In-line inspection is carried out in four levels :

1. Inspection of the pipeline with the help of projectiles - profilers. They determine defects in the geometry of the pipe wall (corrugations, ovality, dents).

2. With the help of ultrasonic projectiles - flaw detectors, they search, measure corrosion defects, delamination of pipe metal

3. With the help of magnetic projectiles - flaw detectors, defects in circumferential welds are detected.

4. With the help of more modern ultrasonic flaw detectors, SD detect and measure crack-like defects in longitudinal seams and in the pipe body.

Classification of pipe defects, determined with the help of VTD.

4 classes of defects:

1. geometry defects (corrugations, dents, ovality). Lead to a decrease in the bearing capacity of the pipe, to a decrease in production.

2. Defects of the pipe wall (stratification of Me pipe, inclusions, cracks, scratches, corrosion damage, loss of Me of local origin). They lead to a decrease in the carrier. help pipe.

3. Defects of cross-welded seams (lack of penetration, pores and displacement of seam edges).

4. Def-you prod-th factory seam (same).

VTD . Before carrying out the VTD, it is necessary to clean the inner cavity of the pipe from deposits. Polyurethane is used as mats for cleaning discs for cleaning equipment.

VTD is carried out in 4 stages: 1. Identification of defects in the geometry of the pipe with the help of profiler shells.

2.defects in the pipe wall were revealed with the help of Ultrascan projectiles.

3. Defects of cross-th welds with the help of magnetic shells "Magniscan"

"-" magnetized pipe

4. Defects in commercial welds, defects oriented in the industrial direction with high-resolution Ultrascan projectiles were detected.

According to the results of the diagnostic examination, all defects are classified into 3 groups:

Defects of the POR type; - defects of the DPR (deficiencies, sub-rep-tu); - defects, not requiring a repair. They are entered into the data bank for the last monitoring.

According to the results of the diagnostics, selective repair or continuous repair (with accumulation of faults)

With the help of programs, the degree of danger of the identified defects is determined.

Diagnostics of the linear part of the gas pipeline .

During the operation of the mg, its inner surface is contaminated with rock particles, scale exfoliated from pipes, condensate, water, methanol, etc. This leads to an increase in the coefficient of hydraulic resistance and, accordingly, to a decrease in the throughput of the gas pipeline. The internal surface of the gas pipeline is cleaned from contamination in the following ways: periodically with cleaning devices without stopping gas pumping; one-time use of treatment devices with the cessation of gas supply; installation of condensate collectors and drains at low points of the gas pipeline; by increasing the speed of gas flows in individual threads of the gas pipeline system and subsequent trapping of liquid in the dust collectors of the compressor station. Cleaning pistons, scrapers, separator pistons are used as cleaning devices. Depending on the type of pollution, certain cleaning devices are also used. The main requirement for them: to be wear-resistant, to have good patency through locking devices, simple in design and cheap. The most commonly used cleaning devices such as DZK-REM, OPR-M, allowing you to simultaneously clean the cavity of the gas pipeline from solid and liquid substances. For cleaning gas pipelines of large diameters, piston separators DZK-REM-1200, DZK-REM-1400, OR-M-1200, OPR-M-1400 are used. The piston is mounted with two, three, or more cleaning elements. For the movement of the piston through the gas, a certain pressure drop is created on it, which depends mainly on its design. The created difference p on the piston is on average 0.03-0.05 MPa. At all designed and newly introduced mg, devices are provided for cleaning the internal cavity of the gas pipeline from pollution by passing cleaning pistons. The structure of the device includes units for starting and receiving cleaning pistons, a system for monitoring and automatically controlling cleaning processes. The units for launching and receiving cleaning pistons are made for a working p of 7.5 MPa and a temperature of the working environment from -60 to 60 ° C. To control the passage of treatment devices through the gas pipeline, piston passage analyzers are installed at its individual points. The Volna-1 complex has been developed, designed both to signal the passage of cleaning devices through the gas pipeline, and to find them in case they get stuck in it.

11. Transitions of pipelines through water barriers and their classification according to the method of construction.

Crossings through water barriers are divided according to the method of construction into:

1. underwater;

2. air: beams on supports, cable-stayed transitions, arched.

The boundary of the air passage of the pipeline through the water barrier includes the above-ground part and sections of the underground pipeline 50 m long from the place where the pipe exits to the surface.

