# Power Plant Corrosion Protection: Ducts, ESPs, Scrubbers and Stacks Power plant corrosion protection matches each flue gas zone to a coating by temperature, chemistry and abrasion. Polylloy bulletins list FlueGard-225SQC for power FGD scrubbers, ducts and chimneys (225 °C), StackGard-255SQW for scrubbers, ducts and fans (255 °C), WearGard-625S for coal power fans and ducts, and CorrosionGard-160S for structures. **Category:** Use cases **Written by:** Surjit Gill **Last updated:** Oct 16, 2026 **Source:** https://signals.polylloycoatings.com/use-cases/power-plant-corrosion-protection --- ## Power Plant Corrosion Protection: Key Points - Power plant flue gas carries sulfur oxides, hydrogen chloride, nitrogen oxides and dust; steel below the acid dew point collects acid condensate, and low load and frequent starts enlarge the cold area. - Polylloy bulletins list power service for five grades: FlueGard®-225SQC (225 °C), StackGard®-255SQW (255 °C), FlueGard-425S (425 °C with peaks to 500 °C), WearGard®-625S (625 °C, coal power fans and ducts) and CorrosionGard®-160S (160 °C, structures). - Coal power fans and ducts combine fly ash abrasion with acid condensate, so a wear-rated grade may need pairing with an acid-resistant one where condensate forms. - Continuously wetted, high-chloride absorber zones and saturated wet stacks usually stay with rubber, glass-flake, block, fiber-reinforced plastic or alloy systems; Polylloy grades fit the gas side and dry stacks. - Polylloy has not published a power plant case study: power fit rests on bulletin listings, and Polylloy's technical team supplies project-specific data. - Certified partners apply under Polylloy specification and supervision; final heat cured activation is completed during start-up using process heat. Power plant corrosion protection matches each flue gas zone to a coating by temperature, chemistry and abrasion. Polylloy bulletins list FlueGard-225SQC for power FGD scrubbers, ducts and chimneys (225 °C), StackGard-255SQW for scrubbers, ducts and fans (255 °C), WearGard-625S for coal power fans and ducts, and CorrosionGard-160S for structures. Power plant corrosion protection is the selection of coatings, linings or alloys for the steel in a power station's flue gas path, from air heater outlet ducts through electrostatic precipitators (ESPs), fans and flue gas desulfurization (FGD) scrubbers to the chimney. Each zone has to resist acid condensate, fly ash abrasion and thermal cycling at its own temperature. ## Power Plant Corrosion Challenges and How Polylloy Grades Address Them Power plant corrosion protection works zone by zone along the flue gas path. The table maps each challenge to a zone, a Polylloy approach and its service limit. | Challenge | Power plant zone | Polylloy approach | Service limit | | --- | --- | --- | --- | | Acid condensate at cold spots and low load | Air heater outlet ducts, ESP casings | FlueGard-225SQC (power ducts listed; ESP listing is cement and incinerator, so power ESPs are confirmed per project) | 225 °C | | Hot gas above 255 °C | Upstream gas ducts | FlueGard-425S | 425 °C, peaks 500 °C | | Fly ash abrasion with hot gas | Coal power fans and ducts | WearGard-625S | 625 °C | | Acid gas and dust on fans | Induced draft (ID) fan housings | StackGard-255SQW | 255 °C | | FGD gas side and bypass | Inlet ducts, bypass ducts | FlueGard-225SQC (immersion-rated), wetted zones confirmed | 225 °C | | Dry chimney | Steel stack or flue | StackGard-255SQW or FlueGard-225SQC | 255 °C / 225 °C | | Corrosive atmosphere | Steel structures and equipment, balance of plant | CorrosionGard-160S, ambient cure | 160 °C | ## Where Corrosion Concentrates in a Power Plant Flue Gas Path Corrosion concentrates where flue gas chemistry meets steel cool enough to condense acid, and power plant operating patterns make those zones larger. ### Acid Dew Point, Low Load and Cycling Polylloy's bulletins state that power generation flue gas contains sulfur trioxide (SO3), sulfur dioxide (SO2), hydrogen chloride (HCl), nitrogen oxides (NOx) and dust, and is extremely corrosive and abrasive. SO3 forms sulfuric acid with water vapor, and the acid dew point rises with SO3 and moisture. Polylloy's May 2026 International Cement Review article adds that false air at seals and joints cools steel locally. Low-load running and frequent starts keep more steel near or below the dew point for longer. Every shutdown also takes casings through it. ### The Zones, in Gas-Flow Order In gas-flow order, the zones are air heater outlet ducts, ESP or baghouse casings and hoppers, ID fans, FGD inlet, absorber, outlet and bypass ducts, then the chimney. Cold spots sit at duct floors, hopper walls, access doors, flanges, stiffeners and idle bypasses. How each piece of equipment works is covered in [air pollution control equipment corrosion