Heat Exchanger Tubes: Materials, Grades & Sizes Selection Guide

Heat exchanger tubes are the thin-walled tubes that form the bundle of a shell-and-tube heat exchanger, condenser, evaporator or feedwater heater — the surface across which heat passes between two fluids. Tube selection is a balance of three things at once: thermal conductivity, mechanical strength at temperature, and corrosion resistance to both the tube-side and shell-side fluids. Get the material wrong and the bundle leaks; get the wall or tolerance wrong and it fails to seal in the tubesheet.

ZC Steel Pipe (ZHENCHENG Steel Co., Ltd.) is a Chinese manufacturer supplying order-to-make heat exchanger and condenser tubes across the full material range — carbon steel, Cr-Mo alloy, austenitic and duplex stainless, copper-nickel, nickel alloy and titanium — to ASTM, ASME, EN, DIN, JIS and GB. This guide gives the governing standards, ASME-verified mechanical properties for the steel grades, dimensional ranges, and a clear material-selection logic for power, refinery, petrochemical, HVAC and marine duty.

CONTENTS

1. What Are Heat Exchanger Tubes?

2. Tube Material Families

3. Standards & Verified Mechanical Properties

4. Sizes, Wall Thickness & Tolerances

5. Tube Configurations & Tubesheet Joints

6. Material Selection by Service

7. How to Specify Heat Exchanger Tubes (PO Checklist)

8. Frequently Asked Questions

1. What Are Heat Exchanger Tubes?

A heat exchanger tube carries one fluid through its bore while a second fluid flows across its outside surface in the shell. Heat transfers through the tube wall, so the tube is the working surface of the whole unit. Because there can be hundreds or thousands of tubes in a single bundle, each one expanded or welded into a tubesheet at both ends, consistency of OD, wall and straightness matters as much as the grade.

DEFINITION — HEAT EXCHANGER / CONDENSER TUBEA thin-walled seamless or welded tube used in shell-and-tube heat exchangers, condensers, evaporators and feedwater heaters to transfer heat between two fluids. Governed by tube-specific standards (e.g. ASTM A179, A213, A249, B111, B338) — not by pipe standards — because acceptance is built around wall control, surface finish and tubesheet-joint integrity rather than line-pressure containment.

That tube-versus-pipe distinction is the single most common spec error in heat exchanger procurement, and it drives the rest of this guide.

2. Tube Material Families

ZC supplies five material families for heat exchanger duty. The right family is fixed first by corrosion environment and temperature, then narrowed by cost and conductivity.

Carbon & C-Mo Steel

Specs: A179, A192, A210, A214

Use: Boiler, feedwater, oil cooler

Limit: Non-corrosive fluids

Cr-Mo Alloy Steel

Specs: A213 T11 / T12 / T22 / T91

Use: Superheater, high-temp HX

Limit: Elevated-temp creep

Stainless / Duplex

Specs: A213 / A249; 2205

Grades: TP304/L, TP316/L

Use: Acids, chlorides, hygiene

Copper / Cu-Ni

Specs: ASTM B111

Grades: 90/10, 70/30 Cu-Ni

Use: HVAC, marine condensers

Nickel Alloy

Grades: Inconel 600/625

Also: Hastelloy C276, Monel 400

Use: Extreme corrosion / heat

Titanium

Grades: Gr.2, Gr.5 (B338)

Use: Seawater, desalination

Strength: Light, chloride-proof

3. Standards & Verified Mechanical Properties

The table below gives the governing tube standard and ASME Section II-A minimum mechanical properties for the carbon and alloy steel grades. Values are taken from the ASME BPVC II-A specifications, not estimated.

Source: ASME BPVC Section II-A (SA-179, SA-192, SA-210, SA-214, SA-213). A179 and A214 carry no mandatory tensile test in the standard body and are accepted on hardness; tensile figures shown for A179/A192 are design values from the explanatory notes.

