RU2621219C1 - Method of identification of offsets of the axial line of pipeline - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: measuring system consisting of a freeform inertial measurement module (IMM) in the form of a three-component angular velocity meter and a three-component meter of apparent accelerations, an odometer and radial distance meters, is installed on the inner tube mobile device and n passes of VPU pass through the pipeline through the pipeline. According to each pass, the pipe lengths are determined, the lengths of the same pipes are compared, the gross errors in determining the pipe lengths are excluded, the measurement result with the longest length is selected, the distance record for each of the gaps is corrected taking into account the maximum results of measuring the lengths of the same pipes. The results of determining the orientation of the pipeline centerline from the reference skip data are used in the feedback as a correction signal in determining the orientation of the pipeline center line from the data of repeated passes. Identification of areas with angular displacement of the pipeline center line is carried out on the basis of detection of the excess of the angle difference between the centerline of the pipeline, determined by the records of the reference and slave passes, the specified threshold value.

EFFECT: Increase of manufacturability and accuracy of definition of local displacements of sites of pipelines.

2 cl, 9 dwg

Description

The method relates to measuring and control equipment, namely, to the field of monitoring and diagnostics of pipelines, and is intended to identify potentially dangerous sections of the pipeline on which the axial line deviated from its original position, as well as to evaluate the angular displacements of the axial line of the pipeline in vertical and horizontal plane in order to control the stress-strain state.

The prior art in this area is characterized by the following inventions.

There is a method of identifying potentially accidentally hazardous sections on gas pipeline routes susceptible to stress corrosion cracking [1], which consists in conducting microseismic surveys exactly above the route of an existing gas pipeline, determining the location of local sections of the pipeline with abnormally high levels of intensity of technological and geodynamic vibrations.

The disadvantage of this method is the low speed of the survey (1-2 km per day), the practical impossibility of use in hard-to-reach sections of the pipeline, as well as in sections of pipelines laid along the bottom of reservoirs.

A known method of monitoring dangerous geodynamic processes [2], which consists in the fact that on the landslide site at a certain distance from each other installed benchmarks, which are used to judge the direction and speed of soil movement. In this case, the benchmarks are additionally equipped with a plastic cylinder, which is divided into several sealed parts, filled with liquid and equipped with a pressure sensor, the cylinder is laid in the ground around the entire landslide perimeter.

The disadvantage of this method is its applicability only in previously known potentially dangerous areas. It is difficult to place the measuring system described in this method on all pipelines.

In the universal diagnostic projectile-flaw detector for monitoring the state of the pipeline [3], a section of navigation and altitude-planning marks has been introduced, which is a sealed enclosure, inside which a navigation module is located, including a command device with a three-axis gyrostabilizer, a digital computer complex and a recording equipment unit. The invention proposes to determine the position of the pipeline in space, its change compared to previous measurements and to identify dangerous areas of stress and strain from external and internal influences on the pipeline according to the energy theory of strength.

In this technical solution, the accuracy of determining the coordinates of the dangerous section is insufficient due to the lack of information about the position of the projectile relative to the pipeline (in the general case, the axis of the projectile and the pipeline do not coincide due to wear and deformation of the supporting elements of the projectile) and the accumulation in time of the autonomous inertial navigation system of determination errors coordinates.

Known inertial monitoring system of pipelines [4], which implements the following method:

1) the system passes through the pipeline and measures the dynamic characteristics of the supporting shells inside the pipeline relative to the inertial coordinate system in the space of this pipeline,

2) record the digital signals of measurements of dynamic characteristics inside the carrier means.

As the dynamic characteristics are measured: accelerometers and gyroscopes - the apparent acceleration and orientation angles of the carrier means in three orthogonal directions; system of ultrasonic sensors - speed and relative orientation of the carrier means in the pipeline. The seams are detected using a microphone, the analog signals are filtered, converted to digital and the dynamic characteristics are calibrated along the seams of the pipeline.

The disadvantage of this method is the low accuracy of determining local displacements of pipelines due to the departure of gyroscopes.

