Choosing between ASTM B861 and ASTM B338 for heat exchangers? Compare mechanical properties, corrosion resistance, and cost implications to make the right decision.
Introduction
When selecting titanium tubing for heat exchangers, engineers and procurement specialists often debate between ASTM B861 (titanium welded tubes) and ASTM B338 (titanium seamless tubes). Both standards have distinct advantages depending on application requirements.
This guide compares:
✔ Mechanical properties (strength, ductility)
✔ Corrosion resistance (critical for seawater & chemical processing)
✔ Cost & availability (impact on project budgets)
✔ Best applications (when to choose B861 vs B338)
1. Key Differences Between ASTM B861 and ASTM B338
1.1 Manufacturing Process
| Property | ASTM B861 (Welded) | ASTM B338 (Seamless) |
|---|---|---|
| Production Method | Rolled & welded from sheet | Extruded or pierced from a billet |
| Wall Thickness | More uniform | Slightly variable |
| Max Diameter | Up to 114 mm | Up to 50 mm (typically) |
1.2 Mechanical Properties
| Property | ASTM B861 (Grade 2) | ASTM B338 (Grade 2) |
|---|---|---|
| Tensile Strength | 345 MPa (min) | 345 MPa (min) |
| Yield Strength | 275 MPa (min) | 275 MPa (min) |
| Elongation | 20% (min) | 20% (min) |
*Note: Both standards offer similar base properties, but seamless tubes (B338) perform better under high-pressure cycling due to no weld seam weakness.*
2. Corrosion Resistance: Does Welding Affect Performance?
2.1 Seawater & Chloride Environments
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ASTM B338 (Seamless): Superior in high-chloride environments (e.g., desalination plants).
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ASTM B861 (Welded): Requires autogenous welding (no filler) to match corrosion resistance.
Case Study:
A chemical plant using B861 welded tubes saw pitting corrosion at welds after 5 years, while B338 seamless tubes lasted 15+ years.
2.2 Acid & Chemical Resistance
Both perform well in:
✔ Sulfuric acid (up to 10% concentration)
✔ Hydrochloric acid (low concentrations)
✔ NaOH & ammonia solutions
Critical Note: Welded tubes must pass ASTM G48 Method A testing to ensure weld zone integrity.
3. Cost & Lead Time Comparison
| Factor | ASTM B861 (Welded) | ASTM B338 (Seamless) |
|---|---|---|
| Price (per kg) | $30-$45 (lower due to simpler manufacturing) | $40-$60 (higher due to extrusion process) |
| Lead Time | 4-6 weeks (readily available) | 8-12 weeks (longer production time) |
| MOQ | 1-2 tons (flexible) | 5+ tons (higher minimums) |
Best for Budget-Conscious Buyers:
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B861 if pressure < 1,000 psi and corrosion risk is low.
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B338 if high-pressure cycling or aggressive media is involved.
4. When to Choose ASTM B861 vs B338?
✅ Choose ASTM B861 (Welded) If:
✔ Low-pressure heat exchangers (<1,000 psi)
✔ Short lead time required
✔ Cost-sensitive projects
✔ Large diameters needed (>50 mm)
✅ Choose ASTM B338 (Seamless) If:
✔ High-pressure or cyclic loading (e.g., power plants)
✔ Seawater or high-chloride environments
✔ Long-term reliability is critical (20+ years service)
✔ Smaller diameters (<50 mm)
5. Free Decision-Making Tool
Still unsure which standard fits your project?
📥 Download our free checklist:
👉 "ASTM B861 vs B338 Selection Guide" (PDF)
👉 Includes:
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Corrosion resistance test criteria
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Supplier evaluation checklist
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Cost comparison calculator
Get Your Free Guide Now, Email: linhui@lhtitanium.com
