We know that inservice grease used in MOVs holds valuable data for failure prediction, reliability assessment, trending and root-cause analysis.  However, the same challenges to efficiently relubricating the stem nut have also created obstacles to obtaining this inservice grease for analysis.  The StemThiefTM, which was designed to make that relubriction practical and easy, also makes obtaining grease samples just easy when used in conjuction with the GreaseThief.

When new grease is pumped into the MOV via the StemThief discharged grease can be captured with a GreaseThief kit that includes a spatula for removing the newly purged grease from the stem nut.

Grease Thief
Grease Thief

The GreaseThief is then sent to the lab for analysis that can provide insight into type and amount of wear in the stem nut and stem. Contaminants and degradation of grease can also be assessed.

Use of the Grease Thief kits for sampling:

  • ASTM D7718 compliant sampling methodology and tools
  • Analysis per ASTM D7918 for inservice grease testing
  • Grease consistency changes and trending (oil separation, hardening, tunneling)
  • Hall-effect sensor for wear trending and comparison
  • FTIR for mixing, contamination, oxidation, and fingerprinting
  • Spectral analysis for additives, wear metals, and contaminants
  • RULER testing for oxidation life evaluation
  • Advanced testing including Analytical Ferrography and Micro-Patch for wear particle analysis; Rheometer testing for lubricating properties; Grease colorimetry for appearance changes, contaminants

StemThiefTM– US Patent 9,360,130