Galvanic Corrosion on Flanges Connection.

[mechengineer]

Dear Corrosion Experts,

A pair of flanges connection:
one is SA-105 and
another is SA-182F316L.
Spiral Wound Gasket, wounding material of SS316L winding and graphite filter. Outer ring is CS and inner ring is SS316L.
Q1, Is there the galvanic corrosion between the CS flange and SS flange?
Q2, Is there the galvanic corrosion between the CS flange and SS winding material of the gasket?
Q3, If Q1 & Q2 are yes. Is there any suggestion or recommendation to resolve the issue (Galvanic Corrosion).

Thanks.

 

[TugboatEng]

There certainly is potential for galvanic corrosion.and it is especially high with graphite. However, the flange faces should not be exposed to the process fluid if the gasket is sealing properly.

What is your process fluid?

 

[EdStainless]

If the process fluid is conductive then you have the potential for accelerated attack at the inner edge of the CS flange against the 316/Graphite gasket. This would be very localized.
If you allow it to get wet from the OD then you could see attack of the CS flange and outer ring where they meet the 316/graphite gasket.
Again, this would be localized to a line of corrosion.
I don't see either of these compromising the seal or flanges.

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P.E. Metallurgy, consulting work welcomed

 

[mechengineer]

@Edtainless,
I tend to your point of view.
1. The outer ring (CS)with SS falnge and outer ring (SS) with CS flange very localized to a lint of corrosion.
2. At the sealing surface (the area contacted by winding material), winding material (SS)+ graphite filter with CS flange at high compressed stress without gas or liquid leak.
The sealing surface of the flanges shall not be corroded in the two case above in the design life of heat exchanger, normally 20 years.
Does Kammprofile gaskst against the galvanica corrosion better than sprial wound gasket as the facing material is insulation materials?

 

[mechengineer]

The threads replated to correcsion for understanding

https://www.eng-tips.com/viewthread.cfm?qid=220853#post

https://www.eng-tips.com/viewthread.cfm?qid=510967

 

[SJones]

https://www.sciencedirect.com/scien...water and hydrocarbon services,et al., 2018).

https://www.sciencedirect.com/science/article/pii/S030801612400084X?dgcid=rss_sd_all

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[mechengineer]

@Sjones,
Thansks for sharing. it's very usefully information from reaserch and study.

 

[ShabsRBI]

In order to stop galvanic corrosion happening between CS and SS flanges, Flange Isolation Kit is used. This kit looks like following. This kit is also used providing Isolation to Cathodic Protection between an underground section to Above Ground section.