Galvanic Cossion, between AB2 and Super Duplex

[MattC1234]

One of my companies customers has requested that stellite be applied to Super Duplex in order to protect super duplex from galvanically interacting with aluminium bronze, where AB2 is the valve body material.

Is galvanic corrosion a problem between these 2 materials -i am unsure on the position of Super duplex in the galvanic series, but i would have thought it were similar to 316 SS, which is reasonably close to AB2 (and therefore not a problem?) - and if so is there anything that can be done to reduce these affects. The customer suggested stellite, but what about pickle and passivating the super duplex or some other method?

Any help would be appreciated

Regards

Matt

 

[EdStainless]

What fluid? seawater? Flowing or stagnant?
Since all stainless grades depend on a chrome oxide passive layer they are very similar, though a super duplex would be more like a 6% Mo super-austenitic grade.
The real risk is dealloying of the AB. If it was a Ni containing grade I wouldn't worry much. A straight AlBronze sounds like a weak link in the system.

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Plymouth Tube

 

[strider6]

it depends also on the surface ratio of the two materials. i've found this ref for Zeron 100, a super duplex
"Severe corrosion has occurred on nickel aluminium bronze valves in ZERON® 100 piping systems"

http://www.ramaterials.co.uk/content/corrosion_galvanic.aspx

S



Corrosion Prevention & Corrosion Control