ASTM B338 vs ASTM B861
The most critical distinction between ASTM B338 titanium tube and ASTM B861 titanium tube lies in their manufacturing scope and end-use intent.
| Standard | Primary Manufacturing Method | Typical End Use | |
|---|---|---|---|
| ASTM B338 | Seamless and Welded Titanium and Titanium Alloy Tubes for Condensers and Heat Exchangers | Seamless (cold drawn) & Welded (strip formed) | Heat exchangers, condensers, surface coolers |
| ASTM B861 | Seamless Titanium and Titanium Alloy Pipes | Seamless only (extruded or pilgered) | High-pressure piping systems, chemical transfer lines |
ASTM B861 seamless titanium pipe is exclusively seamless and intended for high-pressure, large-diameter fluid transmission, while ASTM B338 titanium condenser tube covers both seamless and welded options but is specifically optimized for heat transfer applications with thinner walls.
Unsure which standard applies to your pressure rating? Ask our engineers
Manufacturing Process
ASTM B338 Titanium Tube Manufacturing (Seamless & Welded)
Seamless B338: Produced by cold pilgering or cold drawing from an extruded billet. This process refines the grain structure and allows for very thin walls (as low as 0.020").
Welded B338: Formed from a flat titanium strip, rolled into a tube shape, and welded longitudinally using TIG welding without filler metal. The weld seam is then cold worked and annealed to restore corrosion resistance.
ASTM B861 Titanium Pipe Manufacturing (Seamless Only)
ASTM B861 seamless pipe is manufactured exclusively through hot extrusion followed by cold finishing. Because it is designed for pressure containment rather than heat transfer, the walls are typically thicker, and the diameter range extends much larger (up to 12" or more).
| Process Feature | ASTM B338 | ASTM B861 |
|---|---|---|
| Seamless Available | Yes | Yes (only) |
| Welded Available | Yes | No |
| Minimum Wall Thickness | 0.015" (very thin) | Generally thicker (0.065"+) |
| Max OD Range | Up to 6" (seamless) / 24" (welded) | Up to 12"+ |
| Primary Forming | Cold pilgered / Drawn | Hot extruded + Cold finished |
Dimensional Tolerances: ASTM B338 Tube vs ASTM B861 Pipe
ASTM B338 Dimensional Tolerances (Tubing)
Outside Diameter (OD): Typically ±0.005" for precise heat exchanger tube sheet fit.
Wall Thickness: ±12.5% (tighter upon request).
Straightness: Must be suitable for tube-in-shell assembly.
ASTM B861 Dimensional Tolerances (Piping)
Outside Diameter (OD): Tolerances are based on Nominal Pipe Size (NPS) and are generally looser than tubing (e.g., ±1/32" for smaller diameters).
Wall Thickness: Based on Schedule (Sch 10, Sch 40, Sch 80), not percentage tolerance.
Straightness: Less critical; specified as a maximum deviation per unit length.
Mechanical Properties
Both standards cover Grade 2 commercially pure titanium, but the mechanical requirements are not identical. Because ASTM B861 pipes are intended for pressure service, the tensile and yield requirements are often slightly higher to account for thicker sections.
Comparison of Grade 2 Requirements Across Standards:
| Property | ASTM B338 Grade 2 (Tube) | ASTM B861 Grade 2 (Pipe) |
|---|---|---|
| Tensile Strength (min) | 345 MPa (50 ksi) | 345 MPa (50 ksi) |
| Yield Strength (min) | 275 MPa (40 ksi) | 275 MPa (40 ksi) |
| Elongation (min) | 20% | 20% |
| Hydrostatic Test | Required (per tube) | Required (per pipe) |
| Flattening Test | Required (for welded) | Not applicable |
| Flaring Test | Required (for seamless) | Not applicable |
While the strength numbers appear similar, the titanium pipe standard (ASTM B861) emphasizes burst pressure and leakage integrity, whereas ASTM B338 tubing emphasizes formability (flaring, bending) to allow tube-to-tube sheet expansion.
Where to Use Each Titanium Tube Specification
When to Specify ASTM B338 Titanium Tube
Heat Exchangers: Tube bundles where thin walls maximize heat transfer.
Condensers: Surface condensers in power plants with cooling water on one side and steam on the other.
Evaporators: Desalination and chemical evaporator coils.
Bending Applications: Where the tube must be U-bent or coiled.
When to Specify ASTM B861 Titanium Pipe
Transfer Lines: High-pressure chemical transfer from storage to reactors.
Piping Manifolds: Header pipes distributing fluid to multiple heat exchanger tubes.
High-Pressure Hydraulics: Systems requiring thick walls for burst resistance.
Large Diameter: Projects requiring nominal pipe sizes (NPS) rather than tube OD.
Which Standard Is More Economical?
