Stainless Steel Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Product No. 334) is a precision-engineered seamless or welded tubular product supplied in a coiled configuration, designed for versatile industrial applications requiring high corrosion resistance, structural integrity, and formability. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd, this coil tube is formed from austenitic stainless steel grades and delivered in continuous coil form to facilitate downstream processing such as cutting, bending, and fabrication without the need for straightening or additional handling.
The coil tube format offers significant logistical and manufacturing advantages over straight-length pipe, including reduced material waste, optimized storage density, and compatibility with automated processing lines. This product is particularly suited for applications in HVAC systems, fluid conveying, structural assemblies, and decorative architectural components where dimensional precision and surface finish are critical.
2. Material & Properties
2.1 Grade Composition
The stainless steel coil tube is typically fabricated from the following austenitic grades, selected based on application-specific requirements:
- ASTM A213 TP304 / TP304L — General-purpose grade with excellent corrosion resistance and weldability
- ASTM A213 TP316 / TP316L — Molybdenum-bearing grade offering superior resistance to pitting and crevice corrosion
- ASTM A213 TP321 / TP347 — Stabilized grades suitable for elevated-temperature service
- ASTM A269 TP904L — High-alloy grade for extreme corrosion environments
2.2 Mechanical Properties
| Property | 304 / 304L | 316 / 316L | 321 / 347 |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 515 | ≥ 515 | ≥ 515 |
| Yield Strength (0.2% Proof, MPa) | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 40 |
| Density (g/cm³) | 7.93 | 8.00 | 7.93 |
| Thermal Conductivity at 100°C (W/m·K) | 16.3 | 16.3 | 16.3 |
| Operating Temperature Range (°C) | −196 to +870 | −196 to +870 | −196 to +900 |
2.3 Chemical Composition (Typical, wt%)
| Element | 304 / 304L | 316 / 316L |
|---|---|---|
| Carbon (C) | ≤ 0.08 (≤ 0.03 for L-grade) | ≤ 0.08 (≤ 0.03 for L-grade) |
| Chromium (Cr) | 18.0 – 20.0 | 16.0 – 18.0 |
| Nickel (Ni) | 8.0 – 10.5 | 10.0 – 14.0 |
| Molybdenum (Mo) | — | 2.0 – 3.0 |
| Manganese (Mn) | ≤ 2.0 | ≤ 2.0 |
| Silicon (Si) | ≤ 1.0 | ≤ 1.0 |
| Iron (Fe) | Balance | Balance |
3. Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管) |
| Product Code | 334 |
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (1/4" – 2") |
| Wall Thickness | 0.5 mm – 3.0 mm |
| Coil Inner Diameter | 200 mm – 600 mm (customizable) |
| Coil Length | Up to 2,000 m per coil (standard); negotiable |
| Surface Finish | Pickled & Passivated (2B), Polished (No. 4, Mirror), Matte |
| Tolerance (OD) | ± 0.1 mm (standard); ± 0.05 mm (precision grade) |
| Tolerance (Wall Thickness) | ± 10% of nominal |
| Manufacturing Standard | ASTM A269, ASTM A213, GB/T 12771, EN 10217-7 |
| Delivery Condition | Annealed & Pickled (Solution Treated) |
| Testing | Hydrostatic, Eddy Current, Dimensional Inspection |
| Coil Packaging | Wooden pallet with protective wrapping; moisture-proof inner lining |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Inspection — Incoming stainless steel strip or round billet is verified for chemical composition via optical emission spectroscopy (OES) and mechanical properties via tensile testing.
- Coil Forming / Pipe Making — Cold-rolled strip is fed through a roll-forming line where progressive dies shape the material into a tubular profile. Alternatively, seamless tubes are produced via the Automatic Tubular Mill (ATM) or Mannesmann piercing method followed by cold drawing.
- Welding (for welded coil tube) — The formed tube passes through a high-frequency induction welding station (HFW) or TIG welding head, producing a continuous longitudinal seam with minimal heat-affected zone (HAZ).