Subsea pipelines include a linear part passing through water barriers more than 10 m wide along the water table in low water (lowest water level) and more than 1.5 m deep.

The boundaries of the underwater crossing are:

1. for multi-line crossings - this is a section limited by shut-off valves located on the banks.

2. for single-line - this is an area limited by a horizon of high waters not lower than 10% security.

Pipelines of the main and reserve lines in the section of the underwater crossing and from the underwater crossing to the KPPSSD must be designed in accordance with the highest category of complexity.

PP through water barriers, with a width of more than 75 m along the water table in low water, are necessarily equipped with reserve threads.

PP according to the method of construction are divided into:

1. Built in a trench way. The traditional way of building. Disadvantages: the need for an annual survey, non-ecological method, the need for major repairs in 10-15 years.

2. Constructed by the method of directional drilling. Advantages: ensures the reliability of operation of the underwater section of the pipeline (up to 30 years); environmental friendliness of the method.

3. Constructed by microtunnelling. Used much more recently. Advantages: reliability and durability. Underwater crossings constructed by microtunnelling are divided into: tunnel crossings annular space, which is filled with inert gas under excess pressure; transitions with a tunnel annulus filled with a liquid with anti-corrosion properties, a coating with excess pressure.

4. Built using the "pipe in pipe" method.

The structures for crossing water barriers include the following facilities:

1. section of the main pipeline within the borders of the crossing;

2. nodes of coastal shut-off valves and KPPSOD;

3. bank and bottom protection structures designed to prevent erosion of the coastal and channel part of the crossing;

4. informational signs of the protection zone of the crossing on navigable and raftable rivers; guide signs of the pipeline axis in the onshore sections; signs of fixing the geodetic network of the transition;

5. observation point (checkpoint) of the lineman;

6. along-route transmission line;

7. ECP system within the borders of the transition;

8. transformer substation to provide electric power to shut-off valves and ECP facilities;

9. means and equipment of telemechanics;

10. stationary marker points for carrying out work on in-line diagnostics;

11. pressure sampling sensors, manometric units, signaling devices for the passage of cleaning devices, duck detection systems, annulus control systems;

12. support structures for air crossings.

Requirements for software equipment.

1. BCPs must be equipped with leak detection systems, while pipe-in-pipe crossings must be equipped with annulus pressure monitoring systems. Information about the pressure should be sent to the control room of the nearest station.

2. Reserve threads are equipped with CPPSOD.

3. BCPs across navigable and raftable rivers with a width of more than 500 m along the water surface in low water must have a lineman checkpoint equipped with telephone and radio communications.

4. BCPs are equipped with permanent geodetic markers (benchmarks), which are laid below the freezing depth of the soil to prevent frost rise of the benchmark.

5. Gate valves or cranes installed at the crossing must be electrified, telemechanized and located in the telecontrol system. Gate valves and taps must be supplied from two independent sources.

6. Gate valves have a technological number, valve position indicators, fences, warning notices. Shore valves and cranes must ensure the tightness of the disconnected section of the passage.

7. In order to release the BS from oil in emergency situations by replacing it with water with the passage of separators, the nodes of the onshore valves of the main and reserve lines of the transition are equipped with air vents with a diameter of at least 150 mm.

8. Latches and cranes of transitions should have a dike. Basic requirements for embankment: embankment height 0.7 m; the internal slopes of the embankment must be reinforced with an anti-filtration screen; the distance from the main valves or cranes to the bottom of the embankment is 1.5 m.

9. To carry out work on in-line diagnostics, marker points must be installed within the boundaries of the transition.

Requirements for the equipment of air crossings.

1. Benchmarks are installed on the pipeline and VP supports to perform geodetic control of the positions of the elements of the transition structure.

2. The slopes of ravines and the banks of the water crossing in the places where the coastal supports are installed must be equipped with flow velocity dampers (vegetation cover, stepped drops, drinking wells).

3. Channel supports of beam crossings must have ice cutters in accordance with the project.

Providing pipeline diagnostic services with minimal downtime.

As the most trusted provider of in-line diagnostics and product transfer solutions, T.D. Williamson provides customized pipeline inspection services designed specifically to optimize the performance of pipeline systems with minimal downtime. Technologies of in-line diagnostics of T.D. Williamson are designed to provide pipeline integrity under the most difficult environmental conditions, as well as to provide the most accurate data, typically in a single pass.

