operate the sensors placed in these two points, we record the ins In the case of the three sensors closest to the damage site, to which the pressure drop wave comes faster, a first group of possible locations of the desired fault is determined according to the time difference between the operating times. of the first and second of the three mentioned sensors, a second group of possible locations of the defect is then determined according to the time difference between the operating instants of the first and third of said sensors, and finally a third group of locations is determined possible of the defect according to the time difference between the instants of operation of the second and third of said sensors, after which the location of the defect is determined from the colacidence of one of the possible locations of the defect of a group with the one of the possible locations of the fault of at least one of the two other groups.

 By choosing the locations of the sensor locations as indicated, their number is reduced to the minimum necessary for the location of faults at any point of a complex branched network, any complication of the network resulting in only an increase insignificant number of sensors. With the minimum number of sensors used, that of the connecting paths between the sensors and the data processing devices provided by the sensors will also be minimized, thus increasing the reliability and reducing the short circuit of the system implementing the proposed process.

 The invention will be better understood and other objects, details and advantages thereof will appear better in the light of the explanatory description which follows of a mode of realization is given by way of non-limiting example, with references to the unrestricted unioue drawing annéxé.

 Or a complex network of pipes in load such as the one shown in the drawing and which we want to control. The pipe network consists of pipelines, represented by straight lines, which communicate with each other at nodal points, among which marked on the drawing the nodal points 1,2,3 ... 19,2Q, 21 which are used in the description to make the substance-of the invention clearer. The location of the existing damage in the pipe network is determined by recording a pressure drop wave that originates at this point and spreads through the product, liquid or gaseous, channeled through the pipes (water, oil > gasoline, combustible gas, etc). In order to record the pressure drop wave, the control network has sensors, sensitive to the action of this wave, for example pressure sensors mounted on the walls of the pipes. in order to contact the conveyed product, or vibration sensors mounted on the walls of the pipes without being in contact with the product conveyed. The choice of control points, which are surrounded by small circles in the drawing, is as follows.

 First, we define the value of the minimum leak in the pipes, a leak that must be detected by the sensors and considered as a damage to the piping, for example a leak of 10% of the total flow of pumped product according to the section piping.

 The first control point is chosen at any point in the pipe network, for example at nodal point 3. The second control point, for example control point 9, is chosen at a maximum distance from control point 3 such that a pressure drop wave occurring at the control point 3 has on arrival at the control point 9 an amplitude sufficient for this wave to be recorded by the sensor mounted at the control point 9. It goes without saying that, since the pressure drop wave propagates through the product conveyed in the pipes, the distance between the points 3 and 9 must be measured along the pipes connecting these points.

It is also obvious that this distance must be chosen according to the shortest possible path of propagation of the pressure drop wave between the control points 3 and 9, that is, between the paths 3-2-1-5. -9, 3-2-6-10-9, 3-7-6-10-9, etc. For example, it is possible to determine the shortest path of travel of the pressure drop wave between the two points through the pumped product using Ford's method. It will be assumed that the shortest path of the wave path between control points 3 and 9 is path 3-2-6-10-9.

 Thus, by choosing the control point 9 to install sensors, it is necessary to take into account the first, in time, all the possible operations of the sensor mounted at the control point 9, under the effect of the wave of pressure drop occurring at the control point 3. When this condition of the choice of the control point 9 is satisfied, said pressure drop wave does not cause repeated operations of the sensor placed at this point, propagating according to others, longer portions of the pipe network. Subsequently, by choosing the following control points, we will be guided by the same considerations concerning the first operation of the interested sensors.

 The third control point 18 will therefore be chosen at a maximum distance from the control points 3 and 9, such that the pressure drop wave occurring at the control point 18 has, on arrival at the control points 3 and 9, sufficient amplitude to operate the sensors mounted at these control points. In doing so, the condition of the choice of maximum distances following the most paths. short run of the pressure drop wave remains valid for the third control point 18, as for all subsequent control points.

For example, it is assumed that the shortest path of the pressure drop waveform from point 18 to point 3 is on the 18-13-8-4-3, and from 18 to 9 on the portions 18-17-16-15-10-9.

