316 SS Tank for storage of chemical premixed with Seawater or 4%NaCl

[Cor123]

Dear all
I have been asked to evaluate if it's possible to utilise an existing 316 SS tank for a polymeric hydrate inhibitor containing either seawater or 4% sodium chloride solution.
I highly discourage this given the enormous risk of pitting and crevice corrosion. The piping downstream of the tank are also 316 SS and CS.
I was informed that they can add oxygen scavangers into the chemical mixture to reduce the risk. I am of the opinion that this whilst slightly beneficial, it can cause MIC /SRB proliferation especially if seawater is used.
This is an old asset and no one wants to commission another tank with robust material.
I would like to hear anyone with experience of using similar system? Any advice would be highly appreciated as I am feeling some pressure.
Thanks

 

[EdStainless]

This would surely destroy the tank, and there is good chance that it would fail before they were done with it. Adding an oxygen scavenger (and inert gas blanket) would be not be enough to help in this case.
How about a non-metallic tank?
If that doesn't fly how about a coated CS tank with some sacrificial anodes in it.

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P.E. Metallurgy, Plymouth Tube

 

[TVP]

Ed is an expert in this area, I recommend you heed his advice. Type 316 just isn't suitable for this type of service.

 

[Cor123]

Thanks Ed. That's exactly what I thought.
As always many thanks for sharing your immense knowledge.
If we go other options, the pipework is also mixture of 316 and CS. This would surely cause as much damage?
Thanks

 

[EdStainless]

The 316 pipe is history, remove it.
The CS will depend on the flow conditions.
Will this system always be full?
will it always be flowing?
My hunch is that it would be easier to put non-meallic piping in and be done with it.

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P.E. Metallurgy, Plymouth Tube