31


Focus on Lubricant & Condition Monitoring - Analytical Instrumentation en/oil-gas/blog/varnish-in-oil.html


[4] ASTM D7843 Test Method for Measurement of Lubricant Generated Insoluble Color Bodies in In-Service Turbine Oils Using Membrane Patch Colorimetry. https://doi.org/10.1520/d7843-21


[5] Shy, P. (n.d.). Understanding varnish. Chevron Lubricants. https://www.chevronlubricants.com/en_us/home/learning/from- chevron/industrial-machinery/understanding-varnish.html


[6] Soluble and insoluble varnish – what’s the deal? - learn oil analysis. LEARN OIL ANALYSIS - Secrets of OCM from industry expert. (2022, July 6). https://learnoilanalysis.com/lube-oil-test- analysis-lab-lubrication-reliability-maintenance/soluble-and- insoluble-varnish-whats-the-deal/


[7] Fitch, J. (2021, May 17). Sludge and Varnish in turbine systems. Machinery Lubrication. https://www. machinerylubrication.com/Read/874/sludge-varnish-turbine


[8] CHOKELARB, W., ASSAWASAENGRAT, P., SITTON, A., SIRISITHICHOTE, T., & SRIPROM, P. (2022). Soluble and insoluble varnish test methods for trending varnish buildup in mineral turbine oil. Journal of the Japan Institute of Energy, 101(12), 242–250. https://doi.org/10.3775/jie.101.242


[9] Staff, E. E. (2020, January 21). Varnish kills quietly. Effi cient Plant. https://www.effi cientplantmag.com/2020/01/varnish-kills- quietly/


solution to this issue and will reduce soluble varnish levels in the system. Additionally, it was concluded that the phenolic antioxidant.


levels for this sample dropped to critical levels due to the presence of varnish. This observation implies that the oil has reached the varnish saturation point [8]. Results of this sample can be seen in Table 2: Oil Analysis for Plant #2 Turbine Oil


Sample Three was collected from Small Power Producers (SPPs) power plant, which are private or state enterprise that generates electricity either (a)


non-conventional sources such as wind, solar and mini-hydro energy, or fuels such as waste, residues, or biomass. This power plant experienced an overheating issue in the turbine system. As a result, insoluble black particles were suspended and produced. These particles are carbonized products caused by thermal degradation [8]. However, this was not necessarily varnish because these particles might have been caused by the process of coking, which is the heating of coal in the absence of oxygen to a temperature above 600 °C to drive off the volatile components of the raw coal, leaving a hard, strong, porous material of high carbon content called coke. Results of this sample tested via ASTM D7843 showed that there was a reading as high as 75.4, which is more than twice that of the limit of 30, of insoluble varnish. Carbonized results are not accurate, as the carbonized products infl uenced the result of this method. The modifi ed ASTM D7843 experienced better results, for it enabled the differentiation between IMPC and the coke, providing a better reading of the sample. The powerplant used off-line fi ltration to clean the black particles. This system reduced the amount of insoluble varnish. However, the soluble varnish levels remained the same. This led to the conclusion that the sample oil reached its saturation point and over time, insoluble varnish might stick out again on the surfaces [8].


Data regarding this sample can be seen in Table 3.


The end results of the study conclude that the synergistic effect of testing both soluble and insoluble MPC helps in giving more effective and accurate information that infl uences decisions for maintenance and upkeep. Also, this study gives insight into the root causes of varnish and the justifi cation behind the cause [5]. Furthermore, the appropriate varnish removal technology can also be applied depending on the results of both soluble and insoluble MPC. Therefore, soluble MPC is also another major consideration that the industry must investigate otherwise, it may lead to potential disasters.


Ultimately, varnish control monitoring should be a priority for all companies as the effects of both insoluble and soluble varnish can have detrimental effects on machinery. Furthermore, companies should ensure that their focus does not remain solely on insoluble MPC but also on soluble MPC. If not, the costs of maintenance may drastically increase as the soluble MPC can cause damage to entire lubrication systems, causing more need for maintenance.


Works Cited


[1] Hong, S.-H., & Jang, E. K. (2023, May 15). Varnish formation and removal in lubrication systems: A Review. MDPI. https://www. mdpi.com/1996-1944/16/10/3737


[2] EXXONMOBIL FUELS & LUBRICANTS. (2022, August 1). Using high performance lubricants to prevent gas turbine varnishing. IEN.EU - Industrial Engineering News Europe. https://www.ien.eu/ article/using-high-performance-lubricants-to-prevent-gas-turbine- varnishing/


[3] Understanding varnish contamination in rotating equipment – and how to solve it effectively. Pall. (n.d.). https://www.pall.com/


Authors Dr. Raj Shah is a Director at Koehler Instrument Company in New York, where he has worked for the last 28 years. He is an elected Fellow by his peers at IChemE, CMI, STLE, AIC, NLGI, INSTMC, Institute of Physics, The Energy Institute and The Royal Society of Chemistry. An ASTM Eagle award recipient, Dr. Shah recently coedited the bestseller, “Fuels and Lubricants handbook”, details of which are available at ASTM’s Long-Awaited Fuels and Lubricants Handbook 2nd Edition Now Available (https://bit.ly/3u2e6GY).He earned his doctorate in Chemical Engineering from The Pennsylvania State University and is a Fellow from The Chartered Management Institute, London. Dr. Shah is also a Chartered Scientist with the Science Council, a Chartered Petroleum Engineer with the Energy Institute and a Chartered Engineer with the Engineering council, UK. Dr. Shah was recently granted the honourifi c of “Eminent engineer” with Tau beta Pi, the largest engineering society in the USA. He is on the Advisory board of directors at Farmingdale university (Mechanical Technology) , Auburn Univ ( Tribology ), SUNY, Farmingdale, (Engineering Management) and State university of NY, Stony Brook ( Chemical engineering/ Material Science and engineering). An Adjunct Professor at the State University of New York, Stony Brook, in the Department of Material Science and Chemical engineering, Raj also has 600 publications and has been active in the energy industry for over 3 decades. More information on Raj can be found at https://bit.ly/3QvfaLX


Contact: rshah@koehlerinstrument.com


Elaine Hepley CLS, OMA has 15 years of experience with Condition Monitoring and Varnish Analysis with POLARIS Laboratories. Elaine specializes in varnish detection and prevention; she is always working to fi nd ways to be able to detect early warning signs of varnish formation as well as oil degradation. She works with customers worldwide to provide technical support and assist with varnish detection and mitigation. She is a member of the Board of Directors with STLE and is also Chair of the OMA and DEI Committee. Elaine is dedicated to help bring awareness of Condition Monitoring and Varnish Analysis worldwide.


Mr. Jeff Gao and Ms. Mrinaleni Das are part of a thriving internship program at Koehler Instrument company in Holtsville, and are students of Chemical Engineering at Stony Brook university, Long Island, NY where Dr. Shah is the current chair of the external advisory board of directors.


Author Contact Details Dr. Raj Shah, Koehler Instrument Company • Holtsvile, NY11742 USA • Email: rshah@koehlerinstrument.com • Web: www.koehlerinstrument.com


WWW.PETRO-ONLINE.COM


Elaine Hepley


Jeff Gao


Mrinaleni Das


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