2507 (S32750) Super Duplex Stainless Steel Coil Tube
Product Overview
The 2507 (UNS S32750) Super Duplex Stainless Steel Coil Tube, manufactured by Wenzhou Jixing Metal Materials Co., Ltd., represents the pinnacle of corrosion-resistant and high-strength tubular solutions available in the stainless steel industry. Engineered with an exceptional Pitting Resistance Equivalent Number (PREN) exceeding 40, this super duplex alloy coil tube is purpose-built for the most aggressive environments encountered in offshore engineering, chemical processing, and environmental protection systems.
Delivered in continuous coil form, the product offers significant advantages in fabrication efficiency, material utilization, and cost-effectiveness compared to straight-length tubing. The coil configuration enables seamless integration into automated forming, bending, and welding operations, making it the preferred choice for high-volume production of complex geometries including heat exchangers, heat transfer coils, pressure vessels, and structural assemblies.
Material & Properties
The 2507 Super Duplex Stainless Steel features a balanced austenitic-ferritic microstructure (approximately 40–60% ferrite) that delivers a unique combination of mechanical strength, fracture toughness, and superior resistance to chloride-induced stress corrosion cracking (SCC) and pitting corrosion. The elevated chromium, molybdenum, and nitrogen content synergistically produce a PREN greater than 40, placing this grade among the most corrosion-resistant duplex stainless steels commercially available.
Key Alloying Elements:
- Chromium (Cr): 25% — Provides primary oxidation and pitting resistance
- Nickel (Ni): 7% — Stabilizes austenite phase and enhances toughness
- Molybdenum (Mo): 4% — Significantly improves resistance to pitting and crevice corrosion
- Nitrogen (N): 0.28% — Strengthens the matrix and further elevates PREN
Mechanical Properties (Annealed Condition):
- Tensile Strength: ≥ 620 MPa (90 ksi)
- Yield Strength: ≥ 450 MPa (65 ksi)
- Elongation: ≥ 25%
- Impact Strength (Charpy V-Notch, −40°C): ≥ 70 J
Specifications
| Parameter | Specification |
|---|---|
| Grade / UNS | 2507 / UNS S32750 |
| Equivalent Standards | EN 1.4501, AFNOR Z3N25.07, JIS S32750 |
| PREN (Pitting Resistance Equivalent Number) | > 40 |
| Chemical Composition (Typical, wt%) | C ≤ 0.03, Si ≤ 1.0, Mn ≤ 2.0, P ≤ 0.03, S ≤ 0.02, Cr 22–25, Ni 6–8, Mo 3–5.5, N 0.24–0.32, Cu 0.5–1.0 |
| Product Form | Coil Tube (Continuous Coil) |
| Outer Diameter Range | 6.0 mm – 168.3 mm (¼" – 6½") |
| Wall Thickness Range | 0.5 mm – 12.7 mm (0.020" – 0.500") |
| Coil Inner Diameter | 100 mm – 600 mm (configurable) |
| Surface Finish | Pickled & Passivated, Bright Annealed, or Polished |
| Applicable Standards | ASTM A790 / ASME SA-790, ASTM A928, EN 10217-7, ISO 11431 |
| Service Temperature Range | −50°C to +350°C (−58°F to +662°F) |
| Maximum Operating Pressure | Up to 250 bar (3,625 psi) — dependent on dimensions and design |
| Manufacturing Method | Seamless (hot/cold rolled) or Welded (ERW/AW) |
| Coating / Passivation | Standard passivation per ASTM A380, optional PTFE inner coating available |
Manufacturing Process
Wenzhou Jixing Metal Materials Co., Ltd. employs a rigorous, multi-stage manufacturing process to ensure the coil tube meets the stringent requirements of super duplex stainless steel applications:
- Slab Preparation: Vacuum arc remelting (VAR) or electro-slag remelting (ESR) of 2507 super duplex billets ensures ultra-low sulfur and nitrogen impurity control, critical for maintaining PREN and weldability.