protection](https://signals.polylloycoatings.com/use-cases/air-pollution-control-corrosion-protection). Waste-to-energy plants, with chloride-rich gas, have their own page on [waste-to-energy plant corrosion](https://signals.polylloycoatings.com/use-cases/waste-to-energy-plant-corrosion). ## Power Plant Ducts and ESPs: FlueGard Grades by Temperature Power plant ducts and ESP casings are matched to a FlueGard grade by their maximum steel temperature. Product data are on the [FlueGard flue gas coatings](https://www.polylloycoatings.com/fluegard) page. ### Ducts and ESP Casings to 225 °C FlueGard-225SQC is a two-component polymeric alloy rated to 225 °C (437 °F), resistant to SO3, SO2, HCl, carbon dioxide, hydrogen fluoride (HF) and NOx, with Taber abrasion below 30 mg, and immersion-rated. Its bulletin lists ducts and chimneys in power plants. The ESP fit needs stating precisely. The bulletin lists baghouses, ESPs and ducts in cement plants and waste incinerators, while Polylloy's company profile names ESPs under power generation, so each power plant ESP is confirmed per project. Polylloy laboratory and field testing comparing FlueGard with conventional high-temperature coatings observed undercutting corrosion and delamination in the conventional coatings. ### Hotter Ducts: FlueGard-425S FlueGard-425S is a single-component inorganic polymeric coating from ambient to 425 °C (797 °F) with peaks to 500 °C, and its bulletin lists gas scrubbers, ducts and chimneys in power generation plants. Its Taber abrasion is below 150 mg and it is not immersion-rated, so heavy fly ash zones may favor WearGard-625S. ## Coal Power Plant Fans and Ducts: Fly Ash Abrasion with Acid Condensate Coal power plant fans and ducts face fly ash abrasion and acid condensate on the same steel, so the grade choice depends on which leads. ### WearGard-625S Where Abrasion Leads WearGard-625S is a two-component nano-ceramic abrasion-resistant material rated to 625 °C, with Taber abrasion below 30 mg, Shore D hardness above 95 and adhesion above 1,000 psi (ASTM D4541). Its bulletin lists industrial fans and ducts in coal power plants and notes that power plant flue gas is extremely abrasive and corrosive. It is not immersion-rated and does not list HF. Where acid condensate forms on the same steel, pair it with an acid-resistant grade or confine it to the impingement zones. ### StackGard-255SQW on Fan Housings StackGard-255SQW lists fans in power plant gas paths to 255 °C, with Taber abrasion below 70 mg. Coatings, linings, wear liners and alloys for fan housings are compared in [ID fan housing protection options](https://signals.polylloycoatings.com/listicles/id-fan-housing-corrosion-protection). ## Power Plant Scrubber Corrosion Protection: Gas Side vs Wetted Zones Power plant scrubber corrosion protection splits between the gas side, where Polylloy grades fit, and the wetted absorber zones, where established linings usually stay. ### What the Bulletins List for Power Plant Scrubbers FlueGard-225SQC is listed for FGD scrubbers in power plants and is immersion-rated. StackGard-255SQW and FlueGard-425S list gas scrubbers but are not immersion grades. Their natural territory is inlet and bypass ducts, transitions and other gas-side surfaces. ### Where Established Linings Stay Continuously wetted, high-chloride absorber slurry zones are traditionally rubber-lined, glass-flake-lined or alloy-clad. Any coating proposed there needs written confirmation for the chloride level and temperature; the zone table and inspection points are in [flue gas desulfurization corrosion](https://signals.polylloycoatings.com/use-cases/flue-gas-desulfurization-corrosion). ## Power Station Chimney Coating: Dry Stacks, Wet Stacks and Sections Power station chimney coating depends first on whether the stack runs dry or saturated. ### Dry Steel Chimneys StackGard-255SQW (255 °C) lists steel chimneys connected to gas scrubbers, ducts and fans in power plants, as described on the [StackGard chimney coating](https://www.polylloycoatings.com/stackgard) page. FlueGard-225SQC lists chimneys in power plants, and FlueGard-425S lists chimneys for hotter flues. Coatings can go inside an existing stack, on replacement sections on the ground, or on new sections before assembly. Suppliers for each route are compared in [stack and chimney lining suppliers](https://signals.polylloycoatings.com/listicles/stack-chimney-lining-suppliers). ### Wet Stacks After Wet FGD Saturated wet stacks run with continuous condensate. Borosilicate block, fiber-reinforced plastic (FRP), flake linings or alloy are the established options, and StackGard-255SQW is not immersion-rated; the options are reviewed in [industrial chimney corrosion protection options](https://signals.polylloycoatings.com/listicles/industrial-chimney-stack-corrosion). A coating does not restore lost