Too high projectile velocity affects data quality. The technology of active control of the speed of the diagnostic projectile is specially designed for use with the MFL diagnostic technology in gas pipelines with high flow rates.

The technology was developed using sensors designed to pass directly along the inner wall of the pipe, and not in front of the projectile, which increases their sensitivity. The high resolution data obtained with these tools can be analyzed for signs of dents and help accurately measure pipe expansion.

Provides accurate detection and sizing of internal and external metal loss and other anomalies. Designed to overcome constrictions and reduce frictional resistance to provide a more stable projectile velocity.

Provides accurate detection and sizing of internal and external metal loss and other anomalies.

An economical and convenient method for diagnosing short sections of the pipeline that are inconvenient for in-line diagnostics.

Provides the most accurate diagnosis of longitudinal welds to date without significantly increasing the length of the projectile.

We have cleaned and inspected more than 3800 kilometers of pipelines with diameters from 159 mm to 1420 mm with in-line flaw detectors.

Purpose of the service:

1. Inspection of the technical condition of the pipeline.

2. Calculations for strength (maximum permitted pressure) and durability (residual life) based on the results of the survey.

3. Examination of industrial safety. License No. DE-00-013475.

Stages of in-line diagnostics technology:

1. Preparatory work - determination (according to the data of the questionnaire) and ensuring the testability of the inspected pipeline.

2. Cleaning the internal cavity of the pipeline from foreign objects, scale, electrode residues, asphalt, paraffin and pyrophoric deposits.

3. Calibration of the pipeline - determination of the minimum flow area of ​​the pipeline and ensuring 70% of the patency of the outer diameter (ie, the elimination of all geometry defects exceeding 30% of the outer diameter).

4. Inspection of the pipeline with a profiler - identification of defects in the geometry of the pipeline (dents, corrugations, ovality) and measurement of the radius of turns. Ensuring the patency of the pipeline in 85% of the outer diameter (elimination of all geometry defects exceeding 15% of the outer diameter) and the minimum turning radius of the pipeline equal to 1.5Dn or 3Dn (Rp. must be more than or equal to 1.5Dn or 3Dn, depending from the flaw detector used after the profile measurement).

5. Inspection of the pipeline with in-line magnetic (MFL and TFI) and / or ultrasonic flaw detectors - detection of such defects as: corrosion (internal, external, pitting and continuous), stress stress corrosion, delamination, inclusions, differently oriented cracks and other defects pipeline walls.

6. Calculation for strength and durability (residual life) and industrial safety expertise.

Since 2007, we have carried out works on in-line diagnostics and examination of industrial safety of pipelines (including underwater crossings) in OAO ANK Bashneft, OAO Udmurtneft, OOO Belkamstroy, OAO Belkamneft, ZAO Naftatrans , Surgutneftegaz OJSC, BPO-Otradny LLC, Sheshmaoil JSC, SNPS-Aktobemunaigaz, RN-Krasnodarneftegaz OJSC and etc.

More than 10 years of experience in in-line diagnostics of oil and gas pipelines.

Prior to in-pipe diagnostics, the selection of a site for overhaul was carried out on the basis of accident statistics, results of electrometric tests, and visual control data during grinding.

Limited information with such a choice of a site for repair did not provide reliability and did not allow timely identification of pipeline sections in need of repair in the first place. During hydrotesting to detect defects, as well as during repair of sections, it was necessary to stop the pipeline for a long period, and the discharge of water after hydrotesting significantly worsened the environmental situation. By the beginning of the 1990s, due to the increase in the service life, the traditionally used means and methods for preventing accidents and direct oil losses had exhausted their capabilities; providing targeted use for selective repairs with an economic effect.

The application of this direction led to the creation in 1991. on the basis of AK Transneft, a subsidiary for diagnostics, Diascan.

1.1. General concepts and definitions of technical diagnostics of pipelines

Diagnosis- this is a directed impact on an object or system to preserve, maintain the functioning of their quantitative and qualitative characteristics.

Qualitative assessments involve checking the compliance of the system as a whole with the general principle and its individual subsystems with the available particular recommendations.

