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How to remove the chlorine ions on stainless steels surface
Q. Our company makes petrochemical process equipment in Korea.
Now, we have several pieces of stainless steel equipment like 304, 304L & 316L.
Our client requests us to use de-mineralized water that the chlorine content is under 2 ppm during a pressure test to prevent any corrosion due to chlorine ions.
However, we don't have any facility to make the de-mineralized water; and, the water volume is very big.
Is there any way to remove the chlorine ions on the stainless steel face after the pressure test with general water?
- Changwon, Kyeongnam, Korea
A. Hi S.M. I think the question you are asking is not quite the best one. Rather than talking yourself into working around the specification, the better question might be something like "how can I economically provide the required water of 2 ppm chlorine?" :-)
I don't know whether the chlorine exposure can cause permanent damage to the stainless steel or not, but I don't think we can just arbitrarily rule out that possibility, and assume that it's okay to use chlorine contaminated water for the test as long as we later rinse it off.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
First of two simultaneous responses -- 2007
A. I would look into getting a reasonable sized reverse osmosis unit. A good pre filter, then a granulated carbon filter followed by a lower micron filter than your first filter will remove a large amount of chlorine, but NOT chloride. Recycle your water thru the RO unit into a storage tank that is plastic.James Watts
- Navarre, Florida
Second of two simultaneous responses -- 2007
A. Usually 2 ppm of chlorine does not cause enough of a problem to worry about. If it is chlorIDE, it is more of a problem.
Ted is correct, in that it is not too hard to make water that is less than 2 ppm of chlorine. What quantity are you talking about? There are not too many chlorides that are insoluble in that low a concentration, so you probably need to go to a RO or DI process. You could rent a DI system probably.
Stellar Solutions, Inc.
September 23, 2013
Q. WE ARE CLEANING OUTSIDE OF SEMICONDUCTOR MANUFACTURING EQUIPMENT THAT IS CONTAMINATED BY CHLORINE.
PLEASE LET ME KNOW THE BEST WAY TO REMOVE CHLORINE ON THE SURFACE OF EQUIPMENT.
- Shanghai, China
September 25, 2013
A. Please clarify if your problem is chlorine or chlorides. Removal of chlorine is usually accomplished with activated carbon or then addition of sulfites. Chloride removal is usually by ion exchange or reverse osmosis.
For nearly complete chlorine removal, up to 10 minutes of contact time with activated carbon is needed. If chloramines are present, even longer contact time may be needed. Sulfite addition can be controlled by an ORP controller, or if the chlorine concentration is relatively constant, by a simple, flow proportional dosing rate and a test kit to monitor it.
consultant - Cleveland Heights, Ohio
October 8, 2013
A. If this is just a stainless steel outer casing that has rusted due to proximity to chloride-heavy vapors or fluids, it should be cleaned and repassivated. This kind of chloride exposure can be mitigated with regular rinses of fresh water and frequent passivation treatments.
Stellar Solutions, Inc.