Server maintenance is scheduled for Saturday, December 21st between 6am-10am CST.

During that time, parts of our website will be affected until maintenance is completed. Thank you for your patience.

Menu
Search
Filters
Close
Menu

Penetration of Cathodic Protection into Pipeline Coating Disbondment

Picture for Penetration of Cathodic Protection into Pipeline Coating Disbondment
Available for download

An experimental setup was designed to investigate the cathodic protection (CP) penetration into coating disbondment. Embedded detection probes underneath the disbondment enabled pH and steel potential measurements without disturbing the environment inside the disbondment.

Product Number: 51317--9146-SG
ISBN: 9146 2017 CP
Author: Li Yan
Publication Date: 2017
Industry: Cathodic Protection
$0.00
$20.00
$20.00

The most effective method to mitigate corrosion on the external surface of a buried pipeline is to utilize a protective coating supplemented by cathodic protection (CP). Ideally these two systems work together so that if the coating disbonds or has defects allowing ground water solution to contact the pipe steel surface the CP system will continue to function to protect the pipeline. However the success of this approach greatly depends on the nature of coating failures. CP can only provide corrosion protection to the pipe with coating failures if sufficient CP current is able to reach the exposed pipe steel. For instance if CP current can penetrate into a coating disbondment then corrosion related damages may be prevented. Otherwise the exposed pipe steel could be susceptible to corrosion and environmentally assisted cracking. Due to this very reason disbondment of pipe coatings especially coatings with high impedances is considered to be the most troublesome coating failure mode. Therefore a comprehensive understanding of CP penetration into coating disbondment is essential to coating selection and management i.e. choosing the right coating for the right application and developing mitigation measures for coating failures.This study was intended to conduct a systematic investigation to examine the effect of coating property disbondment geometry and dimension and soil solution on CP penetration into coating disbondment. An innovative experimental setup was designed to enable in-situ monitoring of pH and potentials without disturbing the environment inside the coating disbondment. It was observed that all the three coatings studied namely fusion bonded epoxy (FBE) high performance powder (HPPC) and two-part epoxy showed shielding behaviour and the applied CP could not fully penetrate into the disbondment. The HPPC coating containing a FBE inner layer and a polyethylene outer layer exhibited the highest shielding behaviour. The variation of CP penetration within the entire disbonded area (6.5 cm in diameter) was trivial. The consumption of CP current at each given potential decreased with testing time. The extent of CP penetration was more dependent on the gap size of disbondment than other parameters.

Key words: CP penetration, coating disbondment, detection probe, migration of OH-, calcareous deposit

The most effective method to mitigate corrosion on the external surface of a buried pipeline is to utilize a protective coating supplemented by cathodic protection (CP). Ideally these two systems work together so that if the coating disbonds or has defects allowing ground water solution to contact the pipe steel surface the CP system will continue to function to protect the pipeline. However the success of this approach greatly depends on the nature of coating failures. CP can only provide corrosion protection to the pipe with coating failures if sufficient CP current is able to reach the exposed pipe steel. For instance if CP current can penetrate into a coating disbondment then corrosion related damages may be prevented. Otherwise the exposed pipe steel could be susceptible to corrosion and environmentally assisted cracking. Due to this very reason disbondment of pipe coatings especially coatings with high impedances is considered to be the most troublesome coating failure mode. Therefore a comprehensive understanding of CP penetration into coating disbondment is essential to coating selection and management i.e. choosing the right coating for the right application and developing mitigation measures for coating failures.This study was intended to conduct a systematic investigation to examine the effect of coating property disbondment geometry and dimension and soil solution on CP penetration into coating disbondment. An innovative experimental setup was designed to enable in-situ monitoring of pH and potentials without disturbing the environment inside the coating disbondment. It was observed that all the three coatings studied namely fusion bonded epoxy (FBE) high performance powder (HPPC) and two-part epoxy showed shielding behaviour and the applied CP could not fully penetrate into the disbondment. The HPPC coating containing a FBE inner layer and a polyethylene outer layer exhibited the highest shielding behaviour. The variation of CP penetration within the entire disbonded area (6.5 cm in diameter) was trivial. The consumption of CP current at each given potential decreased with testing time. The extent of CP penetration was more dependent on the gap size of disbondment than other parameters.

Key words: CP penetration, coating disbondment, detection probe, migration of OH-, calcareous deposit

Product tags
Also Purchased
Picture for 07036 PRACTICAL CONSIDERATIONS FOR UPPER LIMITS OF CATHODIC PROTECTION
Available for download

07036 PRACTICAL CONSIDERATIONS FOR UPPER LIMITS OF CATHODIC PROTECTION

Product Number: 51300-07036-SG
ISBN: 07036 2007 CP
Author: Ernest Klechka, Steven F. Daily, and Kevin C. Garrity
Publication Date: 2007
$20.00

This paper reviews the concerns of applying excessive levels of cathodic protection current to pipelines and the need for establishing an upper potential limit. Coating disbondment, hydrogen induced stress cracks, stress corrosion cracking, hard spots and the problems associated with measurement of a true polarized pipe-to-electrolyte potential are addressed.
Picture for 51318-10544-Cathodic Protection, Coatings that Shield Cathodic Protection, Stress Corrosion Cracking and Corrosion Assessment in Aging Coated Pipe Lines and Buried Utility Structures
Available for download

51318-10544-Cathodic Protection, Coatings that Shield Cathodic Protection, Stress Corrosion Cracking and Corrosion Assessment in Aging Coated Pipe Lines and Buried Utility Structures

Product Number: 51318-10544-SG
Author: Mehrooz Zamanzadeh / George T. Bayer / Anil Kumar Chikkam
Publication Date: 2018
$20.00

Here we would like to elaborate on corrosion risk associated with coatings that shield cathodic protection.
Picture for Cathodic Protection and MIC - Effects of local electrochemistry
Available for download

Cathodic Protection and MIC - Effects of local electrochemistry

Product Number: 51317--9452-SG
ISBN: 9452 2017 CP
Author: Stefan Jansen
Publication Date: 2017
$20.00

The goal of this research was to improve the understanding of the mechanisms of cathodic protection (CP) by determining the interactions between corrosion and local chemical parameters, such as pH, under varying CP conditions, both in the absence and presence of MIC.
Categories
Industry
Recently viewed
Popular tags
View all

Association for Materials Protection and Performance

© AMPP All Rights Reserved.
Membership Terms of Content Use
Contact Customer Support