Joints between different metallic piping materials should be made with which type of fittings?

The appropriate choice for making joints between different metallic piping materials is approved dielectric fittings or brass converter fittings. This is essential in preventing galvanic corrosion, which can occur when two dissimilar metals are joined together in the presence of an electrolytic solution that allows electrical current to flow between them. Dielectric fittings are specifically designed to electrically isolate the two metals, thereby reducing the risk of corrosion and prolonging the lifespan of the piping systems.

Brass converter fittings also serve a similar purpose, allowing the connection of different metallic materials without causing an electrochemical reaction that could lead to material degradation. These types of fittings are compliant with many plumbing codes and standards, ensuring that they are suitable for such applications.

While other types of fittings might be considered in certain situations, they do not adequately address the issue of corrosion mitigation when dealing with dissimilar metals. Plastic fittings, for example, would not provide a suitable connection between metallic pipes, and standard metal couplings do not prevent electrochemical reactions. Additionally, welded connections require a uniform material instead of accommodating different metals, limiting their applicability in mixed-metal scenarios.