Why an RFQ Template Matters for Heat Efficiency Tubes

Procurement for heat efficiency tubes is one of those categories where a thin RFQ produces three predictable problems: suppliers quote against different bases, the technical comparison takes two weeks instead of two days, and a critical parameter — usually fin profile, bend radius, or MTC level — is discovered only after the PO is signed.

Across three decades of quoting refinery upgrades, power-plant overhauls, marine engine-room retrofits, and chemical process lines, EZ Steel Industrial has read more than a thousand RFQs for tubes, headers, and bundled piping. The same eight parameters are missing from roughly half of them. This article packages those parameters into a single template you can copy into your next inquiry, with the engineering reason each line matters.

The Eight-Line RFQ Template for Heat Efficiency Tubes

Send these eight lines on every inquiry, even when the project is small. They are the minimum needed to receive a quote that is technically comparable against other bidders and that you can defend at the audit stage.

• Service envelope: hot- and cold-side fluid, design and test pressure, design and operating temperatures (inlet and outlet, both sides), fouling and cleaning method
• Tube type: plain / bare, finned tubes (extruded, G-type, L/LL, HFW, laser-welded), or U bend tubes
• Base tube material and standard: for example 90/10 Cu-Ni per ASTM B466, TP316L stainless per ASTM A213, or chrome-moly P22 per ASTM A335
• Geometry: OD, wall thickness, length, bend radius and leg length (U-bend), fin height and density (finned), quantity per heat / per lot
• Applicable code: ASME, EN, GOST, JIS, GB — and the edition year, because 2017 and 2022 editions do not test the same way
• Testing and NDT scope: hydrostatic, eddy current, ultrasonic, flattening, flaring, hardness, post-bend heat treatment, fin-bond integrity
• Documentation level: EN 10204 3.1 or 3.2, MTC chain, third-party inspector, country of origin and required certifications
• Delivery terms: Incoterm, target date, port of destination, packaging (wooden crate, seaworthy bundle, end caps), and whether connecting pipe, flanges, and gaskets are included

Line 1 — Service Envelope: The First Filter

The service envelope is the most commonly under-specified part of an RFQ, and it is also the one that determines which tube family the supplier should be quoting. The minimum set is six parameters: medium on the tube side, medium on the shell side, design pressure, design temperature, fouling tendency, and cleaning method.

A seawater cooling duty on a marine engine-room cooler, for instance, immediately narrows the field to 90/10 or 70/30 copper nickel alloy base tubes with matching Cu-Ni tube sheets. A high-temperature superheater in a 300 MW coal-fired boiler points toward chrome-moly alloy tubes (P11, P22, P91) with T91 / T92 headers in carbon steel pipe. A hygienic pharmaceutical duty closes the field down to 316L seamless with electropolished ID and full ASME BPE traceability. The same envelope also decides whether plain, finned, or U-bend geometry is the right starting point.

Line 2 — Tube Type: Plain, Finned, or U-Bend

Tube type is the second filter and the one most often chosen from a familiar catalog code rather than the service envelope. Match the type to the duty first; refine the catalog code second.

Plain (Bare) Tubes for Clean, High-Pressure Sides

Plain tubes remain the workhorse for high-pressure, high-temperature, and clean process fluids. They are easier to clean by hydroblasting or chemical descaling, and they tolerate mechanical stress better than finned tubes. In boiler service, superheaters, refinery feed-effluent exchangers, and high-pressure feedwater heaters, bare tubes in chrome-moly or stainless grades are usually the only correct answer.

Finned Tubes for Gas-Side Heat Transfer

Finned tubes are engineered to expand the heat-transfer surface on the gas or air side, where the convective coefficient is low. They are the right answer in waste-heat recovery, fired-heater convection sections, economizers, air-cooled process coolers, and HVAC coils. Choosing the right fin profile is a separate engineering decision driven by temperature, fouling, and cleaning method — not by catalog price.

U-Bend Tubes for Floating-Head, Removable Bundles

U bend tubes allow a shell-and-tube exchanger to be designed with a floating head that absorbs thermal expansion and lets the bundle be pulled for inspection. They are the standard for high-pressure feedwater heaters, condensers, and petrochemical process exchangers where thermal cycling and bundle removal are routine. Tight bend radius, controlled thinning, and post-bend heat treatment are the quality markers to verify on every delivery.

Line 3 — Base Tube Material and Standard

Material selection determines corrosion margin, creep life, and total cost of ownership. Match the base tube to the medium and temperature window you locked down in Line 1, then verify it against the relevant standard. A short reference table helps most specifiers avoid the most common mismatches:

Service Environment	Recommended Base Tube	Common Standards
Seawater cooling, marine heat exchangers	90/10 or 70/30 Copper-Nickel, Aluminium Brass	ASTM B466, B111, EEMUA 234
High-temperature boiler, superheater	Chrome-moly alloy (P11, P22, P91)	ASTM A213, A335
Refinery, hydrocracker, FCC	Stainless steel (TP304, TP316, TP321)	ASTM A213, A249
Chemical, pharmaceutical, hygienic	Stainless steel (316L, duplex)	ASTM A270, A249, EN 10357
Power plant, economizer, air-cooled	Carbon steel, low-alloy	ASTM A192, A210, A179
Cryogenic, LNG, cold box	Austenitic stainless, aluminium alloys	ASTM A213, EN 10216-5

If the system also carries clean utility water or process condensate, our stainless steel pipe range — ASTM A312, A269, and EN 10312 grades — lets you source the tube, the connecting pipe, and the U-bend return from one manufacturer on one MTC chain.

