Metal Bellow Mechanical Seals

Metal Bellow seals are ideal for high temperature applications and harsh chemical services where elastomers cannot be used effectively. This seal type incorporates metal bellows as a spring-loading mechanism to maintain face contact when the seal is not pressurized and eliminates traditional secondary sealing requirements.
In applications where the process temperature exceeds elastomer capabilities, metal bellows mechanical seals with graphite secondary seals are a good sealing option. Metal Bellows Single Seal is designed for high-temperature services typically found in chemical and petrochemical processes. Graphite secondary seals replace O-Rings to achieve the higher temperature requirements.
Advanced bellows design distributes pressure uniformly across the span of the bellows plate to reduce stress and minimize weld fatigue. Component design replaces most OEM seals.

Features of Metal Bellow Mechanical Seals

• For unstepped shafts
• Single seal
• Balanced
• Independent of direction of rotation
• Metal bellows rotating
• Asymmetric bellows form results in even stress distribution with benefits of greater strength and higher rate of flexibilty; seal is bi-rotational and inherently pressure balanced.
• Smooth profile is resistant to clogging and therefore ideal for slurries and fibrous liquids. Similarly, seal unit is easy to clean and sterilize in place.
• Unit construction ensures a simple-to-fit seal, with superior heat dissipation paths. Seal unit is reliable and does not wear the shaft.
• Graphite secondary seals for high-temperature performance
• Advanced bellows design for maximum cycle life
• Rotary bellows for enhanced performance in slurry and particulate services
• Hydraulically-balanced seal design
• Blister-resistant carbon
• Proven heat-treated AM 350 bellows construction
• Graphite secondary seals for high-temperature performance

Advantages of Metal Bellow Mechanical Seals

• For extreme temperature ranges
• No dynamically loaded O-Ring
• Self-cleaning effect
• Short installation length possible
• Pumping screw for highly viscous media available (dependent on direction of rotation).
• For unstepped shafts
• Single seal
• Balanced
• Independent of direction of rotation
• Metal bellows rotating
• Rotating bellows
• Roller bellows
• Recommended applications
• Process industry
• Oil and gas industry
• Refining technology
• Petrochemical industry
• Chemical industry
• Hot media
• Cold media
• Highly viscous media
• Pumps
• Special rotating equipment
  

Materials Combination

• Face: Carbon, SiC, TC
• Seat: Ceramic, SiC, TC
• O-rings: NBR, EPDM, VITON, Aflas, FEP, Kalrez, Chemraz, Grofoil etc.
• Spring: SS316, hastelloy C, AM350
• Metal parts: SS316, hastelloy C

Common malfunction of metal bellow mechanical seals

• At high temperature, the bellows are easier to be broken, also the bellows are broken under high pressure (such as the hot water pump).
• It is easy to occur coking and carbon deposition at the trough between the wave plates, which makes the bellows lose elasticity and cannot compensate, so it can not be used for coking, carbon deposition and crystallized precipitation pump.
• For external installation mechanical seals, the sealing surface can be pushed open when the pressure in the sealing cavity is more than 0.2MPa. This is because the elastic force of the bellows is small and can not withstand the high pressure of the medium. Therefore, it is not possible to use an external bellows mechanical seal when the pressure is high.
• Because the metal bellow type mechanical seal is a balanced structure, the effective diameter and load factor must be calculated in use. Otherwise, in the high-pressure propane and propane pump, the phenomenon of "spray leakage" is easy to occur.