Q: I have a high strength application that requires resistance to damp salt air and occasional sea splash, I’m using Monel 400 but it’s not holding up the the 75ksi of yield I need. Lots of broken bolts? Is is corrosion or  strength? Thoughts?

Q: I’m working on a structural project that not submerged in salt water but exposed to moist salt air. I’m not only concerned about the supports having fasteners that won’t corrode but also having a fastener that is high strength. Any suggestions.

A: Though I don’t know the specific strength requirements, I do know that Duplex 2507 is commonly used in situations that require both salt water corrosion resistance and high strength. Both Duplex 2205 and 2507 offer a high level of resistance to chloride (salt) stress corrosion cracking, as well as pitting and crevice corrosion, but 2507 is much better suited when strength is a concern. Duplex 2507 fasteners provide users yield strength which is twice that of annealed austenitic stainless steels.

Q: We have a pulp & paper digester that is used to cook wood chips in an alkaline solution. The fasteners will be exposed to high temperatures and abrasive conditions. Any suggestions?

A: Without knowing the specifics of your process, I can make two general material suggestions. Duplex 2205 fasteners are often used in pulp and paper digesters for their high resistance to chloride stress corrosion cracking, as well as pitting and crevice corrosion.  But keep in mind Duplex 2205 has a usable temperature limit of 572F. If you have harsher conditions or are are running at higher temperatures, Hastelloy C276 may be a better fit. C276 fasteners are also commonly used in digesters and are a good fit for more severe conditions. They can be used at operating temperatures up to 1900 F and are very resistant to chlorides, as well as hot, extremely caustic media.