Varnish Mitigation & Removal

Varnish Mitigation and Removal

Companies often have unexpected downtimes due to varnish.  As oil is heated and cooled under normal operations, oxidation in lubricants and additives creates organic by-products that form varnish. These soft, sticky, polar insoluble particles floating in oil buildup on metal surfaces and eventually cause sticking valves and other mechanical issues.

Varnish is most often found in areas of low flow and cool temperatures (tanks and reservoirs) and hot surfaces where oxidation is accelerated. Buildup will need to removed system-wide to prevent further issues, as old varnish dissolves from these reservoirs of buildup and gets re-distributed throughout the system every time oil is heated.

We offer a variety of industrial varnish removal services to remove buildup, including:

  • Ion-Exchange Adsorption Systems
  • Sweetening
  • Varnish Mitigation Flushing
  • Chemical cleaning

If you are looking for an experienced varnish removal partner or chemical cleaning services, please don’t hesitate to reach out to one of our certified technicians to discuss your project today.


Varnish Adsorption Equipment


Provided a combined service consisting of varnish mitigation and High Velocity Oil Flushing (HVOF) on the methane, charge gas and refrigerant compressors. See all precommission & reliability services


Provided a combined service consisting of varnish mitigation and High Velocity Oil Flushing (HVOF) on the coker gas compressor. See what we offer in terms of commissioning oil and gas by viewing our precommission & reliability services


Husky Lima OH – New Hydro Plant- The RIG team performed chemical cleaning on the reformer, air blowing of the process lines and continuous steam blows of the header and users.

All oils are susceptible to varnish because oxidation occurs in all systems. Membrane Patch Colorimetry (MPC) varnish potential testing is the industry gold standard to test oil for varnish. It is recommended you have MPC testing incorporated into your lubricant analysis to monitor varnish levels.

There are four technologies that remove insoluble varnish precursors from oil:

  • Depth Media Filters
  • Balance Charge Agglomeration, or BCA
  • Charge Bonding (ICB)
  • Electrostatic filtration

Our team of certified plant technicians can test your oil or perform pre-cursor removal services. We also offer embedded technician programs for those that don’t have the in-house maintenance capabilities or can help you perform regular testing and system maintenance as needed.

In recent years, innovations in varnish removal have created new alternative cleaning processes, including:

  1. Electrostatic
  2. Balanced charge agglomeration
  3. Depth media filtration
  4. Ion charge bonding (ICB)
  5. Electrophysical separation process technologies (ESP)

Most of these technologies are great for slowing or stopping new varnish deposits and removing soluble varnish. But they are not as proven at removing deposited varnish. When deposit varnish deposit levels rise you may need to perform full varnish mitigation flush. Below is a step by step overview of what the Industrial Varnish Mitigation Flush Procedure is:

  • Analysis: Using UC or MPC rating, we take samples of your oil and determine the varnish levels and verify varnish is the issue. Once you decide to move forward with varnish removal, phase one cleaning begins.
  • Phase one: System Cleaner is added at 5-10% to the current lubricant (or carrying lubricant, based on analysis) and run with system pumps in normal flow path for 72-hours. At the end of 72-hours, while the oil is hot, the system is drained including reservoirs, low point drains, filter vessels, coolers and even feed headers. The reservoir is entered and a cursory cleaning of any heavy drop out and residual oil is removed.
  • Phase two: Filters are then replaced and the system is charged with a base oil to the lowest operating level. The oil is then circulated for a 12-hour period. At the end of the 12-hour period, phase one is repeated. The reservoir is cleaned to meet client’s cleanliness specifications.
  • Phase three: A final filter change occurs in both the system and side stream filtration. The final fill oil is filter filled into the reservoir to meet OEM ISO Code requirements. Once full, the system pumps are started while side stream filtration takes place to verify ISO Cleanliness.
  • Testing: It is recommended that the system gets thorough additional testing to see if a VAS (Varnish Absorption System) is required – a system that continually cleans varnish due to high varnish levels.

To have your oil tested or get a quote for varnish removal services, please contact us: 1-800-770-4510

What is varnish?

Oil varnish is a thin, hard, lustrous, oil-insoluble deposit that starts out as a soluble, then deposits onto metal surfaces as it oxidizes, becoming insoluble and creating harmful buildup.

What causes varnish to form?

From the moment your oil is put into use, heating and cooling of your lubrication will start the oxidization process and increasingly form varnish in a solution. Once the varnish buildup reaches a saturation point, the varnish will escape solutions and form harmful deposits—it is only a matter of time

How do I prevent varnish buildup?

It is impossible to prevent varnish. All oils are susceptible to varnish because oxidation occurs in all systems. Prediction and early recognition is the key. Membrane Patch Colorimetry (MPC) varnish potential testing is the industry gold standard to test oil for varnish. It is recommended you have MPC testing conducted monthly to monitor varnish levels. You can remove varnish precursors on a regular basis, or use continuous varnish absorption systems to prevent major buildup.

What is MPC testing and how does MPC testing work?

Membrane patch colorimetry (MPC) varnish potential testing is an analytical test to determine the propensity for a lubricant to form varnish deposits. MPC testing uses a 2 step process, filtration and color analysis. Varnish material is not very soluble in the oil/solvent mixture and tends to color the patch. By measuring the hue, a general characterization is made about the level of varnish in the system.

How do you remove varnish?

Two methods are tried and true for getting rid of varnish from surfaces: heat and chemistry. Some common methods are: Electrostatic Separation, Absorption Systems, Ion-Exchange Adsorption Systems, Sweetening, Anti-Oxidant Replenishment, and High Velocity Oil Flush (HVOF). Varnish Mitigation Flushing with System Cleaner, Ion-Exchange Adsorption, and Chemical Cleaning are RIG’s most common approach to removing system varnish.

What is a varnish adsorption system?

Attached in an offline or kidney looped manner, varnish adsorption systems remove oxidation by-products and prevents varnish formation during the cool down. The adsorption resin media is commonly used in conjunction with micro-glass media filter.  With these filters, it is possible to combine particulate and varnish removal in one system.

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