Stainless Steel Coil Tube for GSP Gasification Furnace Water-Cooled Walls
Product No.: 653 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd
Classification: Technical Literature & Engineering Reference
Reference Document: Analysis of Inspection Strategy and Quality Standards for Water-Cooled Wall Coil Tubes in GSP (Gasification Steam Power) Furnaces
Product Overview
The Stainless Steel Coil Tube (盘管 / Coil Tube) is a critical heat-exchange component engineered for deployment within the water-cooled wall assemblies of GSP (Gasification Steam Power) gasification furnaces. These continuously formed tubular structures serve as the primary barrier between the high-temperature gasification environment—where temperatures routinely exceed 1,200 °C to 1,500 °C—and the internal cooling medium (water/steam). The coil tube configuration enables compact, high-surface-area thermal transfer while maintaining structural integrity under cyclic thermal loading, high-pressure differentials, and aggressive chemical attack from syngas constituents.
Wenzhou Jixing Metal Materials Co., Ltd specializes in the design, manufacturing, and supply of precision stainless steel coil tubes tailored to the demanding operational parameters of modern gasification systems, including entrained-flow, fluidized-bed, and fixed-bed configurations. The product line is developed in accordance with rigorous inspection strategy protocols and quality standards derived from extensive field-service data and failure analysis studies.
Material Composition & Properties
Base Alloy Selection
Coil tubes for GSP gasification furnace water-cooled walls are typically fabricated from austenitic stainless steel grades selected for their superior resistance to thermal fatigue, oxidation, carburization, and intergranular corrosion at elevated temperatures. The following material grades are standard options:
- SAE 304 / UNS S30408 — General-purpose austenitic stainless steel with excellent formability and moderate high-temperature strength. Suitable for water-cooled wall applications where the external gas temperature does not consistently exceed 900 °C.
- SAE 316 / UNS S31608 — Molybdenum-enhanced austenitic stainless steel offering superior resistance to pitting, crevice corrosion, and chloride-induced degradation. Preferred for environments with elevated halide or sulfur compound concentrations.
- SAE 310S / UNS S31008 — High-chromium, high-nickel austenitic stainless steel with exceptional oxidation resistance and thermal stability up to 1,150 °C. Recommended for the highest-temperature zones of the gasification furnace water-cooled wall.
- SAE 321 / UNS S32108 — Titanium-stabilized austenitic stainless steel providing resistance to intergranular corrosion during welding and high-temperature service (up to 870 °C).
- SAE 347 / UNS S34708 — Niobium-stabilized austenitic stainless steel with enhanced resistance to intergranular sensitization and improved high-temperature creep strength.
Mechanical & Physical Properties (Typical Values)
| Property | SAE 304 | SAE 316 | SAE 310S | SAE 321 | SAE 347 |
|---|---|---|---|---|---|
| Tensile Strength (RT) [MPa] | ≥ 520 | ≥ 515 | ≥ 515 | ≥ 520 | ≥ 520 |
| Yield Strength (0.2% Offset) [MPa] | ≥ 205 | ≥ 205 | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation [ % ] | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 40 |
| Density [g/cm³] | 8.00 | 8.03 | 8.00 | 8.00 | 8.00 |
| Thermal Conductivity at 100 °C [W/(m·K)] | 16.3 | 16.3 | 21.5 | 16.3 | 16.3 |
| Thermal Expansion Coefficient 20–100 °C [×10⁻⁶/K] | 17.2 | 17.2 | 18.5 | 17.2 | 17.2 |
| Maximum Service Temperature [°C] | 870 | 870 | 1150 | 870 | 870 |
| Chromium Content [ % ] | 18–20 | 16–18 | 24–26 | 17–19 | 17–19 |
| Nickel Content [ % ] | 8–10.5 | 10–14 | 19–22 | 9–12 | 9–12 |
Specifications
Dimensional Parameters
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | Φ 21.3 mm – Φ 76.2 mm (standard); custom upon request | ASTM A213 / GB/T 12771 |
| Wall Thickness (WT) | 1.0 mm – 8.0 mm (standard); tolerance ±0.1 mm | ASTM A213 / GB/T 12771 |
| Coil Diameter (CD) | 1.0 m – 5.0 m (configurable per furnace layout) | Manufacturer Specification |
| Tube Length per Coil | 10 m – 500 m (continuous coil delivery) | ASME B31.3 |
| Bend Radius (Minimum) | ≥ 3 × OD (cold-bent); ≥ 2 × OD (hot-bent) | ASTM A213 |
| Surface Finish | Baer, No. 1, 2B, or Pickled & Annealed (P&A) | ASTM A240 |
| Internal Surface Roughness (Ra) | ≤ 1.6 μm (standard); ≤ 0.8 μm (polished) | GB/T 1031 |
| Pressure Rating (Design) | Up to 6.5 MPa (water-cooled wall operating pressure) | ASME BPV Section I |
| Operating Temperature Range | -196 °C to 1,150 °C (depending on grade) | Material-specific |
| Applicable Welding Process | TIG (GTAW), MIG (GMAW), SAW | ASME Section IX |
Coil Configuration for Water-Cooled Wall Assembly
| Assembly Zone | Recommended Grade | Typical OD × WT [mm] | Design Rationale |
|---|---|---|---|
| Lower Furnace Wall (Radiant Zone) | SAE 310S | Φ 33.4 × 3.0 | Maximum thermal exposure; superior oxidation resistance required |
| Mid Furnace Wall (Transition Zone) | SAE 321 / 347 | Φ 25.4 × 2.5 | Thermal cycling resistance; intergranular corrosion protection |
| Upper Furnace Wall (Convective Zone) | SAE 304 / 316 | Φ 21.3 × 2.0 | Cost-effective; adequate for moderate temperature service |
| Gasification Burner Refractory Interface | SAE 310S | Φ 42.2 × 4.0 | Extreme thermal gradient; carburization resistance critical |
Manufacturing Process
Process Flow
- Raw Material Procurement & Incoming Inspection: Hot-rolled stainless steel strip or wire rod sourced from certified mills. Each lot undergoes spectral analysis (OES), mechanical testing, and chemical composition verification against ASTM A240 / GB/T 4237 specifications.
