CREVICE CORROSION FACTOR 1

[chtimi]

Our costumer want a pump with metallurgies which have:
A PREN sup 38 and a crevice corrosion factor sup 35.
I don't know what is the CF factor.
Could you help me?
Thank you for your answers.

 

[EdStainless]

There are ways to estimate Critical Crevice Corrosion Temperature from the chemistry. But they are inaccurate and only give you a starting point for lab testing.
The only way to find out your CCCT is to test actual samples.
I would suggest that you might want to recommend that you be allowed to use Critical Pitting Temperature instead. The test is much easier becuase it requires far less sample preperation.
I may have missunderstood your question.
Are you talking about a Critial Crevice Temperature???
There is no alloy with a PREN of 38 that will have a CCCT of 35C. To have that level of CCCT you will have a PREN well over 45. (depending on which PREN formula you are using).

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[mcguire]

EdStainless
Which factor for nitrogen do you use in the PREN equation?
16 or 30 or something else?

 

[EdStainless]

I use Cr+3*Mo+16*N, I find that it is more relalistic. After all this is just an estimate. In order to get real product close to this value you still must make it right.
The CPT and CCCT estimates using the equations in ASTM G48 are fairly accurate also.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm