GR1 Titanium Pipe: Sizes, Specs, and Applications
May 20, 2026
What ASTM Specs Cover GR1 Pipe and Tube
ASTM B861 covers seamless pipe for general industrial piping, with hydrostatic test and standard tolerances. ASTM B338 covers seamless or welded tube for heat exchangers and condensers, requiring flattening and flaring tests with tight tolerances. ASTM B862 covers welded tube for general industrial tubing, with lower cost and flattening test.
GR1 Pipe Sizes (ASTM B861, NPS)
| NPS | OD (mm) | Sch 5S wall (mm) | Sch 10S wall (mm) | Sch 40S wall (mm) |
|---|---|---|---|---|
| 1/2 | 21.3 | 1.65 | 2.11 | 2.77 |
| 3/4 | 26.7 | 1.65 | 2.11 | 2.87 |
| 1 | 33.4 | 1.65 | 2.77 | 3.38 |
| 1-1/2 | 48.3 | 1.65 | 2.77 | 3.68 |
| 2 | 60.3 | 1.65 | 2.77 | 3.91 |
| 3 | 88.9 | 2.11 | 3.05 | 5.49 |
| 4 | 114.3 | 2.11 | 3.05 | 6.02 |
| 6 | 168.3 | 2.77 | 3.40 | 7.11 |
| 8 | 219.1 | 2.77 | 3.76 | 8.18 |
| 10 | 273.0 | 3.40 | 4.19 | 9.27 |
GR1 Heat Exchanger Tube Sizes (ASTM B338)
12.70 mm OD (0.7, 0.9, 1.0 mm wall), 15.88 mm (0.9, 1.0, 1.2 mm), 19.05 mm (1.0, 1.2, 1.6 mm, most common), 25.40 mm (1.2, 1.6, 2.1 mm), and 31.75 mm (1.2, 1.6, 2.5 mm).
Weight Calculation
Weight per meter in kilograms: (OD in mm minus wall in mm) times wall in mm times 0.0142. Example for 2 inch schedule 40 pipe (OD 60.3 mm, wall 3.91 mm): (60.3 - 3.91) x 3.91 x 0.0142 = 3.13 kg per meter.
Seamless vs Welded
Seamless tube is required for high pressure piping, code vessels, and some heat exchanger specs. Welded tube is fully annealed and tested and saves money for non-critical service.
Applications
GR1 pipe (B861): chemical transfer lines, marine piping, industrial process piping, desalination plant piping, and offshore platform piping. GR1 tube (B338): shell-and-tube heat exchangers, U-bend condenser tubes, titanium reactors, and chemical processing equipment. GR1 tube (B862): instrumentation lines, low-pressure chemical transfer, drain and vent lines, and general industrial tubing.
GR1 vs GR2
GR1 has tensile strength 240 MPa min with 24 percent min elongation and excellent formability; GR2 has 345 MPa min and 20 percent min elongation. For straight pipe, either grade works. For tight U-bends, use GR1 because GR2 can crack.
Frequently Asked Questions
What is the difference between pipe and tube? Pipe is measured by nominal size and schedule; tube is measured by exact OD and wall thickness.
What is the most common GR1 tube size? 19.05 mm OD with 1.2 or 1.6 mm wall.
How do I calculate GR1 titanium pipe weight? (OD mm minus wall mm) times wall mm times 0.0142 equals kilograms per meter.
Is welded tube weaker than seamless? Properly made welded tube has a weld strength factor of 0.85 to 1.0; for high-pressure or cyclic service, seamless is safer.
What is the difference between ASTM B861 and ASTM B338? ASTM B861 covers seamless pipe for general industrial piping with hydrostatic testing and standard tolerances; ASTM B338 covers seamless or welded tube for heat exchangers and condensers, requiring flattening and flaring tests with tighter tolerances.
Why is GR1 recommended for tight U-bends? GR1 has a minimum tensile strength of 240 MPa with 24 percent minimum elongation, so it forms tight U-bends without cracking, while the stronger GR2 at 345 MPa minimum can crack in such bends.
