Stainless Steel Coil Tube (盘管 Coiltube) — Technical Product Specification
Product Overview
The Stainless Steel Coil Tube (盘管 Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered continuous-length tubing product supplied in coiled form. This product represents a critical intermediate material in the tubing supply chain, designed specifically for downstream processing through automated bending machinery. The coil tube format eliminates the need for straight-length storage and handling, enabling seamless integration into high-throughput production lines equipped with fully automatic coil tube bending machines (盘管全自动弯管机).
The coil configuration offers superior material utilization rates, reduced waste from cut-off ends, and enhanced logistics efficiency compared to conventional straight-length tubing. This product is particularly suited for applications requiring continuous forming operations where frequent material changeovers would compromise production efficiency.
Material & Properties
Material Grades
- 304 / 304L (UNS S30400 / S30403): General-purpose austenitic stainless steel with excellent corrosion resistance and formability; carbon content ≤ 0.08% for standard grade, ≤ 0.03% for low-carbon (L) grade.
- 316 / 316L (UNS S31600 / S31603): Molybdenum-enhanced austenitic stainless steel offering superior resistance to pitting and crevice corrosion in chloride-containing environments.
- 321 (UNS S32100): Titanium-stabilized austenitic stainless steel providing enhanced resistance to intergranular corrosion at elevated temperatures.
- 310S (UNS S31008): High-temperature austenitic stainless steel suitable for sustained service temperatures up to 1100°C.
Mechanical Properties (Typical — Annealed Condition)
| Property | 304 / 304L | 316 / 316L | 321 | 310S |
|---|---|---|---|---|
| Tensile Strength (Rm), MPa | ≥ 520 | ≥ 520 | ≥ 515 | ≥ 515 |
| Yield Strength (Rp0.2), MPa | ≥ 205 | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (A50), % | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 40 |
| Hardness (HBW) | ≤ 217 | ≤ 217 | ≤ 217 | ≤ 217 |
| Density, g/cm³ | 7.93 | 8.00 | 7.93 | 8.00 |
Chemical Composition (Wt%, Maximum Unless Noted)
| Grade | C | Si | Mn | P | S | Cr | Ni | Mo | Other |
|---|---|---|---|---|---|---|---|---|---|
| 304 | 0.08 | 1.00 | 2.00 | 0.045 | 0.030 | 18.0–20.0 | 8.0–10.5 | — | — |
| 304L | 0.03 | 1.00 | 2.00 | 0.045 | 0.030 | 18.0–20.0 | 8.0–10.5 | — | — |
| 316 | 0.08 | 1.00 | 2.00 | 0.045 | 0.030 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 | — |
| 316L | 0.03 | 1.00 | 2.00 | 0.045 | 0.030 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 | — |
| 321 | 0.08 | 1.00 | 2.00 | 0.045 | 0.030 | 17.0–19.0 | 9.0–12.0 | — | 5×(C+N)–0.40 (Ti) |
| 310S | 0.08 | 1.50 | 2.00 | 0.045 | 0.030 | 24.0–26.0 | 19.0–22.0 | — | — |
Specifications
| Parameter | Specification |
|---|---|
| Product Form | Coil Tube (盘管) — Continuous length in coil configuration |
| Tube Type | Seamless / Welded (EHRW — Electric Resistance Welded, or Laser Welded) |
| Outer Diameter (OD) | 6.0 mm – 219.0 mm (custom sizes available upon request) |
| Wall Thickness | 0.5 mm – 12.0 mm |
| Coil Inner Diameter (ID) | 200 mm / 508 mm (standard); custom available |
| Coil Outer Diameter (OD) | Up to 1200 mm |
| Coil Weight | Typically 1,500 – 5,000 kg per coil |
| Surface Finish | No.1 Annealed & Pickled / BA (Bright Annealed) / 2B / Mirror (6K, 8K) |
| Heat Treatment Condition | Solution Annealed (固溶退火) — 1010–1150°C followed by rapid quench |
| Tolerance — OD | ± 0.05 mm (precision grade); ± 0.10 mm (commercial grade) |
| Tolerance — Wall Thickness | ± 0.03 mm (precision grade); ± 0.05 mm (commercial grade) |
| Length per Coil | Continuous (typically 500 – 5,000 meters depending on size) |
| Standards Compliance | ASTM A213 / A269 / A554; EN 10216-5; GB/T 12771; JIS G3459 |
Manufacturing Process
1. Raw Material Preparation
High-purity stainless steel wire rod or strip is procured from certified mills. Incoming materials undergo rigorous spectrographic analysis (OES — Optical Emission Spectroscopy) to verify chemical composition within specified limits. Each heat lot is traceable through a unique Heat Number (熔炼炉号) for full supply chain accountability.
