Arhipov A. Science basis for corrosion monitoring and residual life prediction of chemical and refining equipment

Corrosion-mechanical damage of steels in aggressive environments after long-term operation under simultaneous effect of corrosion environment, mechanical and thermal loadings. Development of the methodical approaches to the monitoring of corrosion-mechanical damages of equipment and assessment of its technical state, based on electrochemical properties of the deformed steels. Corrosion-fatigue testing of steels, potentiodynamic voltammetry , mechanical testing of steels under static and impact loadings, optical microscopy, measurement of the metal surface hardness. To evaluate the experimental values, that different significantly from the other ones, the method of the purified sampling and the Irwin method are used. A new electrochemical method of assessing the remaining life of the equipment working in the electrolytes environment and subjected to the mechanical loading effect, which is based on the change of polarization current of cyclically deformed stainless steels is developed. A new method of corrosion monitoring that is based on the evaluation of the density of electrochemical pulses under corrosion-mechanical fracture development in operating equipment is developed. It is proposed to use the dependence "potential, polarization current - number of cycles to failure" in corrosion fatigue , as a resource curve on which different periods of equipment exploitation can be defined: safe exploitation, exploitation period under careful control, period of restricted operation. It is established that more than the 2-fold decrease of corrosion resistance of the exploited carbon and low-carbon steel to compare with as-received steels is determined by the increase of the anode processes velocity. New systems of control and monitoring of corrosion-mechanical damages in the electrolyte environment are developed. This allows to check the remaining life of the equipment in real time. New constructions of sensors were designed and their experimental and industrial samples were produced. Their advantages over the available ones are shown. The technological regulations with the use of the polarization current as well as the pulse methods for assessing the damage degree of chemical and oil refining industry equipment at the companies " Linos" and " Severodonetsk amalgamation Azot" Ltd. are developed and introduced.