Stainless Steel Coil Tube (盘管) — Spiral Coil Pipe Product Specification
Product Code: No. 717 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. (温州吉兴金属材料有限公司) | Category: Literature Study / Technical Reference
1. Product Overview
The Stainless Steel Coil Tube (also referred to as Spiral Coil Pipe or 盘管) is a precision-engineered tubular product formed by winding straight stainless steel tubing into a continuous spiral or helical configuration. Unlike conventional straight pipes, coil tubes are manufactured to maintain consistent curvature, dimensional accuracy, and material integrity throughout the entire coil length. These products are predominantly employed in heat exchange applications, cryogenic systems, chemical processing, and energy transfer infrastructure where high thermal efficiency and corrosion resistance are paramount.
The coil tube product line from Wenzhou Jixing Metal Materials Co., Ltd. encompasses both spiral coils (uniform pitch helical winding) and helical coils (tapered or variable-pitch configurations), manufactured to meet international standards including ASTM, ASME, EN, and GB specifications. The company's manufacturing process incorporates advanced winch-based bending technology (卷扬机弯制技术), which ensures precise control over coil geometry, minimizes material deformation, and enhances the structural reliability of the final product.
2. Material & Properties
2.1 Available Material Grades
| Grade (ASTM) | Equivalent (EN) | Equivalent (GB) | Key Characteristics | Maximum Service Temperature |
|---|---|---|---|---|
| ASTM A269 TP304 / TP304L | 1.4301 / 1.4307 | 06Cr19Ni10 / 022Cr19Ni10 | Excellent general-purpose corrosion resistance; weldable; non-magnetic | 870°C (1600°F) |
| ASTM A269 TP316 / TP316L | 1.4401 / 1.4404 | 06Cr17Ni12Mo2 / 022Cr17Ni12Mo2 | Superior resistance to pitting and crevice corrosion; Mo-enhanced | 870°C (1600°F) |
| ASTM A269 TP321 | 1.4541 | 06Cr18Ni11Ti | Ti-stabilized; excellent resistance to intergranular corrosion | 870°C (1600°F) |
| ASTM A269 TP310S | 1.4845 | 06Cr25Ni20 | Ultra-high Ni/Cr content; superior oxidation resistance | 1150°C (2100°F) |
| ASTM A269 TP904L | 1.4532 | 00Cr20Ni25Mo4SiCu | Ultra-low carbon; exceptional resistance to aggressive oxidizing media | 600°C (1112°F) |
2.2 Mechanical Properties (Annealed Condition)
| Property | ASTM A269 TP304/316 | ASTM A269 TP321 | ASTM A269 TP310S |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 515 MPa (75 ksi) | ≥ 515 MPa (75 ksi) | ≥ 515 MPa (75 ksi) |
| Yield Strength (Rp0.2) | ≥ 205 MPa (30 ksi) | ≥ 205 MPa (30 ksi) | ≥ 205 MPa (30 ksi) |
| Elongation (A50) | ≥ 40% | ≥ 40% | ≥ 40% |
| Hardness (HV) | ≤ 210 | ≤ 210 | ≤ 210 |
| Density | 8.0 g/cm³ | 8.0 g/cm³ | 8.0 g/cm³ |
2.3 Chemical Composition Requirements (wt%)
| Element | C (Max) | Cr | Ni | Mo | Ti | Mn (Max) | P (Max) | S (Max) |
|---|---|---|---|---|---|---|---|---|
| 304 / 304L | 0.08 / 0.03 | 18.0–20.0 | 8.0–10.5 | — | — | 2.0 | 0.045 | 0.03 |
| 316 / 316L | 0.08 / 0.03 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 | — | 2.0 | 0.045 | 0.03 |
| 321 | 0.08 | 17.0–19.0 | 9.0–12.0 | — | 5×C to 0.70 | 2.0 | 0.045 | 0.03 |
| 310S | 0.08 | 24.0–26.0 | 19.0–22.0 | — | — | 2.0 | 0.045 | 0.03 |
3. Specifications
3.1 Dimensional Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 108.0 mm (1/8" – 4") | ASTM A269 / A213 |
| Wall Thickness (WT) | 0.30 mm – 6.00 mm (0.012" – 0.236") | ASTM A269 |
| Coil Diameter (Mean) | 50 mm – 1500 mm (2" – 60") | Custom / Customer-Specified |
| Coil Pitch | 10 mm – 200 mm (adjustable) | Custom / Customer-Specified |
| Coil Length (Unwound) | 1 m – 500 m (3.3 ft – 1640 ft) | Custom |
| Number of Turns | 1 – 500+ (depending on configuration) | Custom |
| OD Tolerance | ±0.05 mm (for OD ≤ 25 mm); ±0.10 mm (for OD > 25 mm) | ASTM A269 |
| Wall Thickness Tolerance | ±10% (for WT < 0.50 mm); ±12.5% (for WT ≥ 0.50 mm) | ASTM A269 |
| Coil Diameter Tolerance | ±2.0% of nominal | Internal Standard |
| Straightness (per 1000 mm) | ≤ 1.0 mm deviation | ASTM A213 |
3.2 Surface Finish Options
| Finish Type | Ra Value (μm) | Application |
|---|---|---|
| Pickled & Passivated (P&P) | 0.4 – 1.6 | General industrial, chemical processing |
| Mechanically Polished | 0.2 – 0.8 | Food & beverage, pharmaceutical |
| Electrolytic Polished (EP) | 0.1 – 0.4 | Bio-pharmaceutical, high-purity systems |
| 2B / Bright Annealed (BA) | 0.4 – 1.2 | Decorative, architectural |
4. Manufacturing Process
The production of high-quality stainless steel coil tubes follows a rigorous multi-stage manufacturing workflow, with each step controlled to ensure dimensional accuracy, metallurgical integrity, and surface quality.
