A simple Google search will help you understand! 316 is not the most favoured material for your conditions, I would be looking more toward the duplex range of S/S! However, this is not the place to really discuss these type of decisions! Sometimes you have to bite the bullet and pay for an educated and insured choice of material! Get an engineer or metallurgist to decide!

Your designer may want to review this information on "Crevice Corrosion" in stainless steels.

How Crevice Corrosion Forms on Stainless Steel Shafts -
Six Chemical Stages

1. Crevice Formation - “Crevice Formers” must be present; examples of these
features are sharp corners, overlapping metal surfaces, non-metallic gaskets or
incomplete weld penetration. These can all form tiny crevices which can promote
corrosion. To function as a corrosion site a crevice has to be of sufficient width to
permit entry of the seawater, but sufficiently narrow to ensure that the seawater
remains stagnant. Accordingly  crevice corrosion usually starts in  gaps a few
micrometres wide, (less than 1/10,000 of an inch) and is not found in grooves
or slots in which circulation of the sea water is possible.

2. Oxygen Depletion - Stainless steel depends on a thin oxide (metal bonded to
Oxygen) film on the surface of the metal to resist corrosion. This film is not
stagnant but “grows” using the oxygen from the surrounding sea water to rebuild
and repair this  protective  oxide film wherever gaps or scratches occur.
Within a tiny stagnant crevice the naturally occurring oxygen is gradually used up
by the growth of the  protective  oxide film. The  imbalance in oxygen
concentration between the shielded crevice area where the oxygen has been used
up to repair the oxide film and outside seawater sets up an oxygen concentration
cell or “chemical pump” which drives much of mischief to follow.

3. Acidification (The lower the PH the stronger the Acid) The metal ions present or
entering the moist environment of the tiny crevice hydrolyze, eliminating the
hydroxyl (OH-) ions thus dropping the PH so that the crevice becomes very acidic
as well as positively charged

4. Chlorine Migration Chlorine ions from the bulk sea water outside the crevice
migrate inside to balance the charge resulting from the depletion of the hydroxyl
ions during step 3 (Opposite Charges + & - attract)

5. Initiation Once the PH is low enough (very Acidic) and the Chlorine ion
concentration is high enough (very Salty) the chemical breakdown of the
protective film covering the stainless steel will begin. For stainless steels this
critical point will vary by the composition of the metal for example type 304 will
breakdown at a PH drop to 2.1 or less with a Chlorine concentration of 1.8 times
normal sea water while type  316L remains resistant  until the ph drops  down
further below 1.65 and the Chlorine concentration in the crevice rises to about
7.5 times normal sea water concentrations.

6. Propagation After the initiation process has passed the critical point for the
particular stainless steel in use the shielded crevice becomes anodic (acts like a
tiny anode) with the remaining bulk of the stainless steel acting as the cathode
and traditional galvanic corrosion is underway. In saline sea water environments
galvanic effects favor deep penetration once the initiation phase has started in
each individual crevice corrosion s

It's a well known fact that stainless steels are subject to stress corrosion cracking when in contact with a chloride environment. A few parts per million are sufficient to start the phenomenum; imagine then what 12.000 ppm will do.
You don't need codes nor standards, any textbook dealing with steels and/or corrosion will tell you that. I know three or four of them, unfortunately they're written in Portuguese language. Try Perry's Chemical Engineer's Handbook, published by McGraw Hill, there must be plenty of material there. 
99205 has given us a brilliant lesson on the matter.
Giovanni S. Crisi
Sao Paulo - Brazil