Critical — T91 is NOT a stainless grade. ASTM A213 covers both ferritic and austenitic tubes, and T91 (9Cr-1Mo-V) sits in the ferritic-martensitic family, not the austenitic stainless family. Do not group T91 with TP304 / TP316 in a corrosion table or a welding procedure. Its high-temperature creep strength is excellent, but its corrosion behaviour and weldability (pre-heat, PWHT) are completely different from austenitic stainless.

For austenitic stainless heat exchanger tubes, the correct standards are ASTM A213 (seamless) and ASTM A249 (welded) in grades TP304/304L and TP316/316L; duplex bundles use 2205 (UNS S31803/S32205). Copper-alloy condenser tubes follow ASTM B111, and titanium tubes follow ASTM B338. Confirm exact mechanical minimums for these non-steel grades against the applicable standard and your design code.

Procurement Note — "A312" on a heat exchanger enquiry is a red flag. ASTM A312 is a stainless pipe specification. It shares the TP304/TP316 grade names, so it is easy to copy onto a tube enquiry by mistake — but a heat exchanger tube should be ordered to A213 (seamless) or A249 (welded), which carry the tube-specific dimensional, flattening, flaring and eddy-current requirements a bundle actually needs. Specify the tube standard, and the right product follows.

The carbon and Cr-Mo grades here overlap heavily with boiler-tube practice; for the temperature-limit and grade detail on A192 / A210 / A213, see our boiler tube grades guide →, and for the stainless family, austenitic stainless seamless pipe explained →

4. Sizes, Wall Thickness & Tolerances

Heat exchanger tube is dimensionally controlled far more tightly than line pipe, because tube-side film coefficient and tubesheet expansion both depend on consistent OD and wall. ZC's standard ranges are below; custom sizes are made to order.

Engineering Insight — Average wall vs minimum wall changes the price and the design. Tube can be ordered to average-wall or minimum-wall tolerance. Minimum-wall guarantees the thinnest point but costs more and runs heavier on average; average-wall is lighter and cheaper but allows thin spots within tolerance. Pressure design and U-bend thinning calculations must use the basis you actually ordered — state it explicitly rather than leaving it to the mill default.

5. Tube Configurations & Tubesheet Joints

Beyond grade and size, three configuration choices shape a tube order: the bundle geometry, the tube end finish, and whether the surface is plain or finned.

ZC standard ranges. Tighter OD/wall and average-wall vs minimum-wall basis should be specified on the order to match the exchanger design.

Tube ends are joined to the tubesheet by roller expansion, by welding, or by both (expanded-and-seal-welded) for higher integrity. U-bends introduce wall thinning on the outer radius and may require stress-relief on certain grades, so the U-tube schedule should be stated with the order. For the tube-to-tubesheet weld and broader connection context, see connection types overview →

Critical Engineering Point — Tube-side and shell-side corrosion are two different problems. A tube can pass on the inside and fail on the outside. Cooling water inside an austenitic stainless tube may cause chloride stress-corrosion cracking from the bore, while the same bundle is fine on the shell side. Always evaluate the corrosivity of both fluids, at operating temperature, before fixing the tube material.

6. Material Selection by Service

The decision path below maps the most common service environments to a starting tube material. Final selection must be confirmed against the process datasheet, design code and both fluid chemistries.

Starting-point selection only. Confirm against partial pressures, chloride content, temperature and velocity for the actual duty.

7. How to Specify Heat Exchanger Tubes (PO Checklist)

Engineering Insight — Heat exchanger tube PO must-haves

• Tube standard & grade: e.g. ASTM A213 TP316L (seamless) — not the pipe spec.

• OD & wall: with tolerance basis (average wall vs minimum wall).

• Length & form: straight or U-tube (with bend radii / thinning limit).

• Heat treatment / condition: annealed, solution-treated; PWHT for alloy grades.

• Surface & cleanliness: pickled, bright-annealed, ID/OD finish.

• NDT: eddy-current (ET), ultrasonic (UT), hydrostatic, flaring/flattening tests.