A known method in a device for determining and recording the geometric parameters of pipelines [5]. In this invention, the following method is implemented:

1) an in-tube inspection projectile is passed inside the pipeline;

2) with a three-component angular velocity meter and a three-component apparent acceleration meter, three components of the absolute angular velocity and three components of the apparent acceleration are measured in the coordinate system associated with the in-tube projectile;

3) the odometer measures the increment of the projectile path, with ultrasonic sensors - its position relative to the walls of the pipeline;

4) the measurement results are recorded in the memory of the calculation and registration device, and then converted into the current geographical coordinates of the location of the projectile and the angles of its orientation, as well as the radii of curvature of the longitudinal axis of the pipeline in the vertical and horizontal planes.

The disadvantage of this technical solution is the lack of a method for determining local displacements of gas pipelines, identifying and predicting hazardous sections of pipelines, and compensating for the accumulated over time errors of the navigation system due to correction from other systems.

There is a method of determining local sections of trunk pipelines with maximum deformation [6], in which, according to the results of an in-tube projectile, pipe vibrations in the region of the launch and reception chambers, projectile vibrations in its stationary state are measured, frequencies and damping coefficients in its stationary state are determined, and gas pressure pulsations; at discrete frequencies, the maximum resonance values of the components of the Fourier decomposition of the acceleration signals are detected, the frequencies of three pipe oscillation modes are detected in representative areas identified by soil maps or aerospace images, their position on the main gas pipeline route and the oscillation amplitudes are determined. The disadvantages of this method include the following:

• low sensitivity with low heterogeneity of the soil in the pipeline sections subject to changes in the geometry of the center line;

• does not take into account the significant dependence of the spectra of the measured signals on the velocity of the projectiles and the stiffness of their cuffs, on the relief of the inner surface of the pipeline.

There is a method of determining local displacements of pipelines [7], in the framework of which there are n passes of in-pipe inspection shells equipped with a strap-in inertial orientation and navigation system, an odometer and ultrasonic sensors, over the same section of the pipeline at time intervals characterized by different steady-state temperature and weather conditions, determine the increment of all measured parameters in relation to the corresponding parameters of the first pass.

The disadvantage of this method is the need to measure the coordinates of marker points to solve the navigation problem.

A known diagnostic complex device for determining the position of the pipeline and a method for determining the relative movement of the pipeline according to the results of two or more inspection passes of the diagnostic complex for determining the position of the pipeline [8], designed to determine the position of the pipeline in space during operation and construction of pipelines. The device consists of hardware: accelerometers, gyroscopes and odometer, and software, while the hardware is installed on the in-tube inspection device and consists of a set of sensors. The software part consists of algorithms for determining navigation parameters in the following sequence: calculation of linear velocity, exhibition, that is, determining the position in the space of an in-tube inspection device, calculation of navigation parameters, calculation of pipeline bending radii, and path correction. The data received from the hardware is overwritten and the navigation parameters are calculated using the software. The method consists in the fact that the data obtained from the diagnostic complex for determining the position of the pipeline are arranged according to the tables and combined over distances, and the pass data of the in-pipe inspection device with the hardware of the diagnostic complex installed on it for determining the position of the pipeline with an earlier date are considered basic, and the data of subsequent passes is compared with the basic, and the criterion for the presence of movement of the pipeline in the inspected section is the excess of the module difference curvature of a given threshold value.

The disadvantages of the method for determining local displacements of the pipeline include the following:

• the need for accurate measurement of coordinates at marker points, which is a time-consuming procedure with large material and time costs, especially in sections of pipelines laid in difficult places and along the bottom of water bodies;

• the redundancy of distance measurements is not used for multiple passes of the in-pipe inspection device in one pipeline to compensate for odometric errors, which can lead to unacceptable errors in the positioning of pipeline elements and estimation of difference curvature, especially in areas with a large distance between marker points. This invention is taken as a prototype.

The objective of the invention is to develop an effective method for identifying local displacements of pipelines and improving the accuracy of their localization according to repeated inspection passes of in-tube mobile devices (VPU) equipped with a strap-down inertial measuring module (BIIM).

