Economizers recover heat from boiler flue gases to preheat feedwater, but their position in the low-temperature flue gas path makes them susceptible to acid dew point corrosion (when metal temperatures drop below the sulphuric acid dew point) and cold-end erosion from ash-laden gas flow.
AQ Process Systems sources and exports replacement economizer tubes in both bare and finned configurations, replacement headers, soot blower lance tubes and nozzles, access doors, and casing components. We also support economizer retrofit projects where a new economizer section is being added to an existing boiler to improve efficiency.
Finned tubes are available in solid, serrated, and helical fin configurations, carbon steel or stainless steel fins on carbon steel or alloy base tubes.
| Component | Specification | Description |
|---|---|---|
| Tubes & Coils | ||
| Bare Economizer Tubes | SA 210 Gr. A1/C, SA 178 Gr. A | Seamless or ERW | Unfinned straight or U-bend tubes for tube-in-tube or serpentine economizer configurations. |
| Finned Tubes | Solid, serrated, or helical fins | CS or SS fins on CS/alloy base | Extended-surface finned tubes for high-efficiency compact economizer sections. |
| U-bend Tubes & Returns | Pre-bent to OEM radius | SA 210 / SA 178 | Return bends connecting straight tube runs in serpentine economizer layouts. |
| Tube Bundles | Pre-fabricated assemblies with headers | Complete tube bank assemblies, tubes welded to inlet and outlet headers, hydro-tested. |
| Headers & Structure | ||
| Inlet/Outlet Headers | SA 106 Gr. B/C | Drilled to OEM pattern | Replacement economizer headers, drilled, machined, and supplied with nozzle connections. |
| Access Doors | CS fabricated | Hinged or bolted | Gasketed | Inspection and cleaning access doors for economizer tube bank enclosures. |
| Casing Panels | Insulated CS plate | Flanged or welded joints | Economizer enclosure casing panels, insulated and sealed to prevent gas bypass. |
| Tube Support Structures | CS or alloy | Welded or bolted assembly | Tube support plates, saddles, and guide bars that maintain tube spacing and prevent sagging. |
| Cleaning & Maintenance | ||
| Soot Blower Elements | SS lance tubes | Retractable or rotary | Replacement lance tubes, nozzles, and packing glands for economizer soot blowers. |
| Soot Blower Nozzles | SS or Stellite-tipped | Various patterns | Nozzle tips for soot blower lances, designed for effective cleaning without tube erosion. |
| Ash Hopper Components | CS fabrication | Slide gates, vibrators | Economizer ash hopper doors, slide gate valves, and hopper vibrator assemblies. |
Parts are matched to OEM material specifications and dimensional tolerances. Please provide the equipment manufacturer, model number, and serial number (if available) for precise part identification. Mill Test Certificates (MTC) supplied with all tube materials per EN 10204 3.1.
Economizer tubes most commonly fail due to acid dew point corrosion (when tube metal temperature drops below the sulphuric acid condensation point, typically around 120-150°C), flow-accelerated erosion from ash-laden flue gas, oxygen pitting corrosion on the water side (especially during shutdowns when the tubes are not properly laid up), and external erosion from soot blower impingement.
We supply solid fin, serrated fin, and helical (spiral) fin types. Fins can be carbon steel or stainless steel, welded or resistance-welded to base tubes of SA 210, SA 178, or SA 213 material. Fin density (fins per inch), fin height, and fin thickness are matched to the OEM specification for your economizer.
Yes. We supply pre-fabricated economizer tube bundles (harps) with tubes welded to upper and lower headers, hydrostatically tested, and ready for lift-in installation. This significantly reduces field welding during an outage.
Yes. For boiler efficiency improvement projects where a new economizer is being added, we supply tubes, headers, support structures, casing panels, and all accessories needed for the retrofit installation.
The primary prevention strategy is maintaining economizer tube metal temperature above the acid dew point (typically by controlling feedwater inlet temperature above 105-120°C using a feedwater heater or recirculation system). Material selection also helps, using Corten or enamel-coated tubes in the coldest sections. AQ Process Systems can supply both standard and corrosion-resistant tube materials.
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