Stainless Steel Heat Extraction Coil Tube for Regenerator Applications
Product Overview
The Stainless Steel Heat Extraction Coil Tube (product code: 1606) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular component specifically designed for heat extraction and heat exchange services within industrial regenerator systems. These coil tubes are formed from high-grade austenitic stainless steel, delivering superior resistance to thermal fatigue, oxidation, and corrosion under the extreme operating conditions found in regenerator environments.
Coil tubes serve as critical heat transfer elements, channeling process fluids through compact, high-surface-area configurations that maximize thermal efficiency. In regenerator applications—common in petroleum refining, chemical processing, and power generation—these tubes must withstand cyclic thermal loading, high-temperature oxidative atmospheres, and potentially corrosive process media over extended service lives. The product is engineered to address the failure mechanisms identified in industry studies, including thermal stress cracking, intergranular corrosion, and stress corrosion cracking (SCC), thereby ensuring reliable long-term performance.
Material & Properties
The coil tubes are fabricated primarily from austenitic stainless steel grades conforming to international standards. The following materials are available depending on application requirements:
- AISI 304 (UNS S30408) — General-purpose austenitic stainless steel offering excellent formability and corrosion resistance in moderate-temperature environments.
- AISI 316 / 316L (UNS S31608 / S31603) — Enhanced molybdenum content provides superior resistance to pitting and crevice corrosion, suitable for chloride-containing process streams.
- AISI 321 (UNS S32108) — Titanium-stabilized grade with excellent resistance to sensitization and intergranular corrosion at elevated temperatures (up to 870°C).
- AISI 347 (UNS S34708) — Niobium-stabilized austenitic grade offering superior resistance to thermal fatigue and high-temperature oxidation.
- Super-Austenitic Grades (e.g., Alloy 625, Alloy 800H) — Available for the most demanding applications involving extreme temperatures, aggressive media, or severe thermal cycling.
Key Mechanical and Physical Properties (typical for AISI 316L):
- Tensile Strength (UTS): ≥ 515 MPa
- Yield Strength (0.2% offset): ≥ 205 MPa
- Elongation (A50mm): ≥ 40%
- Thermal Conductivity (20°C): 16.3 W/(m·K)
- Coefficient of Thermal Expansion (20–100°C): 17.3 × 10⁻⁶ /°C
- Maximum Service Temperature: 870°C (oxidizing atmosphere)
Specifications
| Parameter | Specification |
|---|---|
| Product Code | 1606 |
| Product Type | Coil Tube (盘管) — Heat Extraction Coil |
| Material Grades | AISI 304, 316, 316L, 321, 347, Alloy 625, Alloy 800H |
| Outer Diameter (OD) | 6.0 mm – 114.3 mm (¼" – 4½") |
| Wall Thickness | 0.5 mm – 6.0 mm |
| Coil Pitch (Helical Spacing) | 10 mm – 100 mm (customizable) |
| Coil Diameter | 100 mm – 2000 mm (customizable) |
| Length per Coil | 5 m – 100 m (as required) |
| Surface Finish | Mechanically polished, Pickle & Passivated, Ra ≤ 0.8 μm |
| End Condition | Beveled, Flanged, or Threaded (per customer specification) |
| Manufacturing Standard | ASTM A269, ASTM A312, ASME B36.19M, EN 10216-5 |
| Applicable Standards | GB/T 12771, GB/T 13296, JIS G3459 |
| Operating Temperature Range | −196°C to 870°C (grade-dependent) |
| Maximum Operating Pressure | Up to 40 MPa (wall thickness and grade dependent) |
| Heat Treatment | Solution Annealed & Water Quenched; Stabilization Heat Treatment available for 321/347 |
Manufacturing Process
The production of heat extraction coil tubes follows a rigorous multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and resistance to the failure modes documented in regenerator service:
- Raw Material Procurement & Inspection: Premium-grade austenitic stainless steel seamless tubes or welded pipe blanks are sourced from certified mills. Incoming materials undergo spectroscopic analysis (PMI), mechanical testing, and visual inspection to verify chemical composition and mechanical properties conform to specified standards.
