In-line inspection being a highly efficient and informative technique of technical diagnosis plays a key role in the system of trunk line diagnostic study.
In-line inspectionn (ILI) is the complex of technological operations implemented by “intelligent” pipe flaw detectors (inspection pistons) sent through the pipeline.
ILI makes it possible to carry out inspection all along the linear portion of gas mains, to detect, identify and characterize different types of damages and defects.
CJSC “AMT” is an official representative of the diagnostic company ROSEN Europe BV (Netherlands) and is granted the exclusive right to conclude contracts for the use of ROSEN Europe BV equipment and technologies at Gazprom and its affiliates.
Using ROSEN diagnostic tools and technologies CJSC “AMT” successfully performs pipe flaw detection operations both of standard pipeline sections and highly engineered sections unsatisfying testability.
ILI of main pipelines
Standard pipeline sections
Highly engineered pipeline sections
Ground pipeline inspection
Types of ground diagnostic surveys carried out by CJSC “AMT”:
- corrosion (electrometric) pipeline inspection, including by DCVG tehnology (dc voltage gradient measurement);
- acceptance (initial) inspection;
- сomplex periodic inspection;
- detailed сomplex inspection;
- special comprehensive examination using the combined method DCVG/CIPS/MTM;
- comprehensive Approach To Integrity Of Non-Piggable Pipelines Based On DCVG/CIPS Survey;
- compilation survey, structural monitoring and identification of excessive deformations in the pipeline sections of unspecified position;
- pipeline inspection in pits;
- inspection of pipeline valves;
- integrated inspection of regional pipelines and pipeline branches;
- integrated inspection of pipeline crossings;
- integrated inspection of process shunt pipes, tee fittings, T-joints;
- inspection of aerial, road and railway crossings;
- inspection of the sender and reception chambers of pipe devices.
Pipelinediagnostic techniques applied:
- control by visual aids and measurement;
- ultrasonic inspection;
- magnetic inspection;
- vortex-current inspection;
- structural monitoring;
- hardness testing;
- geodesic inspection;
- inspection of coating;
- acoustic-emission technique.
The method of measuring the DC voltage gradient was invented in the 80-ies of the last century and in the thirty-year history of the use of DCVG technology was performed several thousand inspections of pipelines and obtained a vast array of electrometric survey data, confirmed in the test pits.
Today, DCVG method is recognized by pipeline systems operators in most countries of the world and related to NACE ground surveys of pipelines methods group that are regulated by standards API RP 574, NACE SP0207-2007 and NACE TM0109-2009. The main tasks of DCVG method are:
- location of insulation coating defects and damage;
- the significance of the damage assessment;
- interference evaluation of the superimposed and stray currents;
- the determination of corrosion status (nature) of metal loss defect.
The principle of operation in DCVG: when a DC current is impressed onto a pipeline, there will be an associated voltage gradient surrounding the pipe. Well coated sections of line have a high pipeline to ground resistance. Hence, little or no current will flow to these sections and there will effectively no measurable voltage gradient in the surrounding soil. However, at sections which are bare or have defective coatings, the pipe-to-soil resistance is reduced. Consequently, there is a marked increase in current flowing to these sections of line resulting in voltage gradients around the
bare or defective area. The larger the defect the lower the resistance and therefore the higher the voltage gradient for a given soil resistivity. Thus coating defects can be detected by measuring the potential between an over-the-line electrode and one laterally offset.
Once an indication is located, its severity index (%IR) is estimated by measuring the potential difference from the indication epicenter to remote earth (OL/RE). This potential difference is then expressed as a percentage of the total calculated potential shift on the pipeline at the indication location (P/RE)
The following classification of the defects by the severity index was adopted:
Category 1 – the defects with %IR above 35% needed to be repaired;
Category 2 – the defects with %IR in range between 16 and 35% should be taken into consideration as possibly deserving repair;
Category 3 – the defects with %IR under 15% are small and they do not need to be repaired.
To add value to the data collected during DCVG survey, attempts have been made to combine coating-fault location with CP pipe-to-soil potential measurements in DCVG/CIPS hybrid technique. The close interval potential survey (CIPS) alone is not classified as a coating assessment tool and rather is a cathodic protection system assessment tool, but data from CIPS is used in coating condition assessments. Modern digital data loggers allows to run DCVG and CIPS survey simultaneously during one pass along the pipeline route, as well as to detect defects/holidays in the pipeline coating and, most importantly, to measure the “ON” and “OFF” potentials along pipeline with step approximately 1 m, and at all defects epicenters. Thus, in addition hybrid DCVG/CIPS survey allows to determine whether the exposed pipeline wall is effectively protected by CP system.
CJSC «АMT» is an official exclusive distributor of Cathodic Technology Ltd., Canada (http://www.cath-tech.com/) in Russian Federation, and an authorized distributor on the territory of Armenia, Azerbaijan, Byelorussia, Kazakhstan, Kyrgyzstan, Moldova, Tajikistan, Turkmenistan, Ukraine and Uzbekistan.
The Cathodic Technology Ltd. company's equipment was specifically designed for carrying out DCVG and DCVG/CIPS surveys, and is perfect for examination of buried pipelines in multiple technical corridors with well-developed cathodic protection system.
