Case 01: Seal contamination - Lube oil migration from bearing into dry gas seal

Typical machines affected

All cen­tri­fu­gal com­pres­sors


Indications

  • 21 % of dry gas seal failures are caused by lube oil migration *
  • Short operating life of dry gas seal
  • Dry gas seal failures
  • Lube oil at secondary vent casing drain
  • Oil in the secondary vent chamber
  • Lube oil contamination of dry gas seal
  • Fluctuating pressure in primary vent

Causes

  • The installed separation seal is not securely separating the bearing oil from the dry gas seal
  • During stand-still lube oil is likely to migrate into the gap between dry gas seal face and seat (bearing side)
  • During start-up, this can lead to sticking seal faces resulting in increased break-away torque of the secondary dry gas seal
  • Finally, there is a risk of damage of torque transmission mechanism and/or broken seal faces
  • A combination of oil and dirt can lead to hang-ups

EagleBurgmann solution

CobaSeal – coaxial static lift-off type se­pa­ra­ti­on seal

Results & benefits

Reduced costs:
  • No more unplanned compressor shut-downs due to lube oil migration
  • Up to 90 % reduction on nitrogen can save more than 50,000 € per compressor and year compared with labyrinths
Increased safety:
  • No process gas leakage to bearings in case of seal failure

Further information:

 

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* Source: SWRI & GMRC, Analysis of historical dry gas seal failures - Data in natural gas compressors.

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