For engineers designing aerospace actuators, fuel sensors, and high-pressure hydraulic lines, one of the most challenging problems is internal surface contamination. Standard annealing processes leave a layer of black oxide, or "scale," inside the tubing.
Risks of Improper Surface Finishing:
Debris Contamination: Over time, the fragile inner surface scale can flake off, clogging miniature valves and sensitive sensors.
Turbulence: Rough inner surfaces (Ra > 1.6 μm) can lead to unstable pressure drops and fluid readings.
Corrosion Initiation: Residual oxides can become localized initiation points for pitting corrosion in corrosive media.
At Gnee Alloy, we eliminate these risks. Our Bright Annealed (BA) GH4169 tubing undergoes precision heat treatment in pure hydrogen or high vacuum environments, ensuring a mirror-like silver finish on both the inner and outer diameters.
Click to obtain the precision bright annealed GH4169 sample tube
Bright annealed GH4169 / 718 aerospace precision seamless tube
Bright annealed GH4169 / 718 aerospace precision seamless tube
Bright annealed GH4169 (Inconel 718) aerospace precision seamless tubing is a high-performance nickel-based superalloy component designed for harsh environments. It offers exceptional strength, high-temperature resistance, and corrosion resistance. Capable of withstanding temperatures up to 650°C while maintaining high pressure and heat resistance, these tubings are commonly used in aero-engine components such as turbine disks, blades, and fuel lines.
How should INCONEL 718 be heat-treated?
To obtain the optimal combination of tensile and stress-breaking properties, the following heat treatment process should be used: 1 hour, 1750°F to 1800°F (954 to 982°C), air cooling; 8 hours, 1325°F (718°C), cooling at a rate of 100°F/hour to 1150°F (56°C/hour to 621°C), holding at the temperature for 8 hours, air cooling.
1. GH4169 Bright Annealed Tube Applicable Standards
| Parameter | Description |
|---|---|
| Material | GH4169 (UNS N07718 / Inconel 718) |
| Product Form | Bright Annealed (BA) Precision Tube – Seamless |
| Grade | Aviation / Aerospace Grade |
| Applicable Standards | AMS 5589, AMS 5590, ASTM B983, GB/T 14994, Q/S 10-0402 |
| Surface Condition | Bright Annealed (BA) – Hydrogen atmosphere annealed |
2. Chemical composition (weight percentage) of GH4169 bright annealed tube – Aerospace grade
| Element | Content (%) | Standard Requirement | Notes |
|---|---|---|---|
| Nickel (Ni) | 50.0 – 55.0 | 50.0 – 55.0 | Matrix element |
| Chromium (Cr) | 17.0 – 21.0 | 17.0 – 21.0 | Oxidation and corrosion resistance |
| Iron (Fe) | Balance (~18-20) | Balance | Fe-Ni-Cr base alloy |
| Niobium (Nb) | 4.75 – 5.50 | 4.75 – 5.50 | Primary γ″ strengthening element |
| Molybdenum (Mo) | 2.80 – 3.30 | 2.80 – 3.30 | Solid-solution strengthening |
| Titanium (Ti) | 0.65 – 1.15 | 0.65 – 1.15 | γ′ strengthening phase |
| Aluminum (Al) | 0.20 – 0.80 | 0.20 – 0.80 | γ′ strengthening phase |
| Carbon (C) | ≤ 0.08 | ≤ 0.08 | Low carbon for weldability |
| Manganese (Mn) | ≤ 0.35 | ≤ 0.35 | Deoxidizer |
| Silicon (Si) | ≤ 0.35 | ≤ 0.35 | Deoxidizer |
| Phosphorus (P) | ≤ 0.010 | ≤ 0.015 | Aviation grade stricter |
| Sulfur (S) | ≤ 0.005 | ≤ 0.015 | Aviation grade stricter |
| Boron (B) | 0.002 – 0.006 | 0.002 – 0.006 | Grain boundary strengthener |
| Cobalt (Co) | ≤ 1.00 | ≤ 1.00 | Residual element |
| Copper (Cu) | ≤ 0.30 | ≤ 0.30 | Residual element |
| Oxygen (O) | ≤ 30 ppm | – | Aviation grade requirement |
| Nitrogen (N) | ≤ 50 ppm | – | Aviation grade requirement |
| Hydrogen (H) | ≤ 5 ppm | – | Aviation grade requirement |
Click to download the GH4169 alloy PDF file now
