ASTM B338 GR1 Heat Exchanger Tubes Data Sheet
May 20, 2026
| Property | Value |
|---|---|
| Standard | ASTM B338 (ASME SB338) |
| Grade | GR1 (Grade 1, CP1) |
| Material | Commercially pure titanium |
| Product forms | Seamless tube, welded tube |
| Primary application | Heat exchangers, condensers, evaporators |
Chemical Composition
ASTM B338 requires the following chemical limits for GR1 titanium.
| Element | Percentage (max unless noted) |
|---|---|
| Titanium (Ti) | 99.5% minimum |
| Oxygen (O) | 0.18% |
| Iron (Fe) | 0.20% |
| Carbon (C) | 0.08% |
| Nitrogen (N) | 0.03% |
| Hydrogen (H) | 0.015% |
Mechanical Properties
| Property | Requirement |
|---|---|
| Tensile strength | 240 MPa minimum |
| Yield strength (0.2% offset) | 170 MPa to 310 MPa (depending on temper) |
| Elongation | 24% minimum in 50mm (or 4D) |
| Reduction of area | Not specified, typically 30-40% |
| Hardness | 120 HV to 200 HV (Vickers) |
Typical values for annealed tube:
| Property | Typical value |
|---|---|
| Tensile strength | 280-350 MPa |
| Yield strength | 200-250 MPa |
| Elongation | 28-35% |
| Hardness | 140-170 HV |
Physical Properties
| Property | Value |
|---|---|
| Density | 4.51 g/cm³ |
| Modulus of elasticity | 105 GPa |
| Shear modulus | 40 GPa |
| Poisson's ratio | 0.34 |
| Melting point | 1660°C |
| Thermal conductivity | 16 W/m·K (at 20°C) |
| Thermal expansion coefficient | 8.6 x 10⁻⁶ /°C (20-100°C) |
| Electrical resistivity | 55 μΩ·cm (at 20°C) |
| Specific heat | 520 J/kg·K |
Dimensional Tolerances
Outside diameter tolerance (seamless and welded):
| OD (mm) | Tolerance (± mm) |
|---|---|
| Up to 25.4 | 0.10 |
| 25.4 to 38.1 | 0.13 |
| 38.1 to 50.8 | 0.15 |
| 50.8 to 76.2 | 0.20 |
| 76.2 to 101.6 | 0.25 |
Wall thickness tolerance:
| Tube type | Tolerance |
|---|---|
| Seamless | ±10% of nominal wall |
| Welded | ±10% of nominal wall |
Length tolerance:
| Length (m) | Tolerance (± mm) |
|---|---|
| Up to 6 | 3 |
| 6 to 12 | 5 |
| 12 to 30 | 10 |
Straightness tolerance:
| Tube type | Maximum deviation |
|---|---|
| Seamless | 1.5 mm per 3 meters |
| Welded | 1.5 mm per 3 meters |
Standard Sizes
Most common heat exchanger tube sizes:
| OD (mm) | Wall (mm) | Weight per meter (kg) | Typical application |
|---|---|---|---|
| 12.70 | 0.70 | 0.12 | Small condensers |
| 12.70 | 0.90 | 0.15 | Small condensers |
| 12.70 | 1.00 | 0.17 | Small condensers |
| 15.88 | 0.90 | 0.19 | Standard industrial |
| 15.88 | 1.00 | 0.21 | Standard industrial |
| 15.88 | 1.20 | 0.25 | Standard industrial |
| 19.05 | 1.00 | 0.26 | Most common |
| 19.05 | 1.20 | 0.31 | Most common |
| 19.05 | 1.60 | 0.40 | Most common |
| 25.40 | 1.20 | 0.43 | Large exchangers |
| 25.40 | 1.60 | 0.57 | Large exchangers |
| 25.40 | 2.10 | 0.73 | High pressure |
| 31.75 | 1.20 | 0.54 | High capacity |
| 31.75 | 1.60 | 0.72 | High capacity |
| 31.75 | 2.50 | 1.09 | High pressure |
Required Tests
Tests for seamless tube:
| Test | ASTM method | Acceptance criteria |
|---|---|---|
| Chemical analysis | E1409, E1941, E2371 | Within spec limits |
| Tensile | E8/E8M | 240 MPa min, 24% elongation min |
| Flattening | E2750 | No cracks |
| Flaring | E2750 | No cracks |
| Hydrostatic or eddy current | E426 or E571 | Leak free |
Tests for welded tube (additional):
| Test | ASTM method | Acceptance criteria |
|---|---|---|
| Reverse flattening | E2750 | No cracks (weld at 90 degrees) |
| Weld radiography (when specified) | E2737 | No weld defects |
U-Bend Data
Minimum bend radius for GR1:
| Tube OD (mm) | Minimum bend radius (mm) | Recommended radius (mm) |
|---|---|---|
| 12.70 | 19 | 25 |
| 15.88 | 24 | 32 |
| 19.05 | 29 | 38 |
| 25.40 | 38 | 50 |
| 31.75 | 48 | 64 |
Formula: Minimum radius = 1.5 x OD. Recommended radius = 2.0 x OD.
