EP1728895B1 - Surveillance method for detecting the approach of a conductive body to a cathodically protected pipeline for fluids - Google Patents
Surveillance method for detecting the approach of a conductive body to a cathodically protected pipeline for fluids Download PDFInfo
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- EP1728895B1 EP1728895B1 EP06006493A EP06006493A EP1728895B1 EP 1728895 B1 EP1728895 B1 EP 1728895B1 EP 06006493 A EP06006493 A EP 06006493A EP 06006493 A EP06006493 A EP 06006493A EP 1728895 B1 EP1728895 B1 EP 1728895B1
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- 239000012530 fluid Substances 0.000 title claims description 21
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
- C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
- C23F13/04—Controlling or regulating desired parameters
Definitions
- the invention relates to a monitoring method for determining an approximation or a contact between a conductive body, in particular a construction vehicle, and a fluid transport pipeline, which is acted upon by direct current as a cathodic protection current.
- Fluid transport pipelines e.g. As gas, oil or water pipelines, are usually made of welded metal pipes that are laid underground or undersea.
- a passive protection of the transport pipeline is provided in the form of an insulating protective cover.
- active corrosion protection of the transport pipeline is provided by applying a cathodic protection current to the fluid transport pipeline to avoid, as far as possible, electrochemical reactions affecting the metal of the transport pipeline.
- the cathodic protection against corrosion is monitored by measuring the output voltage of the system supplying the cathodic protection current, the protection potential of the transport pipeline charged with the cathodic protection current and the protection or tube current via a pipe flow measuring section with the aid of appropriate sensors.
- the various measured values are transmitted once a day by SMS to a monitoring center for cathodic protection.
- the monitoring center monitors the long-term course of the measured values. Gross damage in cathodic protection (eg a bridging of an insulating piece between two line protection sections can be detected.
- a transport pipeline may be damaged by an accident, such as when a construction vehicle comes into contact with the transport pipeline or its protective cover. Since construction vehicles are conductive bodies, it is important to immediately detect an approach of a conductive body to the transport pipeline in order to prevent or at least minimize damage to the transport pipeline by suitable measures.
- the DE 100 21 994 A1 discloses a method for determining the tube / ground potential on cathodically protected pipelines, especially in the area of stray current influence, for example in the vicinity of DC-powered tracks.
- the protection current is periodically switched on and off and placed on a ground at a reference location Reference electrode, a measured value for the pipe ground potential is detected when the protection current is switched on and at least one measured value is switched off.
- the measured values are evaluated exclusively to determine whether the pipe / ground potential meets the protection criteria. If the pipe / ground potential is too positive, there is a risk of corrosion damage.
- the US 6,107,811 shows a corrosion protection method in which the protection current is clocked. By means of an artificial defect, it is checked whether the cathodic protection is effective.
- the protective current is regularly interrupted or clocked. All known methods serve to check or to prove the effectiveness of the cathodic corrosion protection.
- the cathodic protection current is permanently modulated with rectangular pulses or sinusoidal pulses of different frequencies and evaluated the change in the modulation pulses. Due to the additionally required modulation pulses of the additional equipment technical effort to implement these methods is considerable. The costs are accordingly high.
- a contact between, for example, a conductive construction vehicle and the conductive fluid transport pipeline can be recognized immediately. If the resistance of the environment of the transport pipeline is not too high, for example when submerged in the water, an approach of the construction vehicle or, more generally, of a conductive body can already be ascertained before the conductive body touches the conductive transport pipeline.
- the difference values representative of the difference in the protective currents flowing at the measuring points along the pipeline it is possible to reduce interference. Changes in the protective current due, for example, to stray currents generated by DC tracks or to earth-magnetic variations called Tellurik can be largely eliminated.
- a measured value representative of the protective current flowing at the measuring point is detected at substantially the same time. If more than two measuring points are provided, the difference values should preferably be formed in each case from the measured values of directly adjacent measuring points.
- the measurement value representative of the protection current flowing along the fluid transport pipeline can be both a voltage measurement value and a current measurement value which has been determined, for example, from a voltage measurement value.
- the difference values formed in step b) that represent the difference of the protective currents flowing at the measuring points can be both voltage difference values and protective current difference values in the same way. If protective current difference values are used, these can be determined in two ways, namely by first determining the protective currents for the individual measuring points and then forming the difference or by first forming a voltage difference value and from this a protective current difference value.
- the value indicative of at least one approach of a conductive body to the fluid transport pipeline may be both digital and analog. It is determined from the temporal change of the difference values formed for the given times, ie on the basis of the time course of the difference values formed. For example, if the difference values suddenly rise sharply or fall off sharply, this may be an approximation of a conductive body and there may be a corresponding value indicative of the approximation of a conductive body, e.g. B. be generated as an error message or for their generation. Alternatively, an approximation of a conductive body can only be displayed when the edge of such an increase or decrease has a certain, possibly stored, shape.
- the value indicative of the approach of a conductive body can be representative of the fluctuation range of the difference value in a preceding period, whereby individual "outliers" of the difference value can be disregarded depending on the application: on the other hand, the formed difference values do not vary or fluctuate in time they only in the context of measurement accuracy, there is no approximation of a conductive body. This may be indicated by the value indicating the approach of a conductive body, for example by not displaying an error message.
- the accuracy in determining the location of the approach of a conductive body can be increased by providing the measuring points along the fluid transport pipeline at intervals below 20 km, preferably at intervals below 5 km, and the difference values from the values for immediately adjacent ones Measuring points are formed.
- the accuracy with which an approach of a conductive body can be determined moreover depends on the nominal size and the wall thickness of the fluid transport pipeline and the ratio between the turn-on potential of the fluid transport pipeline loaded with the cathodic protection current and the rest potential of the approaching conductive body , However, since these quantities can not be changed without further ado, the desired measurement accuracy can best be achieved by adjusting the distances between the measuring points accordingly.
- the measured values are recorded at regular time intervals of less than 1 s, preferably every 0.1-0.5 s. If the temporal resolution is 0.2 s, for example, short-term metallic contacts can be reliably detected as early as 0.6 s.
- the DC change of the flowing protective currents is evaluated, it is advantageous that AC components possibly present at the measuring points are filtered out in such a way that DC changes with a duration of at least 200 ms are detected in step a).
- the influences of technical AC voltages can be eliminated by means of filters. Due to the damping characteristic of these filters, DC changes can generally only be detected if they have a duration of at least 200 ms.
- at least three measuring times must be available, ie the external contact must be at least 600 ms. Consequently, in an arrangement with filtering of AC voltages the highest resolution can be achieved if five values representative of the protection current per second are detected.
- a preferred embodiment is characterized in that in step a) a measured voltage value is detected as the measured value.
- each measuring point is assigned a measuring section running along the pipeline, and the voltage between the two end points of the measuring section is measured to detect the voltage measured value.
- the measuring accuracy for the voltage measured value is particularly high if a measuring section of at least 10 m in length, preferably of at least 30 m, is used.
