Titanium Grade 12 (3.7105 / UNS R53400) High-Pressure Alloy Pipe
Oct 21, 2025
What Is Titanium Grade 12?
Titanium Grade 12 (UNS R53400, Werkstoff 3.7105) is a near-alpha titanium alloy containing about 0.3% molybdenum and 0.8% nickel. The additions raise strength above that of commercially pure Grade 2 while improving resistance to crevice corrosion in hot chloride and reducing-acid environments. Grade 12 is therefore a workhorse material for high-pressure heat exchanger tubing, chemical process piping, and geothermal and marine service, and it is covered by ASTM B861 (seamless pipe and tube), ASTM B862 (welded tube), and the corresponding ASME SB861 and SB862 specifications.
Chemical Composition
| Element | Limit (wt %) |
|---|---|
| Nitrogen | ≤ 0.03 |
| Carbon | ≤ 0.08 |
| Hydrogen | ≤ 0.015 |
| Iron | ≤ 0.30 |
| Oxygen | ≤ 0.25 |
| Molybdenum | 0.2-0.4 |
| Nickel | 0.6-0.9 |
| Titanium | Balance |
Mechanical Properties (Annealed)
| Property | Value |
|---|---|
| 0.2% yield strength | ≥ 345 MPa |
| Tensile strength | ≥ 480 MPa |
| Elongation | ≥ 18% |
| Hardness | ≈ 170 HB (typical) |
| Modulus of elasticity | ≈ 105 GPa |
| Density | ≈ 4.5 g/cm³ |
Because the strength of Grade 12 exceeds that of Grades 2 and 7, a thinner wall can be used at the same design pressure, saving material and improving heat transfer in tube bundles.
Standards and Designations
ASTM B861 - seamless and welded titanium and titanium alloy pipe
ASTM B862 - welded titanium and titanium alloy tube
ASME SB861 / SB862 - identical requirements adopted into the ASME Boiler and Pressure Vessel Code
UNS R53400 - unified numbering system designation for Grade 12
Werkstoff 3.7105 - German designation commonly referenced in European projects
High-Pressure and Corrosion Service
Grade 12 resists general corrosion, pitting, and crevice corrosion in hot brines, seawater, and dilute reducing acids, and it is less sensitive to iron contamination than unalloyed titanium. These characteristics make it suitable for high-pressure heat exchangers, process piping, and geothermal wells where Grade 2 would require a thicker wall or where crevice conditions are severe.
Fabrication and Quality Control
Grade 12 is weldable by the same procedures used for CP titanium, with inert-gas shielding on both sides of the joint. Pipe is produced by pilgering or drawing for seamless forms, or by strip forming and welding for welded forms, followed by annealing, sizing, and non-destructive examination. Each heat is delivered with a mill test certificate listing chemistry, tensile properties, and hydrostatic or eddy-current test results.
Frequently Asked Questions
What is the difference between Grade 12 and Grade 2 titanium?
Grade 12 adds about 0.3% molybdenum and 0.8% nickel, raising strength by roughly 40% and improving crevice-corrosion resistance in hot chlorides, while retaining excellent weldability.
Is Grade 12 suitable for seawater heat exchangers?
Yes. Grade 12 has excellent resistance to seawater and hot brine, including crevice corrosion, and is widely used in marine and desalination heat exchangers.
Which standard covers Grade 12 pipe?
Seamless pipe is covered by ASTM B861 and ASME SB861; welded tube by ASTM B862 and ASME SB862. Plate and sheet follow ASTM B265.
What does UNS R53400 mean?
UNS R53400 is the registered number for Grade 12 in the Unified Numbering System for metals and alloys; the R prefix indicates a titanium or reactive metal.
Can Grade 12 pipe be welded?
Yes, with standard titanium welding practice: inert-gas shielding of the weld face and root, clean filler wire of matching grade, and post-weld inspection.
