New Course Offering: Coatings in Conjunction with Cathodic Protection, Presented by Ernie Klechka, Senior Project Manager, CC Technologies, Inc.

02/22/06

Ernie Klechka

Nace International is about to release a new course titled “Coatings in Conjunction with Cathodic Protection” (CP). While this is a new course, it deals with an old subject: “Which coatings work best with CP?”

Often coatings are specified to mitigate corrosion during construction or maintenance of a buried or submerged structure such as a pipeline, underground storage tank, or pier. CP is often applied after construction is complete or many years later. This course brings coatings selection and application together with CP design and installation.

Corrosion is one of the most important problems encountered by the owners and operators of underground, offshore, submerged, and other metallic structures exposed to an electrolyte (water). If corrosion is not controlled, it can lead to large costs for maintenance, repairs, or facility replacement. Even more significant indirect costs can be incurred as a result of environmental damage and cleanup, injuries to personnel, and fatalities. The life of an underground or submerged structure is often controlled by the rate of corrosion.

Pipeline corrosion protection consists of:

• An adequate protective coating, and
• Supplementary CP.

These basic criteria became the foundation for NACE Standard RPO169 in 1969, which was later adopted in 1971 by the U.S. Department of Pipeline Safety (now the Department of Transportation) as the basis for regulations governing protection of pipelines against corrosion.

Yes, the first line of defense against corrosion for buried or submerged structures is a good coating. But, since we all know that no coating can be applied, handled, and installed perfectly, we supplement the coating corrosion protection with CP. This new course addresses many of the issues surrounding coating compatibility with CP.

The primary purpose for pipe coating is to separate the pipe’s base metal from its environment (water). However, even today’s most sophisticated coatings don’t provide absolute barriers to moisture and electric (corrosion-inducing) current.

It is necessary to prevent the access of moisture to the pipe surface because moisture is the electrolyte in the corrosion cell. High resistance to electric current is important because maintaining an electric potential constitutes CP, which is the secondary line of defense against corrosion.

In general, when CP is applied to a buried or submerged structure, the pH will increase at holidays in the coating often to 11 or 12. At the anode the pH can be reduced to 5 or 6. At the cathode hydrogen or hydroxyl ions are generated. At the anode chlorine or oxygen can be generated.

This new course brings the Coating Inspector Program and the CP program at NACE International together.

This new course is a coatings course, in that many different types of coatings are reviewed. This new course is a CP course in that the basic concepts of CP are reviewed. This course also is an external corrosion direct assessment (ECDA) course in that many of the indirect surveys used for ECDA only work because of the coatings on the pipe and the applied cathodic protection.

This headline was originally printed in the NACE International Stay Current publication. Stay Current, Volume 2, Issue 1, NACE Cathodic Protection Training and Certification News. Winter 2006.

For further information about this course, follow this link: www.nace.org

Ernie Klechka is Senior Project Manager at CC Technologies, Inc.