Impedance Spectrometer for Underground Corrosion Monitoring
Impedance Spectrometer for Corrosion Monitoring and Diagnostics of Underground Pipelines
Tech Area / Field
- INS-MEA/Measuring Instruments/Instrumentation
- ENV-MIN/Monitoring and Instrumentation/Environment
3 Approved without Funding
VNIIEF, Russia, N. Novgorod reg., Sarov
- A.N.Frumkin Institute of Physical Chemistry and Electrochemistry, Russia, Moscow
- Swedish Corrosion Institute, Sweden, Stockholm
Project summaryUnderground metal pipelines are a very significant infrastructure in oil, gas, chemical and atomic industries as well as unsafe for the environment. As a rule, ecological catastrophes are caused by external corrosion of pipe’s metal. A protective coating on the outside of a pipe and some techniques of anticorrosion protection are used to prevent the corrosion. However, in practice there is a high probability of corrosion defects appearing under the protective coating of a pipeline. Now the corrosion defects are known to be defined by excavation of the pipe and its visual inspection.
The project's purpose is systematic application of research knowledge to prove on base of impedance spectrometry technique excavationless technology of monitoring and diagnostics of undercoating corrosion of underground pipelines and develop a prototype of the impedance spectrometer designed for this technology implementation.
The state of the art in the field.
The technique of impedance spectrometry is widely used in researches of corrosion processes. It is one of the ways of corrosion monitoring and diagnostics of industrial equipment and constructions. In particular, this technique is used for monitoring of a rate of pipe’s internal corrosion and an efficiency of anticorrosive protection. Impedance measuring is also applied to check protective properties of polymeric coatings of metals in various media. Successful attempts are known to use this technique for estimation of the corrosion rate of steel reinforcement in extensive reinforced concrete constructions. However, at present the technique of impedance spectrometry is not applied for monitoring and diagnostics of external corrosion of pipes with polymeric coating. These pipes are widely used on underground gas-main, oil pipelines.
The impact of the proposed project on the progress in the field.
Such innovation as excavationless technology of monitoring and diagnostics of undercoating corrosion of underground pipelines is supposed to be proved by both theory and experiment. The technology is based on application of the impedance spectrometry technique as well as up-to-date instrumentation. It is proposed to develop a prototype of impedance spectrometer as a tool of this technology.
In the future, development of the prototype ensures success of the technology demonstration in field conditions. Specialists, who are responsible for safety and corrosion protection of underground pipelines, will be supplied such powerful instrument as impedance spectrometer combined with excavationless technology of monitoring and diagnostics of undercoating corrosion of the pipelines.
As a result of the project implementation the expensive excavation of pipeline, its visual inspection and repair in whole will be replaced by local digging of damaged parts of a pipe with an exactness up to a few meters and repair of these parts.
The project contributes greatly to the progress in the field of prevention of ecological catastrophes, caused by accidents at underground gas- and oil-pipelines, both rise of the reliability and reduction of expenses of pipelines operation in the chemical, gas, oil industries, NPPs and in communal services.
Competence of the project team.
Scientists of IPC were the first ones who applied the technique of impedance spectrometry to investigate a corrosion activity under polymeric coating. In recent years VNIIEF and IPC jointly have developed some elements of equipment and software for impedance technique of electrochemical spectrometry as well as basic design principles of diagnostic system based on this technique.
Recently VNIIEF has developed laboratory sample of impedance spectrometer. Preliminary testing of this sample at the corrosion test unit has been completed successfully.
Expected Results and their application.
The following results are expected to obtain in the course of project implementation:
– scientific basis of the excavationless technology of monitoring and diagnostics of undercoating corrosion of underground pipelines by means of impedance spectrometry technique;
– theoretical and experimental fundamentals of methodological manual of the technology for diagnostics and identification of various types of corrosion activities;
– impedance spectrometer prototype which must be developed, designed, manufactured and tested in laboratory conditions, including the corrosion test unit, as the instrumentation of the technology developed.
The expected results are supposed to provide scientific, methodological and technical basis of industrial technology of monitoring and diagnostics of undercoating corrosion of underground pipelines. There is scientific significance in such expected results as scientific basis of the technology and its theoretical and experimental fundamentals for diagnostics and identification of various types of corrosion activities. Impedance spectrometer is supposed to be powerful tool for industrial application of the technology developed. The project results will be the starting-point of the technology demonstration.
As soon as the technology demonstration is completed, the project results are expected to change greatly the situation in the field of prevention of ecological catastrophes, caused by accidents due to pipe’s corrosion on underground pipelines. Besides that both the developed technology and the impedance spectrometer as a standard tool of the technology will have a commercial significance for enterprises of oil, gas, chemical industries, NPPs and communal services. The enterprises are interested in providing environmental safety of production and reduction of expenses of pipelines excavation for repair of their protective coating.
