Monitoring pH Level Using High-Resolution Microwave Sensor for Mitigation of Stress Corrosion Cracking in Steel Pipelines

Abstract

Here, the feasibility of using a non-contact high-resolution microwave sensor for the detection and mitigation of High pH Stress Corrosion Cracking (HpHSCC) through monitoring the pH range beneath the dsibonded coating in buried pipeline steel has been investigated. A modelling method and microwave dielectric sensing for aqueous solution has been studied in order to relate relative permittivity and loss to the pH level using the concentration as a bridge. The experimental results showed the potential of the high quality-factor sensor for monitoring the pH level variation. The resonant frequency of the microwave sensor was the main variable considered in the characterization of the sensor's response to pH level changes or concentration variations in the defect beneath the pipe coating. Additionally, the extracted experimental results for near-neutral and acidic pH environment detection demonstrated the significance of non-contact sensing performance and the sensor's potential to detect and study the pH variation. The results demonstrate significantly distinct frequency shift of 174 kHz as the pH increases from 7 to 11 which is the range of the pH created in HpHSCC. This method, as an example, could be employed in the third stage of Stress Corrosion Cracking Direct Assessment (SSCDA), Direct examination step, to determine whether breeding ground for HpHSCC is created or not.