What should hangers and strapping be made of to prevent promoting galvanic action?

Hangers and strapping should be made of approved materials to prevent galvanic action because these materials are specifically designed to minimize the risk of metal corrosion when in contact with other metals. Galvanic action occurs when two different metals are in electrical contact in the presence of an electrolyte, which can lead to corrosion of one of the metals. Therefore, using materials that are consistent with the types of fasteners or connecting metals being used ensures compatibility and reduces the potential for galvanic corrosion.

Materials that are deemed "approved" typically include those that have been tested and certified to meet industry standards for durability and safety in specific applications. They may also include coatings or treatments that prevent corrosion. In contrast, while plastics might resist corrosion, they often lack the necessary strength for structural applications. Rust-proof metals can indeed be suitable, but they may not be appropriate for every application unless specifically approved. Wood, while durable in some contexts, does not generally offer the necessary structural support in metal connections and would also not address the galvanic action concern. Therefore, choosing hangers and strapping from approved materials addresses both structural integrity and the prevention of galvanic action effectively.