Stainless Steel Steam Heat Exchanger Coil Tube (Coiltube)
Product Overview
The Stainless Steel Steam Heat Exchanger Coil Tube (hereinafter referred to as "Coiltube") is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd., specifically designed for high-efficiency thermal exchange applications. This coil tube integrates advanced simulation-driven structural optimization with premium austenitic stainless steel materials to deliver superior heat transfer performance, mechanical durability, and corrosion resistance in demanding industrial environments.
Rooted in rigorous finite element analysis (FEA) and computational fluid dynamics (CFD) simulation studies, the Coiltube design achieves optimal thermal efficiency through carefully calibrated geometry, wall thickness distribution, and bend radius parameters. The product represents the culmination of extensive academic research and industrial validation, ensuring reliable performance across a broad range of operating conditions.
Material & Properties
The Coiltube is fabricated from high-purity austenitic stainless steel grades, selected to meet the stringent requirements of steam heat exchanger service. The following material grades are available:
- SAE 304 / ASTM A213 TP304 — General-purpose corrosion resistance with excellent formability
- SAE 316 / ASTM A213 TP316 — Enhanced resistance to chlorides and chemical media
- SAE 316L / ASTM A213 TP316L — Low-carbon variant for welding-sensitive applications
- SAE 321 / ASTM A213 TP321 — Stabilized grade for elevated-temperature service
- SAE 347 / ASTM A213 TP347 — Niobium-stabilized alternative for high-temperature environments
Mechanical Properties (Typical for SA316L Grade)
| Property | Value | Standard Reference |
|---|---|---|
| Tensile Strength (Minimum) | ≥ 485 MPa (70 ksi) | ASTM A213 |
| Yield Strength (0.2% Offset) | ≥ 205 MPa (30 ksi) | ASTM A213 |
| Elongation (in 50 mm / 2 in) | ≥ 40% | ASTM A213 |
| Hardness (Rockwell B) | ≤ 95 HRB | ASTM A262 |
| Thermal Conductivity (at 100 °C) | 16.3 W/(m·K) | ASM Handbook Vol. 6 |
| Thermal Expansion Coefficient (20–100 °C) | 16.0 × 10⁻⁶ /°C | ASM Handbook Vol. 6 |
| Maximum Operating Temperature | 870 °C (1598 °F) | ASME BPVC Section I |
| Corrosion Resistance (Pitting) | PIN ≥ 24 (SAE 316L) | ASTM G48 |
Chemical Composition (SAE 316L, wt%)
| Element | Specification Range |
|---|---|
| Carbon (C) | ≤ 0.030 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 16.00 – 18.00 |
| Nickel (Ni) | 10.00 – 14.00 |
| Molybdenum (Mo) | 2.00 – 3.00 |
| Iron (Fe) | Balance |
Specifications
| Parameter | Specification | Notes |
|---|---|---|
| Product Category | Coiltube (盘管) | Series No. 702 |
| Outer Diameter (OD) | 6.0 – 50.8 mm (1/4" – 2") | Custom sizes available |
| Wall Thickness (WT) | 0.50 – 6.35 mm (0.020" – 0.250") | Simulation-optimized |
| Inner Diameter (ID) | Calculated per OD and WT | — |
| Coil Diameter (Bend Radius) | 50 – 500 mm | Minimum bend radius ≥ 3D |
| Tube Length (Coiled) | Up to 100 m per coil | Continuous forming |
| Surface Finish | 2B, BA, or Electropolished (Ra ≤ 0.4 μm) | As specified |
| Tolerance (OD) | ±0.05 mm (±0.002") | Per ASTM A213 |
| Tolerance (WT) | ±10% of nominal | Per ASTM A213 |
| End Condition | Plain, Beveled, or Threaded | Per customer drawing |
| Heat Treatment | Solution Annealed + Water Quenched | 1040–1150 °C |
| Maximum Design Pressure | Up to 40 bar (580 psi) | Per ASME BPVC |
| Operating Medium | Steam, Water, Organic Solvents | Dependent on grade |
Manufacturing Process
The production of the Coiltube follows a rigorously controlled multi-stage manufacturing workflow, each step validated through simulation and quality inspection:
- Raw Material Procurement & Inspection — Virgin stainless steel bar stock is sourced from certified mills and subjected to spectrographic analysis (OES) and ultrasonic testing to ensure compositional conformity and internal soundness.
