Chloride stress corrosion cracking in stainless steel pressure cookers

As per ASM handbook vol 13, any SS with less then 30 % Ni is prone to chloride SCC. Is it possible in SS pressure cookers since chloride is present in the form of NaCl (common salt) and oxygen is also there. If so are we compromising home safety?
The quantity of chloride and oxygen are sufficient to cause corrssion as per the book's guidelines.
Will appreciate your help at jaisinghk@usa.net

 

[ralphsare]

scc refer to stress corrosion cracking. we've been hit with scc big time here in the petrochemical where i work. the service is ethylene oxide and the piping is 304 SS. cause of failure is scc due to a large dosage of diethyelebne chloride.
For scc to exist, threee condition must exist. high residual stress, hight temperature (above 100C) and the presence of chloride. 18-8 SS sereis is suceptioble if all the previous condition is present.

 

[mcguire]

SCC is a problem, especially with 304. Try either a ferritic or a duplex. In the case of the pressure cooker, make sure the material hardness isn't raised above 22Rc by forming or you lose resistance to SCC.
There's been a major movement from 304 and 316 to 2205 in piping to alleviate the SCC problem.

 

[rustbuster1]

Your query seems to be asking why pressure cookers used in the home do not experience CSCC. The most probable reasons are that the time at temperature is too short and that there are not residual stresses at high enough levels. The stresses induced from cooking at less than 15 psi (1 bar) also are very low. Pitting corrosion also does not occur when it theoretically could based on the conditions - primarily because of low times of exposure.

If you are building pressure cookers for another purpose and they will experience extended time at temperature, duplex SS is far more resistant to CSCC, as stated above but costs about the same as 304 or 316

Happy cooking!