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Varnish & Deposit Prevention and Removal (VPR)

To become certified, an individual must meet the following requirements:

  • Education and/or Experience - Candidates must hold either MLA I or MLT I certifications OR have a minimum of 1 year of experience with industrial lubricants and the knowledge base of the Varnish and Deposit Prevention and Removal Body of Knowledge.
  • Examination - Each candidate must successfully pass a written, 25-question, multiple-choice examination that evaluates the candidate's knowledge of the topic. Candidates have 45 minutes to complete the closed-book examination. A score of 70% is required to pass the examination and achieve certification.
The VPR Body of Knowledge is an outline of concepts that one should have in order to pass the exam.

References from which exam questions were derived can be found in the Body of Knowledge below:

I. Problems Associated with Varnish and Deposits (20%)
   A. Flow restriction, starvation and filter plugging
   B. Restricted movement, stiction and silt lock
   C. Increased friction and effect on efficiency
   D. Impaired heat transfer
   E. Bearing operation
   F. Need to flush
   G. Accelerated lubricant degradation
   H. Lubricant performance properties

II. Factors Affecting Breakdown (28%)
   A. Effect of base fluid on breakdown and deposit formation:
       1. Groups I – IV more prone to oxidation.
a. Very non-polar – lower relative saturation point.
       2. Group V prone to hydrolysis (esters), thermal degradation (PAGs) and oxidation (limited discussion).
a. Relatively polar – higher relative saturation point.
       3. Additive Selection.
a. Amine antioxidants, phenol antioxidants and antiwear additives.
b. Additive synergy and anti-synergy.
   B. Contamination:
       1. Catalysis by acids or wear metals (cupric surfaces, babbitt etc.).
       2. Impact of water.
       3. Process chemicals (H2S, process gases, H2, He etc.).
       4. Intermixing of oils (poor maintenance, leakage etc.).
   C. Temperature:
       1. Arrhenius law.
       2. High temperature excursions (microdieseling, electrostatic discharge etc.).
       3. Oxidation of base-stock and additives.
       4. Additive drop out.
       5. Oil base-stock phase separation.

III. Proactive Methods that can be used to Minimize Oil Breakdown (16%)
   A. Keep temperature down during service and storage.
   B. Keep oil clean and dry.
   C. Use thermally/oxidatively-robust formulations.
   D. Use oils with high impurity-holding capacity (IHC).
   E. Nitrogen blanketing (creates potential for entrained gas/nitration).
   F. Antioxidant additives.
       1. Spent additives can actually contribute to deposits.
   G. Controlling aeration and foam.
   H. Controlling electrostatic discharge
   I. Maintaining optimum fluid health

IV. Methods/Technologies that can be used to Remove Oil Breakdown Products and/or Prevent Deposits (36%)
   A. Particulate filtration (pros and cons)
   B. Electrostatic precipitation and agglomeration. (pros and cons)
   C. Centrifugal separation (pros and cons)
   D. Ion exchange resins (pros and cons)
   E. Oil soluble PAGs (pros and cons)
   F. Chemical flush (pros and cons)
   G. Detergents and solvents (pros and cons)
   H. Solubility Enhancers (pros and cons)
   I. Spark-free/antistatic filters