 The fourth control point 19 is chosen on the basis of the considerations set out above, that is to say at maximum distances from the control points 9 and 18, making it possible to record the pressure drop wave that has occurred at the control point 19 , by the sensors mounted at the control point 9 and 18, always taking into account, just as in the previous cases, the operation of the sensors under the action of the wave that reaches them along the shortest paths between the points of corresponding control.

 In the same way, the following control points 20 and 21 are chosen. Generally a rule of the choice of control points. we are nellt.

to say that each control point is separated from the two control points which are the most noisy by maximum distances, for which a pressure loss occurred at this point present, by reaching said control points, a sufficient amplitude to operate the sensors placed at these control points, provided that said pressure drop wave follows the shortest paths. The choice of control points continues until their number is sufficient to control the entire network of pipes. In other words, the number of control points to place sensors there must be such that.

Regardless of where the damage to the pipeline network has occurred, the pressure drop wave from this location is detrimental to at least three control points. With this provision, if one observes the above stated rule of choice of control points, the number of sensors to be used in the control system will be minimal.

 It is assumed that at a certain point in the load pipe network shown in the drawing. there was damage to the pipework. At the location of the damage will then occur a pressure drop wave that propagates through the product @ analised at a known speed which is a function of the hydraulic characteristics of the pipes and phystoues properties of the pumped product, wave that operates three sensors, for example, the sensors mounted on control panels 3, 9 and 18; the first to operate will be, for example, the sensor placed at control point 3, then operate the sensor placed at the control point 9 and the last of the three. that placed at the control point 18. According to the invention, the operating time of these sensors is recorded.

It will be assumed that the operating time of the sensor placed at the control point 3 is t1, the operating time of the sensor placed at the control point 9 is t2 and that of the sensor placed at the control point 18 is t3.

We then determine the difference At1 between the instants
of operation of the sensors mounted at the points of con
control 3 and 9, the difference # t2 between the instants of
operation of sensors mounted at control points
9 and 18 and the difference # t3 between the instants of
sensors mounted at control points 3
and 18.

# t1 = t2 - t1
# t2 = t3 - t2
# t3 = t3 - t1.

Then, according to the differences # t1, / \ t2 ett3
obtained, three groups of degraded
possible, so that the desired point, where
the damage to the piping occurred, neut
to be on any portion of the
network of pipelines between points 3 and 9, either on one
any part of the pipeline network between
points 9 and 18, or on any of the
of the pipe network between points 3 and 18.

On every i th possible path of the wave
of pressure drop between points 3 and 9, we find
the distance Xi from the middle of this path to the possible place of
degradation according to the formula:
Xi = 1/2 V # t1 where V is the velocity of propagation of the pressure drop wave through the product conveyed in the considered pipe network, i = 1,2,3 ... n, the number n possible paths of travel of the wave between points 3 and 9 depending on the configuration of the network of pipes between these points.

We then determine the distance ai on each ith path of one of the control points 3 or 9, for example from point 3 to the possible location of the damage.
ai = Si - Xi,
2
where Si is the extent of the ith path.

 As it is not known on which paths connecting, through the pipes, the control points 3 and 9 is in fact the place of damage, we obtain n possible locations of degradation of the first group, for example a point on the path 3-7-6-10-9, a point a2 on the road 3-2-6-10-9, a point a3 on the road 3-2-1-5-9, etc.

In the same way, a second group of possible locations of degradation is determined, in particular on each
th th possible way of traveling the pressure drop wave between points 9 and 18, we find the distance
Yj from the middle of this path instead of possible degradation, using the relationship
Yj = / 2 V # t2, where j = 1,2,3, ..., m, the number m of possible paths of travel of the pressure drop wave between points 9 and 18 being a function of the configuration of the pipe network between these points.

Then, the distance bj is determined along each jth path of one of the points 9 or 18, for example from point 9 to the possible location of the degradation.
S.

 bj = @ / 2 - Yj, where S. is the extent of the jth path.

