ASTM B861 Titanium Seamless Pipe: Complete Specification Guide | Grade 2, 5, 7, 12
Published by Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd on 2026-10-27
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{"@type": "Question", "name": "What is the difference between ASTM B861 and ASTM B338?", "acceptedAnswer": {"@type": "Answer", "text": "B861 covers general-service titanium seamless pipe and tube (process piping, pressure tubing, mechanical tubing). B338 covers seamless and welded titanium tubes specifically for condensers and heat exchangers. B861 is the correct standard for process piping; B338 is correct for heat exchanger tubing. The chemistry is similar but dimensional tolerances and test requirements differ — B338 has tighter OD tolerance for tube-bundle fit-up, while B861 has broader size coverage for piping."}},
{"@type": "Question", "name": "What is the difference between B861 seamless pipe and B862 welded pipe?", "acceptedAnswer": {"@type": "Answer", "text": "B861 pipe is produced by extrusion or rotary piercing of a solid billet — no weld seam exists. B862 pipe is made by forming titanium strip/plate into a cylinder and welding the longitudinal seam. Seamless pipe has no HAZ, no seam-corrosion risk, and is mandatory for cyclic-pressure or high-reliability service. Welded pipe costs 30-40% less and is acceptable for steady-state, low-cycle, non-critical service. The choice is driven by service criticality, not just cost."}},
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{"@type": "Question", "name": "Can B861 Grade 2 pipe be bent in the field?", "acceptedAnswer": {"@type": "Answer", "text": "Yes, Grade 2 has excellent cold formability. Minimum bend radius is typically 3× OD for Sch 10S and 4× OD for Sch 40S/80S. Cold bending does not require stress relief for Gr2. For Grade 5 (Ti-6Al-4V), cold bending is not recommended — the alloy work-hardens rapidly and requires stress relief at 480-650°C after bending. Always use a mandrel bender for sizes above 2 inch to prevent ovalization."}},
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<strong>On This Page:</strong>
<ol>
<li><a href="#h2-1">Scope and Coverage</a></li>
<li><a href="#h2-2">Grade Selection by Service</a></li>
<li><a href="#h2-3">Chemical Composition</a></li>
<li><a href="#h2-4">Mechanical Properties</a></li>
<li><a href="#h2-5">Dimensional Tolerances</a></li>
<li><a href="#h2-6">Pressure Rating Calculation</a></li>
<li><a href="#h2-7">Procurement Checklist</a></li>
<li><a href="#h2-8">Frequently Asked Questions</a></li>
</ol>
</div>
<h1>ASTM B861 Titanium Seamless Pipe: Complete Specification Guide</h1>
<p><em>Reviewed by the Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd.</em></p>
<h2 id="h2-1">1. Scope and Coverage</h2>
<p>ASTM B861 covers <strong>titanium and titanium-alloy seamless pipe and tube</strong> for general corrosion-resistant, high-temperature, and low-temperature industrial service. This is the primary material standard for titanium seamless piping used in process plants, offshore platforms, desalination facilities, and chemical processing lines.</p>
<p>The standard covers commercially pure titanium (Grades 1, 2, 3, 7, 11, 16, 17) and alloy grades (Grades 5, 9, 12, 23, 24, 25, 26, 27, 28, 30, 31, 33, 34, 35, 36, 37, 38). For process piping, <strong>Grades 2, 5, 7, 9, and 12</strong> represent over 95% of procurement volume.</p>
<p>B861 defines chemistry, tensile properties, flattening test, flaring test (for tubes), hydrostatic or pneumatic test, dimensional tolerances, and marking. It does <strong>not</strong> cover:</p>
<ul>
<li>Welded pipe (ASTM B862 — different manufacturing route, different inspection)</li>
<li>Heat exchanger tubes (ASTM B338 — tighter OD tolerance, different test regimen)</li>
<li>Mechanical tubing for structural/ornamental use (also B861 but different service conditions)</li>
</ul>
<p><strong>Critical distinction:</strong> B861 is for <em>seamless</em> product only — manufactured by extrusion or rotary piercing of a solid billet, with no longitudinal weld seam. For buyers choosing between seamless and welded, the rule is: <strong>seamless for cyclic pressure, welded for steady-state non-critical service.</strong></p>
<h2 id="h2-2">2. Grade Selection by Service</h2>
<table>
<thead>
