Stainless Steel Coil Tube (Coil Pipe) – Technical Product Specification
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Category: Coil Tube / Coil Pipe (盘管)
Reference No.: 329
1. Product Overview
The Stainless Steel Coil Tube (Coil Pipe) is a seamless or welded tubular product manufactured in continuous coil form, designed for downstream processing applications such as forming, bending, machining, and fabrication. This product line is engineered to meet the rigorous demands of the automotive, aerospace, energy, chemical processing, and food-grade industries. The coil configuration offers superior material utilization rates, reduced cutting losses, and enhanced production efficiency compared to straight-length tube formats.
Wenzhou Jixing Metal Materials Co., Ltd. applies advanced metallurgical control methodologies—including optimized annealing cycles, precise wall thickness uniformity management, and comprehensive surface quality inspection—to ensure consistent product performance. The company's production philosophy integrates continuous improvement (Kaizen) principles to simultaneously elevate coil tube quality and minimize unit manufacturing costs, as documented in their internal technical literature on quality enhancement and cost reduction strategies.
2. Material & Properties
2.1 Available Grades
- Austenitic Stainless Steel: AISI 304, AISI 304L, AISI 316, AISI 316L, AISI 321, AISI 347
- Ferritic Stainless Steel: AISI 430, AISI 439, AISI 441
- Duplex Stainless Steel: 2205 (S31803/S32205), 2507 (S32750)
- Super Duplex Stainless Steel: UNS S32750, UNS S32760
- Custom Alloy Compositions: Available upon specification request
2.2 Key Mechanical & Physical Properties (Typical – AISI 304 Annealed Condition)
- Tensile Strength (UTS): ≥ 515 MPa (74,700 psi)
- Yield Strength (0.2% Offset): ≥ 205 MPa (29,700 psi)
- Elongation: ≥ 40% (in 50 mm / 2 in.)
- Hardness: ≤ 92 HRB (Rockwell B Scale)
- Density: 7.93 g/cm³
- Thermal Conductivity: 16.3 W/(m·K) at 100°C
- Modulus of Elasticity: 193 GPa
- Maximum Service Temperature: 870°C (1,598°F)
2.3 Chemical Composition (AISI 304, Typical)
| Element | Carbon (C) | Chromium (Cr) | Nickel (Ni) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Silicon (Si) | Nitrogen (N) |
|---|---|---|---|---|---|---|---|---|
| ASTM A213 / A269 Max | 0.08% | 18.0–20.0% | 8.0–10.5% | 2.0% | 0.045% | 0.030% | 0.75% | — |
| ASTM A213 / A269 Min | — | 18.0% | 8.0% | — | — | — | — | — |
3. Specifications
3.1 Dimensional Specifications
| Parameter | Range / Value | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | Φ 3.0 mm – Φ 300.0 mm (0.118" – 11.81") | ASTM A213, ASTM A269, ASME B36.19M |
| Wall Thickness (WT) | 0.30 mm – 12.0 mm (0.012" – 0.472") | ASTM A213, ASTM A269 |
| Coil Length (per coil) | 20 m – 200 m (65 ft – 656 ft), customizable | Manufacturer Standard |
| Coil Inner Diameter (ID) | 300 mm – 600 mm (11.8" – 23.6") | Manufacturer Standard |
| OD Tolerance | ±0.10 mm to ±0.50 mm (depending on OD range) | ASTM A213 / A269 |
| Wall Thickness Tolerance | ±10% of nominal (or tighter upon request) | ASTM A213 / A269 |
| Roundness | ≤ 0.5% of OD | ASTM A213 |
| Straightness (after straightening) | ≤ 1.0 mm/m | ASTM A213 |
3.2 Surface Finish Options
| Finish Type | Ra Roughness (μm) | Description |
|---|---|---|
| 2B (Cold Rolled & Annealed) | 0.4 – 1.6 | Standard commercial finish with uniform matte appearance |
| No. 4 Brushed | 0.8 – 2.0 | Directional grain pattern, decorative finish |
| Mirror Polish (8K) | ≤ 0.05 | Highly reflective surface, minimum Ra |
| Pickle & Passivate (PP) | Varies | Acid-degreased surface with enhanced chromium oxide passivation layer |
| Heat-Resistant Annealed (HRA) | 2.0 – 4.0 | Bright annealed in protective atmosphere, uniform grain structure |
3.3 Delivery Condition
- Annealed (Solution Heat Treated)
- Pickled and Passivated
- Hot Rolled (HR)
- Cold Drawn (CD)
- Custom heat treatment per customer specification
4. Manufacturing Process
4.1 Process Flow (Seamless Coil Tube)
- Raw Material Preparation: Ingot casting (VIM/VAR) or strip procurement with full mill test certificate (MTC) verification.
- Hot Rolling / Hot Extrusion: Billet heated to 1,100–1,250°C and extruded or rolled to form initial tube blank.
- Piercing & Sizing: Tube blank pierced through mandrel and sized to approximate final dimensions.
- Pickle & Descale: Acid immersion (H₂SO₄ + HNO₃ blend) to remove oxide scale and surface contaminants.
- Cold Drawing / Cold Pilgering: Multi-pass cold reduction through precision tooling to achieve final OD and wall thickness with tight tolerances.
