ASTM B338 Titanium Grade 12 (UNS R53400) Pipe and Bright Tube
Oct 22, 2025 ASTM-B338-Titanium.pdf
What Is Grade 12 Titanium?
Grade 12 titanium, designated UNS R53400 and W. Nr. 3.7105, is a titanium alloy with about 0.3% molybdenum and 0.8% nickel added to commercially pure titanium. The small additions strengthen the alpha matrix and improve resistance to reducing and crevice-corrosion environments, which pure titanium handles less well. Grade 12 is frequently specified for heat exchanger tubing, chemical processing piping and marine service where a combination of corrosion resistance, weldability and elevated-temperature strength is required.
Chemical Composition per ASTM B338
The composition below is specified for Grade 12 seamless and welded tube in ASTM B338. Note that the hydrogen limit is 0.015% maximum, an important control point for weldability and ductility.
| Element | Maximum or Range |
|---|---|
| Titanium | Balance |
| Carbon | 0.08% max |
| Iron | 0.30% max |
| Nitrogen | 0.05% max |
| Oxygen | 0.35% max |
| Hydrogen | 0.015% max |
| Molybdenum | 0.2-0.4% |
| Nickel | 0.6-0.9% |
Mechanical Properties per ASTM B338
Grade 12 tube is supplied in the annealed condition. The specified minimum mechanical properties per ASTM B338 are shown below; typical mill values are usually a little higher.
| Property | Minimum Value |
|---|---|
| Tensile strength | 483 MPa (70 ksi) |
| Yield strength, 0.2% offset | 345 MPa (50 ksi) |
| Elongation in 4D | 18% |
The 483 MPa tensile minimum is roughly 40% higher than Grade 2 commercially pure titanium, which makes Grade 12 attractive for thin-wall heat exchanger tubes that must resist both corrosion and pressure.
Bright Tube Finish and Dimensional Range
Bright tube refers to tube supplied with a bright annealed surface, produced by annealing in a protective atmosphere so that no oxide scale forms. Common surface options include bright, polished, No. 4 finish and matt finish. Typical dimensional ranges for ASTM B338 Grade 12 tube are 5-600 mm outside diameter, 2-120 mm wall thickness and 5-12 m length, with plain or bevelled ends. Tolerances follow ASTM B338 for outside diameter, wall thickness and straightness.
Corrosion Resistance
Grade 12 resists the same oxidizing environments as commercially pure titanium: seawater, chlorides, wet chlorine, nitric acid and most industrial atmospheres. The molybdenum and nickel additions extend protection into mildly reducing media and improve resistance to crevice corrosion in hot chloride solutions, where CP grades can suffer localized attack. Grade 12 also resists stress corrosion cracking and is one of the few titanium grades permitted in some high-temperature brine and sour-service applications.
Applications
Shell-and-tube heat exchangers and condensers in chemical and power plants
Seawater cooling systems, desalination plants and offshore platforms
Chlor-alkali and soda ash process piping
Petrochemical and refinery heat transfer equipment
Pulp bleaching and other chloride-rich process lines
Quality Control and Testing
ASTM B338 tube is verified by chemical analysis, tensile testing per ASTM E8, and one or more non-destructive examinations such as hydrostatic testing, eddy current examination per ASTM E426 or ultrasonic examination. Flattening and flare tests confirm ductility of the tube body and welds. Buyers should request an EN 10204 3.1 certificate with heat number, composition and mechanical results, and confirm the finish and dimensional tolerances against the purchase specification.
Frequently Asked Questions
1. What does UNS R53400 correspond to?
UNS R53400 is the registered number for Grade 12 titanium (Ti-0.3Mo-0.8Ni). The European Werkstoff number is 3.7105.
2. How strong is Grade 12 compared with Grade 2?
Grade 12 has a minimum tensile strength of 483 MPa versus 345 MPa for Grade 2, and a higher yield strength, so thinner walls can be used for the same pressure.
3. Is Grade 12 tube weldable?
Yes. Grade 12 welds readily with argon shielding using matching or Grade 2 filler, and the welded tube form is covered by ASTM B338 with the same property requirements as seamless.
4. What does bright tube mean?
Bright tube is annealed in a protective atmosphere so the surface stays clean and oxide-free. It is often specified where internal cleanliness or a smooth surface is needed, such as instrument lines and polished heat exchanger tubes.
5. Where is Grade 12 preferred over pure titanium?
In hot chloride service with crevice risk, mildly reducing media, and applications above about 150 C where pure titanium loses strength. It is a standard choice for seawater and chemical heat exchangers.
6. What standards cover Grade 12 pipe and tube?
ASTM B338 for heat exchanger tube, ASTM B861 for seamless pipe, ASTM B862 for welded pipe, and the equivalent ASME SB versions. Plate and sheet are covered by ASTM B265.
