Tubular Air Preheaters
Shell-and-tube air preheaters for power boilers, industrial boilers, and waste heat recovery systems. Material grade and supply scope are confirmed against fuel data, operating temperatures, flow conditions, approved drawings, interface dimensions, and project inspection requirements.
Quick Technical Review
Tubular Air Preheater Supply Scope
Use this summary to confirm whether ORL Power fits your project. Final flow arrangement, materials, joining method, inspection plan and interface details are confirmed during technical review.
Send APH Requirements| APH type | Tubular air preheater |
|---|---|
| Supply options | Complete APH, tube bundle, or defined cold-end replacement section |
| Fabrication basis | Approved drawings, operating data and verified site interface dimensions |
| Tube materials | Carbon steel, project-specified corrosion-resistant steel, or coated tube options subject to technical confirmation |
| Tube-to-sheet joint | Expanded, welded, or combined method as specified by the approved design and inspection plan |
| Included components | Tube sheets, supports, casing, baffles, access openings and duct interfaces according to the agreed scope |
| Quality records | Material, dimensional, weld/NDE and test documentation as required by the project ITP |
| Quote input | Drawing or interface dimensions, fuel data, gas/air temperatures and flow rates, tube specification, quantity and delivery date |
Fundamentals
How a Tubular Air Preheater Works
A tubular air preheater (APH) recovers heat from boiler flue gas to preheat combustion air before it enters the furnace. Thermal performance, corrosion risk and service life depend on the approved flow arrangement, fuel composition, operating temperatures, gas velocity, tube material and maintenance conditions.
Construction and Operating Principle
Where APHs Are Used
- Coal-fired power station boilers
- Bagasse & biomass cogeneration boilers
- Industrial package boilers (oil & gas fired)
- CFB boilers — convection pass tail end
- Waste-to-energy boiler tail gas cooling
- Cold-end replacement during scheduled outage
Product Range
Tube Material Options for Technical Review
Carbon steel, corrosion-resistant low-alloy steel and coated tube options may be considered for tubular APH projects. The final selection must follow the approved fuel analysis, temperature profile, corrosion history, mechanical design and project specification.
Carbon Steel APH
Carbon steel may be considered where the approved operating conditions and corrosion assessment support its use. Material grade, tube standard and wall thickness are confirmed from the project specification rather than selected from a website threshold.
Tube material
Project specified
Fuel data
Review required
Cold-end condition
Calculated
Tube sheet
Per drawing
- Common project-specified tube option
- Subject to corrosion and temperature review
- Wall thickness sized for erosion life target
Corrosion-Resistant Cold-End Option
A project-specified corrosion-resistant low-alloy tube may be considered for a cold-end replacement or complete APH. Suitability, grade, chemistry and expected performance must be confirmed against the applicable material standard and actual operating conditions.
Tube material
09CrCuSb (ND)
Fuel suitability
Coal / heavy oil
Performance
Project verified
Common use
Cold-end / full APH
- Cold-end only, or complete APH in ND steel
- Matched to original geometry for drop-in fit
- Most common coal-fired plant replacement
Coated-Tube APH Option
A coated-tube solution may be reviewed for demanding cold-end environments when required by the project specification. Coating system, coverage, thickness, holiday testing, handling and repair criteria must be agreed before quotation.
Tube material
CS + glass enamel
Coating system
Project specified
Application
Technical review
Inspection
Agreed ITP
- Coating details confirmed before order
- Handling and repair plan included where required
- Inspection follows approved project criteria
Preliminary Material Discussion Guide
This table starts the engineering discussion; it is not a final material recommendation.
| Fuel / Application | Data to Review | Primary Concern | Decision |
|---|---|---|---|
| Natural gas | Temperature & flow | Erosion / fouling | Confirm project grade |
| Coal-fired boiler | Fuel analysis & temperature | Corrosion / erosion | Engineering review |
| Cold-end replacement | Failure history & condensate | Geometry / corrosion | Confirm upgrade option |
| Heavy oil / variable fuel | Full fuel analysis | Acid dew point | Project-specific material |
| Waste-to-energy / municipal refuse | Fuel / flue-gas chemistry | Corrosion / fouling | Coating review if specified |
| Bagasse / biomass (mixed fuel) | Moisture / ash / additives | Erosion / blockage | Engineering review |
Not sure which applies to your fuel? Tell us fuel type, sulfur content (if known), and cold-end design temperature — we'll confirm the tube material.
