316Ti Titanium-Stabilized Austenitic Stainless Steel Coil Tube
Product Overview
The 316Ti Stainless Steel Coil Tube (also designated as UNS S316Ti / W.Nr. 1.4571 / EN X6CrNiTi18-10) is a premium titanium-stabilized austenitic stainless steel product supplied in continuous coil form by Wenzhou Jixing Metal Materials Co., Ltd. This alloy represents an enhanced variant of the well-known 316 grade, with the deliberate addition of titanium (Ti) as a grain stabilizer. The primary engineering purpose of this stabilization treatment is to mitigate intergranular corrosion (IGC) susceptibility that can develop in 316 and 316L grades when exposed to temperatures within the sensitization range of approximately 425°C to 870°C (800°F to 1600°F).
By incorporating titanium — which has a stronger affinity for carbon than chromium — the alloy ensures that carbon preferentially combines with titanium to form titanium carbide (TiC) precipitates rather than chromium carbide (Cr23C6). This mechanism preserves the necessary chromium content in the solid solution at grain boundaries, thereby maintaining excellent resistance to intergranular corrosion even after prolonged thermal exposure. This makes 316Ti an indispensable material where both high-temperature structural integrity and superior corrosion resistance are simultaneously demanded.
Material & Properties
Chemical Composition (wt%)
| Element | Minimum | Maximum | Notes |
|---|---|---|---|
| Carbon (C) | — | 0.08 | Higher than 316L; stabilized by Ti |
| Chromium (Cr) | 16.5 | 18.5 | Primary corrosion resistance element |
| Nickel (Ni) | 10.0 | 14.0 | Austenite stabilizer |
| Titanium (Ti) | 5 × C (min) | 0.70 | Stabilizer; forms TiC to prevent IGC |
| Molybdenum (Mo) | 2.0 | 3.0 | Enhances pitting and crevice corrosion resistance |
| Manganese (Mn) | — | 2.0 | — |
| Silicon (Si) | — | 1.0 | — |
| Phosphorus (P) | — | 0.045 | — |
| Sulfur (S) | — | 0.030 | — |
Mechanical Properties (Solution-Annealed Condition)
| Property | Specification | Comparison to 316L |
|---|---|---|
| Tensile Strength (UTS) | ≥ 515 MPa (75 ksi) | Higher (316L: ≥ 485 MPa) |
| Yield Strength (0.2% offset) | ≥ 205 MPa (30 ksi) | Higher (316L: ≥ 170 MPa) |
| Elongation (at fracture) | ≥ 35% | Comparable |
| Hardness (Rockwell B) | ≤ 95 HRB | Comparable |
| Density | 8.0 g/cm³ | Comparable |
Thermal Properties
| Property | Value |
|---|---|
| Thermal Conductivity (at 100°C) | 16.3 W/(m·K) |
| Thermal Expansion Coefficient (20–100°C) | 17.0 × 10⁻⁶ /°C |
| Specific Heat Capacity | 500 J/(kg·K) |
| Maximum Recommended Service Temperature | 870°C (1600°F) — intermittent; continuous up to 800°C |
| Creep Strength Advantage | Significantly superior to 316L in the 450–800°C range |
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Form | Coil Tube (Continuous Coiled Tubing) |
| Material Grade | ASTM A213 TP316Ti / A269 TP316Ti / EN 10216-5 X6CrNiTi18-10 |
| Outer Diameter (OD) | 6.0 mm – 159.0 mm (1/4" – 6") |
| Wall Thickness | 0.5 mm – 12.0 mm (0.020" – 0.472") |
| Coil Inner Diameter | 300 mm – 600 mm (standard); customizable |
| Coil Length per Spool | 15 m – 200 m (adjustable per order) |
| Surface Finish | Pickled & Passivated (P&P); Polished (2B/No.4/8K) available |
| Heat Treatment | Solution Annealed at 1050–1100°C, followed by water quench |
| Applicable Standards | ASTM A213, ASTM A269, ASME SA-213, EN 10216-5, JIS G3459 |
| End Condition | Plain end, beveled end, or threaded (upon request) |
| Packaging | Wooden pallet with moisture-proof wrapping; export-grade crating available |
Manufacturing Process
The production of 316Ti stainless steel coil tube at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorous multi-stage manufacturing sequence designed to ensure metallurgical homogeneity, dimensional accuracy, and optimal mechanical performance:
- Vacuum Arc Remelting (VAR) / Electro-Slag Remelting (ESR): Raw alloy ingots are remelted under controlled atmospheres to achieve ultra-low sulfur, phosphorus, and nitrogen content while ensuring uniform distribution of titanium and other alloying elements throughout the melt.
- Hot Rolling: Remelted slabs are hot-rolled into seamless tube blanks (or hot-rolled strip for welded coil tube) at temperatures above the austenitization range to achieve the desired preliminary dimensions.
- Piercing / Forming: For seamless coil tube, the hot-rolled billet is pierced to produce hollow tubes, which are then mandrel-drawn or rotary-drawn to achieve precise wall thickness and OD tolerances.
- Coiling: The formed tube is wound onto precision spools in a controlled manner to minimize mechanical distortion, residual stress, and surface damage.
