ROC Carbon Type MB carbon/graphite compressor seal rings are typically double-face seals that provide a critical seal to prevent fugitive emissions. The seals are installed over the shaft and are sandwiched between the rotating seal ring and stationary sleeve . The hardness of the carbon and the lubricating properties of the graphite combine to provide a long-life seal; typical service life is one to two years, depending on the application. Type MB compressor seal rings have an outer metal ring that reinforces the carbon/graphite material. The ring prevents damage to the carbon/graphite during handling and installation and preserves seal geometry in high-speed service.

ROC metal-backed seals are available in standard replacement styles and in custom configurations designed to solve specific operating problems.

Precision Manufacturing
Seal geometry is extremely important for proper service life. The two seal faces must be identical so that the seal will rotate at one-half speed relative to the rotating seal ring, subjecting both seal faces to the same wear rate. If the sides are not identical, one seal face will be subjected to an excessive wear rate, shortening seal life. The roundness of the seal assembly is also important, because ovality causes eccentric seal rotation, leading to vibration and premature seal failure.

ROC Carbon's manufacturing technology produces seal rings with high-precision seal surfaces that are lapped and polished for optimum sealing performance. Precise machining also produces perfectly round seals, and careful shrink fitting and stress relieving ensure that the seals retain their roundness in storage and service.

Shrink Fitting and Stress Relieving
Material selection and close machining tolerances are critical to maintaining optimum stress distribution in the seal assembly. To prevent stress buildups that can shorten service life, ROC Carbon follows a proprietary manufacturing procedure that involves high-precision shrink fitting of the metal ring over the carbon/graphite, as well as full stress relieving. For added assurance of optimum geometry, larger ROC Carbon Type MB seal rings are shipped with a precision-machined carbon/graphite plug that helps prevent seal damage during storage and handling. The plug is easily removed at installation.

Materials
The carbon/graphite material is chosen to be compatible with the fluids being handled and with the mating seal surfaces. Typical carbon grades used are in our A Series, which have Shore Scleroscope hardnesses ranging from 50 to 90. For operating temperatures above 500° F, high-temperature-treated or metal-impregnated carbon/graphite is used. Metal for the reinforcing ring is selected according to the metal's coefficient of thermal expansion, which must be compatible with that of the carbon/graphite in order to prevent unwanted stress buildups during thermal transients. The metal also has the appropriate corrosion resistance for the intended service.

To Order
For original equipment replacement parts, please furnish the OEM part number or the specifications of the machine. For custom-designed parts, we manufacture according to your drawings, or, if you wish, we will design a seal for you. For fastest response, call our toll-free number:

1-800-324-7743