Maintaining Integrity: Effects of SIP Sterilization on PTFE Valve Diaphragms

In large, complex SIP systems, multiple steam inlets can be used to avoid high temperature/ pressure steam injection or lengthy overkill SIP cycles. Older manual SIP systems can be upgraded and computer integrated for SIP automation and efficient temperature mapping. In addition, computer-based thermal analysis tools can be used to minimize extreme hot and cold spots when designing process piping systems. SIP systems should also be designed and operated to avoid creating superheated steam conditions. Steam should be injected gradually to keep it in a saturated state. Steam pressure should not be reduced to below 50% or exceed reduction of 2:1 of absolute supply pressure [12,14]. Steam pressure can be reduced in stages or pressure control valves relocated away from PTFE diaphragms [13].

End users should establish PTFE diaphragm inspection and replacement schedules based on SIP cycle parameters and their system design. PTFE diaphragms exposed to more severe SIP conditions, with fast cooling and numerous flex cycles, will require more frequent inspection and replacement. Finally, PTFE diaphragms installed close to steam injection may require replacement before those located closer to the cold spot.

REFERENCES
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About the Authors
Steve Pitolaj is a principal engineer with Garlock Sealing Technologies. He has over 25 years of experience in process development, product design and R&D. His work has focused on innovative processing technologies and products for the company’s line of PTFE gaskets and diaphragms. He holds number of patents for PTFE processes and products used in semi-conductor, chemical process industries (CPI), food and diary, pharmaceutical and bioprocessing industries. He is an active participant of American Society of Mechanical Engineers Bioprocessing Equipment (ASME-BPE). He can be reached at 800-448-6688 or steve.pitolaj@garlock.com.

Jim Drago, P.E., has worked in sealing technology for over 25 years, most recently for Garlock Sealing Technologies. His work has focused on applications, product engineering, engineering management and global business development. He has authored numerous articles and presented papers at technical symposia on sealing to meet fugitive emissions regulations and sealing product selection. He also has contributed to the industry standards of the American Petroleum Institute (API), American Society of Mechanical Engineers (ASME), Electric Power Research Institute (EPRI), and Society of Tribologists and Lubrication Engineers (STLE). Jim is a former member of ASME-BPE Standard committees on sealing and polymers. He can be reached at 800-448-6688 or jim.drago@garlock.com.