SS cladding with Galvanic corrosion issues 2

[Zahib]

Hi guy
This is reactor in Petrochemical process which operating temperature 80 oC and Opeating pressure 10 bar.The original material of Reactor's shell and nozzle are both carbon steel. In case of consider to use Stainless steel cladding material for the nozzle part then I would like to ask that if galvanic will be occurs.The condition during operation is dry without free water but it is wet during SD period and be purged before start up.

Thank for your comment

 

[TugboatEng]

If there is no conductivity there can be no galvanic corrosion.

If there is no simultaneous exposure of both materials to the same fluid there can be no galvanic corrosion.

I find that technicians universally blame pitting on galvanic corrosion and are almost universally wrong.

During the shutdown your stainless steel is going to be subject to crevice corrosion.

You have two choices. Establish a procedure to purge and protect the nozzle during the shutdown or utilize a cladding that tolerates your shutdown conditions. The purpose of cladding is that it requires less of the expensive material which allows you to utilize that expensive material.

 

[EdStainless]

Often the issue during SD is that there are some residual chemicals as well as moisture present.
A process that keeps the SS dry during SD is the safest route.

The key to identifying galvanic driven corrosion is that it is the worst nearest the interface of the two materials.


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P.E. Metallurgy, consulting work welcomed