Abstract
It is rare that structures that include piping, heat exchangers, pumps, and valves are built without resorting to mixed, dissimilar alloys. When dissimilar metals or alloys are used it is necessary to account for the corrosion effects of the mixed metal contact. Contact between dissimilar alloys will generate galvanic currents based on a variety of factors. The extent of risk to the overall systems and specifically to more electronegative alloy materials can be predicted if the magnitude of the corrosion rate at various locations can be modeled and calculated.
It is important to understand the many factors that can influence galvanic corrosion and the magnitude and degree of competition or synergism by which those factors interact in a given service environment. There are a number of examples where the system/component geometry involving dissimilar alloys are neither symmetrical nor simple and the system may involve more than two dissimilar alloys. In addition, the contribution of flow is generally not considered, particularly turbulent flow. In systems containing elbows, the current and potential distribution will not be only in the longitudinal direction, but will have a radial contribution to current flow and corresponding potential changes.
The paper examines numerous factors that influence galvanic corrosion and will attempt to describe the processes and mechanisms by which galvanic corrosion may be modeled and predicted.