J
As it is not known on which paths connecting, through the pipes, the control points 9 and 18 is in fact the place of the degradation, one obtains m possible places of degradation of the second group, for example a point b1 on the way 9-10-6-7-8-8-18, a point b2 on the way 9-10-15-16-17-18, a point b3 on the way 9-10-11-12-13- 18, etc.

A third group of possible degradation sites is likewise determined, in particular for each k th possible path of travel of the pressure drop wave between points 3 and 18, the distance is found
Zk from the middle of this path to the possible place of degradation, using the relation Zk = - V t t3, where k = 1, 2, 3, ... l, the number 1 of possible paths of course of the wave pressure drop between points 3 and 18 being a function of B configuration of the network of pipes between these points.

This being done, the distance ck is determined along each kth path of one of the points 3 or 18, for example from point 3 to the possible location of the degradation.
= Sk
2 - Zk, where Sk is the extent of the kth path.

 As it is not known on which paths connecting the control points 3 and 18 through the pipes is in fact the place of degradation one obtains 1 possible sites of degradation of the third group for example a point c1 on the way 3- 4-8-13-18, a point c2 on the path 3-7-12-17-18, a point c3 air the path 3-7-8-13-18, etc.

The actual location of the degradation is determined with an acceptable error due to the coincidence of one of the possible sites of degradation of a group with one of the possible sites of degradation of another group or other groups. In our case, it is the points a1 and b1 which coincide roughly7, and we conclude that the place of deterioration of the piping is at a certain point
Who is on the stretch bounded by points a1 and b1. In the ideal case, the length of this section is nil (the points a1 and b1 coincide exactly), but in practice, we obtain a coincidence of points a1 and b1 within the limits of a stretch of length up to 3 m .

 The points that will determine are those of the possible places of degradation of the first and second group or of the first and the third group, or of the second and the third group, or the points of the three groups: it depends on the place of the defect with respect to the three control points where the operation of the sensors has occurred, as well as the configuration of the network between these points. If, for example, the place of deterioration was near point 12, there would be three points, namely one point of group "a" with one of the points of group "b" and with the one of the points in group "c". In this case, the pressure drop wave from point 12 would take the path 12-7-3, to arrive at checkpoint 3, the path 12-13- 18 to arrive at Control Point 18, and Route 12-11-10-9, to arrive at Control Point 9, the path of the wave between Control Rails 9 and 3, 9 and 18, 3 and 18 then constituting the sum of the wave motion paths from point 12 to two control points, that is, paths 12-11-10-9 plus 12-7-3, 12-11-10 -9, plus 12-13-18, and 12-7-3 plus 12-13-18, respectively.

 The invention can be used advantageously in the public services for the control of water supply and heating networks in cities and in the chemical industry for the control of coniplex pipe systems in granite chemical companies.

The invention is advantageously distinguished from known methods of similar destination by its increased reliability, the simplicity of its implementation and its relatively low cost.

 Of course, the invention is not limited to the embodiment described and shown which has been given as an example. In particular, it includes all the means constituting technical equivalents of the means described, and their combinations, if they are executed according to its spirit and implemented in the context of the protection as claimed.

Claims (1)

 CLAIM  A method of locating defects in a network of pipes under load, of the type consisting in placing, on sections of the network, sensors responsive to the action of a pressure drop wave Born at the location of the defect and propagating through the product conveyed in said network, and to determine the location of the defect by using the time difference between the operating times of the sensors, characterized in that said sensors are placed in at least three control points of the network of pipes, separated from each other by maximum distances measured along the pipes, for which, for a given minimum leakage value, the pressure drop wave occurring at any control point shall, at both points control units, sufficient amplitude to operate the sensors placed at these two points, the operating times of the three closest sensors are recorded s of the location of the defect that the pressure drop wave will reach the fastest, a first group of possible locations of the fault is determined according to the time difference between the operating instants of the first and second of the three mentioned sensors, then determines a second group of possible locations of the fault according to the time difference between the operating times of the first and third of said sensors, and finally determines a third group of possible locations of the fault according to the time difference between the instants of operation of the second and third of said sensors, after which the fault is located according to the coincidence of one of the possible locations of the fault of a group with one of the possible locations of the default of at least one of the other two groups.