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Self-validating electrochemical methodology for quantifying ionic currents through pipeline coatings
journal contributionposted on 01.07.2018, 00:00 authored by Mauricio Leonel Latino, Bob VarelaBob Varela, Maria ForsythMaria Forsyth, Mike Yongjun TanMike Yongjun Tan
An enhanced electrochemical method for accurately measuring cathodic protection (CP) currents through protective coatings has been developed as a means of quantifying the permeability and ‘cathodic shielding’ characteristics of nominally intact coating films. This method takes advantage of the fact that cathodic currents could significantly affect the alkalinity of areas under disbonded coatings to self-validate the correctness of current density measurements. In addition, the method provides a high level of accuracy and control over the environment. The method was evaluated using a series of ideally CP-shielding and non-CP-shielding materials, as well as, commercial pipeline coatings. A robust correlation of the measured current with generation of hydroxyl ions and the local alkalinity was established in all cases. For some commercial field joint epoxy pipeline coatings, results suggest that low CP levels c ould allow sufficient ionic current through a coating to promote a high-alkalinity local environment. However, this may not be the case for fusion-bonded epoxy coatings, which shielded CP and maintained a near-neutral pH under the coating.
JournalProgress in organic coatings
Pagination153 - 159
LocationAmsterdam, The Netherlands
Publication classificationC Journal article; C1 Refereed article in a scholarly journal
Copyright notice2018, Elsevier B.V.
Read the peer-reviewed publication
pipeline coatingcathodic protectionconducting coatingsshielding coatingsfusion-bonded epoxyepoxy coatingScience & TechnologyPhysical SciencesTechnologyChemistry, AppliedMaterials Science, Coatings & FilmsChemistryMaterials ScienceDISBONDED COATINGSORGANIC COATINGSBURIED PIPELINESCORROSIONSTEELCREVICEDELAMINATIONENVIRONMENTSINTEGRITY