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Monel Bellows Expansion Joints

Salt water can be quite a tough environment on piping components. This is especially true for metal bellows expansion joints. All the excellent marine corrosion resistant materials, like copper and bronze, are not an easy task to weld when creating bellows.

A great bellows alloy material for applications around salt water is Monel, the industry registered trade mark of Special Metals Corporation. [http://monel400.webs.com/ http://nickelalloyspecialist.com], or generically named alloy 400 is really a nickel-copper alloy that's been around for many years and possesses a good corrosion resistant material reputation. The ASTM sheet designation is B127-400. Like with many metals in marine applications alloy 400 is effective in lowing salt water. Stagnant brine may cause pitting corrosion.

The most typical bellows material, series 300 stainless, may be susceptible to stress corrosion cracking and salt water is loaded with chlorides. Alloy 400 is resistance against stress corrosion cracking. The information can also be useful in other corrosive applications like hydrofluric, hydrochloric, and sulfuic environments. As with any material selection, a metallurgist should recommend the bellows material for use for the given application.

Alloy 400 also supports well in sub-zero temperatures just like stainless-steel. In terms of marine engine applications most of the bellows continue to be stainless-steel. This might be because stainless-steel performs better at the higher engine temperatures in addition to having superior fatigue resistance that is needed for engine vibration.

Alloy 400 weld well and forms well, so that it is a good material for bellows manufacture.