Análise da viabilidade técnica do uso da inspeção por PEC na identificação de perda de espessura em tubos de caldeiras

Abstract

The PEC inspection is a multifrequency eddy current technique that is used in several applications. This technique measures the variation in the electromagnetic field caused by eddy currents induced in the metal, relating the signal obtained with the variation of the desired property. This study applies PEC inspection technique in the evaluation of localized tubing wall losses, in boiler tubes, seeking to use the advantageous characteristics of this technique, regarding the speed to perform the test and ease of interpretation of the signals obtained, to increase operational equipment reliability. Pulsed eddy current tests were performed on specimens taken from boilers that showed a localized corrosive process due to under-deposit corrosion and on a specimen that had machined recesses that simulated thickness losses. As a way of evaluating the effectiveness of the use of pulsed eddy currents in the identification of corroded regions, were carried out using thickness measurements by ultrasonic inspection. This work showed that, in a qualitative way, all regions that presented thicknesses with values below a pre-established limit were identified, concluding that the PEC inspection technique can be used in the evaluation of equipment components that present localized wall losses.