Advanced Measures to Control Galvanic Corrosion in Piping Systems

摘要

Mixtures of piping materials have been used in several piping systems during ship retrofitting. The use of dissimilar alloys may initiate galvanic corrosion of the more anodic member which could lead to piping failures. Several control methods have been applied which may introduce secondary corrosion and require periodic inspection and replacement. This study investigated several newer galvanic corrosion control (cathodic protection, barrier coatings, bi-electrode) methods, by the use of mockup piping tests to monitor their effectiveness and performance in flowing, natural seawater from 6 to 20 months. Use of a space separator, cathodic protection, the bi-electrode, and the application of an organic or sealed anodized coating on the cathodic member of the couple were effective to varying degrees (30 to 99% effectiveness) in controlling galvanic corrosion. These newer methods may provide alternative galvanic corrosion control techniques that may allow selective use of mixed piping systems with a minimization of shutdowns for removing, inspecting, and replacing system components.