- the measurement accuracy can be increased by detecting the voltage measurement values with a resolution of at least 1 ⁇ V, preferably of at least 0.1 ⁇ V.
- a development of the invention is characterized in that the measured values acquired in step a) at the various measuring points are transmitted to a central processing device and steps b) and c) are carried out by the central processing device.
- the measured value can be transmitted via a GPRS network.
- the transfer of steps b) and c) in the central processing device has the advantage that only a detection of the measured values and their transmission must be ensured at the different measuring points.
- the central processing of all measured data allows the use of less expensive hardware at the possibly numerous individual measuring points.
- steps b) and c) are performed in real time. This is necessary to detect sudden damage or, more generally, an approach of a conductive body also in real time.
- the data transmission to the central processing device is usually via an online connection.
- Existing pipe flow measuring points can be easily converted to the monitoring method according to the invention by installing monitoring sensors thereon which allow transmission of the measured values to the central processing device and the real-time execution of steps b) and c).
- the type of smoothing can be varied as desired. For example, a single outlier can not be included in the difference values in the smoothing.
- the degree of smoothing can also be adapted individually to the measuring environment.
- FIG. 1 schematically shows the current distribution on a pipe 1 with metallic conductive foreign contact.
- the pipeline 1 used as a gas high-pressure line is connected to a protection system 2 for cathodic corrosion protection, more precisely with its cathode (not shown).
- a protection system 2 for cathodic corrosion protection more precisely with its cathode (not shown).
- On the pipe 1 two measuring points 3 are provided for measuring the cathodic protection current.
- the measuring points 3 each have a measuring length of 30 meters for detecting the voltage measurement U1 or U2.
- the pipeline 1 has at a point 5 on a metallic foreign contact. This is a construction vehicle that has approached the pipeline 1 and now touches it.
- the construction vehicle for example, by the excavator chains or the bucket having a finite propagation resistance to the soil, enters the construction vehicle during the contact time or during the damage an additional current, called fault current I F in the pipe 1 a.
- I F additional current
- the additional power consumption can be detected from the difference of the flowing at the two measuring points 3 pipe streams and thus a sudden contact with the pipe 1 can be detected immediately in a simple manner.
- Six different foreign contacts with a propagation resistance between 5 and 500 ohms were detected and displayed.
- the diagram clearly shows that the voltage difference in the event of a fault is inversely proportional to the nominal diameter of the pipeline. Foreign contacts or sudden pipe damage can therefore be resolved better with smaller pipe diameters.
- the diagram shows that the voltage difference at low-resistance foreign contacts is much higher than for high-resistance foreign contacts. The reason for this is that the voltage difference in case of failure is inversely proportional to the propagation resistance of the foreign contact, such as the construction vehicle, at the contact point.
- FIG. 3 shows a schematic representation of the method of the invention underlying the monitoring principle.
- pipeline 1 consists of two protection sections 5 and 6, each having a protection system 21st or 22 is assigned.
- the protective sections 5 and 6 are insulated from each other by means of an insulating device 7. Further isolating means 7 are provided between the two protection sections 5 and 6 and adjacent protection sections (not shown).
- the protection section 5 comprises a protection system 21 for the cathodic protection of corrosion and six associated measuring points 31 to 36.
- the protection section 6 comprises a protection system 22 for cathodic protection and two associated measuring points 37 and 38.
- the voltage differences are always formed only between adjacent measuring points within a protection section , Measured values from measuring points that are assigned to electrically separate lines are not compared. Consequently, in FIG.
- the measured values of the measuring points 31 and 32, 32 and 33, 33 and 34, 34 and 35, 34 and 36 and 37 and 38 compared. If the resistance values of the individual pipe flow measuring sections are the same, the pipe flow difference is proportional to the voltage difference. Therefore, in this case, the measured voltage values of the individual measuring points can be directly compared as measured values. Otherwise, the voltage measurement values of the individual measuring points must be converted into pipe flow measured values and then compared with each other.
- FIGS. 4a to 4d shows measured values or difference values which were obtained in an experiment according to the method according to the invention.
- the measured values were provided with a time stamp.
- the measured values were recorded with a time interval of 2 sec and a measurement resolution of the sensors of 1 ⁇ V.
- FIGS. 4a and 4b show the time course of the Rohrstrommeßagonist at the measuring points 32 and 33 according to FIG. 3 ,
- the pipeline 1 has an average pipe diameter of 1200 mm and is provided with a PE protective cover.
- the caused by the three simulated error pipe flow changes are in the FIGS. 4a and 4b barely visible. The reason is power fluctuations caused by Tellurik.
- Figure 4c shows the difference measured at the measuring points 32 and 33 and in de Fig. 4a and Fig. 4b shown Rohrstrommeßagonist.
- the three simulated errors are in Fig. 4d and Fig. 4e not recognizable.
- the current differences of about 100 mA to 120 mA are also caused by Tellurik.
- the smaller fluctuations between the measured values are due to the limited measured value resolution of the measuring inputs.
- a sudden increase or decrease in the pipe flow difference which is limited to a measured value, usually indicates no error.
- the pipe flow differences are therefore preferably to be evaluated so that individual outliers are not taken into account. This is possible for example by a suitable smoothing of the pipe flow difference curve. Accordingly, a sudden damage to the pipeline or a sudden approach of a conductive body can usually only be ascertained if not only the pipe flow difference values for immediately successive points in time differ by more than a predetermined threshold value but also immediately before the difference values for the points in time and also differ by more than a predetermined threshold after the previously considered times.
- the measured values representative of the protection current should preferably be detected at the same time at the at least two measuring points. Nevertheless, it may be sufficient in some environments if the measured values are only detected as simultaneously as possible.
- the distances of the measuring points along the fluid transport pipeline can of course be varied as desired, with distances as close as possible being preferred, since it is not the exact location of the damage or the approach of a conductive body that is detected, but only that somewhere between the compared measuring points conductive body of the pipeline approaches or suddenly touched.
- the time intervals between the individual measurements can be changed as desired. If voltage measuring values are detected at the individual measuring points, the pipe flow measured values could also be calculated in the individual measuring points instead of in the central processing device.
- the temporal change of the difference values can be arbitrarily evaluated in order to derive the value indicating an approach of a conductive body. In any case, however, it should be ensured that a sudden increase or decrease of the formed difference values, which persists across several difference values, generates a value indicating an approach of a conductive body.
- the monitoring method of the present invention will typically be limited to detecting an approach of a conductive body to a fluid transport pipeline only upon electrical contact with the transport pipeline so that an approach can not be determined prior to touching the conductive transport pipeline.
- the value indicative of an approach of a conductive body is a value indicating a sudden electrical contact of a conductive body with the transportation pipeline.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
- Pipeline Systems (AREA)
- Prevention Of Electric Corrosion (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Abstract
Description
Die Erfindung betrifft ein Überwachungsverfahren zum Feststellen einer Annäherung bzw. eines Kontakts zwischen einem leitfähigen Körpers, insbesondere einem Baufahrzeug, und einer Fluid-Transportpipeline, die mit Gleichstrom als kathodischen Schutzstrom beaufschlagt ist.The invention relates to a monitoring method for determining an approximation or a contact between a conductive body, in particular a construction vehicle, and a fluid transport pipeline, which is acted upon by direct current as a cathodic protection current.
