ASTM A269 TP316Ti Stainless Steel Seamless Tube: Properties and Applications

What Is ASTM A269 TP316Ti?

ASTM A269 (and its ASME counterpart SA269) covers seamless and welded austenitic stainless steel tubing for general service, including food, chemical, heat exchanger and instrumentation applications. TP316Ti is the titanium-stabilized member of the molybdenum-bearing 316 family: the addition of titanium, at least five times the combined carbon and nitrogen content and not exceeding 0.70%, locks carbon into stable titanium carbides. This prevents chromium depletion at grain boundaries, so the grade keeps its corrosion resistance after welding or after service in the sensitization temperature range.

Chemical Composition of TP316Ti (UNS S31635)

Composition ranges per ASTM A269 (wt%):

Element	TP316Ti (UNS S31635)
Carbon, max	0.08
Manganese, max	2.00
Phosphorus, max	0.045
Sulfur, max	0.030
Silicon, max	1.00
Chromium	16.00-18.00
Nickel	10.00-14.00
Molybdenum	2.00-3.00
Titanium	5 x (C+N) min; 0.70 max

The EN equivalent of TP316Ti is 1.4571 (X6CrNiMoTi17-12-2) in EN 10088. Note that TP316Ti (S31635) is a distinct grade from 316L (S31603): both resist sensitization, but by different mechanisms - titanium stabilization versus extra-low carbon.

Mechanical and Physical Properties

Mechanical properties in the annealed condition per ASTM A269:

Property	Value (min)
Tensile strength (MPa)	515
Yield strength, 0.2% offset (MPa)	205
Elongation, 2 in or 4D (%)	35

Typical physical properties of 316Ti at room temperature:

Property	Typical value
Density	7.99 g/cm3
Specific heat (0-100 °C)	500 J/(kg.K)
Thermal conductivity	14.6 W/(m.K)
Mean coefficient of thermal expansion	16.5 x 10-6 /°C
Modulus of elasticity	193 GPa
Electrical resistivity	74 microohm.cm

Size Range and Tolerances

TP316Ti tubing is available as seamless or welded product in a wide range of sizes and schedules. For cold-drawn seamless tube, ASTM A269 specifies outside-diameter tolerances from +/- 0.005 in for diameters under 1/2 in up to +/- 0.030 in for diameters over 5-1/2 to 8 in, wall thickness tolerance of +/- 10% (with +/- 15% for the smallest diameters), and cut-length tolerances of +1/8 to +3/16 in over nominal length with no minus allowance. Heat exchanger tubes are commonly supplied in straight lengths or U-bent form, and coiled tube is available for instrumentation and process use.

Applications of TP316Ti Tube

Food preparation equipment, particularly in chloride-bearing environments.

Laboratory benches and analytical instrumentation lines.

Coastal architectural panelling, railings and trim.

Boat fittings and marine hardware.

Chemical containers and transport vessels.

Heat exchangers and condensers, including U-tube bundles.

Woven or welded screens for mining, quarrying and water filtration.

Frequently Asked Questions

Why is titanium added to 316Ti?

Titanium combines with carbon (and nitrogen) to form stable carbides, preventing chromium carbide precipitation at grain boundaries during welding or elevated-temperature service. This preserves corrosion resistance without requiring a post-weld heat treatment.

What is the difference between TP316 and TP316Ti?

TP316 (UNS S31600) has no stabilization addition. TP316Ti (UNS S31635) adds titanium at a minimum of five times the combined carbon and nitrogen content, up to 0.70% maximum, which gives it superior resistance to intergranular corrosion in welded service.

What are the mechanical properties of TP316Ti tube?

In the annealed condition per ASTM A269: minimum tensile strength 515 MPa, minimum 0.2% yield strength 205 MPa, and minimum elongation 35% measured in 2 in or 4D.

Where is TP316Ti commonly used?

Food and beverage equipment, chemical processing, heat exchangers, marine and coastal architecture, laboratory equipment and filtration screens - applications where chloride resistance and weldability are both required.

Is TP316Ti weldable?

Yes. It welds like other 316-type austenitic grades, and thanks to titanium stabilization no post-weld heat treatment is required to restore corrosion resistance. Matching filler with titanium or niobium stabilization is typically recommended.

What is the maximum service temperature of TP316Ti?

In continuous air service the practical oxidation limit is approximately 870 °C, similar to other 316-type grades. For load-bearing components, creep strength becomes the governing design factor above about 500-550 °C.