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Chloride attack on 304 L SS.....damage extent ?

We have found high Chloride concentration (~ 0.5 ppm) as compared to our normal limit of (~ 0.1 ppm)in demineralized water used at our plant.

This water passes through a series of heat exchangers to the reactor where the temperature is about 283 deg C.

We have been seing this high Chloride concentration from last 48 hours.........although we have succeeded to reduce the chloride back to normal level, but the extent of damage is still questionable ?

all the metallergy of heat exchangers and reactor is 304 L SS..........Plus the solution being handled is acidic in nature (para toluic acid)..............

Can anyone please comment on severity of the case and extent of damage that could have occurred because of this ?

Zia Naqvi, Process Engineer
acid plant - Karachi, Pakistan
August 10, 2009

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August 12, 2009

Chloride attack on 304 is a function of time, temp and concentration.
Sea water is 30 -35 parts per thousand, so at .5 PPM, you are far below that. your two days, if that is all, is very probably not enough time to cause a real problem.
You temperature will certainly accelerate the attack.
I would just keep a close watch on it and not worry until you see an attack that will first show up on the welds.

James Watts
- Navarre, Florida