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Autoclave Periodic Revalidation Failure

Hello. I’m hoping someone could help provide some guidance and/or recommendation for an issue we recently encountered during a periodic revalidation of an autoclave load.

We had 2 loads (Loads 1 and 2), and per our procedure, periodic revalidation requires 1 production cycle (TC’s only) and 1 validation cycle (TC’s with BI’s), with an acceptable temperature range 121.1 - 124.1 C. After completing all the runs, Load 2 had one location during the validation cycle reaching 124.47C, which exceed the acceptable range. All other locations including the TC placed adjacent to the drain probe were within range. Pressure was also within range at all locations. Post calibration verification of the TC’s was good. The load consisted of 5 bags of metal clamps in a Tyvek bags sealed. The TC is placed inside each bag 2" above the metal parts. The autoclave controlling probe (drain) and an independent monitoring probe (adjacent to drain probe) were also verified to be calibrated.

Due to this failure, we did some investigation runs, as follow:

  1. Investigation Run #1: Not sure if this is logical, but someone suggested the TC tip may have touched the metal surface and resulted in a faulty temp, and recommended putting blue bioshield wrap around each tip to prevent contact with the metal surfaces. We did a run using this setup and all locations with bioshields exceed the acceptable range, with temperature as high as 124.88. Any idea why this could have happened?

  2. Investigation Run #2: We performed an empty chamber cycle with just TC’s place at approximately the same locations as where they would be with the load. All TC locations were within the acceptable range.

  3. Investigation Run #3: We performed a run with the load and TC’s again, normal setup. All TC passed, except the TC adjacent to the drain probe was unable to reach the temperature range, with temperature no higher than 116C. All TC’s met the post calibration verification. The drain probe and monitoring probe are within the acceptable range. Any idea why this could have a happened.

We have since stopped performing any additional test/investigation runs.

Thanks in advance for any help, suggestion, or tips.