Fluid-Transportpipelines, z. B. Gas-, Öl- oder Wasserpipelines, bestehen in der Regel aus zusammengeschweißten Metallrohren, die unterirdisch oder unterseeisch verlegt werden. Im Allgemeinen wird ein passiver Schutz der Transportpipeline in Form einer isolierenden Schutzabdeckung vorgesehen. Darüber hinaus wird ein aktiver Korrosionsschutz der Transportpipeline vorgesehen, indem ein kathodischer Schutzstrom an die Fluid-Transportpipeline angelegt wird, um elektrochemische Reaktionen soweit wie möglich zu vermeiden, die das Metall der Transportpipeline angreifen.Fluid transport pipelines, e.g. As gas, oil or water pipelines, are usually made of welded metal pipes that are laid underground or undersea. In general, a passive protection of the transport pipeline is provided in the form of an insulating protective cover. In addition, active corrosion protection of the transport pipeline is provided by applying a cathodic protection current to the fluid transport pipeline to avoid, as far as possible, electrochemical reactions affecting the metal of the transport pipeline.
Der kathodische Korrosionsschutz wird dadurch überwacht, dass mit Hilfe von entsprechenden Sensoren die Ausgangsspannung der den kathodischen Schutzstrom liefernden Anlage, das Schutzpotential der mit dem kathodischen Schutzstrom beaufschlagten Transportpipeline und der Schutz- bzw. Rohrstrom über eine Rohrstrommessstrecke gemessen werden. Die verschiedenen Messwerte werden einmal täglich per SMS zu einer Überwachungszentrale für den kathodischen Schutz übertragen. In der Überwachungszentrale wird der langfristige Verlauf der Messwerte überwacht. Grobe Schäden im kathodischen Schutz (z. B. eine Überbrückung eines Isolierstücks zwischen zwei Leitungsschutzabschnitten können erkannt werden.The cathodic protection against corrosion is monitored by measuring the output voltage of the system supplying the cathodic protection current, the protection potential of the transport pipeline charged with the cathodic protection current and the protection or tube current via a pipe flow measuring section with the aid of appropriate sensors. The various measured values are transmitted once a day by SMS to a monitoring center for cathodic protection. The monitoring center monitors the long-term course of the measured values. Gross damage in cathodic protection (eg a bridging of an insulating piece between two line protection sections can be detected.
Zusätzlich zu den langfristigen Schäden kann eine Transportpipeline jedoch durch einen Unfall beschädigt werden, wenn beispielsweise ein Baufahrzeug in Kontakt mit der Transportpipeline oder mit deren Schutzabdeckung kommt. Da Baufahrzeuge leitfähige Körper sind, ist es wichtig, eine Annäherung eines leitfähigen Körpers an die Transportpipeline sofort zu erkennen, um Beschädigungen der Transportpipeline durch geeignete Maßnahmen noch zu verhindern oder wenigstens zu minimieren.However, in addition to the long-term damage, a transport pipeline may be damaged by an accident, such as when a construction vehicle comes into contact with the transport pipeline or its protective cover. Since construction vehicles are conductive bodies, it is important to immediately detect an approach of a conductive body to the transport pipeline in order to prevent or at least minimize damage to the transport pipeline by suitable measures.
Die Veröffentlichung "DATABASE INSPEC (Online) THE INSTITUTION OF ELECTRICAL ENGINEERS; STEVENAGE; GB November 1987 (1987-11) RICKEERT H ET AL offenbart ein Verfahren zum Nachweis der Wirksamkeit des kathodischen Korrosionsschutzes für Eisen. Der Schutzstrom wird periodisch für kurze Zeit unterbrochen und der Ausschaltwert als Maß für das Schutzpotential gemessen.The publication "DATABASE INSPEC (Online) THE INSTITUTION OF ELECTRICAL ENGINEERS; STEVENAGE; GB November 1987 (1987-11) RICKEERT H ET AL discloses a method of demonstrating the effectiveness of cathodic corrosion protection for iron. The protection current is periodically interrupted for a short time and the switch-off value is measured as a measure of the protection potential.
Die
Aus der
Die
Bei allen vorgenannten Verfahren wird der Schutzstrom regelmäßig unterbrochen bzw. getaktet Alle bekannten Verfahren dienen zur Überprüfung bzw. zum Nachweis der Wirksamkeit des kathodischen Korrosionsschutzes..In all the above-mentioned methods, the protective current is regularly interrupted or clocked. All known methods serve to check or to prove the effectiveness of the cathodic corrosion protection.
Aus der
Aufgabe der Erfindung ist es, ein kostengünstiges Überwachungsverfahren zur Feststellung einer plötzlichen Annäherung eines leitfähigen Körpers an eine mit einem kathodischen Schutzstrom beaufschlagte Fluid-Transportpipeline zur Verfügung zu stellen.The object of the invention is to provide a cost-effective monitoring method for detecting a sudden approach of a conductive body to a loaded with a cathodic protection current fluid transport pipeline.
Diese Aufgabe wird erfindungsgemäß gelöst durch ein gattungsgemäßes Überwachungsverfahren, das dadurch gekennzeichnet ist,
- a) dass zu vorgegebenen Zeitpunkten an wenigstens zwei beabstandeten Messstellen entlang der Fluid-Transportpipeline jeweils zeitgleich der fließende Gleichstrom gemessen und erfasst wird,
- b) dass für jeden vorgegebenen Zeitpunkt aus den Messwerten jeweils zweier beabstandeter Messstellen ein Differenzwert gebildet wird,
- c) dass aus der zeitlichen Änderung der für die vorgegebenen Zeitpunkte gebildeten Differenzwerte wenigstens ein Wert abgeleitet wird, der eine Annäherung bzw. einen Kontakt zwischen dem leitfähigen Körper und der Fluid-Transportpipeline zwischen den beiden Messstellen anzeigt.
- a) that at predetermined times at at least two spaced measuring points along the fluid transport pipeline each time the flowing DC current is measured and detected,
- b) that a difference value is formed for each given point in time from the measured values of respectively two spaced measuring points,
- c) that from the temporal change of the difference values formed for the predetermined times, at least one value is derived which indicates an approach or a contact between the conductive body and the fluid transport pipeline between the two measuring points.
