Q: I’m looking for a chemically resistant polymer that can withstand chlorine and chlorine dioxide as well as a decent amount of weight and tension (around 27 lbs of weigh). Can you suggest a material?

A: Of course it depends on the concentrations and temperatures you are operating at but generally speaking a very chemically resistant and strong polymer to consider would be PVDF or Kynar fasteners.   PVDF fasteners offers an ultimate tensile strength of 5000-8000 psi providing structural strength. This could also be improved with glass fiber by about 2x.  You will have to consider the diameter of your screw and the temperature of the applications to determine if PVDF is strong enough though

Q: Is there any advantage of using a Hastelloy B3 fastener over a B2 fastener?

A: Both Hastelloy B2 and B3 fasteners provide good resistance to non-oxidizing acids, such as hydrochloric acid and sulfuric acid. The only advantages of Hastelloy B3 fasteners over B2, is that they offer enhanced thermal stability and improved fabrication characteristics. Remember, both B2 and B3 fasteners should not be used in oxidizing media or in the presence of ferric or cupric salts, as it will cause corrosion failure.

Q: Can dissimilar (also called galvanic) corrosion occurs between Inconel bolts and regular carbon steel?

A:   Anytime you have dissimilar materials you have the potential for galvanic corrosion.  For this to happen the materials need to be wet or in some kind of solution. If they are dry it’s greatly reduced although humidity could be enough to cause the materials to galvanically couple.

Also whenever you have dissimilar materials you always want the part with less mass, in the case the bolts, to be the more noble alloy.  Because the carbon steel plate has much more mass than the screw its affects will be greatly minimized.  This is important as you don’t want to corrode the threads of the bolts.