What describes a permanent connection that prevents corrosion in piping systems?

A dielectric union is specifically designed to create a permanent connection in piping systems while preventing corrosion that can occur when dissimilar metals are in contact. This union effectively insulates two metal pipes from each other, which is crucial because when dissimilar metals touch, it can lead to galvanic corrosion, where one metal corrodes faster than the other.

In practical application, dielectric unions use a non-conductive material as a barrier between metal components, which stops the flow of electric current that can initiate corrosion. This is essential in water supply systems where metals like copper and galvanized steel might be used together, as they have different electrochemical potentials, making them prone to corrosion when connected directly.

Other options mentioned, while related to corrosion or piping systems, do not serve the same purpose. For instance, a galvanic union relates to the unintentional connection of dissimilar metals, leading to corrosive issues, whereas an electrolytic connection also involves electrical conduction between metals, which can exacerbate corrosion. A corrosion preventer is too vague and could refer to various products or methods employed to mitigate corrosion but does not specifically describe the function of a dielectric union.