49269

Resistance of SS 304 to ozone at 1.5 PPM [Kenya] 

July 7, 2008

Thank you

I am interested in manufacturing clarification tanks out of ss 304 since it is commercially available in my region

This tanks will be used in primary treatment of water injected with 1.5 ppm of ozone from ozone generator. the flow rate of the water will be 20 m3/h and the tanks are 3 pcs totaling to 30 m3.

My question is , whether this dosage of ozone will corrode the ss304, and if so within what period.

Can i reduce the dosage to say 1ppm if that will preserve the tanks. How about ss 308

thanking you and expecting some ideas

REGARDS

MADUNG WILFRED
TECHNICAL DIRECTOR - KENYA

I have applied ozone dosages up to 20 mg/l into 304SS tanks. They did not corrode. But we knew what was in the water.

If your water has high chlorides, or lots of iron, you may want to insist on 316L SS. I have no experience with 308.

I know of an ozone generator that was cooled with ozonated ground water (drawn from a fossilized redwood forest), the jacket had a weld seam on the bottom, and the ozone activated "chloride pitting" confined to the weld area. More pits near the water inlet, and fewer far away. Like tiny bullet holes right through the jacket. Make sure you get good welds, and put them away from high voltage!

If you only intend to apply 1 mg/L or less, you probably could use a polyethylene-lined poly-wound vessel. If you up the dose, you could simply plan on replacing the vessel periodically. High tolerance for other contaminants in the water, easy to ship, easy to replace. Just small, with "odd" closures.

David A. Smith
water treatment - Phoenix, AZ, USA

A well passivated stainless steel surface should be fine with ozone, in fact the oxidizing properties would only reinforce the protective chrome oxide layer. However David Smith is correct, chlorides will degrade the passive layer and cause problems, and external sources of iron may very well cause rust and/or rouge spots to develop.

Ray Kremer Stellar Solutions, Inc. Algonquin, IL, USA