For quantitative assessments determine the efficiency criteria both for the entire system and its individual parts, compare the obtained criteria, as well as various options calculated taking into account the obtained criteria with given values, and find rational indicators with a single economic criterion for the functioning of the system.

When diagnosing, parametric and non-parametric methods of control are used. Parametric methods initially provide for the control and evaluation of the parameters themselves over time, their change in the process of equipment operation is determined. Based on the values ​​of the complex of controlled parameters, a decision is made in the equipment diagnostic system. At nonparametric control methods use the values ​​of the change in the output values ​​of the element or subsystem (their statistical and dynamic characteristics). Most often, continuous functions or integrally averaged values ​​are used, which explicitly or implicitly include the values ​​of the parameters of an element or subsystem.

When solving technical diagnostics, not only the technical condition of the object is determined at a given time, but also its condition is predicted for some time ahead, which is very important for determining the structure of repair cycles and intervals between inspections of equipment, machines and mechanisms. To do this, an integral approach is used, with the help of which mathematical models are built, with the help of which it will be possible to obtain information about the change in parameters. In addition, with the help of mathematical models built taking into account operational data and appropriate algorithms, they find rational ways to influence technological processes of a technical or economic nature. At the same time, the maximum use of the existing organizational structures of the pipeline transport system should be envisaged.

Currently, a number of technical and physical diagnostic methods (acoustic methods, methods of using the magnetic memory of metal, etc.) are used with varying degrees of success in the study of the technical condition of the heating network. The technical data obtained during the diagnostics of heat networks by various methods are subject to qualitative interpretation and quantitative analysis, as a result of which the entire range of potentially dangerous areas found at the object under study should be classified according to their degree of danger for the further safe operation of heat networks.

JSC "Teploset St. Petersburg" together with research institutes and other scientific organizations are working on the pilot application of known and the development of new technical diagnostic methods for practical use in the inspection of pipelines of heating networks.

acoustic method. Between 2005 and 2009 More than 50 km of heating networks were examined by a diagnostic organization using equipment from NPK Vector (now this technology is being implemented by LLC NPK KURS-OT) using a noise correlation analyzer (Fig. 2).

This diagnostic method does not require shutting down the pipeline. It is possible to diagnose the supply and return pipelines in a short time. The reports visually present information on sections with subcritical and critical wall thinning, and, in agreement with our company, they were understood as values ​​of 40-60% and less than 40%, respectively, of the nominal wall thickness of the pipeline metal, which differs significantly from those allowed for further operation. values ​​specified in RD 153-34.0-20.522-99. Critical sections in total amounted to an average of about 12% of the entire length of both the supply and return pipelines. Subcritical sections in total amounted to an average of about 47% of the entire length of both the supply and return pipelines. For example, in a section of 100 m, critical sections, on average, according to the results of diagnostics, were identified with a total length of 12 m, and subcritical ones - 47 m. In a satisfactory condition - 41 m. without violating the technological regime, without opening heating mains, with a small amount of preparatory work, tens of kilometers of pipeline sections of heating networks were diagnosed. It should be noted that according to the results of the analysis of diagnostic data obtained during the examination and during the subsequent opening of heating mains, it was confirmed that this method better reveals extended corrosion areas, and the method is of little use for detecting local pitting damage in metal. According to the authors, in case of damage (thinning of the walls) with a length of 1 m, the probability of its detection is 80%, and with a length of 0.2 m - 60%. Strictly speaking, using this acoustic diagnostic method, places of mechanical overstressing of the pipeline structure are identified, which in some cases may be due not to the thinning of the pipe wall (which is one of the important factors in making a repair decision), but to other factors, for example, the destruction of sliding supports, thermal deformations and stresses. To confirm the results obtained according to the report, at least only in critical sections, kilometers of heating mains would have to be opened. Such work is actually carried out only in case of emergency repair of damage and during planned reconstructions. Based on a statistical sample, the order of reliability of this diagnostic method is about 40% according to the generalized data of the specialists of the diagnostic service of OAO Teploset St. Petersburg and the contractor. In our opinion, this method does not provide information about the thickness of the pipeline metal wall, which is necessary for making a decision on repair and forecasting the terms of further operation.

Ultrasonic method. Between 2005 and 2009 The diagnostic organization, using the Wavemaker ultrasonic system, carried out work on the diagnostics of heating networks, more than 5 km of heating networks were examined (Fig. 3).

