Does the dairy and/or food industry (specifically but not limited to the USA)considers to replace their stainless steel SS 316 or SS 304 pipes after say 30 years or so? Could someone please share their experience or opinion. I have this question because I wanted to know if the cleaning in place procedures stand ineffective after say 30 years because the metal's surface roughness, hydrophobicity, corrosion resistance would change. If you have an idea about any beverage industry besides dairy or even meat industry, please let me know. It will be very helpful. Thank you in advance.
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1$\begingroup$ I’m voting to close this question because it is about industrial practices and metallurgy, which are not on-topic for this site. Please consult the tour, How to Ask, and other help center pages for more information. $\endgroup$– tyersomeMay 8, 2020 at 3:43
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$\begingroup$ I would appreciate if this question is still visible. I'm new to this website and all I'm interested in is the knowledge that some users are willing to contribute.I would like to defer and say that this question is not just industrial practices and metallurgy based but it also aims towards people contributing to the food industry. I see one useful response. $\endgroup$– grishmaMay 8, 2020 at 15:31
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Stainless does not "wear out" or deteriorate in general food service , so no replacement. There may be some unusual service that causes corrosion . If that occurs I expect a more corrosion resistant alloy replacement is quickly installed. Keep in mind if there is corrosion ,there are traces of Cr, Ni, Mo going into the food . That would bring lawsuits regardless of any harm. It is hard to imagine any surface texture change ;possible exception of raw foods with entrained sand which might cause polishing of the stainless.
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$\begingroup$ Thank you. I agree with the points you have mentioned, I was thinking if there is a general timeline for the SS 316 pipes, where we can say that after say 3 billion production cycles (or say after transferring 20000 liters of milk per hour for say 50 years) of service in the food processing plants, they start to corrode and needs to be replaced; as opposed to replacing them after say 5 years, where they are not showing any signs of possible mechanical failures or alterations in their roughness. I understand that there are no set guidelines. Your response is greatly appreciated. $\endgroup$– grishmaMay 8, 2020 at 15:36
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$\begingroup$ There is no deterioration: Infinite life ( as an engineer I cringe when I use that word). I am sure there are buried carbon steel pipelines that have been in service over 75 years ; much higher corrosion potential inside and outside than SS in food service. $\endgroup$ May 8, 2020 at 19:36
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$\begingroup$ Thank you once again for your response. In that case is there a specific timeline that the industry follows for inspecting the presence of corrosion inside of the pipe? That looks like a reasonable thing to do in this situation. Can you share your experience with any inspection technique used and its timeline followed by the food industry? $\endgroup$– grishmaMay 8, 2020 at 21:05
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$\begingroup$ In a refinery with carbon and low alloy steels metal loss is expected. So very detailed surveys are documented both for the refinery and various government agencies. Usually ultrasonic ; it is important that the UT tests be made at the exact same spot as there are some original variations in wall thickness. Today very accurate inexpensive UT units are available "off the shelf", Frequency of inspection is determined with experience , from a few month to a few years. For SS food piping , likely every 5 years will be enough. . $\endgroup$ May 9, 2020 at 2:08
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$\begingroup$ I expect there are organizations that have written requirements and/or guideline for examination.Likely they concentrate on organic contamination but may have NDE for equipment integrity. ASNT American Society for Nondestructive Testing might have something you can use. $\endgroup$ May 9, 2020 at 2:18