Gr23 (Ti-6Al-4V ELI) Thin-Wall Titanium Heat Exchanger Pipe
Oct 23, 2025
What Is Grade 23 (Ti-6Al-4V ELI)?
Grade 23 is the extra-low-interstitial (ELI) version of the Ti-6Al-4V alloy, containing about 6% aluminum and 4% vanadium with tightly controlled oxygen, iron, carbon, nitrogen, and hydrogen. The lower interstitial limits give Grade 23 higher ductility and fracture toughness than Grade 5, which is why it is the preferred titanium alloy for surgical implants as well as for demanding thin-wall heat exchanger tubing. Thin-wall Grade 23 pipe is produced to ASTM B338 and ASME SB338, the specifications for seamless and welded titanium tubes for condensers and heat exchangers.
Chemical Composition
| Element | Limit (wt %) |
|---|---|
| Aluminum | 5.5-6.5 |
| Vanadium | 3.5-4.5 |
| Iron | ≤ 0.25 |
| Oxygen | ≤ 0.13 |
| Carbon | ≤ 0.08 |
| Nitrogen | ≤ 0.05 |
| Hydrogen | ≤ 0.012 |
| Titanium | Balance |
Mechanical Properties
| Property | Minimum (annealed) |
|---|---|
| Tensile strength | 860 MPa |
| Yield strength, 0.2% offset | 795 MPa |
| Elongation | 10% |
| Reduction of area | 25% |
Because of its higher strength, Grade 23 permits a thinner wall than commercially pure grades such as Grade 2 under the same design pressure, improving heat transfer and reducing tube weight.
Why Thin Walls Matter in Heat Exchangers
Thermal efficiency - a thinner wall lowers conductive resistance and raises the overall heat-transfer coefficient of the bundle.
Material saving - less metal per meter directly reduces cost for long tube bundles.
Weight reduction - important for offshore and floating process units.
Compact design - smaller shell diameters for the same duty.
Typical thin-wall tube dimensions are 12-38 mm outside diameter with 0.5-2.0 mm wall thickness, in straight lengths or U-bends, supplied in the annealed condition.
Manufacturing and Quality Control
Welded thin-wall tube is formed from continuously rolled strip, seam-welded by TIG or plasma welding with inert-gas shielding, annealed in line, and finished by sizing and straightening. Every tube is subjected to eddy-current or ultrasonic examination and hydrostatic or pneumatic pressure tests, together with flattening, flaring, and reverse-bend tests as required by ASTM B338. Chemical analysis and tensile tests are certified against the purchase specification.
Typical Applications
Shell-and-tube heat exchangers and condensers in seawater-cooled plants
Chemical and petrochemical process coolers handling chlorides
Desalination plants and offshore platform heat exchangers
Power-plant surface condensers
Frequently Asked Questions
What standards govern Grade 23 heat exchanger tube?
Seamless and welded titanium tube for condensers and heat exchangers is covered by ASTM B338 and ASME SB338; welded tube for general pressure service may also be supplied to ASTM B862.
Why choose Grade 23 instead of Grade 2 for thin-wall tube?
Grade 23 offers roughly 2.5 times the yield strength of Grade 2, so a much thinner wall can carry the same pressure, improving heat transfer and cutting weight and cost per meter.
Is Grade 23 tube weldable?
Yes. Grade 23 has excellent weldability when welded with proper inert-gas shielding; the ELI chemistry also reduces the risk of interstitial embrittlement in the heat-affected zone.
What surface condition is supplied?
Heat exchanger tube is normally supplied pickled or bright annealed with clean internal and external surfaces, free of scale, grease, and foreign matter, per ASTM B338 requirements.
Can thin-wall Grade 23 tube be U-bent?
Yes, U-bend tubes are common; bending is performed on mandrel benders with the tube in the annealed condition, followed by stress-relief or full annealing as specified.
Does Grade 23 resist seawater corrosion?
Yes. Like all titanium grades, Grade 23 forms a stable passive film and resists pitting and crevice corrosion in seawater, including high-velocity and chlorinated conditions.
