For engineers in aerospace propulsion and high-pressure instrumentation, GH4169 seamless steel tubing is a critical component. However, many commercially available "commercial-grade" tubings suffer from two hidden defects:
Internal oxidation (scaling): Standard annealing processes leave a layer of black oxide inside the tubing. Under high-flow-rate fuel, this oxide layer can flake off, clogging precision sensors and fuel injectors.
Poor concentricity (uneven wall thickness): Inconsistent wall thickness creates localized "weak points." Under extreme pressures (up to 700 bar), these weak points can become the starting point for pipe rupture, ultimately leading to catastrophic failure.
At Gnee Steel, we eliminate these manufacturing bottlenecks through specialized processes, ensuring absolute structural integrity and zero-defect quality.
View our inventory list and pricing for Sch 40 and Sch 80 GH4169
Production process of high temperature resistant AMS 5590 GH4169 (718 alloy) seamless tube
Production process of high temperature resistant AMS 5590 GH4169 (718 alloy) seamless tube
The manufacturing process of AMS 5590 GH4169 (Inconel 718) high-temperature seamless tubes involves a complex, multi-stage process designed to address the alloy's high strength and work-hardening properties. The process typically begins with high-purity melting, followed by hot extrusion to form a hollow tube, cold working to improve precision, and finally, precise heat treatment to obtain the microstructure required for high-temperature applications.
What is the maximum operating temperature of Inconel 718?
-423°F to 1300°F.
INCONEL Alloy 718 (UNS N07718/W.Nr. 2.4668) is a high-strength, corrosion-resistant nickel-chromium alloy with an operating temperature range of -423°F to 1300°F.
1. GH4169 Seamless Steel Tube Scope and Applicable Standards
| Parameter | Description |
|---|---|
| Specification | AMS 5590 (Aerospace Material Specification) |
| Material | GH4169 (UNS N07718 / Inconel 718) |
| Product Form | Seamless Tube – Thin Wall / High Temperature Service |
| Design Focus | High-temperature strength, oxidation resistance, thermal fatigue resistance |
| Typical Applications | Engine bleed air ducts, high-temperature hydraulic lines, afterburner fuel lines, turbine cooling lines, exhaust system components |
| Operating Temperature Range | Up to 700°C (1292°F) continuous; up to 760°C (1400°F) short-term |
Note: AMS 5590 is specifically designed for thin-walled Inconel 718 tubing used in high-temperature aerospace applications. This specification requires a dual melting process (vacuum ion melting + vacuum argon arc welding) to ensure the highest cleanliness and high-temperature reliability.
2. Chemical composition (wt%) of AMS 5590 standard GH4169 seamless tube
| Element | Content (%) | Standard Requirement | Function in High-Temperature Service |
|---|---|---|---|
| Nickel (Ni) | 50.0 – 55.0 | 50.0 – 55.0 | Matrix element; provides high-temperature stability |
| Chromium (Cr) | 17.0 – 21.0 | 17.0 – 21.0 | Oxidation resistance; forms protective Cr₂O₃ scale |
| Iron (Fe) | Balance (~18-20) | Balance | Fe-Ni-Cr base alloy |
| Niobium (Nb) | 4.75 – 5.50 | 4.75 – 5.50 | Core strengthening element – forms γ″ (Ni₃Nb) for high-temperature strength |
| Molybdenum (Mo) | 2.80 – 3.30 | 2.80 – 3.30 | Solid-solution strengthening; enhances creep resistance |
| Titanium (Ti) | 0.65 – 1.15 | 0.65 – 1.15 | Forms γ′ strengthening phase (Ni₃(Al,Ti)) |
| Aluminum (Al) | 0.20 – 0.80 | 0.20 – 0.80 | Forms γ′ strengthening phase; improves oxidation resistance |
| Carbon (C) | ≤ 0.08 | ≤ 0.08 | Low carbon for high-temperature stability |
| Manganese (Mn) | ≤ 0.35 | ≤ 0.35 | Deoxidizer |
| Silicon (Si) | ≤ 0.35 | ≤ 0.35 | Deoxidizer |
| Phosphorus (P) | ≤ 0.015 | ≤ 0.015 | Low for high-temperature toughness |
| Sulfur (S) | ≤ 0.015 | ≤ 0.015 | Low for high-temperature hot workability |
| Boron (B) | 0.002 – 0.006 | 0.002 – 0.006 | Grain boundary strengthener; critical for creep life |
| Cobalt (Co) | ≤ 1.00 | ≤ 1.00 | Residual element |
| Copper (Cu) | ≤ 0.30 | ≤ 0.30 | Residual element |
Click to download the GH4169 alloy PDF file now
3. Production process of AMS 5590 GH4169 seamless tube
Step One: VIM + VAR Dual Vacuum Melting
The creation of high-performance tubing begins in a vacuum furnace. We employ a dual refining strategy to ensure the purest possible microstructure:
VIM (Vacuum Induction Melting): Removes dissolved gases (O, N, H), ensuring perfect balance in basic chemical composition analysis.
VAR (Vacuum Arc Remelting): Removes non-metallic inclusions, eliminating "spots" (macroscopic segregation), ensuring uniform overall mechanical properties of the tubing wall.
Step Two: Precision Cold Drawing and Concentricity Control
To address the issue of uneven wall thickness, we use precision-ground tungsten carbide molds to perform multi-stage cold drawing on GH4169 tubing.
Concentricity Guarantee: We control wall thickness deviation to ≤5%, ensuring a consistent safety factor throughout the circumference.
Dimensional Accuracy: Achieving ultra-strict h-tolerances makes our tubing ideal for interference fits in aerospace components.
Step Three: Vacuum Bright Annealing (BA Surface Treatment)
Unlike standard pickling, our bright annealing process is performed in a high-purity hydrogen or high-vacuum environment.
Mirror-like smoothness: Ensures a smooth surface (Ra ≤ 0.4μm) for both the inner diameter (ID) and outer diameter (OD).
Zero internal scale: The inner wall of the pipe remains mirror-like, eliminating any risk of system contamination during operation.
Why choose to source GH4169 from Tier 1 manufacturer Gnee Alloy?
✅️Direct Factory Pricing: Skip the middleman markups and secure original equipment manufacturer (OEM) rates.
✅️100% NDT Inspection: Every single meter of our GH4169 tubing undergoes Ultrasonic Testing (UT) and Eddy Current Testing (ET).
✅️MTC 3.1 Traceability: Full heat analysis and mechanical test reports included, ensuring total Global Compliance.
✅️Global Fast Shipping: We maintain an extensive inventory of standard ANSI schedules ready for immediate dispatch.
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: Why is the BA finish so important for fuel lines?
A: A Bright Annealed finish (BA) ensures that the ID surface is chemically stable and physically smooth. This prevents fuel turbulence and ensures that no loose scale pollutes the sensitive fuel injectors of the turbine engine.
Q2: Is your GH4169 equivalent to Inconel 718 for international projects?
A: Yes. GH4169 is the technical equivalent of Inconel 718. Our material is globally interchangeable and meets all international requirements for UNS N07718 and W.Nr. 2.4668.
Q3: Do you offer custom wall thicknesses for high-pressure reactors?
A: Absolutely. We specialize in Custom Fabrication and can produce heavy-wall or non-standard thin-wall seamless tubing to meet your exact pressure vessel calculations.
Q4: Can you provide hydrostatic testing for each individual pipe?
A: Yes. For chemical and nuclear projects, we provide 100% Hydrostatic Pressure Testing to verify the structural integrity of the tube before it leaves our factory.
