Q: I am considering using Inconel 718 fasteners with a Monel K-500 flange in seawater. I’m concered as Inconel is the more anodic of the two and is also has a smaller surface area. Would this cause galvanic corrosion?
A: This is a great question. In this case if you plan on using Inconel 718 fasteners with Monel flanges you should be OK. Because the Inconel is the more noble, the galvanic effects will be pushed to the K500 Monel. This is where you want any galvanic effects to be on the larger mass part and not on the fasteners. Because the mass of the flanges is much larger than the bolts, the galvanic effects will be minimized. Furthermore the galvanic effects between Monel and Inconel as relatively minor. See our galvanic compatibility chart