Full definition
Rings of pure or modified PTFE (filled with graphite, glass or bronze) in braided or molded form, used as shaft packing in pumps and valves. Universal chemical resistance (pH 0-14). Maximum temperature: 260 °C. Very low friction coefficient (0.05-0.1). Limitation: tendency to cold flow (creep) under sustained load, requiring periodic re-tightening of the gland. Reference standard: ASTM F1571.