New in the proposed method is the identification of local displacements of pipelines based on identifying sections with an angular displacement of the axial line of the pipeline by deviations of the estimates of the axial line orientation parameters generated from the BIIM signal records during repeated passes of the runway from the corresponding estimates obtained from the reference pass data. In this case, the deviation estimates of the orientation parameters are used to organize the correction when solving the orientation problem according to the repeated passes of the runway, which allows implementing a practically continuous algorithm for observing the angular displacement of its axial line with respect to its position at the time of the runway pass pass. In addition, in the proposed method, the accuracy of determining the parameters of angular displacements is increased by identifying and compensating for the deviation of the longitudinal axis of the runway from the axis of the pipe during the passage through the pipeline, and also the redundancy of information on the lengths of the pipes of the same name obtained from the results of all passes is used to correct the distance in each from VPU passes in order to increase the accuracy of localization of the angular displacements of the pipeline.

The technical result of the proposed method is to obtain up-to-date information on the displacement of pipeline sections, to increase the manufacturability and accuracy of determining local displacements of pipeline sections for predicting stress corrosion and evaluating dangerous mechanical stresses on them, simplifying and cheapening the technology for identifying pipeline displacements.

The invention is illustrated by graphic materials: FIG. 1 - results of solving the problem of orientation of the axial line of the pipeline, FIG. 2 - results of solving the problem of orientation of the axial line of the pipeline with compensation for systematic errors, FIG. 3 - the discrepancy of the orientation parameters of the axial line of the pipeline according to the results of repeated passes VPU, FIG. 4 - estimates of the angle of the center line of the underwater transition based on the results of repeated surveys, FIG. 5 is a plan of the underwater passage according to the results of two surveys, FIG. 6 - the discrepancy of the parameters of the angle of the axial line of the pipeline according to the results of repeated passes VPU, FIG. 7 is a section of an underwater transition plan with a displacement model, FIG. 8 shows course angle estimates based on the results of two passes and with a model of pipeline displacement, FIG. 9 - the difference in the estimates of the orientation parameters of the axial line of the pipeline according to the results of repeated passes of the VPU when modeling the local displacement of the pipeline section.

A method for identifying pipeline offsets is implemented as follows.

On the outer surface of the runway place 2 belts on N measuring radial distance from the outer surface of the runway thermocontainer to the inner surface of the pipe. On one and the same section of the pipeline, two or more inspection passes of the runway are carried out at time intervals characterized by different steady-state temperature and weather conditions. During each of two or more inspection passes of the runway along the entire length of the pipeline route, not less than 100 Hz are recorded in the on-board computer memory of the signals of the radial distance meters, the BIIM signals of the three components of the absolute angular velocity vector and three components of the apparent acceleration vector, as well as odometer signals about runway distance increment.

The processing of this information is carried out in the following sequence.

First, determine the initial orientation of the runway and evaluate the zero signals BIIM channels of angular velocity. Then, the odometer scale factors are calibrated based on a comparison of the odometer distance increments for each of the gaps in a specific section of the pipeline

,

,

where: j is the pass number of the runway; ΔS is the length of the pipeline section, for example, along the reference pass; ΔS _j is the length of the pipeline section according to repeated passes. The signals of the radial distance meters determine the angular displacement of the longitudinal axis of the runway relative to the axis of the pipe for each measurement step in each inspection pass. Based on the results of each of the passes, taking into account the angular displacement of the axis of the runway and the calibrated scale factors of the odometers, the orientation of the axial line of the pipeline is determined, as well as the joints of the pipes and the lengths of the pipes are calculated.

In this case, the orientation is determined in the course of solving differential correctable kinematic equations of orientation:

- вектор или матрица оценок состояния, в данном случае - оценок параметров ориентации ВПУ (вектор углов Крылова-Эйлера (ψ, θ, γ), вектор параметров Родрига-Гамильтона, матрица направляющих косинусов); ω - оценка вектора угловой скорости ВПУ относительно сопровождающего горизонтного трехгранника, формируемая на основе сигналов датчиков угловой скорости БИИМ;Where:

- a vector or matrix of state estimates, in this case, estimates of the VPU orientation parameters (Krylov-Euler angle vector (ψ, θ, γ), Rodrigue-Hamilton parameter vector, guide cosine matrix); ω is the estimate of the VPU angular velocity vector relative to the accompanying horizontal trihedron, formed on the basis of the signals of the BIIM angular velocity sensors;

z is a vector or matrix of measurements, i.e. “Quick” estimates of the orientation parameters relative to the true vertical, formed on the basis of the signals of the linear acceleration sensors BIIM; relative to the meridian - only with a fixed runway (initial exhibition, stop) based on the gyrocompassing method;

F (ω, α) is a matrix function that reflects the relationship between the components of the angular velocity vector, orientation parameters and their derivatives;

H is a measurement matrix linking the state and measurement;

K is the matrix of correction factors;

ψ _T , θ _T are the orientation parameters of the pipe axis,

β _ψ , β _θ - estimates of the angles between the axial line of the in-tube device and the axial line of the pipeline in the horizontal plane and in the vertical plane, respectively, formed on the basis of the conversion of the estimates of the angular displacement of the longitudinal axis of the runway from the signals of the radial distance meters taking into account the estimates of the orientation parameters of the runway.

