Stainless Steel Coil Tube (Coiltube) — Ultra-Long Spool for Concrete Pumping Applications
Product Code: 465 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered, continuous-length stainless steel tubing product supplied in coil (spool) configuration. This product is specifically designed and qualified for demanding applications involving ultra-long-length concrete pumping operations, including scenarios where coil tubes exceed 800 meters in continuous run length. The coil tube form factor eliminates the need for field welding of discrete pipe segments, thereby reducing joint failure points, minimizing pressure loss, and ensuring structural integrity over extended deployment distances.
Based on extensive technical research and field validation documented in studies regarding concrete performance changes and mechanisms during pumping through ultra-long coil tubes (800 m+), Wenzhou Jixing Metal Materials has developed this product to address the unique mechanical, hydraulic, and material compatibility challenges associated with long-run concrete delivery systems. The product represents a convergence of metallurgical science, hydraulic engineering, and practical field experience.
Material & Properties
Base Material Grades
- AISI 304 (UNS S30408): General-purpose austenitic stainless steel offering excellent corrosion resistance, formability, and weldability. Suitable for non-chloride-rich concrete environments.
- AISI 316 (UNS S31603): Enhanced austenitic grade with molybdenum addition (2.0–3.0%), providing superior resistance to chloride-induced pitting and crevice corrosion. Recommended for coastal, marine, and aggressive chemical environments.
- AISI 321 (UNS S32103): Titanium-stabilized austenitic grade suitable for elevated-temperature concrete admixture scenarios.
Mechanical Properties (Typical Values for 304 Grade)
| Property | Symbol | Minimum Value | Unit | Test Standard |
|---|---|---|---|---|
| Tensile Strength | UTS | 515 | MPa | ASTM A213 / GB/T 12771 |
| Yield Strength (0.2% Offset) | YS | 205 | MPa | ASTM A213 / GB/T 12771 |
| Elongation (in 50 mm gauge length) | EL | 40 | % | ASTM A213 / GB/T 12771 |
| Hardness (Rockwell B) | HRB | ≤ 95 | — | ASTM A213 |
| Density | ρ | 8.0 | g/cm³ | — |
Chemical Composition (AISI 304, Typical)
| Element | C | Silicon | Manganese | Phosphorus | Sulfur | Chromium | Nickel | Carbon (Max) |
|---|---|---|---|---|---|---|---|---|
| Typical | 0.03 | 0.60 | 1.20 | 0.035 | 0.015 | 18.50 | 8.20 | — |
| Range | — | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.030 | 18.00–20.00 | 8.00–10.50 | ≤0.08 |
Specifications
| Parameter | Specification | Applicable Standard |
|---|---|---|
| Product Form | Coil Tube (Coiltube / Spool) | ISO 4209 / GB/T 12771 |
| Outer Diameter (OD) | Φ6.0 mm – Φ219.1 mm (customizable) | ASTM A213 / EN 10216-5 |
| Wall Thickness | 0.5 mm – 6.0 mm (tolerance ±10%) | ISO 4209 |
| Coil Length | Up to 800 m (continuous, seamless) | — |
| Coil Inner Diameter | 300 mm – 1200 mm (configurable) | — |
| Surface Finish | Pickled & Passivated, No. 2B, or Custom | ASTM A269 |
| Tolerance on OD | ±0.10 mm (fine tolerance: ±0.05 mm on request) | ISO 4209 |
| Tolerance on Wall Thickness | ±10% | ISO 4209 |
| Pressure Rating | Up to 16 MPa (design-dependent) | ASME B31.3 |
| Operating Temperature | −196 °C to +600 °C | — |
| Manufacturing Process | Seamless (Piercing/Rolling) or ERW (Electric Resistance Welding) | ASTM A213 / ASTM A554 |
| Heat Treatment | Solution Annealed (1050–1150 °C, water/quench) | ASTM A213 |
| End Condition | Plain cut, beveled, threaded, or custom | — |
| Coating / Protection | Passivation film, protective end caps, desiccant packing | — |
| Testing | Hydrostatic (100%), Eddy Current (100%), Spectroscopic Analysis | ASTM A213 |
| Coil Packaging | Wooden crate / steel frame with moisture barrier | — |
Manufacturing Process
Process Flow for Seamless Coil Tube
- Raw Material Selection: High-purity stainless steel billets or slabs (AISI 304/316) are sourced with certified chemical composition and mechanical properties traceable to heat number.
- Hot Piercing / Hot Rolling: Billets are heated to 1150–1250 °C and pierced to form hollow shells, which are then hot-rolled to approximate OD and wall dimensions.
