Galvanic Corrosion Protection System

Why Galvanic Corrosion Occurs

When two dissimilar metals are connected, a galvanic couple is created. This couple will result in corrosion of the anode, which is the less noble of the two metals. The severity of the reaction between the two metals is determined by several factors including:

• The electromotive nature of each metal and the galvanic potential difference between the two.
• The environment the galvanic couple is exposed to including the conductivity, temperature and oxygen concentration.

Some waste injection wells combine carbon steel and Corrosion Resistant Alloy (CRA) casing materials. Carbon steel is utilized in the upper portion above the injection interval and CRA is used for the lower portion from just above the packer to the base of the string. The connection of the carbon steel to the CRA creates a galvanic couple. The resulting galvanic reaction accelerates corrosion of the carbon steel leading to premature failure immediately adjacent to the connection of the dissimilar metals

Galvanic corrosion is halted when the flow of electrical current from the cathode (CRA) to the anode (carbon steel) is eliminated. A common method of eliminating the current flow has been the use of a nonmetallic section of pipe, such as fiberglass, between the carbon steel and the CRA. Limitations have included the inability to maintain a seal in the connection between the nonmetallic and metallic casing. Drilling out or running tools through nonmetallic pipe has always been a concern and historically has created problems.

Our Solution

The solution is JGC's JGC2012 Galvanic Corrosion Protection System (GCPS). This system utilizes a newly formulated abrasion resistant nonconductive ceramic epoxy coating developed expressly for application on CRA pipe. The tested coating is extremely resistant to mechanical abrasion and chemical attack and when applied to a calculated length of CRA pipe below the transition connection of carbon pipe, eliminates the flow of galvanic induced electrical current to the carbon.

JGC2012 GCPS includes a modified, specialty, metal to metal seal, and threaded connection to produce an oxygen free environment within the connection. This eliminates the occurrence of corrosion within the connection. After making up the carbon casing sub on the first joint of CRA, the assembly is surface prepped and the ceramic coating applied to a calculated length of the CRA to one inch past the CRA-carbon interface

The JGC2012 Galvanic Corrosion Protection System provides assurance to a practical and economical solution for the elimination of galvanic corrosion of carbon steel pipe.

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