According to the results of the analysis of measurements of the length of the pipes of the same name, determined by the data of all gaps, the presence of gross blunders in the measurements is determined and excluded from further processing, in the remaining data set for each pipe of the same name, the maximum result of measuring the pipe length is selected, the distance records of all the gaps are specified taking into account the maximum measuring the length of pipes of the same name using odometer coefficients corresponding to the pipes of the same name:

,

,

where: j is the pass number of the runway;

k is the pipe number;

- максимальная длина k-й трубы;

- the maximum length of the k-th pipe;

- длина трубы.

- pipe length.

Gross misses in pipe length estimates are determined, for example, as follows: the maximum pipe length is assumed to be 13 m, pipe length estimates over 13 meters are considered a gross slip; in the presence of 3 or more measurements of the length of one and the same pipe, the confidence interval of measurements is determined by choosing a confidence level, for example, 0.95, and a value that is not included in the confidence interval is considered a gross miss. The orientation parameters of the axial line of the pipeline are determined for each of the runway passes, taking into account the updated distance records. Synchronize the distance of the orientation parameters of the center line for the reference and slave passes; for each measure of the slave pass record, the values of the orientation angles of the axial line of the pipeline obtained from the reference pass, for example, by interpolation, are determined. Identify areas with an angular displacement of the axial line of the pipeline based on the solution of the orientation equations for the data of the slave pass with the introduction of feedback correction, based on the difference in the angles of orientation of the axial line of the pipeline, determined from the records of the reference and slave passes, and detecting if this difference exceeds a predetermined threshold values.

For the case of using the Krylov-Euler angles as orientation parameters, the mathematical basis of the information transformation at this stage can be represented as:

Where

ω _x1 , ω _x2 , ω _x3 - estimates of the angular velocities of the VIP;

k _ψ , k _θ , k _γ - correction factors;

- параметры ориентации оси трубы по опорному пропуску.

- orientation parameters of the pipe axis along the reference pass.

идентифицируется наличие локального углового смещения оси трубопровода на текущей дистанции.Those. at

the presence of a local angular displacement of the axis of the pipeline at the current distance is identified.

It should be noted that in the presence of coordinate reference of marker points of the pipeline obtained, for example, by means of ground-based geodetic positioning, the spatial coordinates of the identified sections with local displacement can be determined, as indicated in the analogue [7] and prototype [8].

The pipeline operation technology provides for regular periodic cleaning with cleaning pistons (in-pipe cleaning devices). So, for example, the cleaning of oil pipelines is carried out up to 3 times a quarter, depending on the properties of the oil being transported [9], and the frequency of cleaning gas pipelines varies from 1 time in 5 years (with mandatory flaw detection) to several times a year, depending on their actual hydraulic state [10]. By placing a strap-on inertial measuring module, an odometer, radial distance meters, an on-board computer with a storage device, and a power source on the in-pipe cleaning device, which are passed through the pipeline as part of the regular pipeline cleaning, it becomes possible to refuse to carry out additional passes of the runway, while the technology is simplified and cheaper identification of potentially hazardous sections of the pipeline by reducing the number of run-through passes; on the other hand, in comparison with the frequency of pipeline flaw detection, the use of this equipment on an in-line cleaning device as part of the mandatory regular cleaning increases the frequency of examination of the geometry of the axial line of the pipeline, thereby increasing the relevance of information about the geometry of the axial line of the pipeline, in particular about angular displacements.

The rationale for the effectiveness and testing of the proposed method

The boundaries of the site of interest for determining VAT, according to the method described in [11], are successfully determined using the proposed method. In FIG. Figure 1 shows graphs of estimates of the azimuth and pitch angles of the center line of the underwater transition section based on the results of surveys conducted in 2012 and 2014. During the time between the surveys, the pipeline was repaired and the pipes were replaced in the sections of 1450 m - 1670 m, 3050 m - 3470 m and 4400 m - 4850 m.It is obvious that the geometry of the axial line of the pipeline in the repaired sections differs from its initial state.

