I've been installing and bringing online (5) 30 bbl FV and (2) 30 bbl BBT, all brand new from China. I began the CIP of the final BBT on Monday and ran into some real issues. All the other tanks cleaned up great and are in use. The manufacturer swears they are passivated so I used a 2% caustic (sodium hydroxide) at 140-150 F for 1 hour followed by 2% acid (phosphoric) at 100 F for 1 hour. I've had trouble finding Nitric to do a full "re" passivation but I will follow up with that soon (even if we have to import).
My problem is with the last BBT. After the caustic clean a lot of weld burns showed up including around jackets, dimples, etc, that really worry me. Lots of dimple spots are burnt, some much worse than others. Also there is this very cloudy film over the entire tank interior, especially prevalent on the polished band areas. It looks kinda like fish scales, not a solid layer of film but variegated, sorry for the shitty description. This really has me perplexed. Also there's one big area that looks like a birthmark for lack of better words where it looks like any kind of passivated layer has been stripped right off. None of this was readily apparent upon initial visual inspection of the tank. It all really showed up strongly after the caustic.
I've tried to CIP again, I've tried to scrub certain areas by hand with caustic, PBW, acid, and nothing seems to have any effect. None of the other tanks had any of these problems, no weld burns, no film, nothing.
Anyone seen this type of thing before? Ideas?
My problem is with the last BBT. After the caustic clean a lot of weld burns showed up including around jackets, dimples, etc, that really worry me. Lots of dimple spots are burnt, some much worse than others. Also there is this very cloudy film over the entire tank interior, especially prevalent on the polished band areas. It looks kinda like fish scales, not a solid layer of film but variegated, sorry for the shitty description. This really has me perplexed. Also there's one big area that looks like a birthmark for lack of better words where it looks like any kind of passivated layer has been stripped right off. None of this was readily apparent upon initial visual inspection of the tank. It all really showed up strongly after the caustic.
I've tried to CIP again, I've tried to scrub certain areas by hand with caustic, PBW, acid, and nothing seems to have any effect. None of the other tanks had any of these problems, no weld burns, no film, nothing.
Anyone seen this type of thing before? Ideas?
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