October 28, 2019 Updated: June 15, 2023 Galvanic Corrosion Explained Contact between dissimilar metals – like copper fittings threaded into steel pipe or copper flashing fastened with steel nails – sets up an electro-chemical reaction that causes corrosion and leads to failure of the “less noble” metal Roofing Siding & Exterior Trim WRB & Flashing Plumbing, Electrical YouTube video