Suitability of Stainless Steel in Potash Mine

[hanksmith]

Currently I am working on a job that requires the use of 316 stainless support brackets in a potash mine (exposure to water, high humidity, potassium chloride, sodium chloride, and magnesium chloride)

The brackets are of a critical nature, basically if they fail the mine will be shut down for an extended period and I have been told there is no inspection schedule for these brackets.

Client would like a 40 year life.

Any thoughts, I am an electrical guy and from my internet searches SS316 should be good but would it last 40 years?

Thanks

 

[dik]

We use stainless steel all the time or HDG (the latter even for rebar).

Bigger problem with potash anchors is that the material is somewhat plastic and creeps or flows...

Dik

 

[EdStainless]

I would suggest that you consider using 2205. 316 is not that corrosion resistant and this will be a low pH high chloride environment.

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Plymouth Tube

 

[cloa]

Chance of getting chloride concentration on 316 with zero maintenance such critical pit over a long time- 100%

 

[corrosionman]

Hanksmith, If any doubts can you not use plastic brackets??
Watch out for dissimilar metal corrosion if the brackets support or contact any other metal. (Are you at Boulby ?)
Corrosionman.

 

[hanksmith]

Ok, I have been in talks with a materials guy at our company and he does not seem to think there is an issue with using 316.

First - He mentioned that since the shaft is a constant temperature the humidity will be non-condensating and therefore any of the chlorides will be in dry salt form and dry chloride salts do not attack stainless.

Second - the water that these brackets come in contact with is potable water used to wash the salts off these brackets.

???any comments??? Would anyone still be concerned with using ss316?

 

[EdStainless]

I see it as a case where for about the same cost you could put in a much more robust alloy.
The salts will be hygroscopic (want to absorb moisture) and dry salt on the surface will not be truly dry.
For long term use I wouldn't risk it. Use 2205.

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Plymouth Tube

 

[dik]

I spec 2205 for high strength anchor rods and 316L for the remainder. There is generally sufficient maintenance that these are not forgotten...

The larger concerns I have are related to the 'creep' of the salt body.

Dik