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08007 Effect of Anode Isolation Methods on Coating Cathodic Disbondment

Product Number: 51300-08007-SG
ISBN: 08007 2008 CP
Author: Amal Al-Borno, Sherry Rao, and Mick Brown
Publication Date: 2008
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$20.00
$20.00
Techniques in anode isolation in laboratory Cathodic Disbondment (CD) testing have been developed to more closely simulate conditions of buried pipelines where there is generally large separation of anode from any holidays in the pipe coating. Various methods of anode isolation have been used but little work has been done directly comparing the effects of different isolation methods. One of the effects of anode isolation in the CD test is that it affects the chemistry of the electrolyte in contact with the holiday in the coating; this is important, especially in long-term tests, as chemical attack can influence disbondment and reduce coating thickness. This study examines different anode isolation techniques and their effects on the pH of the solution and on the coating disbondment results observed in Cathodic Disbondment (CD) tests of two coatings. One was a two-component 100% solids epoxy/urethane coating system and the other coating was a two-component 100% solids epoxy coating system. Both coatings are used for coating of girth welds, as well as many pipeline, marine and industrial applications. Results obtained from this study indicate that there was relatively little difference in disbondment versus the five anode isolation techniques used. However testing with “no anode isolation” resulted in slightly higher disbondment of the coating but significantly lower pH of the test solution.
Techniques in anode isolation in laboratory Cathodic Disbondment (CD) testing have been developed to more closely simulate conditions of buried pipelines where there is generally large separation of anode from any holidays in the pipe coating. Various methods of anode isolation have been used but little work has been done directly comparing the effects of different isolation methods. One of the effects of anode isolation in the CD test is that it affects the chemistry of the electrolyte in contact with the holiday in the coating; this is important, especially in long-term tests, as chemical attack can influence disbondment and reduce coating thickness. This study examines different anode isolation techniques and their effects on the pH of the solution and on the coating disbondment results observed in Cathodic Disbondment (CD) tests of two coatings. One was a two-component 100% solids epoxy/urethane coating system and the other coating was a two-component 100% solids epoxy coating system. Both coatings are used for coating of girth welds, as well as many pipeline, marine and industrial applications. Results obtained from this study indicate that there was relatively little difference in disbondment versus the five anode isolation techniques used. However testing with “no anode isolation” resulted in slightly higher disbondment of the coating but significantly lower pH of the test solution.
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05029 Practical Analysis of Cathodic Disbondment Test Methods

Product Number: 51300-05029-SG
ISBN: 05029 2005 CP
Author: Katherine Cameron, Jiri Holub, and Dennis T. Wong, ShawCor Ltd.
Publication Date: 2005
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