Stainless Steel Coil Tube (Coiltube) — Wenzhou Jixing Metal Materials Co., Ltd
Product Code: 803 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a continuous-length seamless or welded stainless steel tube supplied in a coiled configuration, engineered for applications requiring extended, unbroken tube runs without joints or couplings. Unlike conventional straight-length pipes, coil tubes are wound into large-diameter coils (typically 2.0–5.0 m in outer coil diameter), enabling deployment over distances exceeding several hundred meters in a single continuous segment.
This product category draws upon advanced pumping and deployment technologies, as demonstrated in landmark engineering projects such as the longest coil-pipe pumping test completed in Algeria, where continuous coil tubes were successfully pumped and deployed over record distances using high-pressure concrete and fluid transfer systems. The coil configuration eliminates the need for field welding or mechanical coupling at intermediate points, significantly reducing installation time, leak risk, and maintenance burden.
Wenzhou Jixing Metal Materials Co., Ltd leverages its expertise in precision tube manufacturing to produce coil tubes meeting international standards (ASTM, EN, GB), suitable for demanding industrial, construction, and infrastructure applications worldwide.
2. Material & Properties
2.1 Available Grades
- 304 / 304L (UNS S30400 / S30403): General-purpose austenitic stainless steel with excellent corrosion resistance and formability. Chromium content ≥18%, Nickel content ≥8%.
- 316 / 316L (UNS S31600 / S31603): Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion, particularly in chloride-rich environments.
- 321 (UNS S32100): Titanium-stabilized austenitic grade with enhanced resistance to intergranular corrosion at elevated temperatures.
- 310S (UNS S31008): High-temperature austenitic grade with outstanding oxidation resistance up to 1150°C.
- Custom / Specialty Grades: Available upon request, including duplex (2205), super-austenitic, and precipitation-hardening grades.
2.2 Mechanical Properties (Typical — Annealed Condition)
| Property | 304 / 304L | 316 / 316L | 321 | 310S |
|---|---|---|---|---|
| Tensile Strength (Rm, MPa) | ≥515 | ≥515 | ≥515 | ≥515 |
| Yield Strength (Rp0.2, MPa) | ≥205 | ≥205 | ≥205 | ≥205 |
| Elongation (A50, %) | ≥40 | ≥40 | ≥40 | ≥40 |
| Hardness (HBW) | ≤210 | ≤210 | ≤210 | ≤210 |
| Density (g/cm³) | 7.93 | 8.00 | 7.93 | 8.00 |
| Thermal Conductivity at 100°C (W/m·K) | 16.3 | 16.3 | 16.3 | 26.2 |
| Maximum Service Temperature (°C) | 870 | 870 | 900 | 1150 |
2.3 Key Performance Characteristics
- Corrosion Resistance: Passive chromium oxide layer (Cr₂O₃) provides self-healing protection against atmospheric, chemical, and aqueous corrosion.
- Hygienic Surface Finish: Available in polished (Ra ≤ 0.4 μm), electropolished (Ra ≤ 0.25 μm), and pickled finishes, suitable for food-grade and pharmaceutical applications.
- Formability: Annealed condition ensures excellent bending and coiling capability without cracking or work-hardening failure.
- Weldability: Low carbon variants (304L, 316L) minimize carbide precipitation during welding, preserving corrosion resistance in the Heat-Affected Zone (HAZ).