- Strip Annealing & Pickling: The raw strip is solution-annealed at 1,050–1,100 °C followed by controlled cooling to achieve a fully austenitic microstructure with minimum residual stress. Subsequent pickling in a mixed acid solution (HNO₃/HF or H₂SO₄/HNO₃) removes surface scale and contaminants.
- Forming (Cold Roll or Hot Form): The annealed strip is fed through a series of precision-forming rollers (roll-forming process) to produce a seamless tubular cross-section. For larger diameters (≥ Φ 50 mm), a hot-forming process with in-line annealing is employed to maintain ductility and prevent work-hardening.
- Welding (if applicable for welded coil tube): Longitudinal weld seams, where present, are produced via high-frequency induction welding (HF-W) or TIG welding with argon shielding. Weld parameters are optimized to achieve a single-pass, narrow heat-affected zone (HAZ) with full penetration and minimum dilution.
- In-Line Annealing: The formed tube passes through a radiant tube furnace for continuous annealing at 1,050–1,120 °C, followed by controlled water quenching or air cooling. This step relieves forming and welding stresses, restores full austenitic microstructure, and ensures compliance with mechanical property requirements.
- Precision Coiling: The annealed tube is wound onto a precision coiling mandrel using a CNC-controlled coiling head. The coil diameter, winding tension, and layer alignment are controlled to ±2 mm tolerance to ensure uniform handling and downstream installation.
- Surface Treatment: Optional surface finishing includes mechanical polishing (Ra ≤ 0.8 μm), chemical passivation (citric acid or nitric acid passivation per ASTM A967), and protective coating application for storage and transportation.
- Final Quality Inspection: Each coil undergoes comprehensive non-destructive testing (NDT) including:
- Eddy current testing (ECT) for detection of surface and near-surface defects
- Hydrostatic pressure testing at 1.5× design pressure for leak integrity
- Dimensional verification via laser diameter measurement
- Visual inspection of weld seams and coil geometry
- Packaging & Delivery: Coils are wrapped in moisture-proof PE film, secured with steel strapping, and palletized for containerized or bulk transport. Each shipment is accompanied by a Material Test Report (MTR) and Certificate of Conformity (CoC).
Applications
Primary Application: GSP Gasification Furnace Water-Cooled Walls
The coil tube is the fundamental structural and thermal-management element of the water-cooled wall system in GSP gasification furnaces. The water-cooled wall serves multiple critical functions:
- Heat Extraction & Steam Generation: The coil tubes circulate pressurized water that absorbs radiant and convective heat from the gasification reaction zone, generating high-pressure steam for power generation (typically 3.5–10.0 MPa, 450–540 °C).
- Refractory Protection: By maintaining the inner surface of the furnace wall below the softening point of the refractory lining (typically < 1,050 °C), the water-cooled wall prevents refractory degradation and extends furnace campaign life.
- Structural Integrity: The coil tube assembly provides the primary structural containment for the gasification furnace, resisting internal pressure loads (0.5–2.0 MPa gas-side), thermal stresses, and mechanical vibrations.
- Temperature Zoning: The coil tube layout enables precise thermal zoning within the furnace, allowing independent control of reaction conditions in the reduction zone, gasification zone, and quench zone.
Secondary Applications
- Coal-to-Liquid (CTL) and Coal-to-Chemicals (CTC) Gasifiers: Shell Gasifier, GE Topso Gasifier, and Eastman Gasifier water-cooled panels
- Biomass and Waste-to-Energy (WtE) Gasification Systems: Fluidized-bed gasifier heat exchangers
- Hydrogen Production Reactors: Steam methane reforming (SMR) tube banks
- Industrial Boiler Waterwalls: Utility-scale coal-fired and dual-fuel boiler radiant sections
- Petrochemical Process Heaters: Crude oil heaters, reformer tubes, and catalytic cracker furnace tubes
- Power Plant Economizers and Superheaters: Convective heat exchanger coil assemblies
Inspection Strategy & Quality Standards
Inspection Protocol Framework
Based on the technical literature referenced in the product documentation ("Analysis of Inspection Strategy and Quality Standards for Water-Cooled Wall Coil Tubes in GSP Gasification Furnaces"), the following comprehensive inspection strategy is recommended for both in-service monitoring and post-maintenance verification:
Pre-Startup Inspection (Commissioning)
- 100% hydrostatic pressure test at 1.5× design pressure, held for 30 minutes with zero pressure drop
- 100% eddy current scan of all weld seams and tube surfaces
- Visual inspection of coil geometry, bend integrity, and support structure alignment