Mechanical seals categorized as pusher seals represent an extremely popular and successful style of sealing. A pusher seal relies on the sealability of a flexible element such as an O-ring or U-cup between the seal face and adjoining surface. The assembly of seal faces, spring(s) and flexible element working together is the foundation for proper seal performance. Flowserve’s diverse portfolio is well suited to address numerous application and industry requirements.
Pusher seal designs run the gamut from simple, low duty devices to the highest duty, extremely sophisticated engineered solutions. Besides general services, pusher seals are often selected for light hydrocarbons, high pressures and high speed applications because of their inherently greater strength and damping characteristics compared to bellows seals.
Modern flexible secondary sealing materials allow an ever expanding application of pusher seals. Availability of materials by size, chemical resistance, hardness, and shape is unprecedented and few services exist where O-rings in particular cannot be used.
The most common spring arrangement utilizes multiple small diameter coil springs of a high metallurgy evenly distributed around the seal face. Large section single coil springs are used where long axial travel is required or to prevent clogging. Locating the springs outside the process fluid is another viable solution to avoid clogging with product debris. In axially-compact designs, wave springs can be used.
Besides the versatility of pusher seals and expansive field experience, another compelling attribute is their repairability after years of operating. If the time comes for a repair, usher seals can generally be repaired quickly and returned to service.
