While pusher seals have an intermediate flexible element acting between a seal face and adjoining surface, metal bellows seals use an assembly of edge-welded metal leaflets as the flexible element. High alloy metal bellows provide spring loading for face contact, create a pressure barrier for optimum seal performance and absorb axial shaft movement while retaining the seal face. Without a dynamic gasket, metal bellows seals are applied in a range of applications otherwise untenable with a dynamic gasket pusher seal design:
• High temperature applications up to 427°C (800°F)
• Large axial travel requirements especially at high temperatures
• Corrosive chemicals that degrade elastomers and other dynamic gaskets
Rotating bellows have a beneficial self-cleaning action through centrifugal effects that resist clogging of process solids in the bellows. Solids and wear debris may accumulate on the atmospheric side of the seal faces without hanging up the dynamic contact of the seal faces. Stationary bellows applied to high temperature hydrocarbons are often fitted with a hot steam quench to avoid coking and potentially compromising seal integrity.
Flowserve has proven experience applying metal bellows seals to general and critical services, from hazardous chemicals to refinery processing including full compliance to PI 682 requirements. Configured as single, dual unpressurized or dual pressurized, metal bellows seals provide a high degree of reliability and long term performance
