https://www.nickelalloytubes.com/products/monel-400-n04400-nickel-alloy-pipe-tube.html
Monel N04400 Alloy is a Nickel-Copper alloy that is resistant to seawater and steam at high temperatures as well as to salt and caustic solutions. Monel alloy 400 is a solid solution alloy that can only be hardened by cold working. The Monel 400 pipe using nickel alloy 400 tubing exhibits characteristics like good corrosion resistance, good weldability, and high strength. A low corrosion rate in rapidly flowing brackish or seawater combined with excellent resistance to stress-corrosion cracking in most freshwater, and the resistance of monel 400 seamless pipe to a variety of corrosive conditions led to its wide use in marine application and other non-oxidizing chloride solutions.