Get Material AdviceQuality Assurance
Project Material & Inspection Review
Material specifications, design responsibilities and inspection requirements vary by APH configuration and contract scope. ORL confirms the applicable drawing, material standard and inspection plan before fabrication.
Tube Material by Corrosion Environment
Tube Sheet, Casing & Interfaces
Cold-end replacement supply: If only the cold-end tube section has failed, ORL Power can supply replacement cold-end tubes and tube sheets matched to the original APH geometry — without replacing the shell, casing, or hot-end section. This requires the existing APH drawing or field measurements to confirm tube OD, pitch, and tube sheet thickness.
Certifications & Compliance
Grade A Boiler
ISO 9001
ISO 14001
ISO 45001
EN 1090
EN 3834
ASME S
ASME U
Our Advantage
Why Choose ORL Power
An air preheater that fails between outages forces an unplanned shutdown. The points below reflect what ORL Power does differently to make early failure uncommon — starting with material selection, not ending with it.
Operating Data Review Before Material Confirmation
Before confirming a tube material, we request the available fuel analysis, gas and air temperatures, flow rates, pressure data and corrosion history. Any conflict between the requested material and the reviewed operating conditions is raised during technical clarification.
Material Traceability
Material certificates are reviewed against the purchase specification and project requirements before fabrication. Any additional chemistry verification, PMI or third-party witnessing is defined in the agreed inspection and test plan.
Tube-to-Tube-Sheet Joint Control
The joining method and acceptance criteria follow the approved drawing, procedure and ITP. Tube pitch, projection, joint condition and dimensional results are recorded to the extent required by the project.
Cold-End Replacement Geometry Match
Replacement cold-end sections must fit the existing APH shell without modification. We manufacture to the original drawing dimensions — tube OD, wall, pitch, tube sheet thickness, flange drilling, and nozzle locations. If no drawing exists, we work from field measurements and photographs. The replacement section is pre-assembled and dimensionally verified before crating.
Defined Complete-APH Scope
Where a complete APH is requested, the quotation identifies which tube-bundle, tube-sheet, casing, baffle, access, expansion-joint and duct-interface items are included. Documentation and code applicability are confirmed contractually rather than assumed.
Outage Window Planning
For replacement projects, required site delivery and outage dates are reviewed at enquiry stage. The confirmed schedule depends on drawing approval, material availability, fabrication, inspection, packing and transport scope.
Tell us your fuel type, sulfur content, and cold-end temperature.
We'll confirm tube material, geometry, and delivery schedule in one reply.
Applications
Industries We Serve
Every combustion boiler generates flue gas that can preheat incoming air. The buyer is typically a boiler OEM building a new unit, an EPC contractor specifying the complete boiler island, or a plant owner replacing a corroded cold-end section during a scheduled outage.
Power Plants
Tubular APH assemblies or replacement sections for coal-fired, CFB and biomass boiler projects, manufactured to approved operating data and interface requirements.
Sugar Mills & Cogeneration
Tubular APH supply for bagasse and mixed-fuel cogeneration projects, with material and cleaning provisions reviewed against actual moisture, ash and operating data.
Industrial Package Boilers
Drawing-based tubular APHs for process-steam and packaged-boiler projects, supplied to the agreed mechanical and documentation scope.
Waste-to-Energy & Variable-Fuel Applications
Projects with complex flue-gas chemistry require fuel and condensate review before any material or coating recommendation is made.
Tell us your fuel and boiler type.
We'll confirm tube material, design approach, and lead time in one reply.
Manufacturing Process
Factory & Process
Tubular APH quality depends on material control, tube-to-tube-sheet joint quality and dimensional accuracy. The manufacturing and inspection plan is agreed against the approved drawing, project specification and contractual documentation scope.
Key Production Steps
Customer Visits & Factory Evidence
Factory visits can include review of available material records, fabrication progress and project-specific inspection or test activities agreed in advance.
Frequently Asked Questions
Air Preheater FAQ
Common questions from plant engineers, EPC contractors, and boiler OEMs about tubular APH design, material selection, and cold-end replacement.
How do I choose between carbon steel, ND steel, and enamel-coated tubes?