- Cold Drawing / Cold Rolling: The hot-rolled tube is cold-drawn or cold-rolled to achieve precise final dimensions with tight tolerances (±0.05 mm OD achievable). This step also imparts strain hardening and improves surface finish.
- Solution Annealing: The drawn tube is heated to 1050–1150 °C and rapidly cooled (water quench) to dissolve carbide precipitates, restore full austenitic microstructure, and achieve maximum ductility and corrosion resistance.
- Pickling & Passivation: Acid pickling (HNO₃ + HF blend) removes oxide scale; subsequent passivation (HNO₃ treatment) establishes a protective chromium oxide passive film (Cr₂O₃) on the surface.
- Coiling: The annealed and passivated tube is wound onto a coil form using precision coiling equipment to maintain uniform curvature and avoid ovality or springback deformation.
- Non-Destructive Testing (NDT): 100% eddy current testing and hydrostatic pressure testing are performed on the coiled product to detect subsurface defects, wall thinning, and cracks.
- Coil Straightening & Cutting (On Request): Coils may be uncoiled, straightened, and cut to specified lengths for downstream processing.
Ultra-Long Coil Tube (800 m) Considerations
Based on technical research documented in the study "Performance Changes and Mechanisms of Concrete Before and After Pumping Through 800 m Ultra-Long Coil Tubes", the following engineering considerations are critical for ultra-long coil tube applications:
- Frictional Pressure Loss: In concrete pumping through ultra-long coils (≥800 m), frictional pressure loss increases non-linearly with length. The stainless steel coil tube's smooth inner surface (Ra ≤ 0.4 μm after pickling and passivation) significantly reduces friction coefficients compared to carbon steel alternatives, thereby lowering the required pump pressure and reducing the risk of concrete segregation or bleeding during transit.
- Concrete Rheology Preservation: Studies indicate that concrete pumped through ultra-long coils experiences changes in slump, air content, and workability. The chemically inert surface of passivated stainless steel minimizes interaction with cementitious materials, preserving concrete rheological properties over extended pumping distances.
- Mechanical Fatigue Resistance: Ultra-long coil tubes subjected to repeated concrete pumping cycles experience cyclic internal pressure fluctuations (0–16 MPa). The solution-annealed austenitic microstructure of AISI 304/316 provides exceptional fatigue resistance and eliminates the risk of stress corrosion cracking (SCC) that can affect lower-grade materials in alkaline concrete environments (pH 12–13).
- Coil Springback Management: The manufacturing process incorporates controlled coiling curvature to minimize residual elastic springback, ensuring that the coil maintains its geometry during storage, transport, and deployment without requiring additional straightening operations.
Applications
Primary Application: Ultra-Long Concrete Pumping Systems
- High-Rise Construction: Continuous concrete pumping to elevated floors (up to 600 m vertical) using stainless steel coil tubes as the primary delivery conduit, eliminating the need for multiple pump relay stations.
- Tunnel and Underground Construction: Long-distance horizontal concrete pumping through pre-laid coil tube networks in tunnel boring machine (TBM) support systems.
- Mass Concrete Placement: Large-volume concrete placement in dam construction, nuclear containment structures, and industrial foundations where continuous, uninterrupted pumping is required.
Secondary Applications
- Chemical Processing Piping: Transfer lines for corrosive fluids, acids, and alkaline solutions in petrochemical, pharmaceutical, and food processing industries.
- Hydraulic Systems: High-pressure hydraulic lines in heavy machinery, mining equipment, and offshore platforms.
- Heat Exchanger Tubing: Coil tube configurations for compact heat exchangers in power generation and HVAC systems.
- Structural Applications: Decorative and structural elements in architectural design where corrosion resistance and aesthetic finish are required.
- Automotive and Aerospace: Precision tubing for exhaust systems, fuel lines, and structural components.
Quality Certifications & Standards Compliance
| Standard / Certification | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent product quality and process control. |
| ISO 14001:2015 | Environmental Management System certification demonstrating sustainable manufacturing practices. |
| ISO 4209 | International standard for seamless stainless steel tubes for general applications — dimensional tolerances and technical delivery conditions. |
| ASTM A213 | American standard for seamless austenitic stainless steel tubes for boiler, heat exchanger, and similar high-temperature service. |
| EN 10216-5 | European standard for seamless stainless steel tubes for pressure purposes — technical delivery conditions. |
| GB/T 12771 | Chinese national standard for stainless steel seamless tubes for general use. |