K-MRC Multi-Ring Circumferential Gas Seal

The Kaydon Ring & Seal multi-ring circumferential seal (K-MRC) is a versatile, innovative and economical gas seal solution for low pressure (<100 psi, 6bar) sealing applications where potential for process contamination or space restrictions won’t allow for traditional end-face dry gas seals.

The K-MRC is a standalone, dual purpose main shaft seal that prevents process leakage from escaping through the equipment bearings while also preventing bearing oil migration into the process. The K-MRC utilizes segmented carbon seal rings that act as a wedge between a stationary housing and a hard-coated rotating shaft surface. The seals are buffered with gas at pressure slightly higher than the regions being separated. The seal rings are preloaded by a combination of radial garter springs and axial compression springs. Contact forces are minimized by pressure dams in both the side faces and bore of each ring, which in turn minimize wear, and allows the seal rings to freely follow the movement of the shaft. The rings are designed with an initial overlapping clearance between segment ends. As the bore of the seals wear, the clearance decreases until the segment ends butt together. At this point, the ring is arch bound and continues to function as a clearance seal, providing the same reliable performance.

Kaydon circumferential seals are extremely durable and do not have a catastrophic failure mode. They are able to experience solid and liquid contamination with only minor changes in leakage performance.

Each K-MRC is packaged into a cartridge assembly and configured to meet user requirements for control of gas leakage to process, vent, and atmosphere. Standard offerings include single buffer, single buffer with safety vent, and dual buffer arrangements, but are not limited to these choices.

Features and Benefits

  • No catastrophic failure mode
  • Tolerates liquid and solid contamination without failure
  • Tolerates radial misalignment and vibration without failure
  • No limit for axial movement
  • Can be configured to meet user requirements for process compatibility, environmental safety, and simplicity of operation
  • Bi-directional operation
  • Compact, self-contained cartridge
  • No large rotating mass, avoiding rotor dynamic issues
  • Comparable leakage rates to dry gas face seals
  • Expected run time of 40,000hrs+ prior to archbound condition
  • Compact size allows for retrofit of most labyrinth seals
  • Specialty materials available for low-dewpoint gases
  • Split-housing configurations available
  • Seal repair kits available to rebuild seal on site


  • Refinery
    • Wet gas, coker, alkylation, flare gas recovery, crude unit compressor shaft seals
  • Natural gas processing plants
    • Propane refrigeration, Ethylene refrigeration, Propylene refrigeration compressor shaft seals
  • LNG boil-off and refrigeration compressor shaft seals
  • Petrochemical
    • Propane refrigeration, styrene off-gas, ammonia refrigeration, acetylene

Why Kaydon Ring & Seal?

Each K-MRC is built using the knowledge from decades of experience applying circumferential seals in turbomachinery. Kaydon’s K-MRC seal has proven to be more reliable than conventional face seals in dirty gas applications. The K-MRC has also solved numerous environmental issues as a cost effective retrofit for labyrinth educator seal designs. Kaydon’s engineering team has the experience and expertise to design a sealing package that will fit the needs of the equipment, process, and environment of any user.

Kaydon has the broadest range of compressor seal types available in the industry. Our goal is to supply you with the best solution for your circumstances, whether it is repair, upgrade or replacement of your existing seal.