Line 4 — Geometry: The Numbers That Quietly Drive Cost

Geometry is where most RFQs fall down. OD, wall, length, bend radius, leg length, fin height, and fin density are not interchangeable, and the wrong combination produces a tube that cannot be bundled into the existing shell. Send the numbers, not the catalog code.

• OD and wall: in mm or in, with a tolerance window. Standard OD increments are 19.05 mm, 25.4 mm, 31.75 mm, 38.1 mm, 50.8 mm
• Length: straight length for plain tubes, total developed length for U-bends, and straight-leg / bend-leg split for U-bend designs
• Bend radius (CLR): typically 1.5× to 3× OD for U-bend tubes; tight radius drives thinning and post-bend heat treatment
• Fin height and density: in mm and FPI (fins per inch); FPI 8–10 is typical for air-cooled service, FPI 11–13 for fired-heater convection
• Quantity: total pieces, pieces per heat, and acceptable heat-batch split for delivery

Line 5 — Applicable Code and Edition Year

ASTM A213 published in 2018 and ASTM A213 published in 2024 do not test the same way. The same is true for ASME SB163, EN 10216-5, GOST 9941, and JIS G3463. Send the standard and the edition year, and the supplier will quote against the test schedule you actually need to meet. If the project specification ties the code to a particular year, write that year into the RFQ — not "latest edition", which forces the supplier to either decline or quote with an assumption.

For refinery and power-plant service, the project ITP (inspection and test plan) usually defines the code edition. For marine and offshore, IACS UR series and class society rules (DNV, Lloyd's, ABS) add a second layer on top of the material standard. Send both.

Line 6 — Testing and NDT Scope

Testing scope is the second-largest driver of price after material, and the one that is most often discovered to be inadequate only at the site receipt stage. The minimum set for pressure-side heat efficiency tubes:

• Hydrostatic test on every tube, at the pressure defined by the applicable standard or by the project ITP
• Eddy-current or ultrasonic NDT on every tube, with calibration against reference notches
• Flattening, flaring, and hardness tests per ASTM A213 / A249 / B111 as relevant
• Post-bend heat treatment report and bend-radius verification for U-bend tubes
• Fin-bond integrity test (torque, push-off, or thermal-cycle test) for finned tubes

For pressure-boundary service — boiler tubes, feedwater heater tubes, refinery preheat exchangers — the NDT scope and the MTC level together define what auditors will accept. Confirm both before issuing the PO; it is much harder to upgrade them after delivery.

Line 7 — Documentation, MTC, and Country of Origin

Documentation requirements are a frequent source of RFQ rework. State the MTC level, the third-party inspector (if any), and the country of origin required. Common configurations:

• EN 10204 3.1 — mill-issued test certificate, validated by the manufacturer's independent inspection body
• EN 10204 3.2 — independent witness by a third-party inspector (SGS, BV, TUV, LR, DNV) at the mill
• Country of origin — for tariff classification, sanctions compliance, and project funding requirements
• Additional certificates — CE / PED, AD 2000, EN 1090, ASME U-stamp where the exchanger is ASME-stamped

At EZ Steel Industrial, every tube, fitting, and flange ships with full EN 10204 3.1 certification as standard, and 3.2 certification is available through the third-party inspector of your choice. Our manufacturing facility runs an ISO 9001 certified laboratory and holds API, EN, and ASME accreditation for the relevant product families.

Line 8 — Delivery Terms and Whether to Bundle

Heat efficiency tubes almost always arrive at site together with connecting piping, headers, return bends, flanges, and gaskets. Specifying each item separately invites three classic problems: schedule mismatch, flange-class mismatch, and split MTC chains that auditors do not enjoy reviewing. A bundled sourcing model gives you confirmed compatibility across base tube, header pipe, and connecting fittings; matching pipe flanges and stud-bolt sets at the same pressure class as the exchanger; a single MTC chain; reduced freight and inbound logistics complexity; and one point of accountability for warranty and after-sales support.

State the Incoterm (FOB, CFR, CIF, DAP are all common), the target date, the port of destination, and the packaging required. For sea freight, end caps on every tube, desiccant in each wooden crate, and seaworthy wrapping on finned-tube bundles are the minimum to survive a 30-day ocean transit in humid conditions.

Two Real RFQs, and What They Would Have Looked Like

A Short Self-Check Before You Send the RFQ

• Have you sent the service envelope with side-specific temperatures and pressures?
• Have you specified tube type with the engineering reason, not just a catalog code?
• Have you stated the material standard with the edition year?
• Have you sent geometry in numbers, not a familiar description?
• Have you defined NDT scope and MTC level?
• Have you decided whether to bundle connecting pipe, flanges, and gaskets?