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An overview of techniques for measuring the interaction between erosion and corrosion

conference contribution
posted on 2017-01-01, 00:00 authored by Y Xu, J L Luo, Mike Yongjun TanMike Yongjun Tan
SUMMARY: In the multi-phase flowline environments such as in oil & gas pipelines, the mechanical impact of high-velocity fluids and particles has been found to act synergistically with electrochemical processes, resulting in sustained erosion corrosion damage to metal surface and localised penetration rates significantly higher than either erosion or corrosion acting alone. It is well known that erosion-corrosion occurs once the dense corrosion product film or passive film on the passive metal surface is removed by the multi-phase fluid or slurry, leading to a dramatic increase of the corrosion current. On the other hand, for active metals, the corrosion current may cause the metal surface to become rough and result in the reduction of surface hardness, which causes the acceleration of the erosion rate. Currently there are different views on the interactive effect of erosion and corrosion on metals. Since it is important for forecasting and preventing erosion-corrosion in engineering practice, over the past decades, the interaction between erosion and corrosion has been investigated using various electrochemical and non-electrochemical methods. Electrochemical test devices such as rotating disc electrode and slurry jet impingement facility are frequently used for the measurement of gravimetric mass loss, open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy. Non-electrochemical sensors based on the electrical resistance technique and acoustic sense technique are developed for the probing of erosion-corrosion in real life pipelines. Recently multi-electrode array sensor has also been used in the study of the relationship between erosion-corrosion and flow field distribution in combination with Computational fluid dynamics (CFD) simulations. Based on these test results, some theoretical and empirical models were established to explain both corrosion enhanced erosion and erosion enhanced corrosion. This paper presents an overview and critical discussion on major test methods used for the study of synergistic effect between erosion and corrosion in both laboratory testing and industrial application conditions. It has been found that 1) previous research heavily relied on the measurements of the overall and steady-state electrochemistry over metal electrode surfaces, rather than probing the dynamic electrochemical changes occurring at localised passive film breakdown sites, and therefore localised corrosion activities have not been sufficiently evaluated; 2) the performance of passive films was mostly studied under anodic polarisation conditions, rather than under natural passivation conditions, and therefore the erosion-corrosion behaviour of passive metals has not been completely understood; 3) the ex-situ analysis of corroded metal surfaces has not been directly linked to the localised corrosion processes. Limitations in erosion-corrosion measurement and monitoring methodologies are considered to be the main reasons for presently insufficient understanding of dynamic and localised passive film breakdown and restoration processes, which must be overcome before achieving effective control of the major factors influencing erosion-corrosion and its prevention.

History

Event

Australasian Corrosion Association. Conference (2017 : Sydney, N.S.W.)

Series

Australasian Corrosion Association Conference

Pagination

1 - 12

Publisher

Australasian Corrosion Association

Location

Sydney, N.S.W.

Place of publication

Blackburn, Vic.

Start date

2017-11-12

End date

2017-11-15

Language

eng

Publication classification

E Conference publication; E1 Full written paper - refereed

Copyright notice

[2017, Australasian Corrosion Association]

Editor/Contributor(s)

[Unknown]

Title of proceedings

ACA 2017 : Proceedings of the 2017 Corrosion & Prevention Conference

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