The importance of the project in meeting ISTC goals:
– providing weapons scientists and engineers in Russia, who possess knowledge and skills related to weapons of mass destruction, opportunities to redirect their talents to peaceful activities;
– promoting integration of Russian scientists into the international scientific community;
– supporting technology development for peaceful purposes, notably in fields of environmental protection, energy production, nuclear safety;
– contributing to the solution of national and international technical problems;
– reinforcing the transition to market-based economies responsive to civil needs.
Scope of activities in terms of well-identified tasks as follows:
– development of scientific basis of the excavationless technology of monitoring and diagnostics of undercoating corrosion of underground pipelines by means of impedance spectrometry technique;
– development of methodological fundamentals of the technology for diagnostics and identification of various types of corrosion activities;
– development, design, manufacturing and laboratory testing of the impedance spectrometer prototype for this technology implementation.
The implementation of Task 1 assures scientific foundation of application of impedance spectrometry technique for monitoring and diagnostics of undercoating corrosion of underground pipelines. The main milestones of the task are following:
– detailed analysis of results of previous investigations concerning with both the application of impedance spectrometry technique for monitoring of corrosion and scientific fundamentals of the technology to be developed;
– publication of a paper (or a report on a scientific conference) devoted scientific basis of the technology.
A methodology of the technology well-founded in previous task is developed in the course of Task 2. The task’s milestones as follows:
– development of practical techniques of impedance electrochemical spectrometry for corrosion’s monitoring of underground pipeline;
– development of some principal methods of identification of some types of corrosion activities.
Such deliverable as a technical report is expected. It must be devoted to the fundamentals of the methodology of monitoring and diagnostics of underground pipeline’s corrosion.
The implementation of Task 3 is necessary in order to obtain such equipment for the technology developed as prototype of impedance spectrometer. The task’s milestones are following:
– development and designing of impedance spectrometer’s prototype;
– manufacturing of the prototype;
– testing of the prototype in laboratory and corrosion test unit
– publication of a paper.
A technical report, design documentation, the prototype manufactured, test protocol and publication are deliverables expected in the course of the task.
The following role of foreign collaborators is supposed:
– information exchange in the course of project implementation
– provide comments to the technical reports, submitted by project team to the ISTC;
– testing and evaluation of the prototype, developed in the course of the project;
– participation in technical monitoring of project activities performed by ISTC staff.
Technical approach and methodology.
The scientific approach that must be employed to achieve Task 1 objectives includes theoretical, calculation and experimental methods. The application of the impedance spectrometry technique for monitoring and diagnostics of undercoating corrosion of underground pipelines must be well founded by theory. The results of previous investigations, concerning with the application of impedance spectrometry technique for corrosion’s discovery, are analyzed in detail.
A basic model of electrochemical system which consists of underground pipe, having short section with external corrosion activity under damaged protective coating, and spectrometer’s reference electrodes are described by both differential equations and equivalent circuits. Some frequency locuses of underground pipe’s impedance versus the positions of reference electrodes are calculated. On analyzing these calculations, the location of pipe’s damaged section is predicted. The calculation results for the basic model must be checked by experiment in laboratory.
For Task 2 the following scientific approach is employed to obtain the methodological fundamentals of the technology to be developed. These fundamentals include both practical techniques of monitoring of underground pipeline’s corrosion and principal methods of identification of various types of corrosion activities. The techniques are based on application of impedance electrochemical spectrometry. First of all, they are described in terms of both differential equations and equivalent circuits. On analyzing the calculations done, they are evaluated by experimental simulation of corrosion’s monitoring in laboratory. The techniques been a success are supposed to describe in terms of technical methodology. The principal methods and procedure of identification of corrosion activities as well as the monitoring techniques must be well founded by theory and evaluated by experiment in laboratory. They must be suitable for obtained techniques of monitoring.
The up-to-date technical approach is employed to provide design engineering of the impedance spectrometer’s prototype and achieve objectives of Task 3. All basic technical, metrological, operational and other characteristics of the impedance spectrometer must be well-founded by calculations based on expected results of Task 1 and Task 2. The method of calculation is computer-based simulation of electronic circuits by means of CAM system. In some cases the characteristics obtained are checked by experiment on breadboards.
The impedance spectrometer is developed as a virtual instrument. Software is the key to virtual instruments. That is why such equipment as computer and embedded data acquisition system is used in designing of impedance spectrometer’s prototype. A softbased source of alternating current is necessary in a structure of spectrometer for realization of impedance technique.
Design documentation is prepared by use of CAD system. The prototype manufactured and assembled is examined on a compliance of its design documentation.
Spectrometer’s basic characterictics obtained are checked on a compliance of designed ones in laboratory of VNIIEF.
Spectrometer’s prototype, as the instrument of excavationless technology developed, is tested by experiments in corrosion test unit of IPC. Testing this, both some techniques of monitoring and some methods of corrosion identification, which are obtained in the course of Task 2 and built in spectrometer’s design, are checked and evaluated.
For model of underground pipe, having section with external corrosion activity under damaged protective coating, some frequency locuses of impedance versus the positions of reference electrodes of spectrometer tested must be obtained and the location of damaged section must be predicted too.
Some experiments would be done to identify some corrosion activities by means of impedance spectrometer’s prototype.
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