Mit dem erfindungsgemäßen Überwachungsverfahren kann ein Kontakt beispielsweise zwischen einem leitfähigen Baufahrzeug und der leitfähigen Fluid-Transportpipeline sofort erkannt werden. Sofern der Widerstand der Umgebung der Transportpipeline nicht zu hoch ist, beispielsweise bei unterseeischer Anordnung im Wasser, kann eine Annäherung des Baufahrzeugs bzw. allgemein eines leitfähigen Körpers bereits festgestellt werden, bevor der leitfähige Körper die leitfähige Transportpipeline berührt. Durch die Bildung der für die Differenz der an den Messstellen entlang der Pipeline fließenden Schutzströme repräsentativen Differenzwerte gelingt es, Störeinflüsse zu reduzieren. Änderungen des Schutzstroms, die beispielsweise auf von Gleichstrombahnen erzeugte Streuströme oder auf Tellurik genannte erdmagnetische Variationen zurückzuführen sind, können weitgehend eliminiert werden. Erforderlich ist lediglich, dass an den zwei Messstellen der Fluid-Transportpipeline im wesentlichen gleichzeitig jeweils ein für den an der Messstelle fließenden Schutzstrom repräsentativer Messwert erfasst wird. Sofern mehr als zwei Messstellen vorgesehen sind, sollten die Differenzwerte vorzugsweise jeweils aus den Messwerten unmittelbar benachbarter Messstellen gebildet werden.With the monitoring method according to the invention, a contact between, for example, a conductive construction vehicle and the conductive fluid transport pipeline can be recognized immediately. If the resistance of the environment of the transport pipeline is not too high, for example when submerged in the water, an approach of the construction vehicle or, more generally, of a conductive body can already be ascertained before the conductive body touches the conductive transport pipeline. By forming the difference values representative of the difference in the protective currents flowing at the measuring points along the pipeline, it is possible to reduce interference. Changes in the protective current due, for example, to stray currents generated by DC tracks or to earth-magnetic variations called Tellurik can be largely eliminated. All that is required is that at the two measuring points of the fluid transport pipeline, a measured value representative of the protective current flowing at the measuring point is detected at substantially the same time. If more than two measuring points are provided, the difference values should preferably be formed in each case from the measured values of directly adjacent measuring points.
Der für den entlang der Fluid-Transportpipeline fließenden Schutzstrom repräsentative Messwert kann sowohl ein Spannungsmesswert sein als auch ein Strommesswert, welcher beispielsweise aus einem Spannungsmesswert bestimmt wurde. Die in Schritt b) gebildeten für die Differenz der an den Messstellen fließenden Schutzströme repräsentativen Differenzwerte können in gleicher Weise sowohl Spannungsdifferenzwerte als auch Schutzstromdifferenzwerte sein. Werden Schutzstromdifferenzwerte verwendet, können diese auf zwei Arten bestimmt werden, nämlich indem zunächst die Schutzströme für die einzelnen Messstellen bestimmt werden und dann die Differenz gebildet wird oder indem zunächst ein Spannungsdifferenzwert und daraus ein Schutzstromdifferenzwert gebildet wird.The measurement value representative of the protection current flowing along the fluid transport pipeline can be both a voltage measurement value and a current measurement value which has been determined, for example, from a voltage measurement value. The difference values formed in step b) that represent the difference of the protective currents flowing at the measuring points can be both voltage difference values and protective current difference values in the same way. If protective current difference values are used, these can be determined in two ways, namely by first determining the protective currents for the individual measuring points and then forming the difference or by first forming a voltage difference value and from this a protective current difference value.
Der wenigstens eine Annäherung eines leitfähigen Körpers an die Fluid-Transportpipeline anzeigende Wert kann sowohl digital als auch analog sein. Er wird aus der zeitlichen Änderung der für die vorgegebenen Zeitpunkte gebildeten Differenzwerte, d. h. auf der Basis des zeitlichen Verlaufs der gebildeten Differenzwerte bestimmt. Wenn beispielsweise die Differenzwerte plötzlich stark ansteigen oder stark abfallen, kann dies eine Annäherung eines leitfähigen Körpers anzeigen und es kann ein entsprechender die Annäherung eines leitfähigen Körpers anzeigender Wert, z. B. als Fehleranzeige oder zu deren Erzeugung erzeugt werden. Alternativ kann erst dann eine Annäherung eines leitfähigen Körpers angezeigt werden, wenn die Flanke eines solchen Anstiegs bzw. Abfalls eine bestimmte, ggf. gespeicherte, Form hat. Bei einer weiteren Variante kann der die Annäherung eines leitfähigen Körpers anzeigende Wert repräsentativ für die Schwankungsbreite des Differenzwertes in einem vorhergehenden Zeitraum sein, wobei einzelne "Ausreißer" des Differenzwertes je nach Anwendung unberücksichtigt bleiben können: Verändern sich die gebildeten Differenzwerte zeitlich dagegen nicht bzw. schwanken sie nur im Rahmen der Messgenauigkeit, liegt keine Annäherung eines leitfähigen Körpers vor. Dies kann von dem die Annäherung eines leitfähigen Körpers anzeigenden Wert beispielsweise durch das Nichtanzeigen einer Fehlermeldung angezeigt werden.The value indicative of at least one approach of a conductive body to the fluid transport pipeline may be both digital and analog. It is determined from the temporal change of the difference values formed for the given times, ie on the basis of the time course of the difference values formed. For example, if the difference values suddenly rise sharply or fall off sharply, this may be an approximation of a conductive body and there may be a corresponding value indicative of the approximation of a conductive body, e.g. B. be generated as an error message or for their generation. Alternatively, an approximation of a conductive body can only be displayed when the edge of such an increase or decrease has a certain, possibly stored, shape. In a further variant, the value indicative of the approach of a conductive body can be representative of the fluctuation range of the difference value in a preceding period, whereby individual "outliers" of the difference value can be disregarded depending on the application: on the other hand, the formed difference values do not vary or fluctuate in time they only in the context of measurement accuracy, there is no approximation of a conductive body. This may be indicated by the value indicating the approach of a conductive body, for example by not displaying an error message.
Die Genauigkeit bei der Bestimmung des Ortes der Annäherung eines leitfähigen Körpers kann dadurch erhöht werden, dass die Messstellen entlang der Fluid-Transportpipeline in Abständen unterhalb von 20 km, vorzugsweise in Abständen unterhalb von 5 km vorgesehen werden und die Differenzwerte aus den Messwerten für unmittelbar benachbarte Messstellen gebildet werden. Die Genauigkeit mit der eine Annäherung eines leitfähigen Körpers festgestellt werden kann, hängt darüber hinaus von der Nennweite und der Wanddicke der Fluid-Transportpipeline und dem Verhältnis zwischen dem Einschaltpotential der mit dem kathodischen Schutzstrom beaufschlagten Fluid-Transportpipeline und dem Ruhepotential des sich nähernden leitfähigen Körpers ab. Da diese Größen jedoch ohne weiteres nicht verändert werden können, lässt sich die gewünschte Messgenauigkeit am besten durch die entsprechende Anpassung der Abstände zwischen den Messstellen realisieren.The accuracy in determining the location of the approach of a conductive body can be increased by providing the measuring points along the fluid transport pipeline at intervals below 20 km, preferably at intervals below 5 km, and the difference values from the values for immediately adjacent ones Measuring points are formed. The accuracy with which an approach of a conductive body can be determined, moreover depends on the nominal size and the wall thickness of the fluid transport pipeline and the ratio between the turn-on potential of the fluid transport pipeline loaded with the cathodic protection current and the rest potential of the approaching conductive body , However, since these quantities can not be changed without further ado, the desired measurement accuracy can best be achieved by adjusting the distances between the measuring points accordingly.
