Boiler Convection Tube Bundles

A drawing is the fastest route to quotation. Without one, we work from the following parameters:

• • Boiler type and fuel (or process type for WHB)
• • Flue gas inlet temperature and flow rate (or boiler capacity in t/h)
• • Flue gas dust loading — determines bare vs finned
• • Working fluid: water / steam / other; design pressure and temperature
• • Tube OD, wall thickness, and pitch (if known)
• • Bundle envelope: overall width, height, and depth
• • Number of tube rows and passes
• • Applicable design code (ASME Sec. I / VIII / GB / EN)
• • New build or replacement; if replacement — any upgrade requirements
• • Required delivery date or outage window

The primary criteria is flue gas dust loading and corrosion tendency:

• • Bare tube — for coal, CFB, biomass, and other solid-fuel boilers where ash would block fin channels or cause erosion wear of the fins themselves. Also the correct choice for high-sulphur gas where dew point corrosion on fin surfaces is a risk.
• • Finned tube — for clean or low-dust gas: natural gas, LPG, cement kiln exhaust (after cyclone), gas turbine exhaust (HRSG). Fins increase heat transfer area by 3–6× over bare tube, allowing a more compact bundle at the same duty.

If your application sits between these cases — for example a biomass boiler with a good dust collection system upstream — share the operating data and we'll advise on fin pitch options that stay within self-cleaning limits.

This is common for ageing boilers. Our approach:

• • From site measurements — header interface positions, nozzle sizes, and bundle envelope dimensions taken by your maintenance team, supplied to us with a sketch or photo. We produce a fabrication drawing for your approval before any material is cut.
• • From failed bundle samples — if the failed bundle can be shipped or representative sections sent, we reverse-engineer tube OD, wall thickness, pitch, and header drill pattern directly. We also identify the original material grade and confirm whether an upgrade is recommended.
• • Upgrade during replacement — replacement scope is the right moment to increase tube wall thickness, upgrade from SA-210 A1 to T11 on the hotter rows, or change from bare to finned if operating conditions have changed.

Standard documentation package included with every delivery:

• • Tube and header EN 10204 3.1 Mill Test Certificates (chemistry + mechanical)
• • Fin material certificate (for finned tube bundles)
• • Welding Procedure Specifications (WPS) and Procedure Qualification Records (PQR)
• • Welder qualification records (WPQ)
• • NDE reports — RT/UT on header welds, PT/MT on tube stubs as required by code
• • Hydrostatic test certificate
• • Dimensional inspection report
• • As-built drawing
• • ASME Data Report (for ASME-stamped scope)

Third-party witness inspection (SGS, BV, TÜV) available on request.

Lead time is measured from drawing approval. Typical ranges:

• • Small bare tube replacement bundle (carbon steel, single pass): 6–10 weeks
• • Medium bare tube bundle (multi-pass, with headers): 10–14 weeks
• • Finned tube bundle (fin fabrication adds to schedule): 10–16 weeks
• • T22 or alloy scope (PWHT required, additional NDE): add 2–4 weeks

Share your outage window at enquiry stage — we schedule production backward from your delivery date and flag any risk early.

Yes — ORL Power manufactures all major boiler pressure parts. Common packages including convection bundles:

• • Convection Bundle + Economizer (most common — both sit in the convection pass)
• • Convection Bundle + Superheater / Reheater + Economizer (full convection pass package)
• • Full pressure-parts package including Steam Drum, Water Walls, and Headers

Package supply means a single technical interface, one inspection visit, consolidated documentation, and coordinated shipping — less coordination overhead for EPC contractors and plant owners.