Titanium Tube & Pipe: Selection Guide by Standard, Size and Application
Titanium tube and titanium pipe deliver the corrosion resistance of titanium in a form that flows — process lines, heat exchangers, condensers, exhaust systems and seawater services. But “tube” and “pipe” are specified differently (outside diameter vs nominal size), and the choice between seamless and welded construction changes both performance and price. This guide explains the ASTM standards, the sizing systems, the seamless-vs-welded decision, and the exact information to put on an order for titanium tubing.
Tube vs Pipe: Two Different Sizing Systems
Unlike most materials, titanium tube and titanium pipe are ordered with different conventions — getting this wrong is the most common sourcing error:
| Form | Ordered by | Wall thickness | Governing standard |
|---|---|---|---|
| Titanium tube | Outside diameter (OD) + wall | Specific mm or in | ASTM B338 (seamless/welded) |
| Titanium pipe | Nominal size (NPS/DN) + schedule | Schedule (Sch 10S, 40S, 80S) | ASTM B861 (seamless) / B862 (welded) |
A 1″ titanium pipe and a 25.4 mm titanium tube are not the same item: the pipe has an outside diameter of 33.4 mm (with 1.315″ OD for Sch 40), while the tube has exactly 25.4 mm OD. State “tube OD × wall” or “pipe NPS × schedule” explicitly, and always attach the standard.
Seamless vs Welded: The Core Decision
| Criterion | Seamless tube | Welded tube |
|---|---|---|
| Manufacture | Pierced and rolled from billet | Formed from strip, seam welded |
| Pressure integrity | Uniform, no weld line | Good; weld inspected (hydrostatic/ED) |
| Size range | Limited by billet; thicker walls | Wide range, thin walls economical |
| Cost | Higher | Lower (strip feedstock) |
| Typical use | High-pressure, instrumentation, critical process lines | Heat exchangers, exhaust, structural, general process |
Rule of thumb: choose seamless for high pressure, small OD, or thin-wall critical duty; choose welded for large OD, long runs and cost-sensitive service. Both are available in GR1–GR5, and both must be certified to ASTM B338 (tube) or B861/B862 (pipe).
Standards and Grades at a Glance
| Standard | Covers | Grades | Common use |
|---|---|---|---|
| ASTM B338 | Seamless and welded titanium tube | GR1–GR4 | Heat exchangers, condensers, process tubing |
| ASTM B861 | Seamless titanium pipe | GR1–GR4, GR5 | Process piping, high-pressure lines |
| ASTM B862 | Welded titanium pipe | GR1–GR5 | Large-diameter piping, exhaust |
| ASTM B337 | Seamless/welded pipe (older) | GR1–GR4 | Legacy specifications |
GR2 is the default grade for both tube and pipe; GR1 is chosen for maximum formability (bending, flaring), GR3/GR4 for higher-pressure service, and GR5 for structural or high-strength applications. For fine-diameter work — capillary and instrument lines — GR1 titanium capillary tube is the standard choice.
Standard stock forms: seamless tube is commonly stocked in OD from 3 mm (capillary) to 50 mm, and welded tube/pipe in larger diameters with thin walls. A typical process line spec is “GR2 seamless pipe, 1″ NPS Sch 40S, ASTM B861” — five elements that leave no room for ambiguity.
Application-Based Selection
- Chemical process lines: GR2 seamless pipe per B861; welded for large bore. Titanium handles hot chlorides and oxidants that defeat 316L.
- Heat exchangers & condensers: GR2 welded tube per B338, thin wall (0.5–1.2 mm) for thermal efficiency.
- Seawater service: GR2 tube — titanium is effectively immune to seawater corrosion and erosion-corrosion.
- Exhaust systems: GR2 welded titanium exhaust pipe, often in larger diameters with bends and flanges.
- Instrumentation & sampling: GR1/GR2 small-OD seamless capillary and precision tube.
- Structural & high-strength: GR5 (TC4) tube where strength-to-weight matters, e.g. aerospace struts and race frames.
Titanium’s two great enemies in piping are crevice corrosion under scale at high temperature and galvanic coupling to dissimilar metals — the latter managed by insulated flanges or cathodic protection in seawater systems.
What to Specify on a Titanium Tube Order
- Standard + grade: e.g. “ASTM B338, GR2” — never “titanium tube” alone.
- Form: seamless or welded (welded must state inspection: hydrostatic, eddy-current or both).
- Dimensions: tube: OD × wall in mm (e.g. 25.4 × 1.65 mm); pipe: NPS × schedule (e.g. 1″ Sch 40S).
- Length: random (typically 6 m) or fixed lengths.
- Finish: annealed (M), pickled, or polished — specify for cleanliness in instrument service.
- Tolerances: ASTM default, or tightened OD/wall for precision machining feedstock.
- Certification: MTC with heat number, chemistry and mechanicals; for critical service, also request third-party test reports.
If the tube will be bent or flared, add “shall be capable of bending without cracking” and choose GR1/GR2; if it will be welded into a manifold, confirm weldability and filler requirements with the supplier.
Frequently Asked Questions
What is the difference between titanium tube and pipe?Sizing and standards. Tube is specified by outside diameter and wall thickness per ASTM B338; pipe by nominal size and schedule per ASTM B861/B862. The same physical item can be described both ways — the standard removes the ambiguity.
Is seamless or welded titanium tube better?It depends on duty. Seamless is better for high pressure, small OD and critical service; welded is more economical for large OD, long runs and heat exchangers, provided the weld is properly inspected.
What titanium grade is used for piping?GR2 is the default for process piping, seawater and heat exchangers. GR1 for maximum formability, GR3/GR4 for higher pressure, GR5 where high strength is required.
Can titanium pipe handle seawater?Yes — titanium is one of the few metals practically immune to seawater corrosion, including chloride pitting and erosion-corrosion, which makes it a standard choice for marine and desalination piping.
What does ASTM B338 cover?ASTM B338 covers seamless and welded titanium and titanium alloy tube for condensers and heat exchangers, specifying chemistry, mechanical properties, tolerances and testing.
Need Titanium Tube or Pipe?
TOPTITECHS supplies seamless and welded titanium tube and pipe in GR1–GR5, per ASTM B338/B861/B862, from 3 mm capillary to large-bore pipe — with mill certificates and cut-to-length service.
Related Guides
References & Data Sources
- ASTM B338 — Seamless and Welded Titanium and Titanium Alloy Tubes for Condensers and Heat Exchangers
- ASTM B861 — Seamless and Welded Titanium and Titanium Alloy Pipe
- ASTM B862 — Welded Titanium and Titanium Alloy Pipe
- GB/T 3624 — Titanium and Titanium Alloy Tubes (China)
- TOPTITECHS tube and pipe stock list (2026)