PTFE and Monel Fasteners for Hydrofluoric Acid

Q: I need a material that is resistant to a small concentration of hydrofluoric acid at room temperature? Can you offer any suggestions?
A: Two materials come to mind. First in terms of metal alloys Monel 400 bolts are resistant to most concentrations of hydrofluoric acid. If you prefer a polymer, then I would suggest PTFE. PTFE fasteners are known for their inertness to most acids, even hydrofluoric acid. PTFE is ideal for low temperature, high purity applications.