• Certs: PMI, EN 10204 3.1/3.2 MTR, full traceability.

As an order-to-make manufacturer, ZC produces tubes to your exchanger datasheet — specific grade, tolerance basis, length and U-bend schedule — rather than forcing the job into stock. View the heat exchanger tubes product page →, or our seamless stainless → and welded stainless → ranges.

8. Frequently Asked Questions

What material are heat exchanger tubes made of?

Heat exchanger tubes are made from carbon steel (ASTM A179, A192, A214), Cr-Mo alloy steel (A213 T11/T22), austenitic and duplex stainless steel (A213 seamless / A249 welded, grades TP304/304L, TP316/316L, 2205), copper and copper-nickel alloys (ASTM B111, 90/10 and 70/30 Cu-Ni), nickel alloys (Inconel, Hastelloy, Monel) and titanium (Gr.2, Gr.5). Material is chosen by operating temperature, pressure and the corrosivity of both the tube-side and shell-side fluids.

What is the difference between ASTM A179 and A192 tubes?

A179 is a cold-drawn seamless low-carbon steel tube for heat exchangers and condensers in lower-pressure service; it has no mandatory tensile test and is accepted on hardness (72 HRBW max). A192 is a seamless carbon steel boiler tube for high-pressure service, with a controlled silicon maximum of 0.25% and a hardness limit of 137 HBW. Both share minimum design values of 47 ksi (325 MPa) tensile and 26 ksi (180 MPa) yield.

What is the difference between ASTM A213 and A249?

A213 covers seamless ferritic and austenitic alloy-steel boiler, superheater and heat-exchanger tubes; A249 covers the welded equivalent in austenitic stainless. For stainless heat exchanger tubes, A213 is the seamless route and A249 the welded route. Note that A312 is a pipe specification, not the correct tube spec, even though it shares the TP304/TP316 grade designations.

What sizes do heat exchanger tubes come in?

Common heat exchanger tube outside diameters run from about 6 mm to 50 mm for seamless tube and up to roughly 150 mm for welded tube, with wall thickness from 0.5 mm to 10 mm and lengths from 1 m to 12 m. Thin walls and tight OD/wall tolerances are typical because tube-side heat transfer and tube-to-tubesheet expansion both depend on dimensional control.

Which heat exchanger tube material is best for seawater and marine condensers?

For seawater and marine condenser duty the usual choices are copper-nickel alloys (90/10 or 70/30 Cu-Ni) for good thermal conductivity and biofouling resistance, or titanium Grade 2 where chloride pitting and erosion-corrosion are severe. Standard carbon steel and 304 stainless are generally unsuitable for raw seawater because of chloride attack.

Are heat exchanger tubes seamless or welded?

Both are used. Seamless tube (A179, A192, A213) is preferred for higher-pressure and higher-temperature service and avoids a weld seam. Welded tube (A214 carbon steel, A249 stainless) is cost-effective for large bundles in lower-pressure service and is supplied with the weld zone fully heat-treated and tested. The choice depends on pressure, temperature, fluid and budget.

Source Heat Exchanger Tubes from ZC Steel Pipe

ZHENCHENG Steel Co., Ltd. (ZC Steel Pipe) manufactures order-to-make heat exchanger and condenser tubes to ASTM, ASME, EN, DIN, JIS and GB — carbon steel (A179/A192/A210/A214), Cr-Mo alloy (A213 T11/T22/T91), austenitic and duplex stainless (A213/A249, 2205), copper-nickel, nickel alloy and titanium. Strict QC: chemical analysis, mechanical and hydrostatic testing, eddy-current and ultrasonic NDT, and PMI. Projects delivered across Africa, the Middle East and South America.

Email: mandy.w@zcsteelpipe.com  |  WhatsApp: +86-139-1579-1813

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Related: Heat Exchanger Tubes (product) · Boiler Tube Grades · Austenitic Stainless Seamless · Seamless Stainless Pipe · Welded Stainless Pipe