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Cathodic protection shielding and prevention of the corrosion under disbonded coating in soils

Picture for Cathodic protection shielding and prevention of the corrosion under disbonded coating in soils
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Organic coatings protect the underlying metallic substrate against corrosion by acting as a barrier to corrosive species such as water, ions, and oxygen. Unfortunately, coatings might contain defects and could degrade or disbond under some environmental conditions, resulting in favorable pathways for such corrosive species.


Barrier protection is one of the modes by which intact coatings provide protection to metal substrates through a reduction of the transport of materials, ions, or charge.

Product Number: 51323-19248-SG
Author: Erwan Diler, Nicolas Larche, Jean Vittonato, François Castillon, Sylvain Fontaine, Thierry Kerzerho, Patrice Lucas, Eric Agel
Publication Date: 2023
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$20.00
$20.00

Cathodic protection shielding of pipeline coatings is largely debated among coatings specialists. Under disbonded coating with or without electrolyte renewal, the amount of current passing through is the key of the protection. In this study, the shielding character of field coatings, such as single and dual layers FBE and liquid epoxy was assessed. Different thicknesses were investigated from 350 to 1000 μm. An experimental setup was designed to assess the ability of a disbonded coating to allow the CP currents to protect the steel underneath. Conditions at low and high oxygen contents were considered. This setup aims at reproducing blistering conditions with and without renewal of confined electrolyte. For this purpose, substrate free coating samples were used (membrane type samples). Additional experiments were performed to measure the CP currents passing through similar coatings on steel substrates for 12 months. Finally, a 30 years old FBE disbonded coating, collected from the field and presenting a low shielding behavior, was similarly characterized. The obtained results allow discussing the ability of tested coating (presenting low and high shielding properties) to protect the steel under blistering conditions. Specific soils conditions in terms of resistivity and polarization curves at various moisture level were considered.

Cathodic protection shielding of pipeline coatings is largely debated among coatings specialists. Under disbonded coating with or without electrolyte renewal, the amount of current passing through is the key of the protection. In this study, the shielding character of field coatings, such as single and dual layers FBE and liquid epoxy was assessed. Different thicknesses were investigated from 350 to 1000 μm. An experimental setup was designed to assess the ability of a disbonded coating to allow the CP currents to protect the steel underneath. Conditions at low and high oxygen contents were considered. This setup aims at reproducing blistering conditions with and without renewal of confined electrolyte. For this purpose, substrate free coating samples were used (membrane type samples). Additional experiments were performed to measure the CP currents passing through similar coatings on steel substrates for 12 months. Finally, a 30 years old FBE disbonded coating, collected from the field and presenting a low shielding behavior, was similarly characterized. The obtained results allow discussing the ability of tested coating (presenting low and high shielding properties) to protect the steel under blistering conditions. Specific soils conditions in terms of resistivity and polarization curves at various moisture level were considered.

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CP Shielding and Pipeline Coatings
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CP Shielding and Pipeline Coatings

Product Number: 41206-285-SG
Author: Greg Ruschau
Publication Date: 2006
$20.00

Shielding of cathodic protection (CP) by pipeline coatings poses a serious threat to pipeline integrity.  The difficulty in pipeline coating selection to avoid shielding is that the same properties that make a pipeline coating a good corrosion mitigation material can also lead to CP shielding. The key to proper coating selection is to select a coating that has the necessary properties to provide good corrosion protection but also one that, when disbondment and failure occurs, fails in such a way to allow effective cathodic protection.
Picture for EMAT Pipe Coatings Corrosion Control and Cathodic Protection Shielding
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51313-02378-EMAT Pipe Coatings Corrosion Control and Cathodic Protection Shielding

Product Number: 51313-02378-SG
ISBN: 02378 2013 CP
Author: Markus Ginten
Publication Date: 2013
$20.00
Picture for Penetration of Cathodic Protection into Pipeline Coating Disbondment
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Penetration of Cathodic Protection into Pipeline Coating Disbondment

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

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.
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