Q: What is the best alloy to bolt to use in a flange on the outside Hydrofluosilicic acid storage tank?
A: Probably the best materials for Hydrofluosilicic acid bolting would be a Monel K500 bolt. This material will give you the strength and good corrosion resistance to the this very aggressive acid. Monel K500 bolts also offer high strength approximately 3 times the yield strength (110ksi vs 45ksi) and double the tensile strength (160ksi vs 83ksi) when compared grade 400.