- Tube Straightening & Cutting: Raw tubes are precision-straightened and cut to required lengths with controlled burr-free ends to prevent stress concentrations at coil transition zones.
- Coil Forming (Cold Bending): Tubes are helically formed using CNC-controlled coil bending machines. The forming process is carefully controlled to prevent wall thinning, ovality distortion, and residual stress accumulation—key contributors to thermal fatigue cracking in service. Bending radii are calculated to ensure uniform strain distribution.
- Pickle & Passivation: Formed coils undergo acid pickling (HNO₃/HF blend) to remove mill scale, bending oxide, and surface contaminants. A subsequent passivation treatment forms a stable chromium oxide film, enhancing corrosion resistance.
- Stress Relief (if applicable): For applications subject to severe thermal cycling, an intermediate stress-relief annealing step may be performed to reduce residual stresses introduced during forming.
- Final Inspection & Testing: Completed coil tubes undergo dimensional verification (OD, wall thickness, pitch, coil diameter), surface finish measurement, hydrostatic pressure testing, and optional eddy current testing for defect detection.
- Packaging & Dispatch: Coils are wrapped in protective film, secured with strapping, and labeled with material traceability documentation prior to shipment.
Applications
These stainless steel heat extraction coil tubes are engineered for demanding thermal and chemical service environments, including:
- Petroleum Refining & Petrochemical Processing: Heat extraction coils in fluid catalytic cracking (FCC) regenerators, where temperatures can exceed 700°C with cyclic thermal loading and oxidizing atmospheres.
- Chemical Process Industry: Reactor heat exchange systems handling corrosive organic and inorganic compounds.
- Power Generation: Waste heat recovery systems and superheater coils in thermal power plants.
- Pharmaceutical & Food Processing: Sanitary-grade heat exchange systems requiring high cleanliness and corrosion resistance.
- Cryogenic Applications: Low-temperature heat exchange systems (down to −196°C) where austenitic grades maintain ductility and toughness.
- Heat Recovery Steam Generators (HRSG): Industrial gas turbine exhaust heat recovery systems.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that all coil tube products meet international standards and regulatory requirements:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control.
- ISO 14001:2015 — Environmental Management System certification for sustainable manufacturing practices.
- ASME "U" Stamp — Authorization for pressure vessel and piping component manufacturing.
- EN 10204 3.1 — Third-party inspection and material certification documentation.
- Material Traceability: Each product batch is accompanied by a Mill Test Certificate (MTC) including chemical composition, mechanical properties, heat treatment records, and non-destructive testing (NDT) results.
Unique Selling Points & Failure Prevention Design
Based on documented failure analysis of austenitic stainless steel heat extraction coil tubes in regenerator applications, this product incorporates targeted design and manufacturing features to mitigate the most common failure modes:
- Thermal Fatigue Resistance: Precise control of coil forming parameters minimizes residual stresses, while material selection (e.g., 321/347 with stabilization heat treatment) provides enhanced resistance to cyclic thermal cracking.
- Intergranular Corrosion Prevention: Strict control of carbon equivalent and optional stabilization heat treatment (1050°C for Ti-stabilized grades) prevents chromium carbide precipitation at grain boundaries, eliminating the primary mechanism for intergranular corrosion in high-temperature service.
- Stress Corrosion Cracking (SCC) Mitigation: Material grades with low interstitial content (316L, L-grade variants) and rigorous passivation treatment reduce susceptibility to chloride-induced SCC.
- Dimensional Consistency: CNC-controlled forming ensures uniform coil geometry, eliminating stress concentration points at irregular bends that could initiate cracking under thermal cycling.
- Full Traceability & Verification: Comprehensive material certification and NDT protocols provide complete traceability from raw material to finished product, enabling root-cause analysis in the event of field issues.
Conclusion
The Wenzhou Jixing Stainless Steel Heat Extraction Coil Tube (Code 1606) represents a purpose-engineered solution for regenerator and heat exchange applications where reliability under extreme thermal and chemical conditions is paramount. By integrating advanced material selection, precision manufacturing, and failure-mode-informed design practices, this product delivers extended service life, reduced unplanned downtime, and optimized thermal performance for demanding industrial processes.