Development of a simplified electrochemical noise method to monitor assets under insulation

Caines, Susan (2016) Development of a simplified electrochemical noise method to monitor assets under insulation. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Corrosion under insulation (CUI) is a serious problem in many industries both on and offshore. When operations are conducted in marine environments the opportunity for CUI is increased due to the harsh environment created by salt water. CUI can damage equipment and piping systems leading to loss of product containment which puts personnel and production in jeopardy. This research determines the current understanding of CUI, methods available for determining corrosion rates and develops a simplified electrochemical noise method to determine and predict CUI through laboratory and field operations. From the high level CUI literature review two areas for further investigation were determined. Pitting corrosion was identified as a significant area of study and as it is as a key mechanism of pipe failure in offshore operations. Electrochemical noise was found to be a promising technique for monitoring CUI due to its ability to identify corrosion mechanism as well as corrosion rate. Two objectives for research were identified: 1. To generate corrosion under insulation data 2. To develop a continuous monitoring technique for assets under insulation To satisfy the objective of CUI data generation a comprehensive experimental plan was developed. This plan develops a field test procedure to study corrosion under insulation (CUI) in marine environments that ensures that data collected is representative of CUI developed in the offshore industry. The experimental design was completed and the facilities and equipment installed with monitoring and analysis of the ongoing experiment will be completed over the next three years. This research developed, verified and applied a simplified EPN method to monitor corrosion. This method can be used to recognise different corrosion mechanisms (localized/uniform) and to estimate corrosion rates. A relationship between isolated electrode EPN, mass loss and corrosion rate was established. The simplified method aided in determining that there is increased corrosion activity under insulation due to retained moisture at the pipe surface. The completion of this research expanded the understanding of how and when CUI occurs, developed new and developed a new simplified electrochemical noise method for online monitoring of CUI. These successes will ultimately improve offshore operations; both improving safety and production.

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