Cost is rarely the sole factor, but it is always a significant one. From a procurement perspective, the price difference between ASTM B338 welded tube and ASTM B861 seamless pipe can be substantial.
| Factor | ASTM B338 (Welded) | ASTM B338 (Seamless) | ASTM B861 (Seamless) |
|---|---|---|---|
| Relative Cost | Lowest | Medium | Highest |
| Why? | Strip forming is efficient | Cold pilgering is labor-intensive | Hot extrusion + finishing is costly |
| Lead Time | Shortest (2-4 weeks) | Medium (4-6 weeks) | Longest (6-10 weeks) |
| Volume Flexibility | High (small batches OK) | Medium | Lower (larger MOQ) |
Procurement Insight: If your application allows for welded construction (non-corrosive seam exposure), ASTM B338 welded tubing offers the best value. If you genuinely need seamless for pressure integrity, compare whether ASTM B338 seamless tube meets your requirements before jumping to ASTM B861, as the latter often carries a premium due to its larger diameter capabilities.
Quality Assurance
Our Standard Testing Modules for Tubing (ASTM B338):
Hydrostatic Testing: 100% of tubes are pressurized to specified test pressure, held for minimum 5 seconds, with zero leakage.
Eddy Current Testing (ECT): Automated non-destructive testing of the entire tube length (surface and subsurface flaw detection).
Flattening Test: A ring sample is flattened to verify ductility and weld integrity (for welded tubes).
Flaring Test: A mandrel expands the tube end to 1.5x OD to confirm cracking resistance.
Dimensional Inspection: OD, ID, wall thickness, and ovality measured with laser micrometers.
Our Additional Testing for Piping (ASTM B861):
Ultrasonic Testing (UT): Used instead of ECT for thicker walls to detect internal laminations.
Bend Test: Ensures the pipe can withstand bending without fracture.
Charpy Impact Test: For low-temperature applications where notch toughness is critical.
Request a complete test report matrix for your project
Factory Capabilities
Factory Highlights:
| Capability | ASTM B338 Line | ASTM B861 Line |
|---|---|---|
| Production Method | Cold Pilgering / Strip Welding | Hot Extrusion + Cold Drawing |
| Max Diameter | 6" (seamless) / 24" (welded) | 12" NPS |
| Wall Thickness Range | 0.015" – 0.250" | 0.065" – 1.000" |
| Heat Treatment | Vacuum Annealing | Vacuum Annealing + Stress Relief |
| Monthly Capacity | 400 tons | 150 tons |
Packaging and Shipping
Standard Packaging Modules:
Individual Sleeving: Each tube is slipped into a protective plastic sleeve to prevent scratching.
End Cap Sealing: Both ends are capped with heavy-duty plastic plugs to block moisture and debris (critical for clean-service tubing).
Layer Separation: Tubes are bundled in layers with plywood dividers or foam interleaving to prevent friction galling.
Steel-Framed Crates: For heavy or long pipes, we use reinforced steel-framed wooden crates with lifting lugs.
Desiccant Bags: Placed inside bundles to absorb condensation for sea-freight shipments.
FAQ
Q1: Can I use ASTM B338 titanium tube for high-pressure gas lines?
A: Yes, but only if the pressure rating matches your system. ASTM B338 tubes are generally thinner-walled. For gas lines above 10 MPa, ASTM B861 seamless pipe is usually recommended due to its thicker walls and burst pressure margins.
Q2: Does ASTM B861 allow welded tubes?
A: No. ASTM B861 explicitly covers seamless titanium pipe only. If you require a welded pipe, you should refer to ASTM B862 (Welded Titanium Pipe) instead.
Q3: Which standard is more expensive: ASTM B338 seamless or ASTM B861?
A: ASTM B861 is almost always more expensive for comparable diameters because it requires hot extrusion and larger billet sizes. However, for small diameters (under 2"), ASTM B338 seamless can be competitively priced.
Q4: Is the Grade 2 material identical in both standards?
A: Chemically, yes. Grade 2 has the same limits in both standards. Mechanically, the testing requirements differ (e.g., flattening test applies to B338 tubes but not B861 pipes), but the strength values are the same.
Q5: Can I bend ASTM B861 pipe into a U-shape like B338 tubing?
A: Not recommended. ASTM B861 pipes have thicker walls and larger diameters, making cold bending difficult and potentially causing wrinkling. Use ASTM B338 tubing for U-bend applications.
Q6: What is the main inspection difference between the two standards?
A: ASTM B338 requires flattening and flaring tests for ductility verification. ASTM B861 requires hydrostatic and ultrasonic testing but does not require flattening, as pipes are not usually expanded into tube sheets.
Q7: Can I substitute ASTM B338 seamless tube for ASTM B861 pipe in an emergency?
A: Only if the wall thickness and pressure rating are equivalent. Substitution is not recommended without a full engineering re-calculation, as tubing schedules do not directly correspond to pipe schedules.
Q8: Which standard has a faster lead time?
A: ASTM B338 welded tube has the fastest lead time (2-3 weeks). ASTM B338 seamless is 4-6 weeks. ASTM B861 seamless pipe is the longest, often 8-12 weeks due to the extrusion process.