Damit auch kleinere und/oder besonders kurzzeitige Änderungen des Schutzstroms erfasst werden können, wird vorgeschlagen, dass die Messwerte in regelmäßigen Zeitabständen kleiner als 1 s, vorzugsweise alle 0,1 - 0,5 s erfasst werden. Beträgt die zeitliche Auflösung beispielsweise 0,2 s, können kurzzeitige metallische Kontakte bereits ab ca. 0,6 s zuverlässig erkannt werden.So that even smaller and / or particularly short-term changes in the protective current can be detected, it is proposed that the measured values are recorded at regular time intervals of less than 1 s, preferably every 0.1-0.5 s. If the temporal resolution is 0.2 s, for example, short-term metallic contacts can be reliably detected as early as 0.6 s.
Da erfindungsgemäß die Gleichstromänderung der fließenden Schutzströme ausgewertet wird, ist es vorteilhaft, dass an den Messstellen möglicherweise vorhandene Wechselstromkomponenten derart herausgefiltert werden, dass Gleichstromänderungen mit einer Dauer von zumindest 200 ms in Schritt a) erfasst werden. Auf diese Weise können die Einflüsse von technischen Wechselspannungen mit Hilfe von Filtern eliminiert werden. Aufgrund der Dämpfungseigenschaft dieser Filter können Gleichstromänderungen in der Regel überhaupt erst erfasst werden, wenn sie eine Dauer von zumindest 200 ms aufweisen. Damit ein kurzzeitiger metallischer Fremdkontakt sicher erfasst werden kann, müssen zumindest drei Messzeitpunkte zur Verfügung stehen, d. h. der Fremdkontakt muss zumindest 600 ms bestehen. Folglich kann in einer Anordnung mit Filterung von Wechselspannungen die höchste Auflösung erzielt werden, wenn fünf für den Schutzstrom repräsentative Messwerte pro Sekunde erfasst werden.Since, according to the invention, the DC change of the flowing protective currents is evaluated, it is advantageous that AC components possibly present at the measuring points are filtered out in such a way that DC changes with a duration of at least 200 ms are detected in step a). In this way, the influences of technical AC voltages can be eliminated by means of filters. Due to the damping characteristic of these filters, DC changes can generally only be detected if they have a duration of at least 200 ms. For a short-term metallic foreign contact can be detected safely, at least three measuring times must be available, ie the external contact must be at least 600 ms. Consequently, in an arrangement with filtering of AC voltages the highest resolution can be achieved if five values representative of the protection current per second are detected.
Eine bevorzugte Ausführungsform ist dadurch gekennzeichnet, dass im Schritt a) als Messwert ein Spannungsmesswert erfasst wird.A preferred embodiment is characterized in that in step a) a measured voltage value is detected as the measured value.
Vorteilhafterweise wird jeder Messstelle eine entlang der Pipeline verlaufende Messstrecke zugeordnet und zur Erfassung des Spannungsmesswerts die Spannung zwischen den beiden Endpunkten der Messstrecke gemessen.Advantageously, each measuring point is assigned a measuring section running along the pipeline, and the voltage between the two end points of the measuring section is measured to detect the voltage measured value.
Die Messgenauigkeit für den Spannungsmesswert ist besonders hoch, wenn eine Messstrecke einer Länge von wenigstens 10 m, vorzugsweise von wenigstens 30 m, verwendet wird.The measuring accuracy for the voltage measured value is particularly high if a measuring section of at least 10 m in length, preferably of at least 30 m, is used.
Außerdem kann die Messgenauigkeit dadurch erhöht werden, dass die Spannungsmesswerte mit einer Auflösung von wenigstens 1 µV, vorzugsweise von wenigstens 0,1 µV erfasst werden.In addition, the measurement accuracy can be increased by detecting the voltage measurement values with a resolution of at least 1 μV, preferably of at least 0.1 μV.
Eine Weiterbildung der Erfindung ist dadurch gekennzeichnet, dass die in Schritt a) an den verschiedenen Messstellen erfaßten Meßwerte an eine zentrale Verarbeitungseinrichtung übertragen werden und die Schritte b) und c) von der zentralen Verarbeitungseinrichtung ausgeführt werden. Die Meßwertübertragung kann über ein GPRS-Netzwerk erfolgen. Die Verlegung der Schritte b) und c) in die zentrale Verarbeitungseinrichtung hat den Vorteil, daß an den verschiedenen Meßstellen lediglich eine Erfassung der Meßwerte und deren Übertragung sichergestellt werden muß. Die zentrale Verarbeitung sämtlicher Meßdaten erlaubt die Verwendung kostengünstigerer Hardware an den ggf. zahlreichen einzelnen Meßstellen.A development of the invention is characterized in that the measured values acquired in step a) at the various measuring points are transmitted to a central processing device and steps b) and c) are carried out by the central processing device. The measured value can be transmitted via a GPRS network. The transfer of steps b) and c) in the central processing device has the advantage that only a detection of the measured values and their transmission must be ensured at the different measuring points. The central processing of all measured data allows the use of less expensive hardware at the possibly numerous individual measuring points.
Vorzugsweise werden die Schritte b) und c) in Echtzeit ausgeführt. Dies ist erforderlich, um plötzliche Beschädigungen bzw. allgemeiner ausgedrückt eine Annäherung eines leitfähigen Körpers ebenfalls in Echtzeit zu erkennen. Die Datenübertragung an die zentrale Verarbeitungseinrichtung erfolgt in der Regel über eine Onlineverbindung. Vorhandene Rohrstrommeßstellen können einfach dadurch auf das erfindungsgemäße Überwachungsverfahren umgerüstet werden, daß an diesen Überwachungssensoren installiert werden, die eine Übertragung der Meßwerte an die zentrale Verarbeitungseinrichtung erlauben und die Echtzeit-Ausführung der Schritte b) und c).Preferably, steps b) and c) are performed in real time. This is necessary to detect sudden damage or, more generally, an approach of a conductive body also in real time. The data transmission to the central processing device is usually via an online connection. Existing pipe flow measuring points can be easily converted to the monitoring method according to the invention by installing monitoring sensors thereon which allow transmission of the measured values to the central processing device and the real-time execution of steps b) and c).
Eine Ausführungsform der Erfindung ist dadurch gekennzeichnet, daß im Schritt c) der eine Annäherung eines leitfähigen Körpers anzeigende Wert aus der zeitlichen Änderung der für die vorgegebenen Zeitpunkte gebildeten Differenzwerte abgeleitet wird, indem
- i) Differenzwerte für unmittelbar aufeinanderfolgende Zeitpunkte verglichen werden,
- ii) festgestellt wird, ob sich die Differenzwerte für unmittelbar aufeinanderfolgende Zeitpunkte um mehr als einen vorgegebenen Schwellwert unterscheiden und
- iii) auf der Basis des Ergebnisses dieser Feststellung der eine Annäherung eines leitfähigen Körpers anzeigende Wert erzeugt wird.