- Hot Rolling / Piercing: Billets are heated to 1,100–1,200°C and pierced to form seamless tube blanks, with precise control of wall thickness and outer diameter tolerances.
- Cold Drawing / Reduction: Tubes undergo multi-pass cold drawing through precision tungsten carbide dies to achieve final dimensions within ±0.05 mm tolerance, enhancing surface finish and mechanical properties.
- Stress Relief Annealing: A controlled solution anneal at 1,050–1,100°C followed by rapid water quenching dissolves the brittle χ (chi) phase and ensures a uniform duplex microstructure with optimal ferrite content (40–60%).
- Coiling: Tubes are carefully coiled on precision mandrels to prevent surface damage, ovality, and residual stress introduction. Coil diameters are selected to accommodate downstream forming operations without kinking or deformation.
- Pickling & Passivation: Acid pickling removes mill scale and surface oxides, followed by passivation treatment to restore the chromium oxide protective layer per ASTM A380 standards.
- Final Inspection: Each coil undergoes ultrasonic testing (UT), eddy current testing (ECT), hydrostatic pressure testing, and spectrometric analysis to verify dimensional accuracy, metallurgical integrity, and chemical compliance.
Applications
The exceptional combination of high strength, outstanding chloride resistance, and resistance to stress corrosion cracking makes the 2507 Super Duplex Coil Tube indispensable in the following demanding applications:
Deep-Sea & Offshore Engineering
- Subsea riser systems and flow lines operating at depths exceeding 2,000 meters
- Marine heat exchangers and seawater cooling coils
- Subsea umbilical armor tubes and conduit protection
- Ballast water treatment system tubing
High-Concentration Chloride Environments
- Brine and hypersaline water handling equipment
- Desalination plant condensers and evaporators
- Chlor-alkali and chemical processing plant piping and coils
- Waste water treatment and landfill leachate systems
Flue Gas Desulfurization (FGD)
- Wet FGD absorber internals and demister support structures
- Sulfuric acid spray dryer tubes and heat exchangers
- Scrubber cooling coils exposed to SO₂, H₂SO₃, and particulate-laden environments
- Flue gas ductwork and condensation heat recovery systems
Additional Applications
- Oil and gas wellhead equipment, downhole tubing, and Christmas tree components
- Power generation boiler economizers and air preheaters
- Pharmaceutical and food-grade process coils requiring high corrosion resistance
- Marine propeller shafts and rudder stock components
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring that every 2507 Super Duplex Coil Tube meets or exceeds international standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001 — Environmental Management System Certification
- API Q1 / API Q2 — Quality Management System for Petroleum and Natural Gas Industry
- EN 10204 3.1 — Third-party certified material test reports for every shipment
- CE Marking — Compliance with European Pressure Equipment Directive (PED 2014/68/EU)
- NORSOK M-650 — Approved supplier for Norwegian offshore projects
- DNV-GL Approval — Marine equipment certification for offshore applications
- Mill Test Reports (MTR) — Full chemical analysis, mechanical test data, and NDE results provided per lot
- NACE MR0175 / ISO 15156 — Certified resistance to sulfide stress cracking for oil and gas service
Every coil tube shipment is accompanied by a complete traceability package including heat number, production lot, full chemical composition analysis, mechanical test results, and non-destructive examination reports, ensuring full compliance with the most demanding project specifications and regulatory requirements worldwide.
Why Choose Wenzhou Jixing 2507 Super Duplex Coil Tube
- PREN > 40 — Industry-leading pitting and crevice corrosion resistance for the harshest chloride environments
- 2× the Strength of conventional austenitic grades (316L) at equivalent weight, enabling thinner walls, lighter structures, and lower material costs
- Coil Format Advantage — Superior material yield (up to 98%), reduced fabrication time, and seamless integration with automated manufacturing lines
- Wide Dimensional Range — From precision thin-wall tubing to heavy-wall industrial coils, all available in continuous lengths
- Proven Track Record — Trusted by leading offshore EPC contractors, chemical plant engineers, and environmental system designers globally
- Full Traceability & Certification — Complete documentation package meeting the strictest international project specifications