Simulation of electromagnetic interference on underground pipelines taking into account AC corrosion
Politechnika Poznańska, Instytut Elektrotechniki i Elektroniki Przemysłowej
Induced AC voltage is clearly identified as a potential hazard, from both safety and corrosion standpoints, for all buried pipelines coming into proximity with overhead electric transmission systems. The likelihood of electromagnetic interference (EMI) increases with rising operating currents in the overhead lines, with increasing quality of the coating on the pipeline, and with the length of a line parallel to and close to power lines. It is possible to simulate the conditions that are expected to exist on these pipelines, and calculate the anticipated levels of induced AC voltage and current as well as its intensity and density fl owing into the soil through the coating defect. Determining a pipeline's response to EMI is not an easy task since it depends on three factors, namely the location of the structure with respect to the magnetic field generated by the AC source, the magnitude of the interfering field, and the electrochemical response of the structure to the interference. Many computer programs can be used to calculate a pipeline's AC voltage by taking into account the worst case scenario under normal operating conditions of the interfering systems. The programs however do not take into account the electrochemical phenomena on the pipeline surface at pipeline coating defect locations. It should be noted, that the mechanism of AC corrosion is not very well understood, particularly as it applies to corrosion in soils. A simulation model of a metal pipeline under inductive influence, in which AC corrosion is taken into account has been presented in the paper. An electrical equivalent diagram is presented and the corrosion current, the pipeline potential and the corrosion rate are calculated. The use of the Matlab-Simulink platform for multidomain simulation and model-based-design of dynamic systems permits the complex analysis of the interference on pipelines, whereas the electrochemical phenomena on the interface metal – soil are taken into account. EMI in the circuit is presented by Simulink in the form of a block diagram – a graphical representation of the process, which is composed of an input, the system, and an output. The block connected with the AC corrosion, in which the electrochemical phenomena are represented by the non-linear Butler-Volmer equations, has been implemented in the simulation package. The system is described by state equations, which can be iteratively solved by tools provided by Matlab.
Keywords: inductive interference, pipeline, AC induced corrosion, calculation model, Simulink, earth- return circuit
Cathodic protection – construction potentials
Operator Gazociągów Przesyłowych GAZ-SYSTEM S.A.
Definitions and types of potentials measured in the practice of measuring cathodic protection have been presented and reviewed. Specific characteristics of different types of potentials and a reflection on the nature of the value produced in distributed parameter transmission line equations has been provided.
Keywords: cathodic protection, potential, pipeline
Application of the electrical resistance technique to monitoring of cathodic protection effectiveness
SPZP CORRPOL Sp. z o.o., Gdańsk
Almost 20-years of CORRPOL company's experience in the scope of application of the electric resistance technique for determination of cathodic protection effectiveness has been presented. Selected corrosion monitoring cases of steel underground structures (pipelines and tanks) with cathodic protection, as well as of those not protected against corrosion have been discussed.
Keywords: electrical resistance technique, cathodic protection, corrosion monitoring, effectiveness
Ochrona przed korozją w praktyce - The effects of erroneous projects and unprofessional workmanship of buried metal structure cathodic protection
SPZP CORRPOL Gdańsk
Cathodic protection, a quite complex and very specialist anticorrosion protection technology, is the source of different types of errors in the design, workmanship and operation phases of cathodic protection installations, typically made by insufficiently educated and inexperienced technical personnel. Typical errors and examples of bad workmanship have been presented, which as the result lead to an unexpected anticorrosion protection effect and excessive investment costs. As protected surfaces are usually out of sight and direct effectiveness assessment is difficult, also limited confidence of investors in this cathodic protection technology is the effect of these errors.
Keywords: cathodic protection, designing, workmanship, errors
Ochrona przed korozją w praktyce - Investigation of magnesium anodes quality according to PN-EN 12438 standard
Politechnika Rzeszowska, Wydział Chemiczny
EZAL, Zaczernie k./ Rzeszowa
The procedure of investigation of quality of Mg anodes, according to the standard PN-EN 12438, has been initiated, tested and applied to commercially produced magnesium anodes. Important details concerning construction of applied electrochemical stand and its equipment and details of reliable measurement have been discussed.
Keywords: cathodic corrosion protection, magnesium galvanic anodes, electrochemical testing; magnesium alloys
Ochrona przed korozją w praktyce - Active corrosion protection of marine objects – review of issues
Zachodniopomorski Uniwersytet Technologiczny, Szczecin
Ostrowski Wojciech Usługi Konsultingowe, Handel
Zachodniopomorski Uniwersytet Technologiczny, Szczecin
Issues related to the corrosion of marine objects such as a ships, platforms, quays are discussed, focusing only on protection by galvanic anode and active cathodic protection Key issues regarding the corrosion protection of the a/m objects have been identified. Ways of implementing corrosion protection have also been discussed.
Keywords: corrosion, ICCP, cathodic protection, galvanic anode, underwater technology, corrosion protection