Using the proposed method, it is possible to determine sections of the pipeline with a change in the geometry of the center line; in this example, changes are caused by the replacement of pipes (FIG. 2, FIG. 3).

The differences in the geometry of the axial line caused by the replacement of pipes during pipeline repair are in many respects similar to the changes in the geometry of the axial line of the pipeline when it deviates from any initial, including design, position.

Studies of the effectiveness of the proposed method were also carried out by the method of semi-natural modeling. For this, based on the data of full-scale passes of the VPU with BIIM, carried out at the same underwater passage with an interval of 1 day, the results of solving the problems of orientation and navigation for the axial line of the pipeline are obtained (Fig. 4, Fig. 5).

No additional information is used in the form of coordinates of marker points. After compensating for systematic orientation errors, the difference in the course angles does not exceed 0.2 angular degrees (Fig. 6).

To further investigate the achievable accuracy of determining the displacements of the pipeline, models of four consecutive turns in the horizontal plane were added to one of the passes, simulating a particular case of angular displacements of the pipeline with the formation of zones in which the VAT changes. When modeling, the initial parameters of the turns were adopted - the radius of rotation is 500 pipe diameters, the angle of rotation is 2 degrees. At the same time, the displacement of the route in the plan was 2.7 meters (Fig. 7).

On the graph of the heading angle for pass 2 with the displacement model, when calculating with correction for the first pass, the areas of mismatch with the graph of the heading angle for pass 1 are visible (Fig. 8).

In accordance with the proposed method according to the magnitude of the difference in the orientation parameters of the axial line of the pipeline identify the area that has changed position relative to the original (Fig. 9).

Thus, the effectiveness of the proposed method for identifying sections of the pipeline with an angular displacement of the axial line is shown. After determining the boundaries of the sections, according to [11], the curvature of the axial line of the pipeline section of interest is determined. Moreover, the proposed method provides all the necessary information to determine the curvature of the axial line of the pipeline.

Information sources

1. Pat. 2410723, Russian Federation, IPC G01V 1/00. A method for identifying potentially accidentally hazardous sections on gas pipelines subject to stress corrosion cracking [Text] / Malovichko A.A., Malovichko D.A., Sultangareev R.Kh., Applicant and patent holder Malovichko A.A. - N 2008131240/28, declared. 07/28/2008; publ. 02/10/2010. Bull. Number 4.

2. Pat. 2467287, Russian Federation, IPC G01C 15/04. Method for monitoring dangerous geodynamic processes [Text] / Bakanov Yu.I., Suslikov SP, Kobeleva NI, applicant and patent holder Gazprom Transgaz Krasnodar Limited Liability Company. - N2011107079 / 28, claimed 02/24/2011; publ. 08/27/2012, Bull. Number 24.

3. Pat. 2111453, Russian Federation, IPC G01B 17/00, F17D 5/00, F16L 57/00. Universal diagnostic projectile-flaw detector for monitoring the state of the pipeline [Text] / Vaysberg PM, Emdin MF, Gerdov MG, applicant and patent holder of the Central Research Institute "Hydropribor". - N93045454 / 28, claimed. 09/02/1993; publ. 05/20/1998.

4. Pat. 4945775, United States of America, IPC G01C 9/06. Inertial Sensor Pipeline Monitoring System [Text] / John R. Adams, Patrick S. Price, Jim W. Smith, Applicant and Patent Holder Pulsearch Consolidated Technology Ltd. - US 4945775 A, claimed. 07/07/1989, publ. 06/06/1990.

5. Pat. 2102704, Russian Federation, IPC G01B 17/02. A device for determining and recording the geometric parameters of pipelines [Text] / Plotnikov PK, Bakursky NN, Ramzaev AP, applicant and patentee firm "Saratovgazpriboravtomatika" .- N94029181 / 28, decl. 08/03/1994; publ. 01/20/1998.