Material selection requires more than a single sulfur or temperature threshold. We review the fuel analysis, gas-temperature profile, moisture and contaminants, operating cycles, cleaning method, corrosion history and project specification together.
Carbon steel, corrosion-resistant alloy steel or coated tubes may each be appropriate in different services. Send the operating data and any failed-tube analysis for a preliminary material discussion; the final selection remains subject to engineering approval and the agreed specification.
Can you supply only the cold-end replacement without replacing the entire APH?
Yes. When inspection shows that the reusable shell and hot-end interfaces are suitable, ORL can quote a cold-end tube bundle or replacement section instead of a complete APH. Fit-up is confirmed from approved drawings or verified field dimensions.
To supply a matched replacement cold end, we need from you: the existing APH drawing (or field-measured tube OD, tube pitch, tube length, tube sheet thickness, and flange drilling), the number of tubes in the cold-end section, the current tube material (to confirm what failed and what upgrade is appropriate), and the required delivery date relative to your outage window.
If the original drawing is not available, we work from field measurements and photographs. We generate a detailed drawing for your approval before fabrication begins. The replacement section is dimensionally verified against the drawing before despatch.
What is the difference between a tubular APH and a rotary regenerative APH?
A tubular APH is a recuperative heat exchanger with fixed tube surfaces separating the air and flue-gas paths. Its geometry, flow arrangement and maintainability depend on the project design.
A rotary regenerative APH transfers heat through a rotating matrix and uses seals between sectors. Selection between the two designs depends on duty, available space, leakage limits, maintenance strategy, plant arrangement and lifecycle requirements—not on boiler capacity alone.
What information do you need for a quotation?
The fastest route is to send your APH drawing. If no drawing exists, we need the following minimum information:
- • Fuel type and sulfur content (determines tube material)
- • Flue gas inlet and outlet temperature (°C)
- • Air inlet and outlet temperature (°C)
- • Flue gas flow rate (kg/h or Nm³/h)
- • Air flow rate (kg/h or Nm³/h)
- • Flue gas side design pressure (kPa)
- • Air side design pressure (kPa)
- • Tube OD and wall (or allow us to calculate)
- • Applicable code (ASME Section I / GB/T 16507 / EN 12952 / IBR / other)
- • Supply scope: complete APH, or cold-end replacement only
- • Quantity and required delivery date
For cold-end replacement: additionally tube pitch, tube sheet thickness, shell ID, and flange drilling, so that the replacement section matches the existing APH geometry.
What are typical lead times?
Lead time is confirmed after the drawing status, material availability, supply scope, inspection requirements, packing method and destination are known. For an outage replacement, share the required site-delivery date at enquiry stage so drawing approval, fabrication, inspection and transport can be planned backwards from the outage window.
Do you supply the complete APH or just the tube bundle?
ORL Power can supply either. The standard supply scope for a new APH is the complete assembly: tube bundle (tubes, tube sheets, baffles), flue gas shell (upper and lower headers or box headers), air-side casing, all nozzle connections, access doors, and flue gas duct expansion joints. The complete assembly arrives on site ready to bolt into the duct system.
For cold-end replacement, the supply scope is typically: replacement cold-end tube bundle with tube sheets and connecting flanges, sized to fit directly into the existing APH shell without modification to the hot-end section or shell. In this case the air-side casing and shell are retained from the existing unit. We confirm the supply scope in writing at quotation stage — there should be no ambiguity about what is and is not included.
Have a technical question not covered here?
Ask Our Engineering TeamGet Your Quote
Contact Our Engineering Team
Send your APH drawing, or tell us your fuel type, gas temperatures, flow rates and applicable specification. We will review the inputs and respond with any technical questions needed before pricing and schedule confirmation.
Get Your APH Quote
Share your fuel type and design conditions for a project-specific material, scope and schedule review.
What to Include in Your Inquiry
- • Fuel type and sulfur content (%)
- • Flue gas inlet / outlet temperature (°C)
- • Air inlet / outlet temperature (°C)
- • Flue gas and air flow rates (kg/h)
- • Design pressure — gas side and air side
- • Supply scope: complete APH or cold-end replacement
- • Applicable code (ASME / GB / EN / IBR)
- • Quantity and required delivery date
- • Drawing (if available) — attach or email