- Hot Rolling / Seamless Tubing Formation — Tubes are produced via the seamless piercing method (Plattner or Mannesmann process) to ensure homogeneity without weld seams, critical for high-pressure steam applications.
- Precision Cold Drawing & Sizing — Tubes are cold-drawn through calibrated dies to achieve dimensional tolerances within ±0.05 mm, improving surface finish and mechanical properties.
- Simulation-Driven Coil Forming — Using validated FEA models, the tube is mechanically coiled at controlled bend radii and rates to minimize residual stress and ovality. The forming parameters (tension, speed, die geometry) are optimized through virtual prototyping prior to physical production.
- Solution Heat Treatment — The coiled tube is solution-annealed at 1040–1150 °C followed by rapid water quenching to restore full austenitic microstructure, eliminate strain hardening, and maximize corrosion resistance.
- Pickling & Passivation — Surface oxide scale is removed via acid pickling (nitric/hydrofluoric acid blend), followed by passivation to establish a protective chromium oxide film (minimum 100 ppm free chromium oxide layer).
- Final Quality Control — Includes hydrostatic pressure testing (1.5× design pressure), dimensional verification (CMM), visual inspection, and material certification (Mill Test Report per EN 10204 3.1).
Applications
The Coiltube is engineered for a wide spectrum of thermal exchange and process applications:
- Steam Heat Exchangers — Primary application; efficient condensation and evaporation in power generation, chemical processing, and food sterilization systems.
- Industrial Boilers & Steam Generators — High-temperature steam coils for waste heat recovery and thermal energy storage.
- Pharmaceutical & Food Processing — Hygienic-grade coils for pasteurization, sterilization, and thermal processing of sensitive products (FDA-compliant finishes available).
- Oil & Gas Processing — Corrosion-resistant coils for sour gas environments, condensate separation, and heat tracing.
- Marine & Offshore Systems — SAE 316L coils for desalination plants, ballast water systems, and offshore platform heating.
- Bioreactors & Fermentation Vessels — Jacketed and internal coil configurations for precise temperature control in bioprocessing.
- Heat Recovery Steam Generators (HRSG) — Integral coil assemblies in combined-cycle power plants.
Unique Selling Points
- Simulation-Optimized Design — Unlike conventional coil tubes, this product leverages validated CFD and FEA simulation models to optimize geometry, wall thickness, and bend parameters for maximum thermal efficiency and minimum pressure drop.
- Seamless Construction — Eliminates weld-related failure points, ensuring superior pressure containment and fatigue resistance in cyclic thermal loading conditions.
- Wide Material Selection — Multiple austenitic grades available to match specific corrosion, temperature, and mechanical requirements.
- High-Dimensional Accuracy — Cold-drawn and precision-coiled to achieve dimensional tolerances significantly tighter than industry standards, facilitating seamless integration into heat exchanger assemblies.
- Custom Engineering Support — Wenzhou Jixing Metal Materials Co., Ltd. provides simulation-based design consultation and custom coil configurations tailored to specific thermal load requirements.
Quality Certifications & Compliance
The Coiltube product line is manufactured and certified in accordance with the following international standards and regulatory frameworks:
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ASTM A213 / A269 | Material specification for seamless austenitic stainless steel tubing |
| ASME BPVC Section I & VIII | Boiler and Pressure Vessel Code compliance |
| EN 10216-5 | European standard for seamless austenitic stainless steel tubes |
| GB/T 14976 | Chinese national standard for seamless stainless steel tubes |
| EN 10204 Type 3.1 | Mill Test Report / Material Certification |
| NSF/ANSI 61 | Drinking water system components (where applicable) |
| 3-A Sanitary Standards | Food-grade surface finish and construction |
| NACE MR0175 / ISO 15156 | Sour service resistance (SAE 316L and above) |
Technical Advisory
Note: For optimal performance and longevity, the Coiltube should be installed with appropriate expansion joints or flexible connections to accommodate thermal growth. Regular inspection of surface condition and periodic eddy current testing are recommended for in-service monitoring. Wenzhou Jixing Metal Materials Co., Ltd. provides comprehensive technical documentation, including simulation reports, material traceability certificates, and installation guidance upon request.