ClSCC in a hospital steam sterilizer with tap water 1

[etsen]

Can Chloride stress corrosion cracking (ClSCC) occur in a hospital steam sterilizer with tap water. The steam sterilizer is made of 304 grade stanless steel. Thanks in advance.

Operating temperature is 126 ºC
Operating pressure is 1.4 MPa

 

[metengr]

I would be more concerned with intergranular stress corrosion cracking at weld regions in this environment with 304 versus 304L.

 

[Metalguy]

Do you know the C amount in the 304, and how thick is the part?

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[unclesyd]

Very definate yes, I have seen two of such apparatus taken out of service by CISCC. The 316 SS ones are a little better but are still subject to CISCC, witnessed by the cracking of food preparation steam kettles.
Your problem can be quite hard to work around. The best option is to work with the equipment vendors making sure you give them the expected chemistry of your feed water. I've seen some of this type apparatus that had copper alloys or glass in the steam generator with the remaining parts being 316SS. I'm quite sure with some of the latest alloys there is a better solution.

 

[strider6]

at 126°C if the chloride content is higher enough it's likely for SS 304. the threshold temperature for CSCC is approx 60°C for SS. you should analize the water and see what is the chloride concentration.


S

Corrosion & Rust Prevention Control

 

[EdStainless]

With the stress that these see heating and cooling SCC is going to be assured.
I have failed parts with less than 100ppm Cl.

You need to look at a higher alloy stainless.
316 is really no different from 304 in terms of SCC.
My first suggestion would be 2205.
As a duplex it has good SCC resistance.
The other tip, make the parts as thin as you can. If these are coils then cut the wall thickness to the absolute minimum. You would rather have a little distortion than allow the stresses to build until they force something to fail.
I have also see SEA-CURE superferritic stainless used for coils in these units. It wont crack but it costs more and is more difficult to work with.

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