Metal-Backed Seal Rings
We Offer Only High-Quality MB Seal Rings
ROC Carbon’s Metal-Backed Seal Rings
ROC Carbon Type MB carbon/graphite compressor seal rings are typically double-face seals that provide critical sealing for high-speed compressors and turbines. The seals are installed over the shaft, sandwiched either between a rotating or a stationary face. The hardness of carbon and lubricating properties of graphite combine to deliver long service. Type MB compressor seal rings have an outer metal ring to reinforce the carbon/graphite and preserve seal geometry at high speeds.
ROC metal-backed seals are available in both standard replacement styles and in custom configurations to solve specific operating problems.
Seal geometry is extremely important to service life. The two seal faces must be accurately machined so that the seal rotates at a one-half speed relative to the rotating seal ring, subjecting both seal faces to the same wear rate. If not identical, one seal face will wear excessively, shortening seal life.
ROC seal surfaces are lapped and polished to as flat as 1 helium light band (less than 12 millionths of an inch) for optimum sealing performance. Precise machining also produces perfectly round seals, preventing vibration that causes premature seal failure.
Shrink Fitting and Stress Relieving
To prevent stress buildup that can shorten seal life, ROC Carbon follows a proprietary procedure that involves shrink fitting the metal ring over the carbon/graphite, followed by a full stress relieving process. To further assure optimum geometry, larger ROC Carbon Type MB seal rings are shipped with a carbon/graphite plug that helps prevent seal damage during storage and handling. The plug is removed prior to installation.
Carbon/graphite grades are chosen to be compatible with the fluids being handled and with the mating seal surfaces. Typical carbon grades used are carbon/graphite with resin impregnation, and Shore Scleroscope hardnesses that range from 77 to 100. For operating temperatures above 500° F, metal-impregnated carbon/graphite is used. The metal also has the appropriate corrosion resistance for the intended service.
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