[Chris Nannemann]

Amir,
Sorry for the confusion. The ACC inlet header, not heater… I mean the point at which the steam enters the ACC tube bundles.

Sounds like your steam pH is kept in a good range. We also operate AVT with ammonia only, and have found keeping the steam pH above 9.8 minimizes the 2 pt FAC in the STG exhaust duct and ACC inlet duct.

We also had the same issue that Chris Karch discussed with the hogger isolation valve.

Good luck sir,
Chris

[Chris Nannemann]

Hi Amir,
Have you performed an inspection of the inlet header? Were you able to spray helium at the top of the tube bundles, right next to the inlet header?
We have experienced leaks at our tube inlets. They are sometimes hard to find with helium leak testing if you cannot spray all the way at the top, or if it is windy, etc.

Also, what chemistry program are you running, and what in what steam pH range do you operate?

I ask this because we found that running too low of steam pH leads to excessive FAC in the STG exhaust header and the ACC inlet header. This was causing a lot of leaks and we had trouble maintaining vacuum for a long time.

Regards,
Chris

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