Steam Sterilization Cycle Leads to Seal Breakdown

Ron Cook, Seal Business Unit Manager
The Hope Group

From time to time I will be reporting on some of the solutions that Parker and The Hope Group provide to their customers through the application of advanced o-ring and sealing products and systems. As those within the various Life Science industries become better aware of the critical role rubber seals play in system performance and patient health, material requirements grow increasingly strict.

The so-called “FDA grade materials” are no longer sufficient in applications where the seal or fluids that contact the seal come in contact with the patient. There are several medical-industry requirements for elastomers in common use today:

1. USP Class VI testing is typically required for medical device applications that directly contact the patient. The extraction portion of the test is typically done at 50°C (121°F) since this exceeds the normal exposure temperature of most medical devices.
2. In small molecule pharmaceutical manufacturing and some medical devices, the USP Class VI extraction test is done at 121°C (250°F) to simulate a higher temperature application.
3. For biopharmaceutical manufacturing, the seals must also comply with USP <87> cytotoxicity requirements to ensure that the seals themselves will not kill a cell culture.

Seal Breakdown Resolved
In a recent case, Parker was faced with a problem presented by a pharmaceutical manufacturing facility. The customer was experiencing seal breakdown after only a few steam sterilization cycles. The EPDM seals were breaking down, adhering to the stainless steel gland components, and shedding rubber particles into the process stream.

After review and analysis of the problem, Parker recommended compound E3609-70 for this application. In addition to meeting the USP Class VI biocompatibility requirements at multiple extraction test temperatures, this compound also meets the cytotoxicity requirements of USP <87> and has outstanding resistance to steam, cleaning sterilization agents, and process fluids.

The E3609-70 material was successfully tested to 500 steam sterilization cycles with no leakage, no significant degradation of the material, and no sticking of the rubber material to the mating stainless steel components. O-rings and sanitary gaskets could be easily removed by hand with no damage. In this case, an improved design of the O-ring glands and sanitary gaskets eliminated the shedding of particles into the process stream.

At The Hope Group, we continue to work at solving problems for our customers every day. With Parker as a partner, we are confident that we can solve your o-ring or sealing problem too.