<tr><th>Grade</th><th>UNS</th><th>Key property</th><th>Primary pipe application</th><th>Relative cost index</th></tr>
</thead>
<tbody>
<tr><td>Grade 2</td><td>R50400</td><td>Best all-around: corrosion + formability + cost</td><td>General process piping, seawater lines, chemical transfer</td><td>1.0 (baseline)</td></tr>
<tr><td>Grade 5</td><td>R56400</td><td>High strength (895 MPa), moderate corrosion</td><td>High-pressure hydraulic lines, aerospace fluid systems</td><td>1.8–2.2</td></tr>
<tr><td>Grade 7</td><td>R52400</td><td>Gr2 + 0.12–0.25% Pd</td><td>Reducing acid, chlor-alkali, crevice-critical piping</td><td>1.5–1.8</td></tr>
<tr><td>Grade 9</td><td>R56320</td><td>Ti-3Al-2.5V, cold-workable</td><td>Hydraulic tubing, coiled lines, sporting goods</td><td>1.6–2.0</td></tr>
<tr><td>Grade 12</td><td>R53400</td><td>Ti-0.3Mo-0.8Ni, elevated temp</td><td>Sour service, elevated-temperature chloride lines</td><td>1.4–1.7</td></tr>
</tbody>
</table>
<p><strong>Selection logic:</strong> Grade 2 is the default for 80% of process piping. Grade 7 is specified only when reducing-acid or crevice corrosion is documented. Grade 5 is for high-pressure only — difficult to bend and requires post-weld stress relief. Grade 12 fills elevated-temperature chloride service between Gr2 and Gr5.</p>
<h2 id="h2-3">3. Chemical Composition</h2>
<table>
<thead>
<tr><th>Element</th><th>Gr2 max</th><th>Gr5</th><th>Gr7 max</th><th>Gr12 max</th></tr>
</thead>
<tbody>
<tr><td>N</td><td>0.03%</td><td>0.05%</td><td>0.03%</td><td>0.03%</td></tr>
<tr><td>C</td><td>0.08%</td><td>0.08%</td><td>0.08%</td><td>0.08%</td></tr>
<tr><td>H</td><td>0.015%</td><td>0.015%</td><td>0.015%</td><td>0.015%</td></tr>
<tr><td>Fe</td><td>0.30%</td><td>0.40% max</td><td>0.30%</td><td>0.30%</td></tr>
<tr><td>O</td><td>0.25%</td><td>0.20% max</td><td>0.25%</td><td>0.25%</td></tr>
<tr><td>Al / V</td><td>—</td><td>5.5–6.75% / 3.5–4.5%</td><td>—</td><td>—</td></tr>
<tr><td>Pd</td><td>—</td><td>—</td><td>0.12–0.25%</td><td>—</td></tr>
<tr><td>Mo / Ni</td><td>—</td><td>—</td><td>—</td><td>0.2–0.4% / 0.6–0.9%</td></tr>
<tr><td>Ti</td><td>Balance</td><td>Balance</td><td>Balance</td><td>Balance</td></tr>
</tbody>
</table>
<p><strong>Procurement note:</strong> For Grade 7 pipe, the Pd content is the only difference from Grade 2. PMI (XRF) verification is recommended on every heat — confusion between Gr2 and Gr7 in inventory is the most common grade-mix failure in titanium piping.</p>
<h2 id="h2-4">4. Mechanical Properties (annealed, minimum)</h2>
<table>
<thead>
<tr><th>Grade</th><th>Tensile, min (MPa)</th><th>Yield 0.2% offset, min (MPa)</th><th>Elongation, min (%)</th><th>Reduction of Area, min (%)</th></tr>
</thead>
<tbody>
<tr><td>Grade 2</td><td>345</td><td>275</td><td>20</td><td>30</td></tr>
<tr><td>Grade 5</td><td>895</td><td>828</td><td>10</td><td>25</td></tr>
<tr><td>Grade 7</td><td>345</td><td>275</td><td>20</td><td>30</td></tr>
<tr><td>Grade 9</td><td>620</td><td>483</td><td>15</td><td>25</td></tr>
<tr><td>Grade 12</td><td>483</td><td>345</td><td>18</td><td>25</td></tr>
</tbody>
</table>
<p><em>Per ASTM B861-21. Yield strength measured at 0.2% offset.</em></p>
<h2 id="h2-5">5. Dimensional Tolerances</h2>
<table>
<thead>
<tr><th>Parameter</th><th>Tolerance (B861)</th></tr>
</thead>
<tbody>
<tr><td>Outside diameter (OD)</td><td>±0.5% of OD (min ±0.38mm) for OD ≤48mm; ±0.75% for OD >48mm</td></tr>
<tr><td>Wall thickness</td><td>-12.5% / +22% of nominal wall (no under-tolerance repair allowed)</td></tr>
<tr><td>Length (random)</td><td>3000–9000mm standard; cut lengths +6mm / −0</td></tr>
<tr><td>Straightness</td><td>0.5mm per 300mm, or 1.5mm total over 3m</td></tr>
<tr><td>Ovality</td><td>Within OD tolerance (no separate limit)</td></tr>
</tbody>
</table>
<p><strong>Schedule series per ASME B36.19M:</strong> Sch 5S, 10S, 40S, 80S. Sch 10S is the industry default for chemical process piping (wall thickness ≈40% of standard weight). <span class="fill">[FILL: your actual OD range and wall thickness capability, e.g. "OD 12.7-219mm, Sch 5S/10S/40S/80S"]</span></p>
<h2 id="h2-6">6. Pressure Rating Calculation</h2>
<p>Working pressure is calculated per Barlow's formula (ASME B31.3):</p>
<p><strong>P = 2St / D</strong></p>
<ul>
<li>P = internal working pressure (MPa)</li>
<li>S = allowable stress (Gr2 = 92 MPa at 100°C per B31.3 Appendix A)</li>
