Thermal cycling during the sterilization process affects the sanitary fittings used in both utility and bioprocessing equipment
and systems. The problems with the seal in sanitary fittings discussed here are a result of a lack of containment of the gasket
and of control of the amount of compressive load that can be applied to the gasket during initial make-up and subsequent retightening,
combined with thermal cycling.
Thermal cycling is necessary for steam sterilization and cannot be eliminated. The tests conducted showed that uncontrolled
extrusion of the seal material increases with thermal cycling. The results of comparing the two styles of sealing methods
confirm that proper containment of the seal material and limiting and controlling the compressive loads on the gaskets can
help improve the cleaning, draining, and sterilizing of bioprocessing systems, as well as reduce the amount of fluid holdup
in such systems.
In sanitary fittings, better containment of the seal material and better control of the loads placed on the seal material
to make a leak-tight seal can result in improved ability to withstand the rigors of thermal cycling.
Michael Bridge is a marketing manager, biopharm, at Swagelok Company, Solon, OH, 440.349.5934, firstname.lastname@example.org
1. The American Society of Mechanical Engineers. ASME BPE 2002 Bioprocessing Equipment. New York; 2002 Jul. Available from:
2. Lyderson K, D'Elia A, Nelson L, editors. Bioprocess engineering: systems, equipment and facilities. New York: John Wiley
& Sons, Inc; 1994.
3. Cole G. Pharmaceutical production facilities—design and applications. London: Taylor & Francis Ltd; 1998.
4. Bailey JE, Ollis F. Biochemical engineering fundamentals. 2nd ed. New York: McGraw-Hill, Inc; 1986.
5. Seesdorf D, Simko D, Fisher R. Advanced sanitary fitting technology improves bioprocessing systems operations. INTERPHEX;
New York; Mar 1999.
6. Simko DM. Reliable valve and fitting seals ensure fluid containment and control in bioprocessing systems and equipment.
INTERPHEX; Philadelphia; Mar 2001.