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Corrosion of SS316 Tanker against 100 % NaCl and acetic acid

2007

First situation: What is the best way of cleaning a dedicated tanker ( SS316 and SS316L) after unloading 100% Sodium chloride- dry cleaning only/ blowing the tanker with air or rinsing with potable water and or no cleaning at all.
The tanker is unloaded using presurized air, it means that after unloading it has been dry cleaned already.

Second situation: We are planning to remove the Tanker cleaning requirement for our supplier of 100 % acetic acid ⇦ this on eBay or Amazon [affil links] . Our current supplier is using tanker made of SS316 and SS316 L. Right now we are having problem because of the water residue inside the tanker is causing the Assay of acetic to be below the specification. We would like to eliminate the rinsing of the tanker, Will it cause significant corrosion inside the tanker if we eliminate the rinsing after each load of 100 % acetic acid ?. The auto ignition temp of acetic acid is at 427 C and boiling point is 112 C, the corrosion rate of acetic acid (100%)is 0.09 milli inch - 0.009 milli inch per month. Based on the Risk analysis, there are more risk than benefits for rinsing the tanker. Am I correct?. Need help

Thanks

Ernesto Cortez
Quality Engineer - Irving, Texas

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I assume that both of these situations are dedicated tanks that carry ONLY these two materials.
As long as the tanks are periodically cleaned and repassivated you should be able to get by without rinsing of the tanks in this case.
Even with dry blowing of the NaCl powder you will eventually get some corrosion in that tank, so it will need maintenance periodically. Just the humidity in the air is enough to allow some chloride corrosion in the intergranular boundaries eventually. Careful inspection to make sure that you clean and repassivate the surface BEFORE pit corrosion begins should give you an acceptable result.
With the acetic acid , as long as you keep it dry and do not contaminate the tank with other materials it should be okay (as long as you can tolerate the slow etching of the surface). I am not familiar with the decomposition rate of acetic acid in this environment, if any. Residual acetic acid in the tank will take on water from the humidity in the air, of course.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

2007

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2007

Hello,
Here are some solutions:

I don't know the operational parameters. But, why don't coat your tanker whit a polymer (in the case T < 200 F)?

You are handling liquids that make deposits. So, rinse must be done in order to eliminated them. Rinsing by steps you will optimize the cleaning and water volume.

Jose Castellanos
- Minneapolis, MN, USA