Stainless Steel Coil Tube (Coiltube) — Secondary Furnace Coiling Application
Product Overview
The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product designed for high-temperature industrial applications, particularly in secondary coiling systems within heating furnaces. This product is delivered in a continuous coiled configuration, enabling efficient material handling, storage, and downstream processing. The Coiltube is engineered to withstand extreme thermal cycling, mechanical stress, and corrosive environments commonly encountered in industrial furnace operations.
The product has been subject to rigorous evaluation through Finite Element Simulation (FEM) technology, as documented in the study titled "Evaluation of Secondary Coil Tubes in Heating Furnaces Based on Finite Element Simulation Technology." This analytical approach ensures that the Coiltube meets stringent performance criteria for structural integrity, thermal resistance, and fatigue life under operational conditions.
Material & Properties
Material Grades
- Austenitic Stainless Steels — Grades 304 (UNS S30400), 304L (UNS S30403), 316 (UNS S31600), and 316L (UNS S31603) are the primary material options, selected for their superior corrosion resistance and thermal stability.
- Heat-Resistant Alloys — Grades 310S (UNS S31008) and 321 (UNS S32100) are available for applications requiring sustained high-temperature performance exceeding 900°C.
- Duplex Stainless Steels — Grade 2205 (UNS S32205) is offered for applications demanding enhanced mechanical strength combined with corrosion resistance.
Mechanical Properties (Typical Values for Grade 304)
- Tensile Strength (Rm): ≥ 520 MPa
- Yield Strength (Rp0.2): ≥ 205 MPa
- Elongation (A50): ≥ 40%
- Hardness (HV): ≤ 210
Chemical Composition (Grade 304 — Typical)
| Element | C (Carbon) | Si (Silicon) | Mn (Manganese) | Cr (Chromium) | Ni (Nickel) | Mo (Molybdenum) | N (Nitrogen) |
|---|---|---|---|---|---|---|---|
| Max % | 0.08 | 1.00 | 2.00 | — | — | — | 0.10 |
| Min % | — | — | — | 18.0 | 8.0 | — | — |
Thermal Properties
- Maximum Continuous Service Temperature: 870°C (Grade 304), 1150°C (Grade 310S)
- Thermal Expansion Coefficient: 16–18 × 10⁻⁶ /°C (20–800°C)
- Thermal Conductivity: 16.3 W/(m·K) at 100°C
- Oxidation Resistance: Maintains protective chromium oxide film up to 870°C in still air
Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Product Form | Continuous Coil Tube (Coiltube) | — |
| Outer Diameter (OD) | Φ 6.0 mm – Φ 108.0 mm | ASTM A213 / ASME SA-213 |
| Wall Thickness | 0.5 mm – 6.0 mm | ASTM A213 / ASME SA-213 |
| Coil Inner Diameter (CID) | Φ 300 mm – Φ 1200 mm | Manufacturer Standard |
| Coil Length (Per Roll) | 20 m – 500 m (configurable) | — |
| Coil Weight (Per Roll) | 500 kg – 2000 kg | — |
| Surface Finish | Pickle & Polish (2B), Bright Annealed (BA), or Custom | ASTM A478 |
| Manufacturing Method | Seamless (Cold Drawn) or Welded (Welded & Annealed) | ASTM A213 / EN 10216-5 |
| Tolerance on OD | ± 0.1 mm (standard); ± 0.05 mm (precision) | ASTM A213 |
| Tolerance on Wall Thickness | ± 10% of nominal | ASTM A213 |
| End Condition | Open, Plain, or Cut to Length | — |
| Packaging | Wooden crate, steel banding, moisture-proof wrapping | ISO 4180 |
Manufacturing Process
Process Flow
- Raw Material Procurement — Certified stainless steel billets or strip material sourced from approved mills, with full chemical composition and mechanical property documentation (Mill Test Certificate — MTC).
- Forming — Tubes are produced via seamless cold drawing (for smaller diameters) or precision welding and annealing (for larger diameters). The coil configuration is achieved through controlled bending operations at ambient or elevated temperature.
- Heat Treatment — Solution annealing is performed at 1050–1150°C followed by rapid cooling (water quench or air cool) to restore full austenitic microstructure and maximize corrosion resistance.
- Pickling & Passivation — Surface scale removal using controlled acid baths (nitric/hydrofluoric acid mixture), followed by passivation to restore the chromium oxide passive film.
- Coiling — Precision coiling on calibrated mandrels to achieve target coil inner diameter with minimal springback and deformation. Finite Element Simulation is employed during process design to predict and minimize residual stresses in the coiled geometry.
