Stainless Steel Coil Tube for Industrial Smelting & Thermal Processing Applications
Product Code: 247 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. | Category: Coiled Tubing (Coiltube)
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a continuous, helically wound tubular component engineered for demanding industrial thermal processing environments. Unlike straight-length seamless or welded tubes, coil tubes are manufactured in continuous coil form, offering superior flexibility in installation, reduced welding joints, and enhanced thermal cycling resistance. This product line is specifically designed for high-temperature, high-corrosion, and high-abrasion service conditions encountered in metallurgical smelting operations, including flash smelting furnaces, steam dryers, heat exchangers, and waste heat recovery systems.
Based on extensive field research and wear analysis conducted on coil tubes deployed in flash furnace steam dryers (as documented in metallurgical engineering literature), this product incorporates advanced material selection, optimized microstructure, and protective surface treatments to mitigate erosion-corrosion, thermal fatigue, and mechanical wear — the three primary failure modes identified in high-temperature metallurgical applications.
Unique Selling Points
- Erosion-Corrosion Resistance: Specifically engineered to withstand the combined attack of high-velocity flue gas, molten particulate impingement, and corrosive acidic species (SO2, SO3, H2S) prevalent in smelting environments.
- Continuous Coil Configuration: Eliminates longitudinal weld seams in the coil axis, reducing potential leak paths and improving structural integrity under cyclic thermal loading.
- Thermal Fatigue Durability: Alloy chemistry and heat treatment optimized for repeated thermal cycling between ambient and operating temperatures exceeding 800°C.
- Reduced Installation Complexity: Coil form factor enables on-site bending and layout, minimizing field welding and assembly time in confined furnace areas.
- Extended Service Life: Surface protection strategies (including refractory coatings and alloy cladding options) significantly extend operational intervals compared to conventional carbon steel or basic austenitic alternatives.
2. Material & Properties
2.1 Base Alloy Options
The coil tube is available in multiple stainless steel and heat-resistant alloy grades, selected based on the specific service environment:
| Grade Designation |
UNS |
Primary Application |
Max Service Temp (°C) |
| 304 / 304L |
S30400 / S30403 |
General corrosion resistance, moderate temperature |
870 |
| 310 / 310S |
S31000 / S31008 |
High-temperature oxidation resistance, furnace internals |
1150 |
| 321 / 321H |
S32100 / S32109 |
Sensitization-resistant, thermal cycling service |
980 |
| 347H |
S34709 |
Stabilized austenitic, high-temperature structural |
1093 |
| TP310HCB (Cast) |
— |
Ultra-high temperature, superalloy-grade |
1200 |
| 316L |
S31603 |
Chloride-containing environments, pitting resistance |
870 |
2.2 Mechanical Properties (Typical — Grade 310S, Solution Treated)
| Property |
Specification |
| Tensile Strength (RT) |
≥ 515 MPa (75 ksi) |
| Yield Strength (0.2% Offset, RT) |
≥ 205 MPa (30 ksi) |
| Elongation (50 mm gauge) |
≥ 40% |
| Hardness (Brinell) |
≤ 217 HB |
| Density |
8.0 g/cm³ |
| Thermal Conductivity (100°C) |
~16.3 W/(m·K) |
| Linear Thermal Expansion (20–1000°C) |
17.5 × 10⁻⁶ /°C |
2.3 Chemical Composition (Typical — Grade 310S)
| Element |
C |
Mn |
P |
S |
Si |
Ni |
Cr |
N |
| Max (%) |
0.08 |
2.0 |
0.045 |
0.030 |
1.5 |
— |
— |
0.10 |
| Min (%) |
— |
— |
— |
— |
— |
19.0 |
24.0 |
— |
2.4 Surface Protection Options
- Refractory Ceramic Coating: High-alumina or zirconia-based spray coating (Al₂O₃ or ZrO₂), thickness 2–5 mm, applied to the outer surface to provide a sacrificial barrier against molten slag and abrasive particulate impingement.
- Alloy Cladding (Overlay Welding):strong> Chromium-cobalt or nickel-based overlay weld (e.g., Stellite 6, Hastelloy X) applied to erosion-prone zones, providing localized hardening to 50–60 HRC.
- PVD Coating: Physical Vapor Deposition (PVD) of TiN or CrN for thin-film (< 2 μm) surface hardening in lower-temperature zones.
- Passivation Treatment: Citric acid or nitric acid passivation per ASTM A967 to enhance the native chromium oxide film and improve corrosion resistance.
