Incoloy 800H Coil Tube Heater — Technical Product Specification
1. Product Overview
The Incoloy 800H Coil Tube Heater (Product No. 396) is a high-performance heat exchanger component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is engineered for demanding high-temperature service environments where exceptional resistance to thermal cracking, oxidation, and carburization is required. The coil tube (Coiltube) configuration provides an optimized surface-area-to-volume ratio, enabling efficient radiant and convective heat transfer in industrial furnace systems, petrochemical reactors, and power generation facilities.
The Incoloy 800H alloy — a modified variant of the classic Incoloy 800 — has been specifically developed to offer superior resistance to thermal fatigue cracking (thermal shock cracking) at elevated temperatures compared to its predecessor. This makes it the material of choice for heater tubes, furnace elements, and heat exchanger coils operating in the range of 900 °C to 1150 °C under cyclic thermal loading conditions.
2. Material & Properties
2.1 Alloy Designation
UNS N08810 / INCOLOY® 800H — a nickel-iron-chromium alloy with controlled carbon and manganese levels to minimize sigma phase precipitation and enhance thermal crack resistance.
2.2 Chemical Composition (Weight %)
| Element |
Minimum |
Maximum |
| Nickel (Ni) | 30.00 | 35.00 |
| Chromium (Cr) | 19.00 | 23.00 |
| Iron (Fe) | — | Balance |
| Carbon (C) | — | 0.10 |
| Manganese (Mn) | — | 1.00 |
| Silicon (Si) | — | 1.00 |
| Aluminum (Al) | — | 1.00 |
| Copper (Cu) | — | 0.50 |
| Titanium (Ti) | — | 0.60 |
| Sulfur (S) | — | 0.03 |
| Phosphorus (P) | — | 0.04 |
2.3 Mechanical Properties (Annealed Condition)
| Property |
Value |
Test Temperature |
| Tensile Strength (UTS) | ≥ 517 MPa (75 ksi) | 20 °C (RT) |
| Yield Strength (0.2% Offset) | ≥ 207 MPa (30 ksi) | 20 °C (RT) |
| Elongation | ≥ 40% | 20 °C (RT) |
| Density | 8.0 g/cm³ | 20 °C (RT) |
| Thermal Conductivity | 10.0 W/(m·K) | 20 °C (RT) |
| Thermal Conductivity | 21.6 W/(m·K) | 1000 °C |
| Modulus of Elasticity | 200 GPa | 20 °C (RT) |
| Thermal Expansion Coefficient | 12.6 µm/(m·K) | 20–1000 °C |
2.4 Key Performance Characteristics
- Thermal Crack Resistance: Up to 1150 °C (2100 °F) — significantly superior to Incoloy 800 under cyclic thermal conditions.
- Oxidation Resistance: Excellent in oxidizing atmospheres up to 1100 °C; resistant to sulfur and sulfur dioxide attack.
- Carburization Resistance: Moderate to good resistance in carburizing environments.
- Creep Strength: Maintains structural integrity under sustained loads at elevated temperatures.
- Corrosion Resistance: Immune to stress corrosion cracking (SCC) in chloride environments; resistant to nitric acid, citric acid, and formic acid.
- Weldability: Excellent — weldable by all standard fusion welding methods without preheating or post-weld heat treatment.
3. Specifications
| Parameter |
Specification |
| Product Name | Coil Tube (Coiltube) Heater |
| Product Number | 396 |
| Material Grade | Incoloy 800H (UNS N08810) |
| Tube Outer Diameter (OD) | 12.7 mm – 50.8 mm (1/2" – 2") |
| Wall Thickness | 1.0 mm – 4.0 mm |
| Coil Diameter | Custom (typically 300 mm – 2000 mm) |
| Coil Length | Up to 30,000 mm (custom per drawing) |
| Surface Finish | Pickled & Passivated / Polished (Ra ≤ 0.4 µm available) |
| Forming Process | Cold Drawing / Hot Forming / CNC Spiral Coiling |
| Standard Condition | Solution Annealed (1050–1150 °C, water or air quenched) |
| Maximum Service Temperature | 1150 °C (2100 °F) |
| Applicable Standards | ASTM B407 / B435 / B436; ASME SB-407; EN 10276-2 |
| Manufacturing Standard | GB/T 12770; HG/T 20537; Custom Engineering Drawings |
| Connection Types | Butt Weld / Socket Weld / Threaded / Flanged |
| Available Configurations | Spiral Coil / Helical Coil / Serpentine Coil / U-Tube Array |
4. Manufacturing Process
The production of Incoloy 800H Coil Tube Heaters involves a rigorous multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and long-term service reliability.
4.1 Process Flowchart
- Raw Material Selection & Inspection: Incoloy 800H seamless tubes or drawn tubes sourced from certified mills. Incoming inspection includes chemical analysis (spectrographic), mechanical property verification, and visual surface examination per ASTM B407.
- Cutting & End Preparation: Precision cutting to specified lengths using abrasive or plasma cutting methods. End faces prepared for welding or forming.
