RTO Insulation, Damper & Duct Repair

March 28, 2022

RTO Unit with Replacement Bypass Damper, Ductwork & Insulated Roof:

thermal oxidizer insulation repair completed on 30,000 scfm RTO

Equipment: Regenerative Thermal Oxidizer; 30,000 scfm capacity


A Fortune 500 customer needed to replace a locked-up hot-side bypass damper and related ductwork, and also repair an insulated roof section on their large regenerative thermal oxidizer (RTO). This operation runs 24/7/365 so proper planning and coordination with the production schedule were critical to keep downtime to a minimum.

Hot-side bypass dampers see extreme heat in RTOs and even the best-built dampers will fail eventually. They should achieve at least a 5-year life, and depending on the conditions and prevailing open/close position, a decade of performance is possible. The most typical failure is sag of the main damper shaft caused by extreme temperatures, the weight of the damper blade, and time. The sag requires increasing torque to turn the damper until eventually the actuator cannot overcome the torque.

Hot spots are usually due to voids/gaps in the insulation that allow hot air (1600°F+) to reach the outer wall of the duct. Gaps can be caused by improperly installed insulation modules, or from air leaks through poorly gasketed flanges or weld gaps/holes.

Hot spots are not uncommon and many times are not immediate problems. However, hot spots due to air leaks can quickly progress from small issues to major problems. Most RTOs operate under a positive pressure so any air leaks will pass hot air (1500°-1660°F) to the outside and begin to weaken and degrade the metal as it passes through the hole. The metal wastes away slowly but sometimes quickly, and as the hole increases in size the rate of damage increases exponentially. Air leaks are not only dangerous to equipment health, they pose a danger to personnel from hot air leaking out at pressure.

Damaged Damper, Ductwork & RTO Roof:

RTO with damaged bypass damper and hot spot
RTO with damaged ductwork
RTO with damaged roof


Kono Kogs was hired to remove and replace the hot bypass damper, related (insulated) ductwork, and cut out the compromised roof section and replace it with new metal. The new roof was installed, internally insulated and integrated with the existing uncompromised roof metal and insulation. We also properly re-packed the insulation to prevent hot spots. With proper coordination this repair was completed and the RTO was operational again in under 72 hours. Kono Kogs left an extremely clean job site, and also re-started and confirmed proper RTO operation prior to leaving.

Kono Kogs has experience refurbishing nearly every major RTO model on the market, even obsolete models from OEMs that are no longer in business.

We provide every component or service related to regenerative thermal oxidizers including relocation, trade-in, field repairs, field rebuilds/upgrades, emergency service, preventive maintenance service, and replacement with our refurbished, warrantied long-life RTO systems. We have over 350 refurbished oxidizer units installed worldwide. Why buy new when you can buy better!

Click images to zoom enlarge
RTO with poppet valves & hot bypass duct/damper prior to insulation repair

Prior to Repair: RTO, Poppet Valves & Hot Bypass Duct/Damper

Damage from hot spots on RTO hot bypass duct

Prior to Repair: Hot Spots on Hot Bypass Duct

RTO hot bypass duct showing the side opposite the hot spots

Prior to Repair: Opposite Side of Hot Spots

Side view of RTO with hot bypass duct and damper removed for repairs

Repair Progress #1: Duct & Damper Removed

Overhead view of RTO with hot bypass duct and damper removed for repairs

Repair Progress #2: Duct & Damper Removed

Wide angle view of RTO with hot bypass duct and damper removed for repairs

Repair Progress #3: Duct & Damper Removed

RTO with damaged roof section removed and first replacement duct section installed

Repair Progress #4: Compromised Roof Section Removed; First Duct section installed

Overhead view of RTO with damaged roof section removed for insulation repair

Repair Progress #5: Compromised Roof Section Removed; First duct section installed

Side view of RTO with hot bypass duct and damper removed for repairs

Repair Progress #6: Compromised Roof Section Removed; First duct section installed

Interior view of completed thermal oxidizer insulation repair work

Repair Progress #7: Initial Installation of Roof Repair

Exterior overhead view of RTO roof after completed repairs

Repair Complete #1

Side view of RTO after insulation repair and ductwork replacement

Repair Complete #2

Overhead end to end view of RTO after insulation and damper repair

Repair Complete #3

New replacement hot bypass damper and duct installed on RTO

Repair Complete #4

Wide angle view of RTO exterior after insulation, damper & ductwork repair

Repair Complete #5

Side overhead view of RTO roof and ductwork after insulation repair

Repair Complete #6

Regenerative thermal oxidizer with repaired insulation and newly replaced bypass damper and duct

Repair Complete #7

Equipment / Services provided by Kono Kogs, Inc.
  • Inspect RTO and assess repairs needed
  • Provide new hot-side bypass damper
  • Fabricate and provide new internally insulated ductwork
  • Provide repair plan, schedule work, & provide all materials
  • Equipment and crew
  • Thoroughly clean work site before leaving
  • Equipment re-start

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About Kono Kogs

Kono Kogs has been refurbishing used thermal oxidizers for over 25 years with over 350 installations in nearly every state in the USA and around the world. We offer full refurbishing of quality-built thermal oxidizers and stand behind them with warranties that match new equipment OEM warranties.