- i) difference values are compared for immediately consecutive times,
- (ii) it is determined whether the difference values for immediately consecutive times differ by more than a predetermined threshold, and
- iii) is generated on the basis of the result of this determination of the indicative of a convergence of a conductive body value.
Alternativ kann im Schritt c) der eine Annäherung eines leitfähigen Körpers anzeigende Wert aus der zeitlichen Änderung der für die vorgegebenen Zeitpunkte gebildeten Differenzwerte abgeleitet werden, indem
- i) die Differenzwerte für unmittelbar aufeinanderfolgende Zeitpunkte verglichen werden,
- ii) wenn sich die Differenzwerte für unmittelbar aufeinanderfolgende Zeitpunkte um mehr als einen vorgegebenen Schwellwert unterscheiden, zusätzlich die Differenzwerte für die Zeitpunkte unmittelbar vor und nach den im Schritt i) berücksichtigten Zeitpunkten verglichen werden,
- iii) festgestellt wird, ob sich auch die im Schritt ii) verglichenen Differenzwerte um mehr als den vorgegebenen Schwellwert unterscheiden und
- iv) auf der Basis des Ergebnisses dieser Feststellung der eine Annäherung eines leitfähigen Körpers anzeigende Wert erzeugt wird.
- i) the difference values are compared for immediately consecutive times,
- ii) if the difference values for immediately consecutive times differ by more than a predetermined threshold, in addition the difference values for the times immediately before and after the times considered in step i) are compared,
- (iii) it is determined whether the difference values compared in step (ii) also differ by more than the predetermined threshold, and
- iv) is generated on the basis of the result of this determination of the indicative of a convergence of a conductive body value.
Schließlich besteht eine weitere Möglichkeit zur Ableitung des eine Annäherung eines leitfähigen Körpers anzeigenden Wertes darin, daß im Schritt c) der eine Annäherung eines leitfähigen Körpers anzeigende Wert aus der zeitlichen Änderung der für die vorgegebenen Zeitpunkte gebildeten Differenzwerte abgeleitet wird, indem
- i) der Verlauf der Differenzwerte mit der Zeit durch eine geglättete Kurve angenähert wird,
- ii) festgestellt wird, ob die zeitliche Änderung der geglätteten Kurve einen vorgegebenen Schwellwert überschreitet und
- iii) auf der Basis des Ergebnisses dieser Feststellung der eine Annäherung eines leitfähigen Körpers anzeigende Wert erzeugt wird.
- i) the course of the difference values is approximated by a smoothed curve over time,
- (ii) it is determined whether the temporal change of the smoothed curve exceeds a predetermined threshold, and
- iii) is generated on the basis of the result of this determination of the indicative of a convergence of a conductive body value.
Dabei kann die Art der Glättung beliebig variiert werden. Beispielsweise kann ein einzelner Ausreißer in den Differenzwerten bei der Glättung nicht berücksichtigt werden. Auch das Maß der Glättung kann individuell an die Meßumgebung angepaßt werden.The type of smoothing can be varied as desired. For example, a single outlier can not be included in the difference values in the smoothing. The degree of smoothing can also be adapted individually to the measuring environment.
Im folgenden wird die Erfindung anhand beispielhafter Ausführungsformen näher erläutert. In den Figuren zeigen:
-
eine schematische Darstellung der Stromverteilung an einer Gashochdruckleitung bei metallisch leitendem Fremdkontakt;Figur 1 -
ein Diagramm, das den Einfluß der Nennweite auf die Spannungsdifferenz zwischen zwei Rohrstrommeßstrecken bei metallisch leitendem Fremdkontakt darstellt;Figur 2 -
eine schematische Darstellung des Überwachungsprinzips für eine Gashochdruckleitung mit mehreren Schutzabschnitten;Figur 3 -
Figuren 4a und 4b jeweils Diagramme, die den zeitlichen Verlauf der Rohrstrommeßwerte an zwei Meßstellen zeigen, zwischen denen nacheinander drei metallische Fremdkontakte mit der Rohrleitung realisiert wurden; -
Figur 4c ein Diagramm, das die Differenz der in denFiguren 4a und 4b dargestellten Rohrströme zeigt, und zwar wiederum aufgetragen gegen die Zeit; und -
Figuren 4d und 4e jeweils Diagramme von Rohrstromdifferenzen für die den Leitungsabschnitt unmittelbar stromauf bzw. unmittelbar stromab dem Leitungsabschnitt mit metallischem Fremdkontakt.
-
FIG. 1 a schematic representation of the current distribution at a high-pressure gas line at metallically conductive foreign contact; -
FIG. 2 a diagram illustrating the influence of the nominal diameter on the voltage difference between two Rohrstrommeßstrecken with metallically conductive foreign contact; -
FIG. 3 a schematic representation of the monitoring principle for a high-pressure gas line with multiple protection sections; -
FIGS. 4a and 4b in each case diagrams showing the time course of the pipe flow measured values at two measuring points, between which successive three foreign metal contacts with the pipeline were realized; -
Figure 4c a diagram showing the difference in theFIGS. 4a and 4b shows shown pipe flows, again plotted against time; and -
Figures 4d and 4e each diagrams of pipe flow differences for the line section immediately upstream or immediately downstream of the line section with metallic foreign contact.
