corrosion allowance for stainless steel?
corrosion allowance for stainless steel?
(OP)
Is there any specification for corrosion allowance for stainless steel? I think we don't need to give stainless steel corrosion allowance. Am I right?
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corrosion allowance for stainless steel?
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RE: corrosion allowance for stainless steel?
RE: corrosion allowance for stainless steel?
RE: corrosion allowance for stainless steel?
I doubt that there is any environment that took 12 years to pit stainless. My guess is that it worked fine for 11.75 years and then there was a process upset or chemistry change and the system failed in three months.
If you are in a chemically reducing environment and may see general corrosion, then yes a CA can be used.
In general, you select a stainless or Ni alloy grade with near zero corrosion in you situation and then you do not use a CA.
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Rust never sleeps
Neither should your protection
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RE: corrosion allowance for stainless steel?
The equipment I am talking about is the shell of a stainless steel reboiler on a condensate stabiliser on an oil field. Pitting corrosion was found upon an internal inspection after 7 years of operation (this was the first internal inspection). The pits were 2 mm deep. The postulated mechanism is that corrosive species including mineral salts concentrate themselves in the reboiler liquid circuit (the heavy ends in the circuit essentially circulate in a closed loop) and that these species cause the pitting. This is only a postulate still without proof. Based on the 2 mm pitting in 7 years, the expected lifetime was projected. Is this approach wrong?
Do you know of any method to detect active pitting non-intrusively? The reboiler surface is too hot for manual UT (187°C). Have acoustic emmision methods been used for such applications?
RE: corrosion allowance for stainless steel?
In these cases, most users are applying some corrosion allowance for CRA, such as 1/16~1/8” (or 0.05~0.10mm) CA.
Thomas Eun
RE: corrosion allowance for stainless steel?
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: corrosion allowance for stainless steel?
Jeffrey C
RE: corrosion allowance for stainless steel?
Corrosion allowances for carbon steels are given by the project based on service conditions and expectable uniform corrosion rates.
For stainless steel designers follow the same criteria.
Some specify 0 mm, others 1mm and others 1.6mm.
See the thread338-159732 with some opinions on this subject
Regards
Luis