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Carbon Steel and 304 SS performance in chloride solution

Carbon Steel and 304 SS performance in chloride solution

Carbon Steel and 304 SS performance in chloride solution

(OP)
Howdy, Eng-Tip users,

I have a de-commissioned plant that we are trying to re-use at a different site; however the new feed stream has ~2000 ppm Cl-.  
The CS steel tanks will see a solution pH of ~10, while the 304SS will see ~ 3-5.  The entire process will be at ambient temperature (assume 20°C).

My initial thought is that both the CS and the 304SS tanks will need a passive coating applied to them.  Anyone out there with evidence to the contrary?  Failing that, any recommended coatings for the CS and 304SS tanks?

Thanks in advance,
Cheers,
Brent Baker

RE: Carbon Steel and 304 SS performance in chloride solution

If the operating temperature  is low enough , you may want to get an estimate to replace the tanks with FRP or polypropylene tanks.

Also, the corrosion issue is not limted to tanks- piping,valves, pumps etc have cossion issues as well.

RE: Carbon Steel and 304 SS performance in chloride solution

bbakes,
Without more info re pressure and feed stream make up, it's impossible to provide meaningful answers to your post.   

RE: Carbon Steel and 304 SS performance in chloride solution

(OP)
Thanks for the replies so far.

I'll try and answer some of the queries.

Pressure: the carbon steel tanks are all open top, so therefore will operate at ambient pressure.  The 304SS tanks are operated under a negative pressure, sealed and vented to a scrubber.

Feed make up: Unfortunately, I don't have an ICP analysis of the feed stream. I only know it is a BLS from a gold plant.  So it will contain CN, be about a pH of 9.5, and contain Cu, Ag, and Au.  It shouldn't contain much Fe2+ or Fe3+.

Piping and valves: most of the piping/valving from this plant is PVC, so no worries on that front.  Just interested in re-using the steel tanks.

Cheers,
Brent

RE: Carbon Steel and 304 SS performance in chloride solution

What is the size of your CS tanks?
 

RE: Carbon Steel and 304 SS performance in chloride solution

304 will suffer serious pitting at that pH and Cl.

Line the CS tanks with resin.
Don't use 304 in 2,000ppm Cl, even with liner.

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