Stainless Steel Coil Tube (Trace Heating Coil) — E-GAS Gasification System Grade
Product Catalog No.: 544 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product designed for trace heating applications within high-temperature industrial systems, particularly in coal gasification facilities such as the E-GAS (Enhanced Gasification and Slurry Transport) process. These coil tubes serve as critical components in filter trace heating systems, where they circulate heat transfer media to prevent product freezing, plugging, or condensation within gas-phase separation and filtration equipment.
Wenzhou Jixing Metal Materials Co., Ltd. specializes in the design, fabrication, and supply of stainless steel coil tubes that meet the rigorous demands of gasification, petrochemical, and power generation industries. The product is engineered to withstand extreme thermal cycling, corrosive media exposure, and high-pressure operating conditions inherent to coal gasification environments.
2. Material & Properties
2.1 Base Material
Coil tubes are manufactured from high-grade austenitic stainless steel, with the following common grades available:
- SUS304 / AISI 304 — General corrosion resistance, suitable for moderate-temperature trace heating
- SUS316L / AISI 316L — Enhanced resistance to chlorides and sulfides; preferred for gasification environments with sulfur-bearing gases
- SUS310S / AISI 310S — High-temperature oxidation resistance up to 1150°C; used in zones with elevated radiant heat
- Inconel 625 / Hastelloy C-276 — For extreme corrosion and high-temperature applications
2.2 Mechanical Properties (Typical Values for 316L Grade)
- Tensile Strength (UTS): ≥ 515 MPa
- Yield Strength: ≥ 205 MPa
- Elongation: ≥ 40%
- Operating Temperature Range: -196°C to +550°C (sustained)
- Maximum Design Pressure: Up to 25 MPa (depending on wall thickness and size)
2.3 Corrosion Resistance
The selected alloys provide excellent resistance to:
- Coal gasification syngas (H₂, CO, CO₂, H₂S, HCN)
- Trace moisture and acid condensates
- Chloride pitting and crevice corrosion
- Thermal fatigue and oxidation scaling at elevated temperatures
3. Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Trace Heating Coil) |
| Product Code | No. 544 |
| Outer Diameter (OD) | Φ8 mm – Φ50 mm (customizable) |
| Wall Thickness | 0.5 mm – 4.0 mm |
| Coil Length | 5 m – 500 m per coil (per customer requirement) |
| Bend Radius | ≥ 3D (minimum 3 times outer diameter) |
| Surface Finish | Polished (Ra ≤ 0.8 μm) / Pickled & Passivated |
| End Treatment | Beveled, threaded, or plain per drawing |
| Standard | ASTM A269 / ASTM A213 / GB/T 12771 / EN 10216-5 |
| Heat Treatment | Solution annealed and water quenched |
| Delivery Form | Coiled (random length) or cut-to-length straight sections |
| Heat Trace Medium | Hot water, steam, thermal oil, or electric heating element (in-sheathed) |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Selection: Certified stainless steel seamless tube stock from approved mills (e.g., Outokumpu, Sandvik, Tsingshan) with full material traceability.
- Cutting & End Preparation: Precision saw-cutting to specified lengths with deburring and chamfering of tube ends.
- Coiling / Bending: CNC-controlled cold coiling or orbital bending to achieve precise coil diameters and consistent bend radii without wall thinning or ovality exceeding 3%.
- Welding (if applicable): TIG (GTAW) welding of U-bends, headers, and return connections with full-penetration welds and visual + dye penetrant inspection.
- Heat Treatment: Solution annealing at 1050–1100°C followed by rapid water quench to restore full austenitic microstructure and maximize corrosion resistance.
- Pickling & Passivation: Acid pickling (HNO₃/HF blend) to remove oxidation scale, followed by nitric acid passivation to form a protective chromium oxide layer.
- Pressure Testing: Hydrostatic pressure test at 1.5× design pressure, held for minimum 30 minutes with zero leakage permitted.
- Final Inspection: Dimensional verification, surface finish measurement, and ultrasonic testing (UT) for internal defects.
4.2 Quality Control Milestones
- Incoming material inspection with certified mill test reports (MTR)
- In-process dimensional checks at coiling station
- Post-weld NDT (Dye Penetrant Testing — DPT) on all weld joints
- Final hydrostatic pressure test with documented results
- Surface roughness verification via contact profilometry
5. Applications
5.1 Primary Application — E-GAS Gasification Filter Trace Heating
The E-GAS (Enhanced Gasification and Slurry Transport) process is a coal-water slurry gasification technology developed by the U.S. Department of Energy (DOE). In this system, the filter trace heating coil tubes play a vital role in maintaining the temperature of gas-phase separation filters and downstream piping. Without adequate trace heating, condensable components (H₂S, HCN, water) can freeze or polymerize, causing blockages and catastrophic filter failure.
Leakage Analysis Reference: The "E-GAS Gasification Filter Trace Heating Coil Tube Leakage Analysis" document (internal learning material, Ref. No. 544) provides critical engineering insights into failure modes observed in field-deployed coil tubes, including thermal fatigue cracking, corrosion-assisted stress rupture, and weld degradation under cyclic loading. These lessons inform the current design improvements implemented by Wenzhou Jixing.
5.2 Additional Applications
- Coal gasification syngas cooler and wash tank heating coils
- Petrochemical distillation column trace heating
- LNG (Liquefied Natural Gas) facility cryogenic trace heating
- Pharmaceutical and food-grade hygienic process heating loops
- Nuclear power plant auxiliary system heating coils
- Power plant SCR (Selective Catalytic Reduction) denitration catalyst preheating
6. Quality Certifications & Compliance
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health & Safety Management |
| ASME Stamp (U/U2) | Pressure Vessel & Piping Components |
| EN 10204 3.1 | Material Test Certificate (Third-party inspected) |
| NACE SP0107 | Corrosion Prevention in Petroleum Production |
| GB/T 19001-2016 | Chinese National Quality Management Standard |
7. Unique Selling Points
- Failure-Informed Design: Direct incorporation of lessons learned from E-GAS filter trace heating coil leakage incidents, resulting in optimized wall thickness profiles, enhanced bend radii, and improved weld geometry that significantly reduce fatigue crack initiation.
- Customizable Coil Geometry: CNC coiling capability allows precise replication of complex plant-specific layouts, minimizing field modification and reducing installation labor costs.
- Full Traceability: Each coil tube batch carries laser-marked heat numbers linked to mill certificates, enabling complete material traceability throughout the product lifecycle.
- Multi-Grade Material Availability: Stock of 304, 316L, 310S, and exotic alloys ensures rapid delivery without compromising metallurgical integrity.
- Rigorous NDT Protocol: Multi-method non-destructive testing (UT + DPT + Hydrostatic) provides confidence that no internal or surface defects escape detection.
- Engineering Support: Dedicated technical team provides thermal-hydraulic simulation, fatigue life analysis, and corrosion assessment support for critical applications.
8. Packaging & Delivery
Coil tubes are supplied on custom wooden or steel shipping spools with protective end caps to prevent mechanical damage during transit. Each package includes:
- Mill Test Report (MTR) and Heat Treatment Certificate
- Hydrostatic Pressure Test Report
- NDT Inspection Report (DPT/UT)
- Dimensional Inspection Certificate
- Packaging & Shipping Specification
Lead time for standard configurations: 15–25 working days. Custom projects: 30–60 working days depending on complexity and volume.
Wenzhou Jixing Metal Materials Co., Ltd. — Precision Stainless Steel Coil Tubes for Critical Industrial Applications.