3. Physical properties of GH4169 bright annealed tube
| Property | Value | Notes |
|---|---|---|
| Density | 8.19 g/cm³ | – |
| Melting Range | 1260 – 1336°C | – |
| Thermal Conductivity (20°C) | 11.4 W/m·K | – |
| Coefficient of Thermal Expansion (20-100°C) | 13.0 × 10⁻⁶/°C | – |
| Coefficient of Thermal Expansion (20-600°C) | ~14.5 × 10⁻⁶/°C | – |
| Specific Heat (20°C) | 435 J/kg·K | – |
| Electrical Resistivity | 1.25 µΩ·m | – |
| Magnetic Permeability | 1.005 (slightly magnetic) | – |
4. GH4169 Bright Annealed Precision Tube Dimensions and Specifications
| Parameter | Range | Tolerance (Aviation Grade) |
|---|---|---|
| Outside Diameter (OD) | 1.0 mm – 50.8 mm | ±0.025 – ±0.050 mm |
| Wall Thickness | 0.15 mm – 3.0 mm | ±5% – ±10% |
| Length | 1000 mm – 12000 mm | ±1 mm |
| OD Ovality | – | ≤ 0.75% of OD |
| Wall Thickness Concentricity | – | ≤ 10% of wall thickness |
| Straightness | – | ≤ 0.5 mm/m |
| Surface Roughness (ID) | – | Ra ≤ 0.4 µm |
| Surface Roughness (OD) | – | Ra ≤ 0.4 µm |
Commonly used precision tubing dimensions in the aerospace industry
| OD (mm) | Wall Thickness (mm) | Typical Application |
|---|---|---|
| 3.18 | 0.51 | Instrumentation lines |
| 4.76 | 0.71 | Hydraulic lines |
| 6.35 | 0.89 | Fuel system lines |
| 9.53 | 1.07 | Engine bleed air |
| 12.70 | 1.24 | High-pressure hydraulic |
| 15.88 | 1.65 | Structural lines |
Click to contact us to design the right GH4169 pipe dimensions for your project
5. Applications of GH4169 Precision BA Tubing
As a Tier 1 manufacturer, Gnee Steel supplies high-performance precision tubing for the following applications:
Aerospace Actuators: Piston rods and cylinder blocks requiring smooth surfaces.
Fuel and Pressure Sensors: High-precision housings where no internal impurities are permissible.
Medical High-Temperature Equipment: Specialized instruments for high-temperature environments.
Hydraulic Lines: Precision connections in flight control systems.
Why choose Gnee Alloy?
✅️Direct Factory Price: Eliminate middleman markups and secure the best rates for Wholesale Supply.
✅️100% NDT Inspection: Every tube is verified via Eddy Current (ET) and Ultrasonic (UT) testing.
✅️MTC 3.1 Traceability: Full heat-analysis and surface roughness reports included with every shipment.
✅️Custom Fabrication: We offer precision cutting and specialized end-forming to match your assembly blueprints.
Gnee Steel GH4169(inconel 718) Certificate
📦 Packaging and Shipping
All Nickel Based Alloy products are packaged using the following methods:
Wooden pallets or crates
Moisture-proof packaging
Labels with furnace number, standard, and size labels
Shipped worldwide by sea, air, or express
Gnee Steel GH4169 Product Packing
Contact us for the latest export price quote for GH4169 Alloy
FAQ
Q1: How do you guarantee "No Internal Oxidation"?
A: We use a proprietary Bright Annealing process in a high-purity Hydrogen (H2) or vacuum environment. This prevents oxygen from ever touching the metal during the heating cycle, resulting in a perfectly clean and bright internal diameter (ID).
Q2: Can I get h9 tolerance on both OD and ID?
A: For precision tubing, we primarily focus on OD Tolerance (h8-h11). However, with our multi-stage precision drawing, we can achieve high-accuracy ID control to meet your assembly needs.
Q3: Is GH4169 equivalent to Inconel 718 for precision sensors?
A: Yes. GH4169 is chemically and mechanically identical to Inconel 718. It is globally interchangeable and meets all aerospace certification requirements.
Q4: Do you offer trial orders for small quantities (Prototypes)?
A: Absolutely. We support aerospace innovation by offering Flexible MOQs on standard precision sizes (OD 3mm to 50mm).
