Stainless Steel Spiral Coil Tube (Coil Tube) for Vulcanizer Piping Systems
Product Overview
The Stainless Steel Spiral Coil Tube (also referred to as Coil Tube or Spiral Coil Pipe) is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for use in shaping vulcanizer piping systems (定型硫化机管路系统), where it serves as the primary conduit for circulating thermal media such as steam, hot oil, or compressed air. The spiral coil configuration provides exceptional flexibility, compact footprint, and superior heat transfer efficiency compared to conventional straight-pipe routing in confined industrial environments.
Unlike standard straight seamless tubes, the spiral coil tube is formed through a continuous cold or hot coiling process that preserves the metallurgical integrity of the parent material while creating a helical geometry with consistent coil pitch, radius, and cross-sectional dimensions. This geometry is critical in vulcanizer applications where space is at a premium and where uniform heat distribution across the mold surface is essential for product quality.
Material & Properties
The coil tube is manufactured from high-grade austenitic stainless steel, selected for its outstanding combination of corrosion resistance, thermal conductivity, mechanical strength, and formability at elevated temperatures.
- Primary Grades: SUS304 / ASTM A269 TP304 (UNS S30400), SUS316 / ASTM A269 TP316 (UNS S31600), and SUS321 / ASTM A269 TP321 (UNS S32100)
- Chemical Composition (SUS304): Carbon (C) ≤ 0.08%, Chromium (Cr) 18.0–20.0%, Nickel (Ni) 8.0–10.5%, Manganese (Mn) ≤ 2.0%, Silicon (Si) ≤ 1.0%, Phosphorus (P) ≤ 0.045%, Sulfur (S) ≤ 0.030%
- Chemical Composition (SUS316): Carbon (C) ≤ 0.08%, Chromium (Cr) 16.0–18.0%, Nickel (Ni) 10.0–14.0%, Molybdenum (Mo) 2.0–3.0%, Manganese (Mn) ≤ 2.0%
- Tensile Strength: ≥ 515 MPa (75,000 psi) for annealed condition
- Yield Strength: ≥ 205 MPa (29,750 psi)
- Elongation: ≥ 40% in 50 mm gauge length
- Thermal Conductivity: 16.3 W/(m·K) at 300 K
- Operating Temperature Range: −196°C to +870°C (SUS304); −196°C to +925°C (SUS321)
- Surface Finish: 2B (cold-rolled and annealed), BA (Bright Annealed), No.4 Brushed, or Electropolished (Ra ≤ 0.4 μm)
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Tube Outer Diameter (OD) | Φ3.18 mm – Φ50.8 mm (1/8" – 2") | ASTM A269 / GB/T 12771 |
| Wall Thickness (WT) | 0.30 mm – 3.00 mm | ASTM A269 / EN 10217-7 |
| Coil Radius (R) | 50 mm – 500 mm (customizable) | Per customer drawing |
| Coil Pitch (P) | 5 mm – 30 mm (adjustable) | Per customer drawing |
| Number of Turns | 3 turns – 500+ turns | Per application requirement |
| Coil Length (L) | Up to 20,000 mm (single continuous coil) | WJM-CT-2024 |
| OD Tolerance | ±0.05 mm (precision grade); ±0.10 mm (standard grade) | ASTM A269 / GB/T 12771 |
| WT Tolerance | ±10% (standard); ±5% (precision grade) | ASTM A269 |
| Coil Radius Tolerance | ±1.0 mm | Internal Quality Standard |
| Pitch Tolerance | ±0.5 mm | Internal Quality Standard |
| End Treatment | Flat cut, beveled (V-groove), threaded, or flanged | Per customer specification |
| Heat Treatment | Solution annealing at 1010–1150°C followed by water quench | ASTM A269 / AMS 5510 |
| Pressure Rating | Up to 1.6 MPa (PN16) standard; up to 6.4 MPa (PN64) heavy-wall | EN 10217-7 / GB/T 12459 |
| Corrosion Resistance | Pitting Resistance Equivalent Number (PREN) ≥ 19 (SUS316: ≥ 24) | ASTM G48 |
| Storage Temperature | −40°C to +60°C (ambient) | WJM Storage Guideline |
Manufacturing Process
The production of the stainless steel spiral coil tube follows a rigorous multi-stage process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection & Inspection: Virgin stainless steel seamless tubes conforming to ASTM A269 or GB/T 12771 are procured from certified mill suppliers. Incoming material undergoes 100% visual inspection, spectroscopic chemical composition verification (OES), and mechanical property testing (tensile, hardness).
- Deburring & End Preparation: Tube ends are deburred and chamfered to eliminate burrs that could obstruct fluid flow or damage downstream components during assembly.
- Cold Forming / Coiling: The straight tube is fed into a precision coiling machine equipped with adjustable mandrels and guide rollers. The tube is progressively bent into the specified helical geometry through a continuous rolling action. The coiling process is performed at ambient temperature (cold forming) to maintain the solution-annealed microstructure and avoid strain-induced precipitation of chromium carbides. For larger diameters or tighter coil radii, intermediate warm forming at 200–300°C may be employed to reduce springback and residual stress.
