Field Services

Hot Oil Cleaning

Stop Oxidation in Its Tracks with Hot Oil Cleaning

Extend transformer life by removing oxidation decay products and preventing irreversible damage to paper insulation.

Why Transformers Need Hot Oil Cleaning

Oxidation is a silent enemy of transformer insulation. Over time, heat, moisture, and oxygen combine to create acids and other harmful byproducts that attack and weaken paper insulation. Left unchecked, these oxidation decay products accelerate aging and cause permanent damage that cannot be reversed.

Once paper insulation life is lost, it cannot be restored. Early intervention is the only way to preserve what's left and extend your transformer's reliable operating life.

Key warning signs your transformer may need hot oil cleaning:

  • Rising acid levels in oil analysis
  • Declining dielectric strength
  • Increased power factor values
  • Evidence of sludge formation
  • Elevated operating temperatures
  • Transformer approaching 20–25 years of service

Our Hot Oil Cleaning Process

Our proprietary hot oil cleaning process goes beyond standard filtration. We recirculate heated oil through your transformer using specialized recyclable filter media that captures and removes oxidation decay products from both the oil and the solid insulation. This halts the aging process and extends transformer life for years.

Proprietary recyclable filter media

Go beyond standard filtration with specialized recyclable media that leaves zero waste at your site.

Cleans both oil and paper insulation

Halts the aging process and extends transformer life for years.

Energized or de-energized service

Flexible service scheduling to minimize downtime.

Expert execution

Performed by trained technicians with proper instrumentation and quality test equipment.

How Oil Cleaning Works

01

Assessment

Oil analysis confirms oxidation levels and cleaning requirements.

02

Circulation

Heated oil circulates through proprietary recyclable filtration media, removing decay products.

03

Monitoring

Continuous testing ensures thorough cleaning of oil and paper insulation.

04

Verification

Final oil analysis confirms successful removal of contaminants.

Learn More About Our Capabilities

What Is Hot Oil Cleaning?

Bob Rasor, Director of Transformer Services at SDMyers, explains how hot oil cleaning works, the benefits associated with the process, and the long-term effects of using the method to increase transformer reliability.

See Hot Oil Cleaning In Action

Ever wondered what goes on inside the transformer as the oil is being cleaned? This timelapse shows the Hot Oil Cleaning process up close.

SDMyers Transformer Maintenance

Your transformer is the heart of your operation. Keep it healthy and extend its life with hot oil cleaning and routine maintenance from the experts at SDMyers.

Why Partner with the Experts

Proven track record.

60+ years of successful transformer life extension and maintenance expertise.

Expert technicians.

Trained professionals with proper instrumentation and quality equipment.

Proprietary process.

Unique recyclable filter media that cleans both oil and insulation.

Comprehensive testing.

Before, during, and after service to ensure thorough cleaning.

Total reliability focus.

Part of complete transformer lifecycle management services.

Resources

We’re the transformer experts so you don’t have to be. Explore resources backed by 60+ years of end-to-end transformer care experience and diagnostics data.

Frequently Asked Questions

Hot oil cleaning or oil reclamation is an advanced maintenance process that removes oxidation byproducts — such as acids, sludge, and moisture — from transformer oil and solid insulation. By circulating heated oil through specialized filtration media, it cleans both the liquid oil and the internal paper insulation, helping stop further deterioration.

Over time, heat, moisture, and oxygen combine to create acids and harmful byproducts that attack paper insulation. Left unchecked, these oxidation decay products accelerate aging and cause permanent, irreversible damage and eventual failure. Hot oil cleaning halts this process and extends transformer life.

Routine oil testing is the best way to identify the right timing. Schedule hot oil cleaning if your oil analysis shows rising acid numbers, declining dielectric strength, or increased power factor values — or if you notice sludge formation, elevated operating temperatures, or your transformer is approaching 20–25 years of service.

Yes. SDMyers can perform hot oil cleaning on both energized and de-energized transformers, giving you flexible scheduling options to minimize operational downtime.

Standard filtration primarily removes particles and moisture from the oil. Hot oil cleaning goes further by:

  • Removing dissolved oxidation byproducts (like acids)
  • Cleaning solid insulation, not just the oil
  • Actively slowing insulation aging, not just improving oil clarity

SDMyers’ process is designed to:

  • Clean both oil and solid insulation
  • Use proprietary recyclable filter media
  • Leave zero waste on-site
  • Include continuous monitoring and verification testing

Hot oil cleaning halts further degradation, significantly slowing the aging process and extending its usable life, but it cannot restore paper insulation life that has already been lost. Early intervention is critical — the sooner it's performed, the more transformer life can be preserved.

Talk with a Transformer Expert

Get a free quote or consultation — we’re here to help.

Call (330) 630-7000 or fill out the form to connect with an SDMyers transformer expert today.

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