Corrosion issues of anhydrous hydrogen fluoride
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I haven’t been designing equipment for a few months now, and suddenly I encountered a case where the medium used in the equipment contained anhydrous hydrogen fluoride. The corrosion allowance specified in the original drawings was 2, but I don’t think that’s sufficient; after all, the drawings are quite old. I believe the minimum corrosion allowance should be 3. Of course, there are other substances present as well, such as HCl, F141b, VDC, and high-boiling-point compounds. Just considering the corrosion caused by HCl alone, an allowance of 3 is necessary. So I think the value of 2 specified in the original drawings isn’t appropriate. What do you all think?
Then there’s an extra margin; two is a bit too little – it’s not very secure
It’s safer to use a corrosion margin of 3mm!
It’s not necessary; if corrosion occurs under abnormal conditions, adding one more won’t be of any use.