This diagnostic method does not require shutting down the pipeline. An inflatable ring with transducers is put on a previously prepared surface, free from thermal insulation. A spiral acoustic wave propagates in both directions from the ring, and its reflection from inhomogeneities can be used to judge the change in the cross-sectional area of ​​the metal. In the process of diagnostics, places are identified with a change in the cross-sectional area by 5% or more of the nominal wall thickness of the pipeline metal. The acoustic wave generated by the generator has a limited power, its attenuation is determined by the presence of welds, rotation angles, diameter transitions. Before us, this method has never been used to diagnose pipelines of heating networks. Thus, when laying underground, it is possible to use the Wavemaker method only for diagnosing sections of pipelines adjacent to thermal chambers, as well as during pitting (scheduled and emergency). The greatest advantage of the method is the comparative speed of obtaining the diagnostic result, which in some cases makes it possible to obtain information about the state of the metal directly at the place of emergency work. The application of this method on heating networks requires significant efforts to prepare the workplace and, most importantly, to remove thermal insulation with an area of ​​300x300 mm, followed by stripping the pipeline and restoring the destroyed insulation. As a result of the diagnostics, due to the attenuation of the acoustic wave created by the generator, long sections of pipelines are not examined. After drilling and inspection of pipelines, it was concluded that the reliability of the method is no more than 50% and does not provide complete information about the state of the pipeline and such information as the wall thickness of the pipeline metal, necessary for making a decision on repair and forecasting the terms of further operation.

Acoustic emission method. In the period from 2005-2008. using the method of acoustic emission, a specialized organization carried out work on the diagnostics of heat networks. More than 2 km of heating networks were surveyed (Fig. 4).

The method is based on the principle of generation (emission) of acoustic signals in places where the metal structure is broken with a gradual stepwise increase in the pressure of the working medium. With one increase in pressure, this method can diagnose about 1000 m of the pipeline.

As the experience of practical application has shown, careful preparation of the workplace is necessary to inspect a section of a heating network. The sensors are installed on the pipeline longitudinally along the length of the section, the distance between adjacent sensors should be about 30 m. In the places where the sensors are installed, the metal must be carefully cleaned to a mirror shine with “spots” with a diameter of about 7 cm. To carry out diagnostic work, the coolant pressure must be increased by at least 10% of the operating value and then record acoustic signals for 10 minutes. After computer processing of the information received, the report provides the coordinates of defects in the metal indicating the degree of their danger (from 1st to 4th class). One set of equipment includes 16 sensors.

Taking into account the laboriousness of the preparatory work for the survey of an underground pipeline by this method, it seems more appropriate to use it in areas of above-ground laying. The efficiency of the method of acoustic emission control can be conditionally assessed as average. The reliability of the results in the diagnostics by the method of acoustic emission of areas was, according to our estimate, at the level of 40%. This method does not provide information about the thickness of the pipeline metal wall, which is necessary for making a decision on its repair and predicting the terms of further operation.

The methods of technical diagnostics described above do not allow to fully carry out technical diagnostics of the state of underground heat pipelines and identify all areas requiring repair, i.e. do not allow to fully obtain the required information about the actual state of pipelines, which necessitates the improvement of these methods, as well as the development of new instrumental methods based on the modern development of technical means.

One example of the improvement of existing methods is the work carried out by JSC "Teploset St. Petersburg" together with specialized diagnostic organizations to assess the state of corrosion-hazardous zones using software systems for the analysis of statistical information and the results of thermal imaging, as well as devices moving inside the pipe. which are equipped with television and ultrasonic equipment.

But before talking about the developed modules designed for carrying out in-line diagnostics, let's dwell on the principles of forming programs for carrying out this type of diagnostics.

Formation of diagnostic programs and criteria for selecting a site for in-line diagnostics (ITD). The selection of sites for inspection by the VTD method is carried out by specialists of the diagnostic service using the geographical information and analytical system "Teploset" (GIAS "Teploset") and the results of the survey of infrared thermal imaging aerial photography, loaded into the GIAS "Teploset" (Fig. 5).

