In cryogenic applications rolling bearings very often operate in the harshest environment, characterized by temperature far below 0°C and poor lubrication, because the lubrication with oil and grease becomes a challenge at temperatures close to absolute zero (0 K). Small wonder then that conventional steel bearings provide short service life and are the main root cause not only for planned maintenance cycles but also premature equipment failures and unplanned machinery shutdowns.
CEROBEAR‘s cryogenic bearing specification features races either made from AISI 440C or High-Nitrogen-Steel (e.g. Cronidur® 30, XD15NW). High-Nitrogen-Steel provides excellent resistance against corrosion, wear and fatigue, particularly in combination with silicon nitride ceramic (Si3N4) rolling elements. Si3N4 rolling bodies, balls or rollers are available, prevent adhesive wear by their inert behavior and significantly reduce abrasive wear and bearing friction. Thus CEROBEAR hybrid bearings are especially qualified for media lubrication operation. While polyamide (PA)- and PEEK-cages tend to get brittle at ultra low temperature, CEROBEAR‘s LNG pump bearings feature retainers made from fluoropolymer compound material, which remains ductile, provides self-lubrication and hence operates perfectly at temperatures down to -269°C.
CEROBEAR does not only pay careful attention to all bearing materials, but also adapts the inner and outer bearing geometry to the cryogenic environment. CEROBEAR‘s bearing engineers consider the different thermal properties of all materials, including shaft and housing, during the design phase, so that our bearings provide an optimized radial play or contact angle as well as perfect fits to the mating parts at operating temperature. This leads to maximized load capacity and superior bearing life. CEROBEAR offers customized bearing dimensions and tolerances on request, even in small quantities.
CEROBEAR has a long tradition in supplying hybrid ceramic bearings to the cryogenic industry, for Liquefied Gas Pumps (LNG, LN2, LO2, LH2, LHe2) but also Turbo Expanders, Liquid Turbines and Chillers.
CEROBEAR bearings for cryogenic applications are designed to fulfil the requests of improving productivity and cutting maintenance costs. Skilled CEROBEAR bearing engineers are happy to consult customers to lift their cryogenic rotating equipment to the next performance level.
In Liquefied Gas Pumps (LNG, LN2, LO2, LH2, LHe2) rolling bearings are designed directly into the flow path of the process media. The advantage of this design principle is, that the construction becomes less complex. Rotary seals, which separate and protect the bearings from the process media, and which are typical wear parts, are no longer necessary. The trade-off is, that the bearings must be capable to cope with the various liquefied gases, which act as their only lubrication. Special advanced bearing materials are required to enable bearings for media lubrication by cryogenic liquids and CEROBEAR’s long time proven bearing specification for cryogenic temperature perfectly reflects these requirements.
CEROBEAR LNG pump bearings are available not only as deep groove ball bearings but also as angular contact ball bearings and Four-Point contact (QJ) bearings. This leads to increased load capacity, particularly in thrust direction and hence superior bearing life.