- Stress Relief Annealing (if required): For applications demanding minimal residual stress, the formed coil may undergo stress relief annealing at 300–400°C for 1–2 hours, followed by controlled cooling. This eliminates coiling-induced residual stresses without affecting the austenitic grain structure.
- Surface Finishing: Depending on the application, the coil tube may undergo:
- Pickling & Passivation: Immersion in nitric acid/hydrofluoric acid solution to remove surface oxides, followed by passivation to establish a protective chromium oxide film (minimum 1000 Å thickness).
- Electropolishing: Electrochemical polishing to achieve surface roughness Ra ≤ 0.4 μm, critical for hygienic and high-purity applications.
- Brushing / Grinding: Mechanical surface finishing for specific aesthetic or functional requirements.
- Dimensional Inspection: Each coil is inspected using calibrated calipers, micrometers, and coordinate measuring machines (CMM) to verify OD, WT, coil radius, pitch, and total length within specified tolerances. Hydrostatic pressure testing at 1.5× the maximum working pressure is performed for leak integrity verification.
- Final Packaging & Shipping: Coils are protected with VCI (Vapor Corrosion Inhibitor) paper wrapping, placed in wooden crates or export-grade packaging, and labeled with material certificates, batch numbers, and handling instructions.
Applications
The spiral coil tube is widely deployed across multiple industrial sectors, with particular prominence in the following applications:
Primary Application: Shaping Vulcanizer Piping Systems
In the molding vulcanizer (硫化机) industry—particularly in rubber and plastic processing—the spiral coil tube serves as the core heating and cooling medium circuit. The coil is installed within the mold cavity or surrounding the mold platen to distribute thermal energy uniformly. Key advantages in this context include:
- Compact Heat Transfer Surface: The helical geometry maximizes the heat exchange surface area within a confined volume, enabling faster cycle times and improved energy efficiency.
- Uniform Temperature Distribution: The continuous spiral path ensures even flow distribution of the thermal medium (steam or hot oil), minimizing hot spots and cold spots across the mold surface.
- Space Efficiency: The coil occupies significantly less space than equivalent-length straight pipe runs, facilitating integration into compact vulcanizer frames.
- Thermal Shock Resistance: Austenitic stainless steel retains excellent mechanical properties during rapid heating and cooling cycles inherent to vulcanization processes (temperature cycling between ambient and 150–250°C).
Additional Applications
- Automotive Rubber Component Vulcanization: Tire curing, seal molding, gasket production
- Plastic Injection Molding: Mold temperature control systems (MTC) using heated water or oil circuits
- Heat Exchanger Coils: Spiral wound heat exchangers, condensers, and evaporators
- Chemical Processing: Reactor jacket piping, distillation column internals
- Food & Pharmaceutical: Hygienic process piping requiring electropolished surfaces
- Automotive & Aerospace: Fuel lines, hydraulic circuits, brake systems
- Oil & Gas: Downhole tubing, wellhead connections (SUS316 for sour service)
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and adheres to the following international and national standards:
- ISO 9001:2015 — Quality Management System certification for consistent manufacturing quality
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health and Safety Management
- ASTM A269 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for Chemical and Fossil Fuel Process Applications
- GB/T 12771 — Chinese National Standard for Seamless Stainless Steel Tubes for General Purposes
- EN 10217-7 — European Standard for Non-Alloy and Alloy Steel Tubes for Mechanical and Thermal Uses
- JIS G3459 — Japanese Industrial Standard for Seamless Stainless Steel Tubes for General Purposes
- ASME B36.19M — Welded and Seamless Wrought Stainless Steel Pipe (for reference dimensions)
- Mill Test Certificates (MTC): EN 10204 Type 3.1 or Type 3.2 certificates provided with each shipment, including chemical analysis, mechanical test results, and heat treatment records
- Third-Party Inspection: Available upon request (SGS, BV, TÜV, DNV)
Unique Selling Points
- Application-Specific Engineering: Coil tubes are engineered specifically for vulcanizer piping systems, with optimized coil radius and pitch for maximum thermal transfer efficiency in confined mold geometries.
- Precision Coiling Technology: Proprietary coiling equipment ensures coil radius tolerance of ±1.0 mm and pitch tolerance of ±0.5 mm, critical for consistent mold temperature profiles.
- Full Material Traceability: Each coil is traceable from raw material mill certificate through the entire manufacturing process, ensuring complete quality documentation.
- Customizable Geometry: Coil radius, pitch, number of turns, and end treatments are fully customizable to match specific vulcanizer mold designs and piping layouts.
- Multi-Grade Availability: SUS304, SUS316, SUS321, and specialty grades (SUS316L, SUS310S) available to match specific corrosion and temperature requirements.
- Integrated Surface Treatment: Pickling, passivation, and electropolishing capabilities in-house ensure consistent surface quality without third-party handling risks.
- Competitive Lead Times: Standard configurations available for immediate shipment; custom coils delivered within 15–30 business days.
Technical Note: For vulcanizer applications operating at temperatures exceeding 200°C, it is recommended to specify SUS321 (stabilized with titanium) or SUS310S to prevent intergranular sensitization. For applications involving chlorinated environments or sulfur-containing rubber compounds, SUS316 or SUS316L with molybdenum addition provides superior pitting and crevice corrosion resistance.