4.1 Raw Material Procurement & Inspection
- Source Material: Cold-rolled stainless steel strip from certified mills (e.g., Outokumpu, Voestalpine, POSCO, Taiyuan Stainless Steel)
- Incoming Inspection: Verification of chemical composition via Optical Emission Spectrometry (OES); mechanical property confirmation through tensile testing; surface condition assessment
- Traceability: Full heat-number tracking from raw material to finished product
4.2 Seamless Tube Forming (ERW or Cold Drawing)
- Electric Resistance Welding (ERW): Used for larger diameter tubes; strip is formed into a tube shape and the seam is welded using high-frequency resistance heating
- Cold Drawing: Used for smaller diameter and precision tubes; ERW tube is cold-drawn through a die to achieve precise dimensions and improved mechanical properties
- Weld Seam Treatment: Internal and external weld seam grinding, followed by pickling and passivation to restore corrosion resistance at the weld zone
4.3 Heat Treatment (Solution Annealing)
- Process: Tubes are heated to 1050°C – 1100°C in a protective atmosphere (vacuum or argon), held for sufficient time for carbide dissolution, then rapidly quenched (water or air)
- Purpose: Restore full solution-annealed condition; eliminate residual stresses from forming; ensure uniform microstructure and maximum corrosion resistance
- Post-Annealing Treatment: Pickling (acid bath to remove oxide scale) and passivation (citric acid or nitric acid treatment to form protective chromium oxide layer)
4.4 Winch-Based Spiral Coiling (卷扬机弯制技术)
This is the core differentiating technology employed by Wenzhou Jixing Metal Materials Co., Ltd. The winch-based bending system represents a sophisticated approach to coil tube formation that offers significant advantages over conventional rotary bending or press bending methods.
Technical Principle: The winch (卷扬机) is a motorized cable drum mechanism that applies controlled tensile force to the tube end while the tube passes through a fixed or guided bending die. The tension force, combined with the geometric constraint of the die, produces a uniform curvature along the tube length without requiring the tube to rotate about its own axis during bending.
- Process Description:
- The straight stainless steel tube is fed from a straightener/straightening station into the winch bending apparatus
- The winch drum applies a precisely calibrated tension force at the tube exit point
- The tube passes through a bending die (or set of dies) that constrains the tube into the desired helical path
- The combination of tensile force and die geometry produces a smooth, uniform spiral coil
- The coil pitch, coil diameter, and number of turns are controlled by adjusting the winch speed, die geometry, and feed rate
- Advantages of Winch-Based Bending:
- Minimal Cross-Sectional Deformation: The tensile force-based bending mechanism avoids the compressive and shear stresses associated with rotary bending, resulting in near-circular cross-sections throughout the coil (ovality typically < 2%)
- High Production Speed: Continuous feeding enables significantly higher throughput compared to discrete bending operations
- Consistent Curvature: The uniform tension application ensures repeatable coil geometry with minimal variation in bend radius
- Reduced Work Hardening: The bending process is gentler on the material, preserving the ductility and fatigue resistance of the annealed tube
- Long Coil Lengths: Continuous coiling enables production of coils up to 500+ meters in unwound length without intermediate stops
- Low Residual Stress: The process generates lower residual stresses compared to press bending, reducing the risk of stress corrosion cracking in service
- Process Parameters (Typical):
Parameter Range Control Method Winch Tension Force 2 kN – 25 kN Load cell feedback + servo control Feed Rate