Small Changes, System-Wide Impact

The butterfly effect is a much cited phenomena where a small change in a system can have a significant effect on the overall state of the system. In a similar way, relatively inexpensive elastomers can contribute disproportionately to the cost of running a biopharmaceutical manufacturing operation.

Simon Chalk

Elastomers and plastics play a vital role in the operation of a bioprocessing plant, forming gaskets, "o"-rings, and diaphragms deep within the structure of the processing equipment. Their function is to prevent leaks and to separate fluids that should never come into contact. These rubber-like materials are useful because they are flexible, elastic, and can ensure tight seals between hard metal surfaces.

Over time, and with the harsh temperature, chemical, and pressure cycles that they are subjected to, these materials can become brittle and deformed, and can fail. They need to be exchanged well before there is a risk of failure, the consequence of which could be a contaminated product or a dangerous breach of a system. Many biopharmaceutical plants have a large installed base of valves for example, maybe 5000 or more. Each one needs to be maintained correctly to avoid problems.

Although the cost of failure is high, the cost of exchange is also high. It is estimated that up to 50% of maintenance activity is consumed by soft parts changeout. Add this to the plant downtime and there is a clear target for cost-saving scrutiny. So, what scope is there for improvement? Can current practice be challenged?

The currently accepted and common approach for elastomer changeout is temporal based (i.e., there is a fixed frequency—perhaps annually or biannually—for scheduled maintenance to replace the component).

Although this approach is acceptable, it does not take into account the conditions that the elastomer has been subjected to. In cases where the component has been lightly used, it may be exchanged even though continued use would be perfectly acceptable. At the opposite end of the spectrum, severe use could risk failure of the elastomer before its fixed time period had been reached.

Several engineering leaders in biopharmaceutical operations are questioning this methodology. They are being driven by the unrelenting quest for operational excellence and more effective ways of working. As well as cost savings, there is the realization that their talented engineers could be better deployed working on high value-adding technical projects rather than routine maintenance.

One such engineer got into the habit of collecting discarded soft parts from changeovers and visually inspecting them. His curiosity and dislike of waste led him to ask whether there was a better way to systemize the replacement of these items so that they were used for longer but without risking failure in operation. His involvement in a cross-industry benchmarking group and discussions with his like-minded peers showed that better practices did exist. This knowledge spurred him to implement a new way of working, leading to significant cost savings.

By following simple scientific and risk-based approaches, some companies are now extending the life of elastomers by three, four, or five times. The previous time-based maintenance cycles have been replaced with condition-based cycles whereby the wear and tear on the components are carefully analyzed and graded so that the life of the components can be accurately predicted. The factors affecting wear and tear, such as the numbers of cleaning cycles, temperatures and chemicals used, are recorded to provide a rational basis for analysis and later, measurement.

Operational data showing variations from predicted results are further sources of insight, shedding light on unknown factors that lead to variability reduction and greater confidence levels predicting component condition. One such root-cause analysis revealed that correct or incorrect assembly of diaphragm valves can contribute significantly to performance of the soft parts. Correct lubrication of fixing bolts and accurate torque setting for instance was discovered to be a contributory factor in the life of diaphragms.

The question of conformance to specification was another target-rich area with lack of clear standards and nonexistent or inconsistent industry wide test methods. Elastomer suppliers have a long way to go to meet the exacting needs of the biopharmaceutical environment. Performance has historically been the customer problem. Lack of control around changes being a particular concern where the supply chain of suppliers and suppliers suppliers is not rigorously managed.

The same industry best-practice sharing group is now advancing the cause by proposing customer centric standards covering generic-test sequences, visual inspection criteria, and better change control. With agreement by the various stakeholders, these standards will be written into globally recognized codes that set the scene for better industry compliance.

In this example of a drive for best practice in biopharmaceutical manufacturing, one can trace a direct line from one engineer examining the disassembled parts of a butterfly valve to a new industry system of standards and quality performance levels previously not experienced.

Simon Chalk is director of the BioPhorum Operations Group, simon@biophorum.com