2. Tube Forming
Two primary forming routes are employed:
- Seamless Tube Production: Hot-rolled or cold-drawn seamless tubes are produced via the Mannesmann piercing method, followed by cold-drawing and cold-rolling (CDR) for dimensional precision.
- Welded Tube Production: Precision-cut strip is roll-formed into a tube shape and joined using Electric Resistance Welding (ERW — 电阻焊) or Laser Welding technology. The weld seam undergoes internal and external grinding to achieve seamless-equivalent surface quality.
3. Solution Annealing (固溶处理)
Formed tubes are heated to 1010–1150°C in a controlled-atmosphere furnace (protective atmosphere: 99.99% N₂ or vacuum) to dissolve carbides and restore full austenitic microstructure. This critical step eliminates residual stresses from cold working and ensures optimal corrosion resistance and ductility.
4. Pickling and Passivation (酸洗钝化)
Post-annealing oxide scale is removed through pickling with mixed acid solutions (HNO₃ + H₂SO₄ or proprietary organic acid blends). A subsequent passivation treatment establishes a protective chromium oxide film on the tube surface, enhancing passive corrosion resistance.
5. Coil Winding (盘卷)
The continuous-length annealed tube is wound onto precision mandrels to form coils of controlled geometry. The winding process ensures uniform tension distribution, preventing tube deformation, ovality, or surface damage. Coil geometry parameters (inner diameter, outer diameter, layer count) are optimized for compatibility with downstream automatic bending machine loading systems.
6. Quality Inspection
Every coil undergoes comprehensive non-destructive testing (NDT — 无损检测):
- Eddy Current Testing (ECT — 涡流检测): Detects surface and near-surface defects along the full tube length.
- Hydrostatic Testing (水压试验): Verifies weld integrity and dimensional compliance at 1.5× working pressure.
- Dimensional Inspection: Automated laser gauging for OD, wall thickness, and roundness tolerance verification.
- Visual Inspection: Surface quality assessment for scratches, inclusions, or discoloration.
7. Packaging and Shipping
Finished coils are wrapped with protective film, secured with steel banding, and palletized with wooden or steel skids. Each coil is clearly labeled with material grade, heat number, dimensions, coil weight, and production date for traceability.
Applications
Primary Application Domains
- Automotive Industry: Fuel system lines, turbocharger exhaust manifolds, heat exchanger tubes, and air conditioning evaporator/condenser coils. The coil format enables high-speed automated bending for complex 3D tube geometries.
- Heat Exchanger Manufacturing: Production of serpentine coils, double-pipe heat exchangers, and spiral-wound heat exchangers for HVAC, power generation, and petrochemical applications.
- Medical Equipment: Surgical instrument tubing, infusion system components, and medical gas delivery lines requiring high purity and biocompatibility.
- Food and Beverage Processing: Hygienic fluid transfer lines, CIP (Clean-In-Place) systems, and beverage carbonation lines.
- Electronics and Optics: Precision tubes for camera lens barrels, semiconductor equipment fluid lines, and LED heat dissipation channels.
- Construction and Architectural: Decorative railings, structural bracing, and curtain wall support systems.
- Aerospace: Hydraulic lines, fuel system tubing, and pneumatic control lines.
Compatibility with Fully Automatic Coil Tube Bending Machines (盘管全自动弯管机)
This coil tube product is specifically engineered for seamless integration with fully automatic coil tube bending machines. The consistent coil geometry, uniform material properties, and stable surface finish ensure:
- Continuous uncoiling without stoppage or material jamming
- Predictable bending behavior with minimal springback variation
- Reduced tool wear due to homogeneous material hardness
- High production throughput with minimal operator intervention
- Electrical control system compatibility — the coil's consistent feed characteristics enable stable servo motor control and precise PLC (Programmable Logic Controller) program execution
Quality Certifications
System Certifications
- ISO 9001:2015 — Quality Management System (质量管理体系)
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health and Safety Management System
- ASME Section IX — Welding and Brazing Qualification
- EN 10204 — Type 3.1 Test Certificates (3.1检验证书) available upon request
Product-Specific Certifications
- ASTM International — Compliance with ASTM A213, A269, A554 specifications
- EN 10216-5 — European standard for austenitic stainless steel tubes
- NACE MR0175 / ISO 15156 — Suitability for sour service environments (H₂S-containing)
- 3-A Sanitary Standards — Food-grade surface finish certification
- NSF 61 — Drinking water system components approval
- PED (Pressure Equipment Directive 2014/68/EU) — European pressure equipment compliance
Traceability and Documentation
Every coil tube shipment is accompanied by a comprehensive Mill Test Report (MTR — 材质证明书) documenting:
- Chemical analysis results (OES and wet chemistry)
- Mechanical test data (tensile, hardness, elongation)
- Heat treatment parameters (temperature, duration