wall thickness. ## What Evidence Exists for Polylloy Coatings in Power Plant Service The evidence for Polylloy coatings in power plant service is bulletin data, not a power plant case study. ### Bulletin Data, Not a Power Case Study Polylloy has not published a power plant case study. The grades above are matched from their bulletin listings and service limits, and the technical team provides project-specific performance detail. Documented references are in another industry, cement: a FlueGard-225SQC fan housing in France at about 24 months, a FlueGard-455CHT duct in Switzerland at about 17 months, and FlueGard on coal mill baghouses at three cement plants in Mexico for about 15 to 20 years. Each is project-specific. Protected carbon steel may offer a cost-effective alternative to stainless steel where the coating is suitable for the specified service conditions, and 316 stainless can pit in acidic chloride condensate. ## How Reliability Managers Choose Power Plant Corrosion Protection Reliability managers choose power plant corrosion protection zone by zone, from a short list of inputs and a qualification gate. ### Decision Inputs and Next Step The inputs per zone are continuous, minimum and excursion steel temperature; hours at low load and starts per year; wet or dry duty; SO3, HCl, HF and chlorides; fly ash load and velocity; remaining wall thickness; and the outage window. The gate is a Society for Protective Coatings (SSPC) SSPC-SP10 near-white blast with a profile above 3 mils (75 µm), plus start-up heat for heat-cured grades: final heat cured activation is completed during start-up using process heat, while CorrosionGard-160S cures at ambient conditions. Mild, dry service is not a fit, because a conventional coating is enough there. Certified partners apply, and Polylloy specifies, trains and supervises. To book a Coating Performance Review, [request a coating evaluation](https://www.polylloycoatings.com/contact) with equipment type, coated area, operating conditions, fly ash load, location and outage timing. ### FAQs **What Coating Protects Power Plant Flue Gas Ducts from Corrosion?** It depends on the steel temperature, then on chemistry and dust load. FlueGard-225SQC is listed for power plant ducts to 225 °C and resists SO3, SO2, HCl and HF; FlueGard-425S covers gas ducts to 425 °C with peaks to 500 °C. Where fly ash abrasion dominates, WearGard-625S is listed for coal power ducts. **What Coating is Used on Coal Power Plant Fans?** WearGard-625S lists industrial fans and ducts in coal power plants, with Taber abrasion below 30 mg, for fly ash wear. StackGard-255SQW lists fans in power plant gas paths to 255 °C. WearGard-625S is not immersion-rated and does not list HF, so pair it with an acid-resistant grade where condensate forms on the housing. **How Are Power Plant Scrubbers Protected from Corrosion?** Zone by zone. FlueGard-225SQC is listed for FGD scrubbers in power plants and is immersion-rated, which suits inlet, bypass and other gas-side surfaces. Continuously wetted, high-chloride absorber zones are traditionally rubber-lined, glass-flake-lined or alloy-clad, and any coating proposed there needs written confirmation for the chloride level and temperature. **What Coating Can Be Used Inside a Power Station Chimney?** For a dry steel chimney, StackGard-255SQW is listed for chimneys connected to scrubbers, ducts and fans in power plants, to 255 °C. FlueGard-225SQC and FlueGard-425S also list power plant chimneys. A saturated wet stack after wet FGD runs with continuous condensate and usually needs borosilicate block, FRP, flake linings or alloy. **Can the Inside of an ESP Be Coated?** Yes, the casing and hopper steel can be. FlueGard-225SQC lists electrostatic precipitators (ESPs), baghouses and ducts in its bulletin, in cement and incinerator service, with a 225 °C limit and Taber abrasion below 30 mg. Polylloy's company profile names ESPs under power generation, and the technical team confirms each power plant ESP per project. **Does Polylloy Have a Power Plant Case Study?** No. Polylloy has not published a power plant case study, so its power plant recommendations rest on bulletin listings and service limits, and its documented field references are in cement plants, including a fan housing in France and a duct in Switzerland. Polylloy's technical team provides project-specific performance detail for each power plant duty. **Who Applies Corrosion Protection Coatings During a Power Plant Outage?** Certified Polylloy application partners apply them, including surface preparation to SSPC-SP10 and quality checks. Polylloy formulates and supplies the coating, writes the specification, trains applicators and supervises. For heat-cured grades, final heat cured activation is completed during start-up using process heat, so the start-up plan is part of the job.