<li>t = nominal wall thickness (mm)</li>
<li>D = outside diameter (mm)</li>
</ul>
<p><strong>Example:</strong> NPS 4 Sch 10S (OD 114.3mm, t = 3.05mm), Gr2 at 100°C:</p>
<p>P = 2 × 92 × 3.05 / 114.3 = <strong>4.9 MPa (≈710 psi)</strong></p>
<p><strong>Temperature derating:</strong> Allowable stress for Gr2 drops from 138 MPa at ambient to 92 MPa at 100°C, 69 MPa at 200°C, and 41 MPa at 300°C. Always calculate at design temperature, not ambient.</p>
<h2 id="h2-7">7. Procurement Checklist</h2>
<ol>
<li><strong>Standard + grade:</strong> "ASTM B861 Grade 2 (UNS R50400)" — not "titanium pipe" alone</li>
<li><strong>Size:</strong> NPS × Sch (e.g., NPS 4 × Sch 10S) or OD × wall thickness (mm)</li>
<li><strong>Length:</strong> Random (3–9m) or cut-to-length with tolerance</li>
<li><strong>Condition:</strong> Annealed (standard), pickled surface, end bevel per B16.25</li>
<li><strong>Hydrotest:</strong> Required per B861; specify test pressure if different from standard</li>
<li><strong>Surface:</strong> Pickled, no free iron (ferroxyl test per ASTM A380 on 10% of lot)</li>
<li><strong>Marking:</strong> Grade, heat number, manufacturer, standard on each length</li>
<li><strong>Certification:</strong> EN 10204 3.1 MTR minimum; PMI for Gr7/Gr12; UT for heavy wall</li>
</ol>
<p><strong>Common failures:</strong> Not specifying grade (supplier ships lowest-cost available), not specifying schedule (wall thickness defaults to minimum), no hydrotest documentation, no PMI on Gr7.</p>
<h2 id="h2-8">8. Frequently Asked Questions</h2>
<div class="faq-item">
<div class="faq-q">Q1: What is the difference between ASTM B861 and ASTM B338?</div>
<div class="faq-a">B861 covers general-service titanium seamless pipe and tube (process piping, pressure tubing, mechanical tubing). B338 covers seamless and welded titanium tubes specifically for condensers and heat exchangers. B861 is the correct standard for process piping; B338 is correct for heat exchanger tubing. The chemistry is similar but dimensional tolerances and test requirements differ — B338 has tighter OD tolerance for tube-bundle fit-up, while B861 has broader size coverage for piping.</div>
</div>
<div class="faq-item">
<div class="faq-q">Q2: What is the difference between B861 seamless pipe and B862 welded pipe?</div>
<div class="faq-a">B861 pipe is produced by extrusion or rotary piercing of a solid billet — no weld seam exists. B862 pipe is made by forming titanium strip/plate into a cylinder and welding the longitudinal seam. Seamless pipe has no HAZ, no seam-corrosion risk, and is mandatory for cyclic-pressure or high-reliability service. Welded pipe costs 30-40% less and is acceptable for steady-state, low-cycle, non-critical service.</div>
</div>
<div class="faq-item">
<div class="faq-q">Q3: What wall thickness schedules are available in B861?</div>
<div class="faq-a">B861 uses the ASME B36.19M 'S' schedule series: Sch 5S, 10S, 40S, 80S. Sch 10S is the most common for chemical process piping (approximately 40% of standard wall). Sch 5S is used where corrosion allowance is generous and pressure is low. Sch 40S and 80S are for higher-pressure service.</div>
</div>
<div class="faq-item">
<div class="faq-q">Q4: Can B861 Grade 2 pipe be bent in the field?</div>
<div class="faq-a">Yes, Grade 2 has excellent cold formability. Minimum bend radius is typically 3× OD for Sch 10S and 4× OD for Sch 40S/80S. Cold bending does not require stress relief for Gr2. For Grade 5 (Ti-6Al-4V), cold bending is not recommended — the alloy work-hardens rapidly and requires stress relief at 480-650°C after bending.</div>
</div>
<div class="faq-item">
<div class="faq-q">Q5: How do I calculate the pressure rating of B861 titanium pipe?</div>
<div class="faq-a">Use Barlow's formula: P = 2St/D, where S = allowable stress (Gr2 = 92 MPa at 100°C per ASME B31.3), t = wall thickness, D = outside diameter. Always derate for temperature — allowable stress drops at elevated temperature. For design, use ASME B31.3 Appendix A or consult the mill for tested burst pressure data.</div>
</div>
<hr>
<p><em>Maintained by the Engineering Team at Shaanxi Qianyi Tuoda Technology Co., Ltd. Data per ASTM B861 / ASME SB-861. Procurement support: <a href="mailto:sales@sxqytd.com">sales@sxqytd.com</a>.</em></p>
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