Use of electrochemical current noise method to monitor carbon steel corrosion under mineral wool insulation

Mariano Iannuzzi,Thunyaluk Pojtanabuntoeng,Yang Hou

doi:10.1038/s41529-020-00144-3

Mariano Iannuzzi, Thunyaluk Pojtanabuntoeng + Show 1 more

Open Access

https://doi.org/10.1038/s41529-020-00144-3

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Journal: npj Materials Degradation	Publication Date: Dec 1, 2020
Citations: 12	License type: open-access

Affiliation: Curtin University

Abstract

Corrosion of carbon steel under mineral wool insulation was studied using the electrochemical current noise (ECN) method. Intensities of corrosion were validated using gravimetry, and the form of corrosion confirmed using optical microscopy. The standard deviation of the current noise signal agreed with weight loss results and was demonstrated as a reliable indicator of the degree of corrosion under mineral wool insulation. Recurrence quantification analysis was used to extract feature variables from ECN signals, which were later used to develop a random forest model to identify the type of corrosion, i.e., uniform or localised corrosion. The trained model was successfully applied to predict the extent of localised corrosion associated with mineral wool insulation.

Highlights

Petrochemical plants and refineries, among others, have been fighting corrosion under insulation (CUI) for decades
Some non-destructive examination (NDE) techniques can be used for CUI detection without having to remove—or only require partial removal of—the insulation and jacketing or cladding[4], in a complex industrial site there are always areas that are impossible to access
In both situations, the samples placed at the 6 o’clock position were uniformly corroded, while localised corrosion occurred on the top samples (i.e., 12 o’clock position)

Summary

Introduction

Petrochemical plants and refineries, among others, have been fighting corrosion under insulation (CUI) for decades Despite these efforts, CUI occurs recurrently and remains a focal challenge for safe operations in those industries. CUI occurs recurrently and remains a focal challenge for safe operations in those industries In this regard, ~40–60% of the pipe maintenance costs is related to CUI detection and damage repairs[1,2]. The full removal of the insulation becomes the most effective approach to assess the severity of CUI in those areas[5] This process is expensive and time-consuming requiring, e.g., inspecting extensive insulated pipe networks and components, long process downtime and high labour cost[6,7]

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