NaOCl & ClO2

[sk10009]

Hi

I'd like to know the corrosion rates of the stainless steel(304)pipes used in 3% NaOCl(Sodium Hypochlorite) and
8% Clo2(Chlorine Dioxide) service.

Thanks in advance

 

[gr2vessels]

The Outokumpu Corrosion Handbook Ed. 9th is listing severe pitting and corrosion rates of over 1.0 mm/year for similar concentrations at 20 deg C. Higher temperature increases the rates considerably...The 904L seems to be more resistant, but pitting is still likely at 20 dec C and high corrosion / SCC /pitting at boiling point.
cheers,
gr2vessels

 

[strider6]

Selection of stainless steels for handling sodium hypochlorite (NaOCl)

The hypochlorite ion (OCl-) is aggressive to stainless steels, acting in a similar way to wet chlorine gas, and like the chloride ion (Cl-), is a dangerous pitting corrosion hazard.
Pitting or crevice corrosion can occur on most stainless steel grades in a 5% solution at ambient temperatures.
There is an additional risk of stress corrosion cracking (SCC) at higher temperatures.
Stainless steels should not be considered suitable for storage or transport tank applications with concentrated (15%) hypochlorite solutions or bleaches (5%).

http://www.bssa.org.uk/topics.php?article=35

http://www.outokumpu.com/applications/corrosion/search_head.asp?id=s

http://www.corrosionist.com/isocorrosion_curves.htm

http://www.outokumpu.com/applications/corrosion/search_head.asp?id=c

s.



Metal Corrosion