Galvanic corrosion is an electrochemical action of two dissimilar metals. It occurs when dissimilar metals are in contact. In order for galvanic corrosion to occur, all three elements are required.1) Dissimilar metals 2) Metal-to-metal contact 3) Metals in the same solution (such as water or vapor) If any of these elements is missing, galvanic corrosion cannot occur. If, for example, the direct contact between the two metals is prevented (plastic washer, paint film etc.) there cannot be galvanic corrosion. Galvanic corrosion only causes deterioration of one of the metals, the anodic side (see below chart). If you do not use dielectric fittings, in time (couple years / decades, who knows) the connections will start to fail. Usually at the thinnest point, the threads.
Winter, concrete and Ice, three words that should not be mixed, however, we cannot stop construction in the Winter. When we mix all three items, we have a conflicting issue with quality & safety, and how to control both without sacrificing either.
Guidelines for selection of fasteners based on galvanic action.
As we discussed before, not all fasteners that are zinc coated are for exterior use. Whenever we are installing fasteners that will be exposed to the exterior, we should be asking the question and verifying the fastener. This includes bolts, screws, expansion type anchors, epoxy type anchors, etc.
Common Building Material Compatibility - The following is a list of common building materials that we deal with daily. The list compiled below represents typical building material incompatibility. If specifications or drawings have any of these items together, please contact the manufacturer and the architect to discuss compatibility issues with the materials specified.