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Electrochemically monitoring localized corrosion patterns and CP effectiveness under disbonded coatings

conference contribution
posted on 01.01.2015, 00:00 authored by Bob Varela, Maria ForsythMaria Forsyth, Mike Yongjun TanMike Yongjun Tan
This paper presents new experimental evidences on the capability of a novel electrochemical corrosion monitoring sensor, which was recently conceived, for measuring localized corrosion under disbonded pipeline coatings. The sensor's design includes an artificial crevice for simulating the conditions developed under disbonded coatings and an electrode array for measuring current density distribution over its surface. The sensor capabilities were further evaluated by studying the dependency of corrosion patterns and current density distribution on the Cathodic Protection (CP) potential applied upon immersion in an aqueous environment. At the less negative CP potential, a good correlation was found between the inhomogeneous corrosion distribution under the disbonded coating as measured by the sensor and actual metal loss and corrosion attack observed on its surface at the end of the test. At more negative CP potentials no corrosion was detected or observed on the sensor's surface. In addition, characteristic changes in the cathodic current distribution at different CP potentials illustrated the possibility of employing the sensor to obtain valuable feedback on the performance of a given CP setup, without requiring its interruption or compensation of IR-drops. Furthermore, the sensor's capability to detect some of the effects of overprotection were shown at the most negative CP potential applied.

History

Event

NACE Corrosion Conference and Expo (2015 : Dallas, Tex.)

Volume

2015-January

Pagination

1 - 10

Publisher

NACE International

Location

Dallas, Tex.

Place of publication

Houston, Tex.

Start date

15/03/2015

End date

19/03/2015

ISSN

0361-4409

ISBN-13

9781510801882

Language

eng

Publication classification

E Conference publication; E1 Full written paper - refereed

Copyright notice

2015, NACE International

Title of proceedings

NACE 2015: Proceedings of the International Corrosion Conference and Expo Series

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