Stainless Steel, Duplex and Nickel Alloy Tubes for Heat Exchangers and Boilers
Recommended Pipe & Tube Materials
Heat exchangers, condensers and boilers depend on thousands of thin-walled tubes transferring heat reliably for decades. A single leaking tube can shut down a unit or contaminate a process. This guide explains how to choose stainless steel, duplex and nickel alloy heat exchanger tubes and which standards to specify.
What Heat Exchanger Tubes Must Do
- Resist corrosion on both sides: tube side (process fluid) and shell side (cooling water, steam, gas)
- Resist stress corrosion cracking, especially in chloride-bearing cooling water
- Transfer heat efficiently with thin walls and clean surfaces
- Withstand pressure and temperature cycles without fatigue failure
- Be formable into U-bends and expandable into tubesheets
Common Materials and Where They Fit
| Material | Typical use |
|---|---|
| 304 / 304L | Clean water, food and general process, low-chloride services |
| 316 / 316L | Chemical, process and cooling water with moderate chlorides |
| 317L, 904L | Higher chlorides and acid conditions |
| Duplex 2205 | Chloride-bearing cooling water, higher pressure; resists chloride SCC |
| Super duplex 2507, 6Mo | Seawater and brackish water coolers |
| Alloy 825 (N08825) | Acid and chloride SCC resistance, e.g., sulfuric and phosphoric acid services |
| Alloy 625 (N06625) | Severe corrosion and high-temperature services |
| Alloy 800 / 800H | High-temperature process heaters, steam generation |
Titanium is also common for seawater condensers, but stainless steel, duplex and nickel alloys cover a much wider range of process conditions.
Choosing Between Seamless and Welded Tubes
- Seamless (ASTM A213, A789, B163): preferred for high pressure, critical services and severe conditions
- Welded and cold-drawn (ASTM A249, A268/A269, A789 welded): cost-effective for many condenser and low-to-medium pressure services, with good dimensional accuracy
Key Standards
- ASTM A213: seamless ferritic and austenitic boiler, superheater and heat-exchanger tubes
- ASTM A249: welded austenitic boiler, superheater, heat-exchanger and condenser tubes
- ASTM A789 / A688: duplex and feedwater heater tubes
- ASTM B163: seamless nickel and nickel alloy condenser and heat-exchanger tubes
- TEMA standards for exchanger construction, and ASME Section VIII for pressure design
Specification Details Buyers Should Not Forget
- OD, wall thickness and tolerances (tube-to-tubesheet fit requires tight control)
- Length and straightness, including straight tubes or U-bend tubes with specified radius
- Heat treatment: solution annealed, with stress relief of U-bends where required
- Testing: hydrostatic or eddy current testing of every tube, flattening and flaring tests, and IGC test where required
- Surface condition: bright annealed for clean heat transfer or pickled, depending on the service
- Packaging: protection for ends and bundles to avoid damage during shipping
- Email: info@duplex-stainless-steel.com
- WhatsApp / WeChat: +86-13587686960
- Send Your Inquiry →
Frequently Asked Questions
Q1: Which is better for heat exchanger tubes, 316L or duplex 2205?
If the cooling water or process stream contains significant chlorides, duplex 2205 is better because of its higher resistance to chloride stress corrosion cracking and pitting, and its higher strength allows thinner walls.
Q2: What is the difference between ASTM A213 and A249?
A213 covers seamless tubes and A249 covers welded tubes. Both are used for boilers, superheaters, heat exchangers and condensers, in austenitic and other grades.
Q3: Can you supply U-bend tubes?
Yes, please provide the bend radius, number of bends and heat treatment requirements in your inquiry.
Q4: What tests are performed on heat exchanger tubes?
Typical tests include hydrostatic or eddy current testing, flattening, flaring, hardness and intergranular corrosion tests, depending on the specification and customer requirement.
Request a Quote for Heat Exchanger and Boiler Tubes
Send us your grade, standard, OD × wall thickness × length, U-bend details, quantity and testing requirements, and we will reply with pricing and lead time within 24 hours.