3. Specifications
| Parameter |
Specification / Range |
| Tube Outer Diameter (OD) |
Φ 19 mm – Φ 159 mm (custom sizes available) |
| Wall Thickness (WT) |
1.5 mm – 8.0 mm |
| Coil Diameter |
1.2 m – 6.0 m (adjustable per installation requirements) |
| Coil Length (per coil) |
50 m – 500 m (continuous) |
| OD Tolerance |
± 0.5 mm or ± 2% (per ASTM A312) |
| WT Tolerance |
± 10% (standard) / ± 5% (precision) |
| Surface Finish |
Mirror polished (Ra ≤ 0.2 μm) / Brushed (Ra ≤ 0.8 μm) / Pickled & Passivated |
| Bend Radius (Cold) |
≥ 3D (D = outer diameter) |
| Maximum Operating Temperature |
Up to 1150°C (Grade 310S) / Up to 1200°C (TP310HCB) |
| Maximum Operating Pressure |
Up to 25 MPa (design-dependent) |
| Service Life (Design) |
≥ 5 years continuous operation (with coating protection) |
| Standards Compliance |
ASTM A312 / A213 / A269, EN 10216-5, GB/T 13296, JIS G3459 |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Procurement: Virgin or certified remelted stainless steel ingots/billets from accredited steel mills, with full Chemical Composition Analysis (CCA) and Mechanical Test Report (MTR) documentation.
- Hot Rolling: Billets heated to 1150–1250°C and hot-rolled to near-final dimensions in a continuous tube mill, followed by coil cooling and descaling.
- Intermediate Annealing: Solution annealing at 1050–1150°C with controlled cooling to restore ductility and eliminate rolling-induced residual stresses.
- Precision Cold Drawing / Cold Rolling: Tube drawn through precision dies (or cold-rolled) to achieve final dimensional tolerances and surface finish requirements. Drawing lubricants selected to avoid contamination of the austenitic matrix.
- Final Solution Annealing & Pickling: High-temperature solution treatment (1050–1150°C) followed by rapid water quench to fully austenitize and dissolve carbide precipitates. Subsequent acid pickling (HNO₃/HF blend) removes oxide scale.
- Passivation: Citric acid or nitric acid immersion passivation per ASTM A967 to establish a uniform, stable chromium oxide passive film.
- Surface Coating (Optional):strong> Application of refractory ceramic spray coating, overlay weld cladding, or PVD coating as specified for the target application.
- Coiling & Packaging: Final tube coiled onto mandrel of specified diameter, wrapped with VCI (Vapor Corrosion Inhibitor) paper and protective plastic film, secured with steel strapping, and labeled with heat traceability markings.
4.2 Quality Control Measures
- Incoming Inspection: Spectroscopic verification (OES) of each heat, visual inspection of billet surface quality.
- In-Process Monitoring: Online dimensional measurement (laser OD gauge), continuous hardness testing at drawing stations, visual surface inspection at each forming step.
- Final Testing:
- Hydrostatic Testing per ASTM A312 (test pressure = 1.5 × design pressure, minimum 30 MPa)
- Eddy Current Examination (ECE) per ASTM E309 for internal/external defect detection
- Ultrasonic Testing (UT) per ASTM A777 for wall thickness uniformity verification
- Piezoelectric Testing per ASTM A999 for subsurface discontinuity detection
- Mechanical Testing: Tensile test (ASTM E8), impact test (ASTM E23) at specified temperatures, hardness testing (ASTM E10/E92).
- Microstructural Examination: Metallographic analysis per ASTM E3 for grain size (ASTM E112), phase identification, and intergranular corrosion susceptibility (ASTM A262 Practice E or A923 Practice C — Streicher test).
5. Applications
5.1 Primary Applications
- Flash Smelting Furnace Steam Dryers: Coil tubes serve as heat exchange elements in the waste heat recovery system of flash smelters (e.g., CuFlash, Outotec/Outotec Flash). Flue gas at 1000–1300°C flows through or around the coil tubes, generating high-pressure steam. This is the most demanding application, subject to severe erosion-corrosion from fly ash, sulfur compounds, and thermal cycling.
- Metallurgical Heat Exchangers: Gas-gas and gas-liquid heat exchangers in non-ferrous smelting (copper, zinc, lead, nickel), steelmaking, and cement kilns.
- Reformer Tubes: High-temperature process tubes in ammonia synthesis and hydrogen production reformers, operating at 800–1000°C with reducing atmospheres.
- Boiler & Fired Heater Tubes: Waterwall tubes and convection section tubes in industrial boilers and fired heaters in petrochemical and power generation facilities.
- Waste Heat Boiler Systems: Coil tubes in waste heat recovery boilers capturing thermal energy from industrial exhaust streams.
5.2 Secondary Applications
- Chemical processing heat exchangers and reactor internals
- Food and pharmaceutical processing equipment (hygienic coil configurations)
- Automotive exhaust system components and turbocharger housings
- Marine engineering — marine boiler tubes and exhaust systems
- Solar thermal energy collection systems
6. Quality Certifications & Standards Compliance
| Certification / Standard |
Description |