Part of diagnostic equipment
Features: Portable current interrupter GPS continuously synchronized Microprocessor driven Flash memory 5 programmable time schedules, Interruption cycle, Start and stop times, Start and stop dates Included: Technical Specification: Features Benefits Included Tecnnical specmcation Features Ideal for Included Technical Specification
CI-100 Current Interrupter with GPS
Hexcorder MM CIPS / DCVG Surveys
Designed for close interval potential surveys (CIPS), direct current voltage gradient surveys (DCVG) or both combined
Smart Logger II Dual Input with GPS
Smart Logger II
Portable current interrupter GPS continuously synchronized Microprocessor driven Flash memory
5 programmable time schedules, Interruption cycle, Start and stop times, Start and stop dates
Special comprehensive examination using the combined method DCVG/CIPS/MTM
Magnetic Tomography Method (MTM) was developed in early 2000s and is patented in Russia, Malaysia, USA, and Canada. MTM is based on the inverse magnetostrictive effect (Villari effect) - the change of the magnetic susceptibility of a material when subjected to a mechanical stress. Method uses “natural” magnetization of the ferrous pipes by magnetic field of the Earth.
Magnetic tomography charts the attributes and characteristics of pipe sections by registering and analyzing changes in the magnetic field of the pipeline. These changes are related to stress which in turn are related to defects in the metal. Magnetic measurements data is collected from the ground surface and anomalies detected are a function of stress, mechanical loading and structural changes in the metal.
MTM does not measure the dimensions of geometric defects alone but instead it measures the stress caused by these defects and identifies their character, location and orientation in accordance with the location and orientation of the stress concentration area. Linear and angular coordinates of flaws in the metal and coating are defined within a tolerance of +/-0,25m.
In last year’s MTM method held large-scale testing at facilities: ОJSC «Gazprom», OJSC «Transnefteproduct», TNK-BP, OJSC «Lukoil» etc. with a total length of over 17,000 km.
COMBINED DCVG/CIPS/MTM METHOD
Given above investigation of aboveground techniques and their inherent limitations bring AMT to present on market the combined survey technique - DCVG/CIPS/MTM - as an effective instrument for comprehensive integrity assessment of non-piggable pipelines.
Combined DCVG/CIPS/МТМ corrosion survey allows:
- To compensate limitations of each method (DCVG/CIPS and MTM);
- To evaluate coating and pipe integrity in one-pass;
- To conduct survey with same conditions (soil moisture, temperature, weather, etc.);
- To align data easily since all records are assigned to only linear reference system;
- To increase the confidence level of MTM data interpretation.
Corrosion survey process using combined DCVG/CIPS/MTM technique engages five main steps: design, operation and survey data gathering; DCVG/CIPS/MTM survey; direct assessment (excavations); FFP analysis; development of rehabilitation plan.
Scheme illustrates a typical DCVG/CIPS/MTM survey process scheme, where five surveyors are involved.
Scheme Decision matrix for developing an effective pipeline rehabilitation plan
Aerospace data-based geotechnical diagnostics
Pipeline systems are geotechnical systems comprising two subsystems: technosphere which is a package of engineering structures (pipelines, compressor and pumping stations, field construction and infrastructure facilities, roads, etc.) and geosphere as natural-geological environment.
There is a continuous interaction of technical and natural components in the process of pipeline maintenance. Generally it results in negative effects in both subsystems, such as breaking of natural regimen of areas causing ablation, removal of materials, floating-up of pipelines, intensification of corrosion processes, etc.
Geotechnical diagnostics of pipelines is diagnosis of geotechnical system formed as a result of pipeline runs-environment interaction, and its inspection within diagnosis corridors.
The purpose of geotechnical diagnostics (GTD) is working out of measures to ensure reliable and safe operation of linear trunk pipeline portions (LP TP) considering negative impacts of natural and anthropogenic factors.
- detection, positioning and impact evaluation of natural processes and phenomena on LP TP technical state (both direct causes of accidents, resulting in pipeline failure - slides, spring floods, torrents, etc. and sources of long term impacts leading to damage accumulation, thus lowering pipeline reliability as a whole and its structural elements – geodynamic, erosion, cryogenic processes, etc);
- mapping of active pipeline routes;
- detection and positioning of LP TP sections being in unspecified position (floated up and bared);
- detection and positioning of disturbances of guard and minimum distance bands;
- detection, positioning and identification of social, natural and business-industrial pipeline environment;
GTD data allow identification of potential accident sections for rehabilitation and diagnosis scheduling, preparation of recommendations for LP TP and guard band engineering protection.
Indication of places of disturbance of the protective zone and minimum distances
GEOTECHNICAL DIAGNOSTICS OF RAILROAD INFRASTRUCTURE OBJECTS ACCORDING TO AEROSPACE MONITORING MATERIALS
GTD purpose – obtaining reliable information about the condition of infrastructure objects of railway transport based on an assessment of their interaction with the environment.
Goals of Geotechnical diagnostics:
- the identification, location and characteristics of railroad defects (deformations), artificial structures, etc.;
- the identification, location and characteristics of sources (natural and anthropogenic) appearance of railroad defects and artificial structures;
- the monitoring of potentially hazardous locations (karst, termokarst, landslides, mudslides, etc);
- inventory of easement area and protective zones;
- defining the boundaries of the environmental pollution areas in case of rail transport accidents.
Geotechnical diagnostics allows complementing the system of comprehensive technical diagnostics of railway infrastructure due to the advantages of the method such as:
- informative value (taking into account the negative impact of natural and anthropogenic factors in the assessment and prediction of technical state of objects);
- efficiency (due to the high speed of information processing);
- the visibility provided by a large swath;
- mapping (the presentation of information on the plan, linked to the coordinates).
The application of geotechnical diagnostics method in comprehensive diagnostics provides:
- evaluation and prediction of technical state of infrastructure taking into account environmental effects;
- increase the validity of planning diagnostic and repair works;
- development of technical and design solutions for engineering protection and stabilization of the subgrade with the influence of natural and anthropogenic factors.
Potentially dangerous areas identification
Identification of karst hazardous areas
Identification of mudflow dangerous areas
Railway technical state evaluation
The choice of the route of the railway construction (predesign stage) to satellite imagery ("Sirt-Benghazi" Libya)