Domain of Knowledge

  • Fuchs, G. H., Diamond, H., “Oxidation Characteristics of Lubricating Oils,” Ind. Eng. Chem., 1942, 34, 927.
  • Fitch, J.C. “Using Oil Analysis to Control Varnish and Sludge,” Machinery Lubrication magazine,
  • Sasaki, A. “Hydraulic Valve Problems caused by Oil Oxidation Products,” Hydraulic Failure Analysis: Fluids, Components, and System Effects, ASTM STP 1339, G. E. Totten, D. K. Wills and D. Feldmann, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2001.
  • Yamaguchi, T., Kawaura, S., Honda, T., Ueda, T., Iwai, Y., Sasaki, A, “Investigation of Oil Contamination by Colorimetric Analysis,”, STLE 2001, San Francisco, California, USA.
  • Johnson, M., Livingstone, G. “Identifying varnish and oxidation precursors in lubricant sumps” Tribology & Lubrication Technology, Society of Tribologists and Lubrication Engineers, April 2001, Pages 22-27.
  • A. Yano, S. Watanabe, Y. Miyazaki, MHI Ltd, Y. Yamamoto, Kyushu University – “Study on Sludge Formation during the Oxidation Process of Turbine oils” – Tribology Transactions, 47, 111-122, 2004, Presented at the STLE/ASME Tribology Conference, October 2003, Florida.
  • Livingstone, G., Thompson, B., Okazaki, M. “Physical, Performance and Chemical Changes in Turbine Oils from Oxidation” Journal of ASTM International, Vol. 4, No. 1, Paper ID JAI100465, ASTM Symposium on Oxidation and Testing of Turbine Oils on 5–8 December 2005.
  • Fitch, J. and Gebarin, S., "Review of Degradation Mechanisms Leading to Sludge and Varnish in Modern Turbine Oil Formulations," Journal of ASTM International, Vol. 3, No. 8, 2006, pp. 1-10.
  • Fitch, J.C. “What is your Oil’s Impurity Holding Capacity,” Machinery Lubrication Magazine. 
  • Atherton, B., “Discovering the Root Cause of Varnish Formation,” Machinery Lubrication, March 2007. 
  • Moehle, W., Gatto, V., Wooton, D., Livingstone, G., “Practical Approaches to Controlling Sludge and Varnish in Turbine Oils”, Proceedings for Lubrication Excellence, May 2007.
  • Gato, V., Moehle, W., Schneller, E.R, Cobb, T.W., - “The Relationship Between Oxidation and Antioxidant Depletion in Turbine Oil Formulations with Group II, III and IV Base Stocks,” Journal of Synthetic Lubrication, April/June 2007, Volume 24, Issue 2, Pages 75–124.
  • Aguilar, M., Mazzamaro, G., Rasberger, M., “Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants,” Chemistry and Technology of Lubricants, Mortier, R. M., Fox, M. F., Orszulik, S. T. Eds., Springer, New York, 2010.
  • Hannon, J., “Vanquish Varnish to Improve Gas-Turbine Reliability,” 2011 Outage Handbook – Lubricating/Control Oil, Combined Cycle Journal, 2011.
  • Livingstone, G., Ameye, J. “Selecting the Best Varnish Mitigation Technology based on the Application” 2011 Oildoc Conference. Rosenheim, Germany. February 2011.
  • Dufresne, P., Hobbs, M. G., MacInnis, G. “Lubricant Varnishing and Mitigation Strategies,” Combined Cycle Journal, Fourth Quarter, 2013, 34.
  • Johnson, B., Livingstone, G., Wooton, D., “Root Cause Determination of an Unusual Chemical Deposit on a Key Oil Wetted Component” Proceedings for OilDoc 2013, Rosenheim, Germany.
  • Quick, L, Ameye, A., Livingstone, G., “Turbine Oils”, Encyclopedia of Lubricants and Lubrication, Springer Publishing, 2014, pp 2183-2194.
  • Hobbs, M. G., Dufresne, P., "Varnish Mitigation: Relative Effectiveness of Non-Deposit-Forming Next Generation Lubricants vs. the Use of Varnish-Removal Filters with their Conventional Counterparts," as presented at LUBMAT 2016, Bilbao, Spain.
  • Hobbs, M. G., Dufresne, P., "Why Varnish Removal Fails: The Soluble-Insoluble Varnish Equilibrium," as presented at OilDoc 2017, Rosenheim, Germany.
  • Behyan, S., Hobbs, M. G., Kennehpohl, P., Dufresne, P., “Mechanisms of mineral oil-based lubricant degradation and aggregation: towards an understanding of varnish formation,” STLE 2017 Annual Meeting and Exhibition, Atlanta, Georgia, USA.
  • Hobbs, M. G., Dufresne, P., “What EHC Fluid Analysis Misses: Improved Phosphate Ester Maintenance Through Non-Routine Testing,” as presented at STLE 2017 Annual Meeting and Exhibition, Atlanta, Georgia, USA.
  • Wooton, D., Livingstone, G., "Analysis, Characterization and Sources of Varnish," Proceedings for Reliability World 2007, USA
  • Wooton, D., Livingstone, G., "Lubricant Deposit Characterization," Oildoc Conference. Rosenheim, Germany. January 2013.

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