Question 96General Subjects - QMED

The correct answer is A) The plates should be electrically insulated from one another by use of non-conductive gaskets and non-conductive ferrule sleeves with the bolts. This is the correct answer because steel and aluminum are dissimilar metals on the galvanic series, which means they have different electrode potentials. When these metals are in contact and exposed to an electrolyte (such as moisture), it can create a galvanic corrosion cell, accelerating the corrosion of the more anodic metal (aluminum). Electrically insulating the steel and aluminum plates at the bolted joint using non-conductive materials prevents this bimetallic corrosion from occurring. The other options are incorrect because option B would create a direct electrical connection, option C is false as steel and aluminum are not close enough on the galvanic series, and option D would promote galvanic corrosion by ensuring good electrical contact between the dissimilar metals.