Da die Rohrströme nicht ohne weiteres gemessen werden können, werden an den Meßstellen 3 jeweils die Spannungsmeßwerte U1 bzw. U2 für die zugehörigen Meßstrecken erfaßt. Der Widerstand einer Rohrstrommeßstrecke berechnet sich wie folgt:
wobei
- RStrom =
- Widerstand der Rohrstrommeßstelle
- ρ =
- spezifischer elektrischer Widerstand von Stahl
- l =
- Länge der Rohrstrommeßstrecke
- da =
- Rohraußendurchmesser
- di =
- Rohrinnendurchmesser
- d =
- mittlerer Rohrdurchmesser
- s =
- Wanddicke der Rohrleitung
- UEin =
- Einschaltpotenzial
- UR =
- Ruhepotenzial des Baufahrzeuges
- RKontakt =
- Ausbreitungswiderstand des Baufahrzeuges an der Kontaktstelle
- I1, I2 =
- Rohrstrom
- IF =
- Fehlerstrom
- ΔU =
- Spannungsdifferenz zwischen den beiden Rohrstrommeßstrecken
- ΔI =
- Stromdifferenz zwischen den beiden Rohrstrommeßstrecken
in which
- R current =
- Resistance of the pipe flow measuring point
- ρ =
- specific electrical resistance of steel
- l =
- Length of Rohrstrommeßstrecke
- d a =
- External pipe diameter
- d i =
- Inside pipe diameter
- d =
- average pipe diameter
- s =
- Wall thickness of the pipeline
- U A =
- Einschaltpotenzial
- U R =
- Rest potential of the construction vehicle
- R contact =
- Propagation resistance of the construction vehicle at the contact point
- I 1 , I 2 =
- tube current
- I F =
- fault current
- ΔU =
- Voltage difference between the two Rohrstrommeßstrecken
- ΔI =
- Current difference between the two Rohrstrommeßstrecken
Die Rohrströme 11 und 12 sind in der Regel gleich. Daraus folgt für die Spannungsdifferenz, wenn die Rohrabmessungen und die Längen der beiden Rohrstrommeßstrecken konstant sind:
Es zeigt sich also bei diesen Voraussetzungen, daß im Fehlerfall die Spannungsdifferenz zwischen zwei Rohrstrommeßstrecken proportional zum Fehlerstrom ist. Für den Fehlerstrom selbst gilt:
In
ρ = 0,13 Ohm*mm2/m, l = 30 m, d = 250 - 1200 mm, s = 12 mm, UEin = -1,7 V, UR = -0,5 V und RKontakt = 5 - 500 OhmIn
ρ = 0.13 Ohm * mm 2 / m, l = 30 m, d = 250 to 1200 mm, s = 12 mm, U A = -1.7 V, U R = -0.5 V and R = Contact 5 - 500 ohms
Das Diagramm zeigt deutlich, daß die Spannungsdifferenz im Fehlerfall umgekehrt proportional zur Nennweite der Rohrleitung ist. Fremdkontakte oder plötzliche Rohrbeschädigungen können daher bei geringeren Rohrdurchmessern besser aufgelöst werden. Darüber hinaus zeigt das Diagramm, daß die Spannungsdifferenz bei niederohmigen Fremdkontakten wesentlich höher als bei hochohmigen Fremdkontakten ist. Der Grund hierfür ist, daß die Spannungsdifferenz im Fehlerfall umgekehrt proportional zum Ausbreitungswiderstand des Fremdkontakts, beispielsweise des Baufahrzeugs, an der Kontaktstelle ist.The diagram clearly shows that the voltage difference in the event of a fault is inversely proportional to the nominal diameter of the pipeline. Foreign contacts or sudden pipe damage can therefore be resolved better with smaller pipe diameters. In addition, the diagram shows that the voltage difference at low-resistance foreign contacts is much higher than for high-resistance foreign contacts. The reason for this is that the voltage difference in case of failure is inversely proportional to the propagation resistance of the foreign contact, such as the construction vehicle, at the contact point.
Die in
Im Vergleich dazu sind die Rohrstromdifferenzen für benachbarte Rohrabschnitte außerhalb des fehlerbehafteten Abschnitts in
Die drei simulierten Fehler sind in
Den
Mit dem erfindungsgemäßen Überwachungsverfahren gelingt es bei vorhandenem kathodischen Korrosionsschutz, ohne zusätzlich zu überlagernde Signale plötzliche Beschädigungen einer Rohrleitung zuverlässig, ohne besonderen technischen Aufwand und kostengünstig festzustellen.With the monitoring method according to the invention, it is possible with existing cathodic corrosion protection, without additional to superimposed signals sudden damage to a pipeline Reliable, without special technical effort and inexpensive to determine.
Im Rahmen der Erfindung sind zahlreiche Abwandlungen denkbar. Die für den Schutzstrom repräsentativen Meßwerte sollten an den wenigstens zwei Meßstellen vorzugsweise zeitgleich erfaßt werden. Dennoch kann es in manchen Umgebungen genügen, wenn die Meßwerte lediglich möglichst zeitgleich erfaßt werden. Die Abstände der Meßstellen entlang der Fluid-Transportpipeline können selbstverständlich beliebig variiert werden, wobei möglichst nahe Abstände vorzuziehen sind, da nicht der genaue Ort der Beschädigung bzw. der Annäherung eines leitfähigen Körpers festgestellt wird, sondern nur, daß sich zwischen den verglichenen Meßstellen irgendwo ein leitfähiger Körper der Rohrleitung nähert bzw. diese plötzlich berührt. Auch die Zeitabstände zwischen den einzelnen Messungen können beliebig verändert werden. Wenn an den einzelnen Meßstellen Spannungsmeßwerte erfaßt werden, könnten die Rohrstrommeßwerte statt in der zentralen Verarbeitungseinrichtung auch in den einzelnen Meßstellen berechnet werden. Ferner kann die zeitliche Änderung der Differenzwerte beliebig ausgewertet werden, um den eine Annäherung eines leitfähigen Körpers anzeigenden Wert abzuleiten. In jedem Fall sollte allerdings sichergestellt werden, daß ein plötzlicher Anstieg bzw. Abfall der gebildeten Differenzwerte, welcher über mehrere Differenzwerte anhält, einen Wert erzeugt, der eine Annäherung eines leitfähigen Körpers anzeigt. Außerdem wird das erfindungsgemäße Überwachungsverfahren in der Regel auf das Feststellen einer Annäherung eines leitfähigen Körpers an eine Fluid-Transportpipeline erst bei elektrischem Kontakt mit der Transportpipeline beschränkt sein, so daß eine Annäherung vor Berühren der leitfähigen Transportpipeline nicht festgestellt werden kann. In diesem Fall ist der eine Annäherung eines leitfähigen Körpers anzeigende Wert ein einen plötzlichen elektrischen Kontakt eines leitfähigen Körpers mit der Transportpipeline anzeigender Wert.Numerous modifications are conceivable within the scope of the invention. The measured values representative of the protection current should preferably be detected at the same time at the at least two measuring points. Nevertheless, it may be sufficient in some environments if the measured values are only detected as simultaneously as possible. The distances of the measuring points along the fluid transport pipeline can of course be varied as desired, with distances as close as possible being preferred, since it is not the exact location of the damage or the approach of a conductive body that is detected, but only that somewhere between the compared measuring points conductive body of the pipeline approaches or suddenly touched. The time intervals between the individual measurements can be changed as desired. If voltage measuring values are detected at the individual measuring points, the pipe flow measured values could also be calculated in the individual measuring points instead of in the central processing device. Furthermore, the temporal change of the difference values can be arbitrarily evaluated in order to derive the value indicating an approach of a conductive body. In any case, however, it should be ensured that a sudden increase or decrease of the formed difference values, which persists across several difference values, generates a value indicating an approach of a conductive body. In addition, the monitoring method of the present invention will typically be limited to detecting an approach of a conductive body to a fluid transport pipeline only upon electrical contact with the transport pipeline so that an approach can not be determined prior to touching the conductive transport pipeline. In this case, the value indicative of an approach of a conductive body is a value indicating a sudden electrical contact of a conductive body with the transportation pipeline.
Schließlich kann die Erkennbarkeit einer Annäherung eines leitfähigen Körpers oder einer plötzlichen Beschädigung mit dem erfindungsgemäßen Verfahren dadurch je nach Anwendung erhöht werden, daß sämtliche Baufahrzeuge im Bereich der Rohrleitung gezielt niederohmig geerdet werden.Finally, the recognition of an approach of a conductive body or a sudden damage with Depending on the application, the method according to the invention can be increased in that all construction vehicles in the area of the pipeline are grounded in a specifically low-resistance manner.
