Stainless Steel Coil Tube (Coiltube) — Model 606
Product Overview
The Stainless Steel Coil Tube (Coiltube), catalogued as Model 606 by Wenzhou Jixing Metal Materials Co., Ltd, is a precision-engineered continuous-length tubular product supplied in coil form. This product is specifically designed for high-temperature and high-pressure industrial applications, particularly in combined burner systems, water-cooled wall assemblies, and thermal process equipment. The coil tube configuration enables seamless integration into complex piping networks, minimizing weld joints and reducing potential leak points.
Unlike straight-length tubing, coil tubes offer superior flexibility in installation routing, making them ideal for convoluted heat exchanger geometries, furnace water-cooled wall systems, and burner-manifold assemblies where space constraints and thermal expansion management are critical design considerations.
Material & Properties
Coiltubes are manufactured from austenitic and duplex stainless steel grades selected to deliver exceptional resistance to oxidation, scaling, and corrosion under severe thermal cycling conditions. The primary alloy compositions include:
- AISI 304 / 304L (UNS S30400 / S30403) — General-purpose austenitic grade with excellent weldability and formability; suitable for moderate-temperature service environments.
- AISI 316L (UNS S31603) — Enhanced pitting and crevice corrosion resistance due to molybdenum (Mo) addition; preferred for aggressive chemical and marine-adjacent industrial environments.
- AISI 321 (UNS S32100) — Titanium-stabilized grade offering superior resistance to intergranular corrosion during prolonged exposure to temperatures between 425 °C and 870 °C.
- AISI 347 (UNS S34700) — Niobium-stabilized austenitic grade providing enhanced strength retention at elevated operating temperatures.
- AISI 310S (UNS S31008) — High-chromium, high-nickel grade designed for sustained service temperatures exceeding 1100 °C; used in furnace and burner applications.
Key Mechanical and Physical Properties (Typical — AISI 321)
| Property | Unit | Typical Value |
|---|---|---|
| Tensile Strength (Rm) | MPa | ≥ 520 |
| Yield Strength (Rp0.2) | MPa | ≥ 205 |
| Elongation (A5) | % | ≥ 40 |
| Density | g/cm³ | 7.93 |
| Thermal Conductivity (at 100 °C) | W/(m·K) | 16.3 |
| Thermal Expansion Coefficient (20–100 °C) | 10⁻⁶/K | 17.2 |
| Maximum Service Temperature | °C | 1100 |
| Minimum Service Temperature | °C | −196 |
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Catalogue Number | 606 |
| Outer Diameter (OD) | φ6.0 mm – φ325.0 mm (custom dimensions available) |
| Wall Thickness | 0.3 mm – 20.0 mm (±10% tolerance per ASME B36.19M) |
| Coil Inner Diameter (ID) | 400 mm – 1200 mm (adjustable per customer requirement) |
| Coil Length per Spool | 50 m – 1000 m (continuous, joint-free) |
| Surface Finish | No. 4 Brushed / BA (Bright Annealed) / Mirror Polished (Ra ≤ 0.4 μm) |
| Applicable Standards | ASTM A213 / A269, ASME SA-213 / SA-269, EN 10216-5, GB/T 12770, JIS G3459 |
| End Treatment | Plain end / Beveled end / Flanged connection (per specification) |
| Heat Treatment | Solution Annealing + Pickling (SA+P) at 1050–1150 °C followed by water quench |
| Coil Packing | Wooden pallet + VCI (Vapor Corrosion Inhibitor) wrapping + seaworthy export packaging |
Manufacturing Process
The production of stainless steel coiltubes at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorously controlled multi-stage manufacturing sequence designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Strip Preparation: Cold-rolled stainless steel strip is received from certified mill sources, inspected for chemical composition (per ASTM E1049 OES analysis), and verified for mechanical properties prior to processing.
- Forming & Welding: The strip is fed through a high-precision roll-forming station where it is shaped into a tubular cross-section. Seam welding is performed using either Automatic Submerged Arc Welding (SAW) or High-Frequency Induction Welding (HFW) with continuous inline monitoring of weld quality via ultrasonic testing (UT) and eddy current inspection (ECT).
