Initially used as a high-performing substitute for metallic linings, engineered polymers now provide increased bearing capacity and reliability for a wide variety of rotating equipment.
Polymer-lined and solid polymer components can serve as direct replacements for babbitt components or be incorporated into new designs to extend operating limits.
Thinner Hydrodynamic Films
Surface properties and the mechanical strength of engineered polymers allow bearings to operate with thinner films than traditional babbitt bearing materials, providing:
Higher Temperature Capability
Polymer materials have higher operating temperature capabilities – up to 250°C (482°F) – and retain their mechanical properties at higher temperatures than babbitt, allowing exceptional performance at elevated temperatures.
Operation with Challenging Lubricants
Advanced materials are compatible with even the most challenging lubricants and process fluids, including mineral/synthetic oils, water/seawater, water-glycol, freon, toluene, amine, crude oil, hydrocarbon condensates, liquid O2, liquid CO2, methane, propane, butane, and hexane.
Engineered polymers are resistant to most chemicals, including hydrogen sulfide and ammonia. This prevents bearing damage associated with chemical attack by the working fluid.
Polymers, in a similar way to babbitt, will embed dirt that enters the fluid film, preventing damage to the journal or collar.
The high electrical resistance of polymers is utilized in motor and generator applications to prevent damaging currents from passing through the bearing and housing to ground. This characteristic eliminates the need for a separate insulating layer.
Reduction of Start-up Torque
Polymer bearing materials have a lower coefficient of friction than babbitt and can be used to reduce torque and wear at start-up, eliminating the need for hydrostatic lift systems in some applications.
Subsea Pumps and Motors
Polymer-lined thrust and journal bearings, widely used in multi-phase booster pumps and water injection pumps, operate on very thin hydrodynamic films to meet the demand for high load capacity and long life.
Polymer-lined tilt pad thrust and journal bearings can replace babbitt bearings to withstand high temperatures resulting from heat soak. This high-temperature capability provides additional safety in the event the back-up lubrication system fails or can even eliminate the need for a back-up system, saving on both weight and cost.
Electric Submersible Pumps (ESPs)
Polymer-lined tilt pad thrust bearings are the standard for ESP operating temperatures up to 200°C (392°F) and loads up to 8 MPa (1160 psi). They are used in the motor to account for thermal expansion and in the seal/protector section to withstand the pump load. The high temperature and load capabilities of the polymer lining are complemented by the Hidrax™ tilt pad design’s tolerance for misalignment. As an additional benefit in the motor, the bearings provide electrical insulation.
Polymer bearings can use process fluids as the lubricant, requiring fewer seals in a pump and eliminating the need for a separate oil lubrication system. Solid polymer bearings provide a solution for load capacities up to 10 MPa (1500 psi) in clean water and have been used successfully in reverse osmosis pumps, boiler feed pumps and mine-dewatering pumps.
Thrust bearings with polymer surfaces support high pump loads in water-filled motors and are lubricated by the water cooling the motor.
Using polymer bearings with water lubrication in compressors eliminates oil contamination of the compressed product and simplifies the sealing components.
Organic Rankine Cycle (ORC) Turbines
ORC turbines use solvents such as toluene and hexane as both the working fluid and the lubricant for the bearings. Polymer journal and thrust bearings can sustain the thin films associated with these low-viscosity fluids. The sealing and the flow path of the lubricant are key design considerations for successful operation.