- Forming & Coiling:
- Cold Forming: Suitable for tube diameters ≤ 25.4 mm. Utilizes CNC-controlled coiling machines to produce precise helical or serpentine geometries with controlled springback compensation.
- Hot Forming: Employed for larger diameters or tighter bend radii. Tubes are heated to 800–950 °C and formed under controlled conditions to prevent cracking or excessive grain growth.
- Spiral Coiling: Continuous coiling process for long-length coils, maintaining uniform bend radius and pitch throughout the coil length.
- Welding: All joints welded using GTAW (Gas Tungsten Arc Welding) or GMAW (Gas Metal Arc Welding) with matching filler metals (Incoloy 800H or Inconel 625 filler wire per AWS A5.9). Welding parameters are controlled to minimize heat-affected zone (HAZ) sensitization. Argon shielding gas ensures oxide-free welds.
- Solution Heat Treatment (Annealing): The formed coil assembly undergoes solution annealing at 1050–1150 °C followed by rapid water quenching. This step:
- Relieves forming-induced residual stresses
- Dissolves any precipitated phases (sigma, Laves)
- Restores full ductility and corrosion resistance
- Produces a uniform microstructure
- Pickling & Passivation: Post-welding and post-heat-treatment chemical cleaning using a mixed acid solution (nitric + hydrofluoric acid blend) to remove oxide scale and form a protective chromium oxide passive layer. Alternative methods include electrolytic pickling for environmentally controlled facilities.
- Dimensional Inspection & Quality Control:
- Coordinate Measuring Machine (CMM) verification of coil geometry, pitch, and bend radius
- Visual and dye penetrant testing (DPT) of all welds per ASTM E709
- Radiographic testing (RT) of critical welds per ASTM E94
- Hydrostatic pressure testing at 1.5× design pressure for 30 minutes minimum
- Positive Material Identification (PMI) via XRF spectroscopy
- Final Cleaning & Packaging: Acid-free cleaning, protective end caps, individual wrapping, and export-grade packaging with moisture barriers and desiccant packs.
4.2 Critical Process Parameters
| Parameter |
Specification |
Control Method |
| Minimum Bend Radius (Cold) | ≥ 3× OD | CNC Forming Tooling |
| Minimum Bend Radius (Hot) | ≥ 2× OD | Induction Heating + Forming |
| Welding Heat Input | ≤ 2.5 kJ/mm | Parameter-Locked Welding Stations |
| Annealing Temperature | 1050–1150 °C | Calibrated Furnace with Continuous Monitoring |
| Quench Rate | ≥ 100 °C/min (water quench) | Immersive Quench Tank |
| Hydrostatic Test Pressure | 1.5 × Design Pressure | Automated Pressure Test Rig |
5. Applications
5.1 Primary Industrial Sectors
- Petrochemical & Refining: Crude oil fractionation heaters, reformer tubes, hydrotreater heater tubes, and catalytic cracker regenerator coils operating at 600–1100 °C.
- Power Generation: Boiler economizer tubes, superheater coils, and waste heat recovery (WHR) systems in combined cycle gas turbine (CCGT) plants.
- Chemical Processing: Reactor jacket coils, distillation column reboilers, and heat transfer coils handling aggressive chemical media at elevated temperatures.
- Aerospace & Defense: Jet engine exhaust heat exchangers, thermal management systems, and high-temperature gas path components.
- Hydrogen Production: Steam methane reforming (SMR) furnace tubes and autothermal reformer (ATR) coil elements where thermal cycling is severe.
- Environmental Systems: Flue gas desulfurization (FGD) heat exchangers and incinerator heat recovery coils.
5.2 Typical Operating Conditions
| Application |
Temperature Range |
Atmosphere |
Design Pressure |
| Crude Oil Heater | 400–850 °C | Hydrocarbon / Sulfur-bearing | 5–30 bar |
| Steam Methane Reformer | 800–1000 °C | Reducing (H₂/CO/CH₄) | 20–40 bar |
| Waste Heat Boiler | 500–900 °C | Flue Gas / Oxidizing | 10–60 bar |
| Catalytic Cracker | 600–950 °C | Endothermic / Carburizing | 1–5 bar |
| Hydrogen Reformer | 700–950 °C | Reducing / H₂-rich | 15–35 bar |
6. Quality Certifications & Compliance
6.1 Company Quality Management System
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control throughout the manufacturing lifecycle.
- ISO 14001 — Environmental Management System certification for sustainable manufacturing practices.
- ISO 45001 — Occupational Health and Safety Management System.
6.2 Product-Specific Certifications
- Material Traceability: Full mill certificate traceability from raw tube supplier through to finished coil assembly. Each product batch accompanied by EN 10204 Type 3.1 material test certificate.
- Welding Qualification: Welding Procedure Qualification Records (WPQR) and Welder Performance Qualifications (WPQ) maintained per ASME Section IX and ISO 15614.
- Third-