3. Specifications
3.1 Dimensional Range
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 219.1 mm (¼" – 8") | ASTM A511, ASTM A213, EN 10217 |
| Wall Thickness | 0.5 mm – 12.7 mm (0.020" – 0.500") | ASTM A511, GB/T 12771 |
| Coil Length (Continuous) | 50 m – 1,200 m per coil (custom lengths available) | — |
| Coil Outer Diameter | 2,000 mm – 5,000 mm | — |
| OD Tolerance | ±0.05 mm to ±0.5 mm (per diameter range) | ASTM A511, EN 10217-1 |
| Wall Thickness Tolerance | ±10% (standard) / ±5% (precision) | ASTM A511 |
| Roundness | ≤ 0.5% of OD | EN 10217 |
| Surface Finish | Pickled, Polished, Electropolished, Passivated | ASTM A967, GB/T 8898 |
| Manufacturing Process | Seamless (Hot/Cold Drawn) or ERW Welded | ASTM A213, ASTM A511 |
| Heat Treatment | Annealed (Solution Treated), Stress-Relieved | ASTM A967 |
| Coating (Optional) | PVD Coating, Dacromet, None (bare stainless) | — |
| End Condition | Plain, Beveled, Threaded, Flanged | ASME B16.11 |
| Strut / Spool Configuration | Flexible loop spools, accordion bellows, straight coil | — |
3.2 Material Composition (Typical — wt%)
| Element | 304 / 304L | 316 / 316L | 321 | 310S |
|---|---|---|---|---|
| Carbon (C) | ≤0.08 / ≤0.03 | ≤0.08 / ≤0.03 | ≤0.08 | ≤0.08 |
| Chromium (Cr) | 18.0–20.0 | 16.0–18.0 | 17.0–19.0 | 24.0–26.0 |
| Nickel (Ni) | 8.0–10.5 | 10.0–14.0 | 9.0–13.0 | 19.0–22.0 |
| Molybdenum (Mo) | — | 2.0–3.0 | — | — |
| Titanium (Ti) | — | — | 5×C to 0.70 | — |
| Silicon (Si) | ≤1.00 | ≤1.00 | ≤1.00 | ≤1.50 |
| Manganese (Mn) | ≤2.00 | ≤2.00 | ≤2.00 | ≤2.00 |
| Phosphorus (P) | ≤0.045 | ≤0.045 | ≤0.045 | ≤0.045 |
| Sulfur (S) | ≤0.030 | ≤0.030 | ≤0.030 | ≤0.030 |
4. Manufacturing Process
4.1 Seamless Coil Tube Production
- Raw Material Selection: High-purity stainless steel billets or slabs sourced from certified mills (e.g., Outokumpu, Voestalpine, POSCO, Baosteel), subjected to spectroscopic analysis to verify chemical composition.
- Hot Rolling / Piercing: Billets are heated to 1,150–1,250°C and pierced to produce hollow shells (seamless tube blanks).
- Hot Drawing / Elongation: Tubes are drawn through calibrated dies at elevated temperatures to achieve target dimensions and uniform wall thickness.
- Cold Drawing / Mandrel Drawing: Tubes are cold-worked through precision dies to achieve tight dimensional tolerances (±0.05 mm OD) and superior surface finish.
- Intermediate Annealing: Periodic solution annealing (1,020–1,100°C) relieves accumulated cold-work stresses and restores ductility for continued forming.
- Coiling: Continuous tube is wound onto large-diameter coilers at controlled tension to produce uniform coils. Coiling tension is precisely managed to prevent ovality or residual deformation.
- Final Annealing & Pickling: Tubes are solution-annealed and acid-pickled (nitric/hydrofluoric acid blend) to remove oxide scale and restore full corrosion resistance.
- Passivation: Chemical passivation treatment (per ASTM A967) enhances the passive chromium oxide layer for maximum corrosion protection.
- Surface Finishing: Mechanical polishing (Ra ≤ 0.4 μm) or electropolishing (Ra ≤ 0.25 μm) applied as specified.
4.2 Welded Coil Tube Production (ERW)
- Strip Rolling: Cold-rolled stainless steel strip is slit to target width and edge-trimmed.
- Forming: Strip is progressively formed into a tubular shape through a series of roll stands.
- ERW Welding: Resistance welding fuses the seam using controlled electric current and mechanical pressure, producing a high-integrity weld with minimal Heat-Affected Zone.
- Weld Annealing: Localized annealing of the weld zone restores metallurgical homogeneity and corrosion resistance at the seam.
- Sizing & Coiling: Tubes pass through sizing rolls and are coiled at controlled tension.
4.3 Quality Control Integration
Every production batch undergoes multi-stage quality verification:
- Chemical Analysis: Spark-OES and wet-chemical verification of all alloying elements.
- Mechanical Testing: Tensile, hardness, and impact testing per ASTM E8 and ASTM E10.
- Dimensional Inspection: Ultrasonic thickness gauging (UT), laser OD measurement, and roundness profiling at intervals along the coil. <