Tanks for the Memories

Single-use systems have greatly improved and simplified common manufacturing issues.
Mar 01, 2009

James M. Robinson
The benefits of single-use manufacturing systems have been widely touted by their suppliers and by early adopters in the pharmaceutical industry. Their implementation has been shown to have many advantages: reduced initial capital investment, accelerated project execution through the use of off-the-shelf systems versus highly customized skids with a challenging support infrastructure, reduced labor for preparing equipment for re-use, and energy savings from reduced cleaning and sterilization of fixed equipment. The trade-offs are also well-documented: potential supply-chain security issues with lack of redundancy of supply and managing supplier change control, the ability to manage large volumes and high flowrates, waste management for plastics that are difficult to recycle and, of course, the fear of change itself. In this assessment of a potential technology change, we often overlook some of the underlying challenges of the fixed equipment, perhaps because as we have accepted them as the price of doing business in a current good manufacturing practices (cGMP) environment.

For a plant manager, the elimination of a number of typical facility issues may be a good incentive to implement single-use systems. In the two years I have worked with disposables, I've learned that there are new challenges with single-use manufacturing systems, but there are also a few things I do not worry about anymore.

For example, there is a long list of preventative maintenance items that need to be managed routinely (and sometimes in an emergency basis) with stainless-steel based facilities, including replacement of diaphragm valves, mechanical seals, and pipe gaskets. We cannot forget the associated qualification and validation of repairs that are non-routine and often unplanned.

Stainless steel cannot be entirely eliminated in the production plant. Even with single-use systems for manufacturing, you will likely still need a stainless steel water for injection (WFI) system. This pure water source is corrosive and will deteriorate the piping (and welds) over time. The systems are periodically purged with acid to remove the corrosion and are re-inspected to confirm weld integrity on a regular basis. Although problems with WFI cannot be eliminated with the use of single-use systems, the associated issues can be isolated to your WFI and clean steam systems; your product path can be single-use tubing. The elimination of fixed equipment allows you to shrink your WFI use for equipment cleaning, reduce water sampling points, and eliminate much of your WFI distribution systems, which will lead to a simpler facility.

The elimination of long runs of stainless process piping also reduces product hold-up in the equipment, thereby improving product recovery. A bag of product and the connecting lines between processes can be drained completely because they are easily manipulated by the operator at the end of a process step. The headaches of designing, confirming, and maintaining pipe slope through the equipment lifecycle, which is key to cleaning and sterilization performance for fixed equipment, can now become a distant memory.

In considering single-use systems, you may face the natural resistance to change and fear of the unknown. But just as personal computers, PDAs, and other new equipment of the last few decades have changed (and hopefully improved) the way we live and work, there is a whole new world of single-use manufacturing technology that is worth exploring. Someday, you may wonder how you lived without it.

James M. Robinson is vice president, technical and quality operations, Novavax, Inc., Rockville, MD, 240.268.2019,