Material selection between AISI 316 L / AISI 316 L NACE / Duplex

[Giorgio B.]

Hello,

I have the following problem.
I need to select the proper material between AISI 316 L / AISI 316 L NACE / DUPLEX to be suitable for following working condition:

pH = from 2 to 5
Chloride (Cl-) = less than 500 ppm
Sulfates (SO42-) = less than 13700 ppm
Temperature = 25 - 30 °C

In the above stream, I'm dosing following additive:

- Ozone (O3) = dosing rate 280 g/m3 - Injection concentration 8%
- Hydrogen peroxide (H2O2) = dosing rate of pure product (100% H2O2) 75 mg/L - Injection concentration 35%

Could you please help me to understand which is the most suitable material?

Thanks in advance

 

[EdStainless]

Is this an existing application?
I have seen 316L pit in pH=4 with 10ppm Cl.
IF you are rally going to pH=2 with any real chlorides you need more corrosion resistance.
Either a 6%Mo superaustenitic (AL-6XN) or a superduplex (2507) would withstand it.
Now if your pH is actually 4 or higher then you should be able to use 317LMN or 2205.

The O3 and H2O2 will help, but I wouldn't rely on having the extra oxygen just to keep the material passive.

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P.E. Metallurgy, Plymouth Tube