The input of passport information about pipelines, as well as information obtained as a result of inspections of defects, diagnostics, corrosion measurements, is performed according to a certain algorithm in the electronic circuit of the heat network. In our case, the monitoring system is, in essence, a software shell based on a digital spatial model that allows you to work with information from all databases related to the heat network and present it in a form that is convenient for viewing and perception. The working name of this system is GIAS "Teploset" (for details, see the article by I.Yu. Nikolsky on pp. 19-24 - ed.). At present, the monitoring system makes it possible to rationally draw up programs for both reconstruction and selective overhaul in order to extend the life of the pipeline before it is put into reconstruction and determines areas for diagnostics.

Criteria for selecting a site for diagnostics in GIAS "Teploset":

■ coefficient of specific damage;

■ presence of external factors accelerating corrosive wear;

■ technological significance of this section of the heating network, which is directly related to the magnitude of the predicted undersupply of thermal energy in case of emergency repair of damages in the winter period;

■ social significance, determined by the severity of possible socio-economic consequences in case of damage;

■ results of thermal imaging survey and temperature gradient at the site.

Areal aerial photography in the IR range (Fig. 6) is performed using a thermal imager, a Mi-8 helicopter is used as a vehicle.

Reporting materials are presented in the form of a catalog of temperature anomalies. In a form convenient for comparison, fragments of a map of the location of heating networks, surveys in the optical and infrared wavelengths are given. The method is very effective for planning repairs, diagnosing and identifying areas with increased heat losses. Shooting is carried out in spring (March - April) and autumn (October - November), when the heating system is working, but there is no snow on the ground. It takes only two weeks to examine and receive results throughout the city of St. Petersburg. This method allows not only to determine the places of destruction of insulation and depressurization of pipelines, but also to track the development of such changes over time. Based on the results of thermal imaging, diagnostic service specialists perform an above-ground survey using correlation and acoustic diagnostic devices in order to determine the cause of the anomaly (places of increased heat loss).

Diagnostic module for in-line diagnostics Du700-1400. In 2009, our company, together with a diagnostic organization, experimentally introduced a new diagnostic method - in-line diagnostics (ITD) using a remote-controlled diagnostic complex (RTD) (Fig. 7).

The remote-controlled diagnostic complex designed for in-line diagnostics includes an explosion-proof delivery vehicle (in-line flaw detector), on which various replaceable non-destructive testing modules can be installed: visual and measuring testing (VIK module), as well as non-contact (“dry”) ultrasonic testing using electromagnetic-acoustic transducers (EMAT) for direct and oblique input of an ultrasonic pulse (EMA-module).

Loading of an in-line flaw detector with installed diagnostic modules is carried out through the existing necks of heating chambers and manholes (manholes Du600), and, if necessary, at repair sites. To prepare the place for launching an in-line flaw detector inside the pipeline, a canopy 800x800 mm in size is cut (Fig. 8), a 200x200 mm cut is made in the adjacent chambers to ventilate the diagnosed section of the pipeline. The in-line flaw detector can move both along horizontal pipelines DN700-1400 at a speed of 50 mm/s, and along inclined and vertically located sections DN700-1000 at a speed of 25 mm/s, as well as pass steep bends and equal tees. The in-line flaw detector is capable of moving inside technological pipelines at a distance of up to 240 m from the loading points. Diagnostic and auxiliary equipment is located in a mobile auto laboratory based on the Gazelle car.

The use of EMAT allows diagnosing pipelines, including diagnosing objects with a contaminated surface (rust, corrosion, etc.), without the use of a contact liquid, on an unprepared surface, through an air gap of up to 1.5 mm. The range of wall thicknesses available for control is in the range of 6-30 mm. To carry out the control, EMATs are located diametrically opposite in the EMA-module installed on the rotation unit of the in-line flaw detector. The rotation unit ensures the rotation of the transducers along the circumference of the pipeline, and telescopic manipulators - the extension of the transducers to the surface of the pipeline to ensure a constant air gap between the controlled surface and the transducers. The in-line flaw detector provides translational and spiral movement of the module inside the pipeline, due to which dynamic control modes are implemented - continuous scanning of the pipe body or scanning with a specified step from 10 to 200 mm.

Continuous and step-by-step EMA control is carried out on straight sections of the pipeline, and inside the bends, the residual wall thickness is measured. The results of in-line scanning using VIC and EMA modules are displayed on the monitor screens of the receiving and control computers (Fig. 9) installed in the auto laboratory in order to evaluate the detected defects in the pipe body by the inspector.