- Heat Treatment (Solution Annealing): The formed tube is passed through a continuous annealing furnace at 1050–1150 °C under a protective nitrogen or argon atmosphere to prevent oxidation. This step relieves internal stresses introduced during cold forming and restores full austenitic microstructure.
- Pickling & Passivation: Post-annealing, the tube surface is subjected to acid pickling (HNO₃/HF mixture) to remove any residual oxide scale, followed by passivation to restore the passive chromium oxide layer, ensuring optimal corrosion resistance.
- Coiling & Sizing: The finished tube is wound onto a coil former at controlled tension to achieve the specified coil inner diameter. Dimensional verification (OD, wall thickness, straightness) is performed at regular intervals using laser measurement systems.
- Final Quality Inspection: Each coil undergoes 100% non-destructive testing (NDT) including ultrasonic wall-thickness gauging, magnetic particle inspection (MPI) of the weld seam, and visual surface examination per ASME BPV Code Section VIII requirements.
Applications
The stainless steel coiltube is deployed across a broad spectrum of industrial sectors where thermal efficiency, corrosion resistance, and structural reliability are paramount:
- Combined Burner Systems & Water-Cooled Walls: Coiltubes serve as the primary structural and cooling elements in water-cooled wall assemblies of industrial boilers and furnaces. Their continuous coil configuration facilitates installation in complex geometries surrounding burner nozzles, reducing the number of butt welds and enhancing thermal cycling durability. The coil tube design allows for efficient water circulation through convoluted channels, providing uniform heat absorption and protecting refractory linings from thermal degradation.
- Power Generation: Used in superheater tubes, reheater circuits, and economizer sections of coal-fired and gas-fired power plants.
- Petrochemical & Refining: Employed in heat exchanger bundles, reactor internals, and distillation column cooling systems where hydrocarbon corrosion resistance is essential.
- Food & Pharmaceutical Processing: Suitable for sanitary-grade applications requiring high-purity fluid transport and compliance with FDA and EHEDG standards.
- Shipbuilding & Marine Engineering: Applied in boiler systems, condensate lines, and seawater-cooled heat exchangers aboard naval and commercial vessels.
- Nuclear Industry: Utilized in secondary coolant loops and steam generator tube bundles where radiation-resistant stainless alloys are specified.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management infrastructure ensuring traceability and conformance to international standards:
- ISO 9001:2015 — Quality Management System certification covering all manufacturing and inspection processes.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
- ASME "S" Stamp — Authorization to manufacture stainless steel tubing for pressure-containing applications per ASME Boiler and Pressure Vessel Code.
- EN 10204 Type 3.1 / 3.2 — Inspection and Test Reports (ITP) issued by authorized quality representatives, providing full chemical and mechanical test data for each heat number.
- PEP (Pressure Equipment Directive) Compliance — Conformance with EU Directive 2014/68/EU for equipment subject to pressure.
- Mill Test Certificates (MTC) — Provided per EN 10204-3.1, including full chemical composition (C, Si, Mn, P, S, Cr, Ni, Mo, Ti, Nb), tensile test results, hardness data, and NDT reports.
Unique Selling Points
1. Continuous Joint-Free Length: The coiltube format eliminates longitudinal weld discontinuities, providing superior structural integrity and leak-tight performance compared to field-welded straight pipe assemblies.
2. Precision Dimensional Control: Laser-based inline monitoring ensures outer diameter and wall thickness tolerances within ±0.05 mm, critical for tight-fit heat exchanger tube sheet installations.
3. Optimized for Combined Burner & Water-Cooled Wall Applications: The product is specifically engineered to withstand the thermal shock, radiant heat flux, and cyclic loading conditions encountered in burner-manifold and water-cooled wall service, as validated through field experience in boiler maintenance and refurbishment programs.
4. Full Traceability: Every coil is laser-marked with heat number, grade, size, and manufacturing date, enabling complete supply-chain traceability from raw material to final installation.
5. Custom Engineering Support: Wenzhou Jixing offers tailored solutions including custom coil diameters, special alloy grades, and application-specific surface treatments to meet unique project requirements.