316 SS - CORROSION in Stagnant Ground Water 1

[FYS]

Is 316 SS, susceptible to pitting/crevice corrosion in stagnant groundwater at less than 30 deg C. with chloride in the range of 2000 ppm. Also possibility of MIC (SRB) corrosion in swampy.

 

[unclesyd]

I think MIC will be your worst enemy based on my experience.

You will eventually get pitting at the ground air interface. From what I've seen pitting isn't really a big problem as the pits are very shallow. The only thing you will notice is the pipe will be a little rusty.

 

[strider6]

a "safe" limit of chloride concentration for SS 316 in water is set to approx 1000-2000 ppm. This limit is a function of several factors like:
-possibility of crevice conditions
-possibility of evaporation and concentration of chlorides
-condition of the exposure, fluid velocity; stagnant water will cause the steel to become active if no oxygen will reach the steel surface
-composition of the weater and possibility of MIC
-temperature..

In my opinion in your conditions you'll have the possibility of either pitting and crevice.
The acceptable limit of chloride is also a function of the criticality of your service.

Stainless Steel Corrosion

GUIDELINES FOR SELECTION OF NICKEL STAINLESS STEELS FOR MARINE ENVIRONMENTS, NATURAL WATERS AND BRINES (1987) (pub. 1987)

http://www.enia.org/index.cfm/ci_id/15786/la_id/1/ci_doc_id/3277/search_keyword/metal/method/.html

S.

Metal Corrosion