monel vs stainless how do you tell them apart

[karlhead]

How do you tell the difference, for example, when a seller says that the fuel tank is monel and not some kind of stainless steel? What type of material is best for water and fuel tanks?

[Capnblu]

I don't think a lay-person will be able to tell the difference between SS and Monel. It is an excellent material for either water or fuel. I don't know if its hardening properties would be a problem at the welds over time.

[sahara]

The question was posted and answered at another forum:

Monel has a somewhat duller appearance as it has no chromium. It's a nickel-copper alloy. The K-500 version includes some titanium for strength. I had some valve stems made of K-500 monel for acidic salt water service (oilfield, produced water in a CO2 flood) where 316 SS was dying in 3-4 months. Last I knew, those valve stems had lasted 6 years.

If you attempt to polish a small section, it will be pretty obvious that it's not SS due to the dull appearance. It will look much more like nickel than like chrome. Monel is very, very corrosion resistant, but is typically much more expensive than even 316L stainless.

Monel is a superior fuel tank material, hard to imagine anything better. If you could afford it, it would probably be great for water tanks, too, but at the high end these are usually 316L stainless.

I am aware of only one US production boat manufacturer who has used it for fuel tanks - Hinckley - but there may be others.

It's actually quite obvious when they are side by side. A few years ago I was having my (monel) fuel tank cleaned, the technician under the cockpit came up to me and asked "what is that fuel tank made of? It's not stainless and it's not aluminum". Even though he didn't know what it was, he knew it wasn't stainless, it has a very dull lustre.

[Gary M]

Monel has a slightly greenish tinge to it, SS is easy to spot, silvery but not overly shiny unless it has been buffed.

Monel has better resistance to the salt water environment than SS.

Gary

[Pamlicotraveler]

Sam Bush's Gibson mandolin strings are made of monel. Oh, what was the question?