In order to obtain information about the residual thickness of the pipe wall in potentially hazardous areas, it was decided to equip the remote-controlled diagnostic complex with an eddy current control module, which will allow determining wall thinning in the range of 0.5-6 mm on corroded surfaces.

To ensure full control of the technical condition of heating pipelines in 2010-2011. The following upgrades have been made:

■ the design has been improved to ensure the operation of the TDK in conditions of high humidity (up to 100%), as well as in a state partially submerged in water;

■ equipped with TDK eddy current testing module to determine the residual thickness in the areas of corrosion damage to pipelines in the range of 0.5-6.0 mm;

■ a new scanner was developed to move the EMAT along the axis of the pipeline with an inspection capacity of at least 10 m/h;

■ EMAP was modified to ensure control under the conditions of the state of internal surfaces, specific for pipelines of heating networks;

■ specialized software was developed to provide archiving and real-time display of inspection results.

The main criterion taken into account when making a decision to replace a pipeline was information about the actual thickness of the pipe metal wall, which is necessary for strength analysis and MTBF of a heat network pipeline. The immediate emergency repair program included sections with thinning of metal thickness from 40% or more, sections with metal thinning from 20 to 40% are planned to be replaced in subsequent periods.

In 2009, diagnostics of 800 pm was performed, 24 potentially hazardous areas were discovered, 11 pm of the supply pipeline were replaced.

In 2010, diagnostics of 1,400 pm was completed, 33 potentially hazardous areas were discovered, and 106 pm of the supply pipeline were replaced.

In 2011, diagnostics of 2700 pm was performed, 52 potentially dangerous sections were discovered, and 240 pm of the supply pipeline were replaced.

Diagnostic module for in-line diagnostics DN 300-600. Taking into account the technological need for diagnostics of pipelines with a diameter of 300 to 600 mm, St.

In 2011, for the first time, a diagnostic module was used that allows diagnosing pipelines with a diameter of DN300-600, which was developed by a contractor in close contact with St. Petersburg Heating Grid OJSC (Fig. 10).

This module is an electromechanical carriage with rear wheel drive. The maximum distance of delivery of video and ultrasonic equipment is limited by the traction force of the carriage engine and is 130 m. in the electromechanical drive robot (Fig. 11). Pneumatic grinders have petal-type circles used to clean the inner surface of the pipeline from corrosion. Air is supplied to the pneumatic tool through pneumatic fuses through high-pressure pneumatic tubes from an autonomous gasoline compressor. Thickness measurement is carried out by means of two thickness gauges installed in the body of the robot carriage. The thickness gauge sensors are placed on the head of the robot and are located on the same axis as the cleaning pneumogrinders. As a contact liquid between the sensors and the metal surface, water is used, which is supplied through an electrovalve through a pneumatic tube using a water pump. The extension of the pneumatic grinders and the tight fit of the thickness gauge sensors to the controlled section of the pipe wall is carried out using pneumatic cylinders.

The loading of the in-line flaw detector with installed diagnostic modules is carried out through the pits (Fig. 12), the overall dimensions of the equipment currently do not allow loading it through the Du600 manholes. To prepare the place for launching an in-line flaw detector inside the pipeline, the metal of the pipeline is cut in the upper part at the place of pitting with a length of at least 1.2 m and a width of 0.5 DN of the pipeline, and in the adjacent chambers a cut of 200x200 mm is made to carry out ventilation of the diagnosed section of the pipeline. The in-line apparatus can only move horizontally, the control speed is more than 100 mm/s.

Diagnostic and auxiliary equipment is located in a mobile auto laboratory based on the Gazelle car. The in-line flaw detector is controlled via a laptop using a specialized program. Control is carried out with a given step of 100 mm. The results of in-line scanning using visual measurement control and ultrasonic thickness measurement are displayed on the monitor screens of the receiving and controlling computer in order to assess the damage detected by the inspector as a result of the control (Fig. 13).

In order to adapt the existing flaw detector and ensure full control of the technical condition of heating network pipelines, the following modernization was carried out in 2011:

■ a damper cushion is installed on the ultrasonic sensor, which provides more even contact between the surface of the pipe metal wall and the ultrasonic sensor;

■ to improve the reliability of data transmission on the wall thickness of the metal of the inspected pipeline, the technology for transmitting information via the Ethernet protocol between the in-line flaw detector and the operator was replaced by the Com protocol.

