Why is Monel Used in PVF?
Monel 400 has been around since the early 1900s, developed by the International Nickel Co., and it's still one of the go-to materials when seawater and corrosion are part of the equation. It's a nickel-copper alloy built for tough environments such marine applications, chemical processing, oil and gas, etc... Think anywhere you're dealing with fluids that would eat through lesser materials.
Fair warning though: Monel can be trickier to machine and work with compared to some other nickel alloys, so it's worth knowing that going in.
Where it really shines is in damper, salty, or chemically aggressive conditions. It handles seawater, steam, caustic solutions, and a wide range of acids well, particularly hydrochloric and hydrofluoric acids as long as they're de-aerated. You'll commonly find it in strainers, valve components, fasteners, wiring, and other hardware that lives in corrosive service.
A few things worth knowing about how it performs:
- Holds up well across a wide range of environments, from pure water to non-oxidizing mineral acids, salts, and alkalis
- Good mechanical strength from sub-zero temperatures up to around 480°C
- Excellent resistance to chloride stress corrosion cracking
- Resists sulfuric and hydrofluoric acids well, though aeration will speed up corrosion rates
- Handles neutral, alkaline, and acid salts fine - but steer clear of oxidizing acid salts like ferric chloride
- Does better in reducing environments than oxidizing ones, sitting between nickel and copper in terms of resistance depending on conditions
