18-20 April 2023
To keep a pharmaceutical water system in a qualified condition, a suitable maintenance strategy with appropriate maintenance intervals is required. This is demanded by GMP and also makes sense from an operational point of view. Maintenance intervals are already determined in the design phase based on the criticality of the individual components and are specified and controlled in the subsequent commissioning and qualification steps.
System suppliers are an important source. They usually give good recommendations for maintenance content and intervals. For the duration of the manufacturer's warranty, it is customary to adhere to these specifications. However, it is also possible to make specifications based on one's own operational experience, especially with existing systems. Maintenance contents and cycles are first discussed during the DQ (Design Qualification) or FAT (Factory Acceptance Test) and defined during the commissioning phase.
The manufacturer's specifications are incorporated into the operational systems, adapted if necessary and with fixed responsibilities. Companies installing a water system for the first time or working with new / inexperienced personnel should take special care during this step. Otherwise, there is a risk to run into the "classic" problem: a system stop because, for example, salt was forgotten to be added to the softener. In any case, an initial operation and maintenance plan must be available at the end of the SAT (Site Acceptance Test) with the transfer of the responsibility to the pharmaceutical company. Subsequent changes in responsibilities or maintenance intervals can be made via the change control procedure or can be - in the case of non-critical operations - regulated by SOP. In any case, such changes must be carefully documented. In this context, it should also be checked whether and how alarms and their acknowledgement are documented. In modern facilities, this is done automatically together with the audit trail. It is advisable to check alarms that have occurred at least once a year, ideally together with the trending of the recorded data and the review of the logbook entries, which is mandatory anyway.
What should be the guidelines for maintenance intervals to start with? What are empirical values for the service life of the individual components?
Rubber seals and diaphragms in valves (often EPDM) are replaced in most companies every 12 months as a preventive measure. However, there are also companies that use high-quality fluorine-stabilised plastics and have thus been able to extend the cycle to five years or longer. The resin in the softener should be replaced every 3-5 years. This can be seen as a preventive measure against biofilm formation. For reverse osmosis membranes, but also for ultrafiltration and EDI modules, a preventive replacement every 3-5 years should also be provided. The service life of these modules depends strongly on the design and also on the frequency of thermal sanitisation. The specified value applies to a system in which reverse osmosis, EDI and ultrafiltration are hot sanitised approx. every three months. The more often hot sanitisation takes place there, the more frequently the replacement of the components mentioned must take place. The frequency of system start-ups and shutdowns as well as the quality of the feed water also play a major role and may, for example, necessitate more frequent module or filter changes.
The UV lamps used for ozone destruction are usually replaced after 8000 operating hours or after 12 months.
The numerical values mentioned are to be understood as benchmark values; in individual cases, longer or shorter intervals may be sensible or necessary.