For welded tube U-bends: Weld seam must be placed on neutral axis of the bend.
Leg length tolerance: ±1.5 mm typical. Tighter tolerances available upon request.
Bend angle tolerance: ±1 degree typical.
Tube Expansion Data
Recommended expansion parameters for GR1 tube:
| Parameter | Value |
|---|---|
| Expansion method | Roller or hydraulic |
| Target expansion | 5-8% increase in OD |
| Lubricant | Titanium-compatible (no chlorinated solvents) |
| Roller passes | 2-3 light passes (not one heavy pass) |
Why titanium expands differently than steel:
Titanium work-hardens quickly
One heavy pass causes uneven expansion and galling
Multiple light passes produce smooth, uniform expansion
Seamless vs Welded
| Parameter | Seamless | Welded |
|---|---|---|
| ASTM B338 coverage | Yes | Yes |
| Weld seam | None | Longitudinal |
| Reverse flattening test | Not required | Required |
| Cost | Higher (baseline) | Lower (15-25% less) |
| Typical lead time (custom) | 6-8 weeks | 4-6 weeks |
| U-bend capability | Excellent | Excellent (with seam placement) |
GR1 vs GR2 for Heat Exchanger Tubes
| Parameter | GR1 | GR2 |
|---|---|---|
| Oxygen max | 0.18% | 0.25% |
| Tensile strength | 240 MPa | 345 MPa |
| Elongation | 24% | 20% |
| U-bend suitability | Excellent | Not recommended |
| Corrosion resistance | Excellent | Excellent (same) |
Common Applications
| Industry | Application | Typical size (OD mm) |
|---|---|---|
| Power generation | Steam condenser | 19.05, 25.40 |
| Chemical processing | Acid cooler | 19.05, 25.40 |
| Marine | Seawater cooler | 19.05, 25.40 |
| Desalination | Brine heater | 25.40 |
| HVAC | Chiller condenser | 15.88, 19.05 |
| Pharmaceutical | Sterile cooler | 12.70, 15.88 |
FAQ
1. What is the difference between ASTM B338 and ASME SB338?
No difference. SB338 is the ASME adoption of B338 for pressure vessel code applications. Same material, same tests, same tolerances.
2. What is the oxygen limit for B338 GR1?
0.18% maximum. This is the same for all GR1 specifications including B861 and B862.
3. What is the minimum bend radius for B338 GR1 tube?
1.5 times the outside diameter. For 19.05mm OD, minimum is 28.6mm.
4. What tests are required for B338 welded tube?
Chemical, tensile, flattening, reverse flattening, flaring, and hydrostatic or eddy current.
5. What is the reverse flattening test?
A flattening test with the weld seam at 90 degrees to the compression direction. Tests weld seam ductility.
6. What is the wall thickness tolerance for B338 GR1 tube?
±10% for both seamless and welded.
7. How do I calculate tube weight?
(OD in mm minus wall in mm) times wall in mm times 0.0142 equals kg per meter.
8. What is the standard length for B338 tubes?
6 meters is standard. Cut lengths from 1 to 30 meters available.
9. Can I get B338 GR1 tube in stock?
Common sizes (19.05mm and 25.40mm OD) are typically in stock. Contact us for current availability.
10. What is the difference between seamless and welded for heat exchangers?
Seamless has no weld seam and costs more. Welded has a longitudinal weld seam and costs 15-25% less. Both are allowed by B338.
11. Is welded tube acceptable for U-bends?
Yes, with weld seam placed on the neutral axis of the bend.
12. What is the maximum temperature for B338 GR1 in service?
300-400°C in air. Above that, oxidation becomes a concern. In reducing atmospheres or with inert gas protection, higher temperatures possible.
13. Does B338 GR1 require post-weld heat treatment after bending?
No. GR1 does not require heat treatment after cold bending.
