Galvanic Corrosion of Piping and Fitting Alloys in Sulfide-Modified Seawater

Two wrought piping alloys, 70-30 and 90-10 copper-nickel, were each galvanically coupled to each of four fitting alloys in sulfide-modified seawater for 30 days. The fitting alloys used were bronze (Composition M), cast Monel^®, wrought nickel-aluminum bronze, and cast 70-30 copper-nickel. The piping material to fitting material area ratio was 3:1 and the seawater velocity was 2.4 m/s. Results indicated that the galvanic relationship between M-bronze or Monel and 70-30 copper-nickel is affected by sulfide additions, in a manner that increases the corrosion of the fitting material, whereas similar couples with 90-10 copper-nickel show little effect of sulfide.