- Inline Annealing — A continuous annealing furnace (typically 1,050–1,150°C) relieves cold-work stresses, restores full solution-treatment microstructure, and ensures uniform mechanical properties.
- Pickling & Passivation — The annealed coil is conveyed through a pickling line where hydrofluoric-nitric acid baths remove scale, followed by a passivation dip to establish a protective chromium oxide film (Cr₂O₃).
- Surface Finishing — Depending on specification, the coil undergoes polishing (No. 4 finish), mirror polishing (8K), or matte brushing.
- Coiling — The finished tube is wound onto a precision coiler with controlled tension to maintain dimensional accuracy and prevent ovality or kinking.
- Quality Control & Packaging — Each coil undergoes final dimensional verification, surface inspection, and hydrostatic testing before packaging.
4.2 Key Process Parameters
- Welding Energy: 20–80 kW (HFW), optimized per wall thickness
- Annealing Temperature: 1,050–1,150°C with controlled cooling rate
- Pickling Duration: 3–8 minutes (temperature-dependent, 80–100°C)
- Coiling Tension: 5–15 kN, calibrated to coil OD and wall thickness
5. Applications
5.1 Primary Application Domains
- HVAC & Refrigeration Systems — The coil tube format is extensively used in fan coil units, air handling units, and heat exchanger coils where compact thermal exchange surfaces are required. The continuous coil form allows seamless integration into automated coil-winding machinery for evaporator and condenser assemblies.
- Fluid Conveyance & Piping Systems — Used for sanitary, chemical, and pharmaceutical process lines where hygienic standards (FDA-compliant, 3-A) and corrosion resistance are paramount.
- Automotive & Aerospace — Fuel lines, exhaust systems, hydraulic circuits, and structural brackets benefit from the combination of lightweight, high strength, and fatigue resistance inherent in austenitic stainless steel.
- Architectural & Decorative Applications — Mirror-finish coil tubes are coiled and formed into handrails, balustrades, and ornamental structures.
- Food & Beverage Processing — Hygienic-grade tubing for dairy, brewing, and beverage transfer systems.
- Medical Equipment — Endoscopic instrument tubing, surgical tool handles, and sterilizable fluid lines.
5.2 Performance Advantages in Application
The coil tube format eliminates the need for field welding and joining, reducing potential leak points by up to 60% compared to straight-length assemblies. Additionally, the continuous coil enables automated CNC cutting and forming, reducing fabrication labor costs by approximately 30–40%.
6. Quality Certifications & Compliance
6.1 Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- EN 10204 3.1 — Material Test Certificate (MTC) per individual heat number
- CE Marking — Compliance with European Pressure Equipment Directive (PED 2014/68/EU)
- ASME Stamp (upon request) — For pressure-vessel and boiler applications
- NSF/ANSI 61 — For potable water applications
- 3-A Sanitary Standards — For food and pharmaceutical processing
- RoHS & REACH Compliance — Restricted substances and chemical safety
6.2 Testing & Inspection Protocol
| Test Method | Standard | Acceptance Criteria |
|---|---|---|
| Hydrostatic Pressure Test | ASTM A269 / GB/T 12771 | No leakage at 1.5× design pressure for 30 seconds |
| Eddy Current Testing | ASTM E309 | No indications exceeding reference block |
| Dimensional Inspection | ISO 6508 | Within specified tolerances (OD, wall thickness, roundness) |
| Corrosion Testing | ASTM A967 (Intergranular Corrosion) | No intergranular attack; acid test pass |
| Mechanical Testing | ASTM A370 | Tensile, yield, and elongation values per grade specification |
| Surface Finish Verification | ASTM A240 | Surface roughness Ra ≤ 0.4 µm (polished); Ra ≤ 1.6 µm (2B) |
7. Unique Selling Points
- Continuous Coil Configuration — Enables automated, high-throughput downstream processing with minimal material waste and reduced handling costs.
- Multi-Grade Availability — Supply from 304L through 904L provides engineers with a comprehensive material palette for diverse service environments.
- Precision Dimensional Control