In 2011, the total length of the diagnosed sections was 1665 linear meters, 132 linear meters of the supply pipeline were replaced. More than 30 potentially dangerous sections of heating networks and two misalignments of bellows expansion joints, detected by the results of the IIC, were promptly eliminated before the damage occurred.

The advantages of in-line diagnostics using a remote-controlled diagnostic complex are as follows.

1. Displaying the results of diagnostics (primarily the actual wall thickness) in real time and ensuring their archiving.

2. Obtaining reliable information about the actual geometry of the pipeline, the actual location of welded joints, as well as the state of the internal space of the pipeline.

3. A significant reduction in the volume of excavation and preparatory work for the inspection of the pipeline from the outside compared to pitting.

4. The use of various non-destructive testing modules during ITD allows you to identify:

■ surface defects of welded joints (lack of penetration, undercuts, sinkholes, etc.);

■ dents, foreign objects, contamination in the tube space;

■ internal defects of the pipe body (laminations, non-metallic inclusions);

■ sections of the outer surface of the pipeline with continuous and pitting corrosion, nicks, etc.;

■ crack-like defects oriented along the axis of the pipeline;

■ pipe wall thickness.

Limitations of in-line diagnostics. Work experience has shown a number of significant differences in the internal state of pipelines of heating networks from gas pipelines, which has made its own adjustments to the established methodology for monitoring pipelines of heating networks, they are as follows.

1. The presence of solid corrosion deposits (Fig. 14), non-dismantled tie-ins of a temporary pipeline (Fig. 15), deformations of bellows compensators (Fig. 16), which do not allow EMA and ultrasonic testing in dynamic mode (as well as the FEA of circumferential welds) .

2. Bilateral corrosion damage to the pipe body (outer and inner surface), causing unstable acoustic contact.

3. Significant temperature and humidity inside the pipeline, which requires serious preparatory work before starting diagnostics.

In this regard, an in-line inspection was carried out on the pipelines with the identification of dents, foreign objects, contamination in the in-line space, as well as ultrasonic testing and EMA-thickness measurement in a static mode. In the plane of the pipeline section, thickness measurements were performed every 60 O (2 hours) along the circumference and with a step of 100 mm along the pipe axis; based on the measurement results, a thickness chart was built for each tested pipe.

1. The implementation of the VTD and the performance of repair work based on the results of diagnostics made it possible to significantly increase the operational reliability of the pipelines of OAO Heating Grid of St. Petersburg.

2. The use of VTD ensures the detection of corrosion damage without preliminary surface preparation in the range of 3 mm and more.

3. In order to improve in-line diagnostics and its wide application, the following modification of the VTD equipment is necessary:

■ modification of existing samples of in-line flaw detectors in order to adapt them to control pipelines of heating networks with high humidity inside the pipeline and high temperatures up to 60 ° C;

■ development of additional cleaning methods, such as hydrodynamic cleaning of pipelines, etc.;

■ reducing the dimensions of the modules and making it possible to pass several pipeline rotation angles (more than 2 in one section of the heating network);

■ increasing the distance of movement from the place of loading up to 500 m.

Conclusion

Summing up, it should be noted that today the existing methods of in-line diagnostics are not able to give a 100% idea of ​​the actual state of the pipeline and its working life. It is necessary to carry out a set of diagnostic measures using a number of other types of non-destructive testing (infrared diagnostics, acoustic and correlation diagnostics, etc.). The reliability of the available methods of in-line diagnostics is at the level of 75 - 80%, which is 1.5-2 times higher than the reliability of other non-destructive testing methods that provide information about the state of the pipeline metal and were previously used at St. Petersburg Heating Network OJSC. Thanks to the improvement of the method of in-line diagnostics and non-destructive testing modules, as well as the development of new instrumental methods for monitoring pipelines based on the modern development of technical means, it will be possible to replace hydraulic tests for diagnosing heating network pipelines with non-destructive testing methods.

In this regard, it is necessary to continue work to improve the methods of in-line diagnostics used, modernize equipment, reduce costs, and increase the volume of diagnostic work.