- Intermediate Annealing: Periodic annealing at 1,050–1,150°C followed by controlled cooling to relieve cold work stresses and restore ductility.
- Final Annealing (Solution Treatment): Full solution heat treatment at 1,050–1,150°C with rapid quench to achieve austenitic microstructure and maximum corrosion resistance.
- Pickle & Passivate: Final surface cleaning and passivation to form protective chromium oxide film (Cr₂O₃).
- Straightening & Coiling: Tube straightened through roller or pay-off/pay-in system and wound onto coil reel with controlled tension.
- Quality Inspection: Full dimensional verification, hydrostatic testing, eddy current inspection, and surface examination.
4.2 Quality Enhancement Methodology
Based on the company's documented technical literature on quality improvement and cost reduction, the following advanced methodologies are integrated into the manufacturing workflow:
- Process Parameter Optimization: Statistical Process Control (SPC) applied to critical dimensions including wall thickness uniformity, roundness, and coiling tension.
- Tooling & Die Management: Precision die maintenance schedules to minimize dimensional drift and surface defects.
- Atmosphere Control: Inert gas or vacuum annealing furnaces to prevent surface oxidation and intergranular contamination.
- Non-Destructive Testing (NDT): Eddy current (ET) and ultrasonic testing (UT) for internal and external defect detection.
- Material Yield Optimization: Coil-length optimization algorithms to minimize trim losses and maximize usable material per coil.
5. Applications
5.1 Industry-Specific Applications
- Automotive Industry: Exhaust system tubing, fuel lines, sensor housings, heat exchanger tubes, structural components.
- Aerospace: Hydraulic lines, fuel system tubing, exhaust components, landing gear assemblies.
- Petrochemical & Oil/Gas: Process piping, heat exchanger tubes, subsea tubing, chemical transfer lines.
- Food & Pharmaceutical: Sanitary process tubing, CIP (Clean-In-Place) systems, beverage processing lines, medical device tubing.
- Energy Sector: Solar thermal collector tubes, fuel cell components, nuclear-grade heat exchanger tubing.
- Architectural & Decorative: Handrails, balustrades, structural framing, facade elements.
- Medical Devices: Surgical instrument tubing, endoscope channels, implant-grade components (316L).
- Heat Exchangers & Boilers: Condenser tubes, evaporator coils, superheater elements.
5.2 Coil Configuration Advantages
- Continuous feeding capability for automated forming and machining lines
- Reduced material waste (up to 15–20% improvement over cut-length delivery)
- Lower inventory and logistics costs due to compact coil packaging
- Improved production throughput for high-volume fabrication operations
- Consistent material properties throughout the coil length
6. Quality Certifications & Standards Compliance
6.1 Applicable International Standards
- ASTM A213 / A213M: Standard Specification for Seamless Austenitic Stainless Steel Tube for High-temperature Service
- ASTM A269 / A269M: Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for Chemical and Similar Severe Service
- ASTM A312 / A312M: Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for Chemical and Heat-Transfer Applications
- ASME SB3619 / SB3619M: Specification for Seamless and Welded Austenitic Stainless Steel Tube for Chemical and Heat-Transfer Service
- EN 10216-5: Technical Delivery Conditions for Seamless Tubes of Stainless Steels for Pressure Purposes – Part 5: Non-heat-resistant Austenitic Tubes
- JIS G3459: Seamless Stainless Steel Tubes for General Use
- GB/T 12771: Chinese National Standard for Seamless Stainless Steel Tubes for Fluid Transport
6.2 Quality Management Certifications
- ISO 9001:2015 – Quality Management System
- ISO 14001:2015 – Environmental Management System
- ISO 45001:2018 – Occupational Health and Safety Management System
- EN 10204 3.1 / 3.2 – Material Test Certificate compliance
- NACE MR0175 / ISO 15156 – Resistant Materials for Use in H₂S-Containing Environments in Oil and Gas Production (applicable grades)
6.3 Testing & Inspection Protocol
- Chemical Analysis: Spectrographic verification (OES / XRF) of each heat lot
- Mechanical Testing: Tensile, hardness, and impact testing per ASTM E8 / E10
- Hydrostatic Testing: Performed at 2.5×–3.0× the maximum allowable working pressure per ASTM A213
- Eddy Current Inspection: 100% inline inspection for internal and external surface defects
- Dimensional Verification: OD, wall thickness, roundness, and length measured at defined intervals
- Intergranular Corrosion Testing: ASTM A262 Practice E (for sensitization resistance verification)
- Pitting Corrosion Testing: ASTM G48 (for 316L and duplex grades)
7. Unique Selling Points
- Integrated Quality-Cost Optimization: Proprietary methodology combining SPC-driven process control with material yield maximization to deliver superior quality at competitive pricing.
- Wide Dimensional Range: Capability to produce coil tubes from micro-diameter (Φ 3 mm) to heavy-wall (Φ 300 mm) configurations from a single production platform.
- Customization Flexibility: Tailored surface finishes, delivery conditions, coil configurations, and packaging to meet specific customer requirements.
- Full Traceability: Complete heat-to-heat traceability from raw material mill certificate through final product delivery, supported by digital documentation systems.