Nearly every end consumer is familiar with the phenomenon of oil varnish and oxidation. Varnish removal filters, routine oil changes and overhauls do not offer a solution to this problem. Tanis Engineering can show you that the cause often lies with oil quality. Why does one type of oil form a lot of varnish deposits, whereas others do not? Tanis Engineering advises on the use of the right oil type with which your installation can perform optimally, making varnish and oil oxidation things of the past.

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Oxidation/ degradation

A crucial installation such as a gas or steam turbine needs constant, clean and dry oil for the right lubrication of everything ranging from bearings and the gearbox to the control hydraulics. Yet, it is often the case that the oil is (extremely) contaminated, despite the standard filters being replaced on time. How is this possible?


Oil ages as it is impacted by oxygen, metal, temperature, water and contamination. Here, a chemical reaction occurs in the oil, namely oxidation. These oxidation products then precipitate on metal surfaces and cause a brown deposit, also known as varnish. Varnish formation does not only cause the oil to oxidise even faster but it also accumulates on the walls of the tank and settles in the plumbing of the entire system, in the pumps and valves, and causes the existing filters to be clogged. This results in increased bearing temperatures and vibrations, deteriorating temperature regulation, poorly functioning pumps and valves, and having to replace the filters and even the oil more frequently. In extreme cases, this can even lead to unplanned downtime of machines, resulting in large production losses.