Galvanic corrosion bewteen 316L st st and 6Mo st st subsea
Galvanic corrosion bewteen 316L st st and 6Mo st st subsea
(OP)
Hello all,
I have an application where I need to connect a 316L st steel component to a 6Mo st steel component.
I have been prompted to assess the potential (no pun intended) for galvanic corrosion between these two components.
I would appreciate your thoughts and advice.
Here are my thoughts:
1. They are both austenitic st steels, so should be close on the galvanic series? (need to be <-0.15V potential difference).
2. Would adding sacrificial anodes (zinc) immediately adjacent to the joint prevent the galvanic corrosion?
3. Separate the compnents with an intermadiate material that would be compatible with the other two, e.g. Inconel625 / Titanium? All materials must be non-magnetic due to high electrical current passing within the items.
4. Components cannot be (electrically) isolated from each other as a metal-metal seal ring must fit between the two items.
Many thanks in anticipation of your advice,
Rob
I have an application where I need to connect a 316L st steel component to a 6Mo st steel component.
I have been prompted to assess the potential (no pun intended) for galvanic corrosion between these two components.
I would appreciate your thoughts and advice.
Here are my thoughts:
1. They are both austenitic st steels, so should be close on the galvanic series? (need to be <-0.15V potential difference).
2. Would adding sacrificial anodes (zinc) immediately adjacent to the joint prevent the galvanic corrosion?
3. Separate the compnents with an intermadiate material that would be compatible with the other two, e.g. Inconel625 / Titanium? All materials must be non-magnetic due to high electrical current passing within the items.
4. Components cannot be (electrically) isolated from each other as a metal-metal seal ring must fit between the two items.
Many thanks in anticipation of your advice,
Rob





RE: Galvanic corrosion bewteen 316L st st and 6Mo st st subsea
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/
RE: Galvanic corrosion bewteen 316L st st and 6Mo st st subsea
There should be "dissimilar metal crevice corrosion" data in the AL-6XN source book at the Allegheny Ludlum web site that shows 6XN-316-6XN tested in seawater for one year.
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Plymouth Tube
RE: Galvanic corrosion bewteen 316L st st and 6Mo st st subsea
this doc can give you some advice, but not much..
http://www.csidesigns.com/PDFs/AL-6XNCatalog.pdf
this doc can also help you, look at page 67-69.
http://ww
hope this help
S.
Corrosion Protection & Corrosion Control
RE: Galvanic corrosion bewteen 316L st st and 6Mo st st subsea
If two dissimilar metals are immersed in seawater and a potential exist between them, then , even if the assembly is subject to a cp system, that same potential will still exist, and , presumeably there will be massively increased corrosion on the least noble of the immersed metals.
You can minimise corrosion by coating both of the immersed metals. you can eliminate it by electrically insulating all metals from each other (but you say this is not possible ). Best of luck.
CM
RE: Galvanic corrosion bewteen 316L st st and 6Mo st st subsea
That 'same potential' may not exist if an external anode is added. The resultant potential difference between the two alloys will be dependent upon their polarisation behaviour in seawater and not their individual rest potentials in seawater.
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/