Change in SIP leads to no Re-Qualification?

We had qualified the SIP cycle of a particular process system. Upon start-up of the process verification a protion of piping segment was deemed inefficient. This portion of piping was modified, so that the length remained the same but the diameter increased from 3/4" to 1".

We strongly feel that this does not alter the validated cycle, and are trying to determine an educated defense to this hypothesis.

Here is what we have thus far:

  • the increase in surface area with respect to the entire system is negligible (but we have not defined “negligible”)

  • the change was for process improvement, since we are increasing the dimaeter of the pipe the pressure in that protion of line shall increase and the stem flow should decrease (Bernoulli’s principle), thus the residence time of steam sterilizing that portion of piping shall lead to a higher theoretical yield in Lethality associated with it.

Not to sure if we can do this, can anyone shed some light?

SIPCIP systems can be quite critical especially where the steam is used at low pressures.
You really have not given enough detail to be decisive about this. You have not given pressures, and of course this is the major parameter. There is a lot of heat in steam at 3 bar, however steam at 0.5 bar will often condense out, and leave you with nothing, and this pressure range is often use in SIPCIP systems.

With low pressure everything becomes critical, the flow, volume and pipe surface area are all critical. You have increased the volume of the pipes by circa 77% and the surface area by circa 32%, so the length could become a critical factor.

In this form of sterilising you are reliant on the condition of the steam, to set the duration of the effective cycle. You have not mentioned the length of the pipe in question, however unless the steam pressures are high and or the pipes length is very short, I would definitely verify the sterilising cycles.

Regulatory inspectors world wide always target everything to do with cleaning and sterilising. They will expect to see your calculations documented (no matter how simplistic).

Alex Kennedy