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Stein’s custom-engineered barrier seals can be used independently or mounted behind various dry gas seal designs. When mounted on the bearing side of a dry gas seal and buffered with inert gas or air, these seals will:

  • Act as a barrier to prevent the leakage of hazardous gasses from entering the bearing cavities.
  • Exclude oil from getting into the dry gas seal area if the compressor bearing is lubricated with oil.
  • In the event of a dry gas seal malfunction, the circumferential bather seal will contain the excessive loss of compressor gasses until the compressor is safely shut down.

Circumferential seals are field proven, with over 50 years of experience in aircraft gas turbine engines and industrial turbomachinery applications. These seals are readily available to meet the stringent and demanding requirements of today’s turbomachinery industry.

Our commitment to continuous product improvement and ongoing R&D programs has produced cost-effective, high-performance circumferential seals.

Independent gas barrier seals offer an economical price point for low-pressure applications of 200 PSIG (14bar). The added benefit to the Stein barrier seals is the working envelope and cartridge designs making installation a quick and failsafe exercise.


  • Very low buffer gas consumption – in some cases, a few tenths of an SCFM.
  • Prevention of hazardous gas and process leakage from entering bearing cavities
  • Exclusion of bearing oil from dry gas seal area
  • Provision for safe shutdown upon wear-out
  • Virtually unlimited shaft axial travel
  • Minimal seal cavity space required
  • Available in cartridge assemblies for easy installation and removal
  • Horizontally-split assemblies are available for applications where access to the end of the shaft is not possible
  • Bi-directional – no sensitivity to direction of rotation
  • Demonstrated performance over a wide range of operating conditions
  • Field-proven longevity – over five years of seal life at normal operating conditions


The overlapping joints of the seal segments are designed with a specified circumferential end gap. When the seal bore wears out after several years of regular operation or under abnormal operating conditions, the seal ring segments become archbound: the gap in the joints closes, and the bore contacting circumferential seal becomes a minimal-clearance bushing. Once the circumferential seal has worn into a bushing mode, seal leakage increases. However, no further wear or increase in leakage is noticeable. This feature provides the capability of continued safe operation until a shutdown can be performed, thereby preventing a possible catastrophic failure.


Split-type circumferential barrier seals are one of Stein’s specialty products. Split seals originally developed for steam and gas turbines can be readily adapted to centrifugal compressors. The split seals can be easily and quickly installed in seal cavities without significant tear-down of turbomachinery components.

Barrier seal with a stepped-diameter housing
Horizontally split barrier seal
Barrier seal with a flanged seal housing