- Solution Annealing: The coiled tube is heat-treated at 1050–1100°C (1922–2012°F) followed by rapid water quenching. This step dissolves any secondary phases (including TiC and Cr23C6), restoring full austenitic microstructure and maximum corrosion resistance.
- Pickling and Passivation: The annealed coil is subjected to acid pickling (typically HNO₃/HF blend) to remove oxide scale, followed by passivation treatment to establish a stable chromium oxide surface film (Cr₂O₃), ensuring optimal passive layer integrity.
- Non-Destructive Testing (NDT): Each coil undergoes 100% inspection using eddy current testing (ECT) and/or ultrasonic testing (UT) to detect internal and surface discontinuities. Hydrostatic or pneumatic pressure testing verifies weld integrity (for welded products) or wall soundness (for seamless products).
- Dimensional Inspection: Laser-based OD and wall thickness gauging systems verify compliance with specified tolerances (typically ±10% for OD and ±10% for wall thickness per ASTM A213).
Key Technical Advantages & Unique Selling Points
- Superior High-Temperature Strength: Compared to 316L, the 316Ti grade retains significantly higher creep strength and yield strength at elevated temperatures (450–800°C). The titanium carbide (TiC) precipitates act as effective dispersion strengthening agents, impeding dislocation motion at high temperatures.
- Excellent Intergranular Corrosion (IGC) Resistance: Titanium stabilization eliminates the sensitization risk associated with 316 in the 425–870°C range, making 316Ti the preferred choice for heat-exposed components in aggressive environments.
- Direct 316L Replacement in Chlorinated Environments: 316Ti serves as a drop-in upgrade for 316L applications involving chlorides at 450–800°C, offering extended service life without redesign. The molybdenum content (2–3%) provides robust resistance to pitting and crevice corrosion in chloride-containing media.
- Continuous Coil Form Factor: The coiled configuration enables high-throughput downstream processing (cut-to-length, forming, welding, bending) with minimal material waste, making it ideal for heat exchanger manufacturing, process piping, and tube-in-tube applications.
- Weldability: 316Ti maintains good weldability in the solution-annealed condition. Post-weld heat treatment (PWHT) at 1050–1100°C restores full corrosion resistance at weld zones.
- Regulatory Compliance: Available with full material traceability, mill test certificates (MTC) per EN 10204 3.1/3.2, and compliance with PED (Pressure Equipment Directive) 2014/68/EU for pressure-containing applications.
Applications
316Ti coil tube is deployed in demanding industrial environments where the combination of high-temperature structural integrity and corrosion resistance is critical:
- Chemical Processing: Reactor tubing, heat exchanger tubes, and process piping in chlorinated service (hydrochloric acid, sodium hypochlorite solutions) at elevated temperatures (450–800°C).
- Pulp and Paper Industry: Bleaching equipment, digester tubes, and effluent handling systems exposed to chlorinated compounds and high temperatures.
- Marine and Offshore: Heat exchanger tubes in seawater-cooled systems, ballast water treatment equipment, and desalination plant components.
- Pharmaceutical and Food Processing: Sanitary-grade heat exchangers, steam-jacketed vessels, and CIP (Clean-in-Place) systems requiring both high-temperature sterilization and corrosion resistance.
- Petrochemical and Refining: Crude oil distillation heat exchangers, reformer tubing, and flue gas desulfurization systems where chlorides and high temperatures coexist.
- Power Generation: Boiler tubes, economizer tubes, and superheater elements in waste-to-energy plants and biomass combustion systems.
- Aerospace and Defense: Exhaust system components and high-temperature structural tubing where weight, strength, and corrosion resistance are paramount.
- Environmental Protection: Flue gas scrubber internals, wastewater treatment heat exchangers, and incinerator components exposed to acidic, chlorinated flue gases.
Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification for manufacturing operations |
| ISO 14001:2015 | Environmental Management System certification |
| EN 10204 3.1 / 3.2 | Material Test Certificates (Mill Certificates) with chemical analysis, mechanical test data, and heat treatment records |
| ASTM A213 / A269 | Full compliance with American Society for Testing and Materials specifications for seamless/welded austenitic stainless steel tubing |
| ASME SA-213 | Compliance for pressure-containing heat exchanger and boiler tubing applications |
| EN 10216-5 | European standard for austenitic stainless steel seamless and welded tubes for pressure purposes |
| PED 2014/68/EU | Pressure Equipment Directive compliance (CE marking available for Category I–IV) |
| NACE MR0175 / ISO 15156 | Resistance to sulfide stress cracking in H₂S-containing environments (verified) |
| Third-Party Inspection | Available upon request: SGS, Bureau Veritas, TÜV, Lloyd's Register |
Summary
The 316Ti Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd represents a technologically advanced solution for applications demanding the dual performance of high-temperature mechanical strength and exceptional corrosion resistance in chlorinated environments. By leveraging titanium stabilization technology, this alloy overcomes the fundamental limitations of 316L at elevated temperatures, offering engineers a reliable, code-compliant material for heat exchangers, process piping, and structural tubing operating within