Claims (13)
- A monitoring method for determining any proximity or contact between a conductive body, in particular a construction vehicle, and a fluid transport pipeline to which direct current is applied as a cathodic protection current, characterised in thata) the flowing direct current is measured and recorded at specified times at at least two measuring points spaced along the fluid transport pipeline, in each case at the same time,b) a difference value is formed for each specified time from the measurements of two spaced measuring points in each case,c) at least one value is derived from the change in time of the difference values formed for the specified times, said value indicating a proximity or contact between the conductive body and the fluid transport pipeline between the two measuring points.
- A monitoring method according to claim 1, characterised in that the measuring points are provided along the fluid transport pipeline at distances of less than 20 km, preferably at distances of less than 5 km.
- A monitoring method according to either claim 1 or 2, characterised in that the measurements are recorded at regular intervals of less than 1 sec, preferably every 0.1 to 0.5 sec.
- A monitoring method according to any one of claims 1 to 3, characterised in that any alternating current components which may exist at the measuring points are filtered out in such a way that changes in the direct current lasting at least 200 ms are recorded in step a).
- A monitoring method according to any one of claims 1 to 4, characterised in that a voltage measurement is recorded as the measured value in step a).
- A monitoring method according to claim 5, characterised in that a measuring section running along the pipeline is assigned to each measuring point and that, to record the voltage measurement, the voltage is measured between the two end points of the measuring section.
- A monitoring method according to claim 6, characterised in that a measuring section of a length of at least 10 m, preferably at least 30 m, is used.
- A monitoring method according to any one of claims 5 to 7, characterised in that the voltage measurements are recorded with a resolution of at least 1 µV, preferably of at least 0.1 µV.
- A monitoring method according to any one of claims 1 to 8, characterised in that the measurements recorded in step a) at the different measuring points are transferred to a central processing facility and that the steps b) to c) are performed by the central processing facility.
- A monitoring method according to any one of claims 1 to 9, characterised in that the steps b) and c) are performed in real time.
- A monitoring method according to any one of claims 1 to 10, characterised in that in step c) the value indicating the proximity of a conductive body is derived from the change in time of the difference values formed for the specified times in thati) difference values for immediately consecutive times are compared,ii) it is determined whether the difference values differ for immediately consecutive times by more than one specified threshold value andiii) the value indicating the proximity of a conductive body is generated on the basis of the result of this determination.
- A monitoring method according to any one of claims 1 to 10, characterised in that in step c) the value indicating the proximity of a conductive body is derived from the change in time of the difference values formed for the specified times in thati) the difference values are compared for immediately consecutive times,ii) if the difference values for immediately consecutive times differ by more than one specified threshold value, the difference values for the times directly before and after the times allowed for in step i) are compared in addition,iii) it is determined whether the difference values compared in step ii) also differ by more than the specified threshold value andiv) the value indicating the proximity of a conductive body is generated on the basis of the result of this determination.
- A monitoring method according to any one of claims 1 to 10, characterised in that in step c) the value indicating the proximity of a conductive body is derived from the change in time of the difference values formed for the specified times in thati) the curve of the difference values as a function of time is approximated by a smoothed curve,ii) it is determined whether the change in time of the smoothed curve exceeds a specified threshold value andiii) the value indicating the proximity of a conductive body is generated on the basis of the result of this determination.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PL06006493T PL1728895T3 (en) | 2005-06-02 | 2006-03-29 | Surveillance method for detecting the approach of a conductive body to a cathodically protected pipeline for fluids |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102005025824A DE102005025824A1 (en) | 2005-06-02 | 2005-06-02 | A monitoring method for detecting an approximation of a conductive body to a cathodic protection flow applied fluid transport pipeline |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1728895A1 EP1728895A1 (en) | 2006-12-06 |
EP1728895B1 true EP1728895B1 (en) | 2009-02-11 |
Family
ID=36375087
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP06006493A Active EP1728895B1 (en) | 2005-06-02 | 2006-03-29 | Surveillance method for detecting the approach of a conductive body to a cathodically protected pipeline for fluids |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP1728895B1 (en) |
AT (1) | ATE422566T1 (en) |
DE (2) | DE102005025824A1 (en) |
DK (1) | DK1728895T3 (en) |
ES (1) | ES2322489T3 (en) |
PL (1) | PL1728895T3 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102017113633A1 (en) | 2017-06-21 | 2018-12-27 | Steffel Kks Gmbh | Method for monitoring an electrically conductive object protected by cathodic corrosion protection |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2009019717A1 (en) * | 2007-08-07 | 2009-02-12 | Icsa India Limited | Intelligent cathodic protection system (icap) |
DE102010021992B4 (en) | 2010-05-29 | 2012-10-31 | EnBW Energie Baden-Württemberg AG | A method of detecting damage to the enclosure of objects buried in soil and / or water and protected by cathodic corrosion protection |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0829736A3 (en) * | 1996-09-13 | 1999-12-01 | MetaPhysics S.A. | Measuring earth magnetic field distorsions and object sensor embodying the method |
US6107811A (en) * | 1998-02-12 | 2000-08-22 | Cc Technologies Laboratories, Inc. | Coupon monitor for cathodic protection system |
US6617855B2 (en) * | 2000-03-24 | 2003-09-09 | Radiodetection Limited | Pipeline mapping and interrupter therefor |
DE10021994A1 (en) * | 2000-05-05 | 2001-11-08 | Ruhrgas Ag | Arrangement for determining the pipe/ground potential on cathodically protected pipelines comprises measuring value receivers for acquiring measured and reference values for the pipe/ground potential |
WO2003056364A1 (en) * | 2002-01-03 | 2003-07-10 | Bacab Sa | Method for measuring distortions in a field |
-
2005
- 2005-06-02 DE DE102005025824A patent/DE102005025824A1/en not_active Withdrawn
-
2006
- 2006-03-29 EP EP06006493A patent/EP1728895B1/en active Active
- 2006-03-29 DK DK06006493T patent/DK1728895T3/en active
- 2006-03-29 DE DE502006002788T patent/DE502006002788D1/en active Active
- 2006-03-29 ES ES06006493T patent/ES2322489T3/en active Active
- 2006-03-29 AT AT06006493T patent/ATE422566T1/en active
- 2006-03-29 PL PL06006493T patent/PL1728895T3/en unknown
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102017113633A1 (en) | 2017-06-21 | 2018-12-27 | Steffel Kks Gmbh | Method for monitoring an electrically conductive object protected by cathodic corrosion protection |
WO2018234005A1 (en) | 2017-06-21 | 2018-12-27 | Steffel Kks Gmbh | Method for monitoring an electrically conductive object which is cathodically protected against corrosion |
Also Published As
Publication number | Publication date |
---|---|
ATE422566T1 (en) | 2009-02-15 |
DE502006002788D1 (en) | 2009-03-26 |
EP1728895A1 (en) | 2006-12-06 |
PL1728895T3 (en) | 2009-09-30 |
DK1728895T3 (en) | 2009-05-25 |
DE102005025824A1 (en) | 2006-12-07 |
ES2322489T3 (en) | 2009-06-22 |
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