6. Pat. 2272248, Russian Federation, IPC G01B 17/02. The method for determining local sections of trunk pipelines with maximum deformation [Text] / Sinev A.I., Ramzaev A.P., Makarov V.Z., applicant and patent holder Closed Joint-Stock Company Gazpriboravtomatikaservis ". - N2004120010 / 28, declared. 30.06.2004 ; publ. March 20, 2006, Bull. No. 8.

7. Pat. 2206871, Russian Federation IPC G01B 17/02, G01N 29/04. The method for determining the local displacements of the main pipelines [Text] / Plotnikov P.K., Sinev A.I., Ramzaev A.P., applicant and patentee Sinev Andrei Ivanovich.- N2001122939 / 28, decl. 08/14/2001; publ. 06/20/2003, Bull. Number 17.

8. Pat. 2558724, Russian Federation IPC F17D 5/00. The device of the diagnostic complex for determining the position of the pipeline and the method for determining the relative movement of the pipeline according to the results of two or more inspection passes of the diagnostic complex for determining the position of the pipeline / Miroshnik A.D., Gurin S.F., Kiryanov M.Yu., applicant and patent holder open joint stock Joint Stock Company Transneft Oil (Transneft, JSC), Transneft Diaskan Joint Stock Company (Transneft Diaskan JSC). - N2013155927 / 06, declared 12/17/2013; 06/27/2015, Bull. Number 18.

9. Rules for conducting surveys of the corrosion state of main oil pipelines [Text]: PR 13.02-74.30.90-KTN-003-1-00 - approved. OAO AK Transneft November 2000, 2003 - State Unitary Enterprise Oil and Gas Publishing House No. 2003.

10. Rules for the operation of main gas pipelines [Text]: STO Gazprom 2-3.5-454-2010 - approved. OAO Gazprom 2010.05.24. - M: OAO Gazprom.

11. Recommendations for assessing the strength and stability of the operated gas pipelines and pipelines [Text]. - approved. 2006-11-24. - pos. Fork Leninsky district. Moscow Region, 2006 .-- 64 p.

Claims (2)

1. A method for identifying displacements of the axial line of a pipeline, which consists in carrying out two or more inspection passes of in-tube mobile devices (VPU), determining, using a strap-down inertial measuring module (BIIM), three components of the absolute angular velocity vector and three components of the apparent acceleration vector of the VPU, determining using the odometer of increments of its path with recording the entire amount of information in the memory of the on-board computer, processing this information after skipping the VPU with the determination of the orientation of the runway and the assessment of zero signals BIIM on the channels of angular velocity, the determination of the orientation of the runway during skipping, characterized in that on the outer surface of the hermetic container of the runway place 2 belts on N measuring radial distance from the outer surface of the hermetic container of the runway to the inner surface of the pipe, scale odometer odds calibrated based on a comparison of the increments of odometric distances for each of the gaps in a particular section of the pipeline, according to the signals of the radial distance meters I determine the angular displacement of the longitudinal axis of the runway relative to the axis of the pipe for each measurement step in each inspection pass, according to the results of each of the passes, taking into account the angular displacement of the axis of the runway and the calibrated scale factors of the odometers, determine the orientation of the axial line of the pipeline, and also determine the joints of the pipes and calculate the pipe lengths , according to the results of the analysis of measurements of the length of the pipes of the same name, determined according to the data of all gaps, the presence of gross misses in the measurements is determined and excluded from further processing taps, in the remaining data set for each pipe of the same name, select the maximum of the length measurement values, record the distances of all passes of the same accuracy, take into account the maximum lengths of pipes of the same name, determine the orientation parameters of the axial line of the pipeline according to the data of all passes, taking into account the updated distance records, synchronize the distance of the parameters centreline orientations for reference and driven passes; for each slave pass point, determine the values of the orientation angles of the axial line of the pipeline obtained from the reference pass, identify areas with an angular displacement of the axial line of the pipeline based on the solution of the orientation equations for the data of the follow pass with the introduction of feedback generated based on the difference in the axial orientation angles the pipeline line, determined from the records of the reference and slave passes, and the detection of exceeding this difference by a predetermined threshold value. 2. A method for identifying displacements of the axial line of a pipeline according to claim 1, characterized in that the strapdown inertial measuring module, odometer, radial distance meters, an on-board computer with a storage device, and a power supply are installed on the in-line cleaning device, which is passed through the pipeline as part of regular cleaning the pipeline.

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