- Quality Inspection — Comprehensive testing including dimensional measurement, visual inspection, eddy current testing, and pressure testing as applicable.
- Packaging & Shipping — Coils are secured with steel banding, wrapped in moisture-proof material, and shipped in wooden crates or on steel pallets.
Finite Element Simulation Integration
The manufacturing process design incorporates Finite Element Analysis (FEA) to evaluate stress distribution, deformation behavior, and fatigue life of secondary coil tubes under furnace operating conditions. This simulation-driven approach ensures that the Coiltube maintains structural integrity throughout its service life, particularly at critical coil bend radii where stress concentrations are highest.
Applications
Primary Application Domains
- Industrial Heating Furnaces — Secondary coil tubes for heat exchangers, radiant tubes, and process heating systems where continuous high-temperature exposure is required.
- Chemical Processing — Reactor coils, condenser tubes, and distillation column internals in petrochemical and pharmaceutical manufacturing.
- Power Generation — Superheater tubes, economizer coils, and steam generator components in boiler systems.
- Food & Beverage Industry — Heat exchange coils in pasteurization, sterilization, and brewing equipment (hygienic grade surfaces).
- Pharmaceutical Manufacturing — Clean-in-place (CIP) compatible coil systems for GMP-compliant production environments.
- Marine & Offshore — Corrosion-resistant coil assemblies for heat recovery systems in offshore platforms.
Unique Selling Points
- Simulation-Validated Design — Product geometry and performance are validated through Finite Element Simulation, providing quantifiable assurance of structural reliability in high-temperature coiling applications.
- Flexible Configuration — Wide range of OD, wall thickness, coil diameter, and length options enable customized solutions for diverse process requirements.
- Superior Thermal Fatigue Resistance — Optimized material selection and heat treatment provide exceptional resistance to thermal cycling, extending service life in furnace environments.
- Continuous Form Advantage — Coiled delivery eliminates field welding requirements, reducing installation time and potential failure points.
- Full Traceability — Each coil is traceable to its heat number with complete documentation including MTC, dimensional reports, and NDT results.
Quality Certifications & Standards Compliance
Applicable Standards
| Standard | Description |
|---|---|
| ASTM A213 / ASME SA-213 | Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubes for High-temperature Service |
| EN 10216-5 | Non-alloy and alloy steel tubes for pressure purposes — Technical delivery conditions — Part 5: Austenitic stainless steels |
| ASTM A478 | Standard Specification for Stainless Steel Bars and Shapes (surface finish reference) |
| ISO 4180 | Steel tubes for the transportation of fluids — General conditions for delivery |
| GB/T 12771 | Chinese National Standard for Stainless Steel Seamless Tubes for General Purposes |
| GB/T 14976 | Chinese National Standard for Cold-rolled Stainless Steel Tubes for Fluid Transport |
Certification & Testing
- ISO 9001:2015 — Quality Management System certification for manufacturing processes.
- ISO 3834 — Welding quality requirements for pressure equipment (applicable to welded tube variants).
- Mill Test Certificate (MTC) / EN 10204 3.1 — Third-party verified chemical and mechanical property documentation for every production lot.
- Non-Destructive Testing (NDT) — Eddy current testing (ECT), ultrasonic testing (UT), and dye penetrant inspection (DPI) performed per ASTM E709 and ASTM E165.
- Hydrostatic/Pneumatic Pressure Testing — 100% tested per ASTM A213 requirements to verify weld integrity and structural soundness.
- Intertek / SGS Inspection — Available upon request for third-party verification of product conformity.
Documentation Provided with Each Shipment
- Mill Test Certificate (EN 10204 Type 3.1)
- Dimensional Inspection Report
- NDT Test Reports (where applicable)
- Heat Treatment Records
- Coil Identification Labels with Heat Number and Production Date
- Packing List and Certificate of Origin
Technical Notes
Handling Advisory: Stainless steel coil tubes should be stored in a dry, ventilated environment away from carbon steel materials to prevent cross-contamination and intergranular corrosion. During installation, avoid direct contact with ferrous materials and use appropriate gaskets or spacers. Cleaning should be performed using stainless steel-compatible tools and non-chloride cleaning agents to preserve the passive film integrity.
Finite Element Simulation Note: The evaluation methodology referenced in the product development process utilizes three-dimensional nonlinear finite element models to assess stress-strain behavior at coil bends under combined thermal and mechanical loading. This ensures that the minimum bend radius, maximum allowable stress, and fatigue life predictions are validated prior to production release.