INCONEL Alloy 740H Seamless Pipe | UNS N07740 ASTM B983
INCONEL alloy 740H seamless pipe and tube is a precipitation-hardenable nickel-chromium-cobalt product identified as UNS N07740. It was developed for high-temperature steam systems where creep strength, metallurgical stability and resistance to fireside and steam-side corrosion must be considered together.
SASA ALLOY reviews N07740 seamless pipe and tube requirements to ASTM B983 and the applicable project or code requirements. For quotation, state the outside diameter, wall thickness, length, solution-annealed or solution-annealed-and-aged condition, testing, certification and intended service.
Product Identification and Supply Scope
| Product | INCONEL alloy 740H seamless pipe and tube |
|---|---|
| Material designation | INCONEL alloy 740H / UNS N07740 |
| Primary product standard | ASTM B983 for precipitation-hardened or cold-worked seamless nickel alloy pipe and tube |
| Typical ordered condition | Solution annealed or solution annealed and aged, according to the approved specification and component route |
| Dimensional scope | Outside diameter, wall thickness and length to ASTM B983, drawing and project requirements |
| Documentation | MTC / EN 10204 certificate, heat-treatment records and supplementary inspection reports as ordered |
Why Alloy 740H Is Different
Alloy 740H is not a general corrosion-resistant tube grade. It is engineered for long-duration elevated-temperature service and gains strength from a controlled gamma-prime precipitate.
- High chromium content: supports resistance to elevated-temperature fireside and steam-side corrosion.
- Gamma-prime strengthening: niobium, aluminum and titanium form the Ni3(Al,Ti,Nb) phase required for age hardening.
- High-temperature stability: the alloy is designed to retain useful strength and microstructural stability during prolonged service.
- Condition-sensitive procurement: solution annealing, aging, section size and final fabrication route directly affect acceptance.
ASTM B983 and Code Requirements
| Reference | Purpose | What the buyer should state |
|---|---|---|
| UNS N07740 | Defines the material identity and chemical-composition limits | Use the UNS number with the product standard |
| ASTM B983 | Covers precipitation-hardened or cold-worked seamless nickel alloy pipe and tube, including N07740 | Standard edition, pipe or tube designation, dimensions, condition and supplementary tests |
| ASME Code Case 2702 | Section I construction provisions for qualified Alloy 740H components | Specify when code construction applies; do not assume every industrial order is code-qualified |
| ASME B31.1 Code Case 190 | Requirements for applicable power-piping construction | Provide the project design basis and required documentation |
Chemical Composition Limits
The following values identify UNS N07740. They are specification limits, not the heat analysis of a particular shipment. Order-specific values must be taken from the MTC.
| Element | Limit, % | Role in the alloy |
|---|---|---|
| Nickel | Balance | Austenitic nickel-alloy matrix |
| Chromium | 23.5–25.5 | High-temperature corrosion and oxidation resistance |
| Cobalt | 15.0–22.0 | High-temperature matrix stability |
| Aluminum | 0.2–2.0 | Gamma-prime formation |
| Titanium | 0.5–2.5 | Gamma-prime formation |
| Niobium | 0.5–2.5 | Precipitation strengthening and phase control |
| Iron | 3.0 max. | Controlled content |
| Molybdenum | 2.0 max. | Controlled alloying addition |
| Carbon | 0.005–0.08 | Carbide population and grain-boundary behavior |
| Boron | 0.0006–0.006 | Controlled micro-alloy addition |
Heat Treatment and Manufacturing Control
The public manufacturer bulletin describes Alloy 740H as typically supplied in the solution-annealed and age-hardened condition. It references solution annealing from approximately 1100–1160°C followed by water quenching, and aging from 760–815°C for at least four hours, with added time for heavier sections and air cooling afterward.
The final heat-treatment cycle must follow ASTM B983, the applicable code case, section size and the approved manufacturing route. Buyers should state whether final aging is completed by the tube producer, pipe fabricator or component manufacturer.
| Manufacturing stage | Control focus | RFQ detail |
|---|---|---|
| Billet and extrusion | Heat identity, hot-working temperature and dimensional route | Required OD, wall and machining allowance |
| Cold working / sizing | Dimensional control and work-hardening history | Final tolerance and surface requirement |
| Solution annealing | Temperature, hold time and quench | Condition required before fabrication |
| Age hardening | Temperature, time and cooling control | Supplier or fabricator responsibility |
| Final inspection | Dimensions, surface, NDE, mechanical tests and traceability | ASTM B983 and project supplementary requirements |
Typical Applications
- Advanced ultra-supercritical boiler superheater and reheater tubing.
- High-temperature steam headers and transfer piping.
- Power-generation piping systems requiring high creep strength and hot-corrosion resistance.
- Research, test and thermal-processing systems where N07740 is specified by the project engineer.
Application suitability depends on operating temperature, pressure, steam chemistry, fireside atmosphere, stress, weld design and code requirements. The alloy designation alone does not establish component approval.
Inspection and Documentation
- Chemical analysis confirming UNS N07740.
- Heat-treatment records for solution annealing and aging.
- Tensile, yield, elongation and hardness results in the ordered condition.
- Outside diameter, wall thickness, length, straightness and surface inspection.
- Hydrostatic, pneumatic, eddy-current, ultrasonic or other NDE as required by ASTM B983 and the project.
- MTC / EN 10204 documentation, heat-number traceability and code documentation when applicable.
Packing for Shipment
Pipe packing is selected according to outside diameter, wall thickness, length, surface condition and transport method. Typical protection can include end bracing or caps, waterproof wrapping, bundled packing, wooden supports or cases, and secure container loading. Final packing requirements should be confirmed with the order.
FAQ
What is the ASTM standard for Alloy 740H seamless pipe?
ASTM B983 covers precipitation-hardened or cold-worked seamless nickel alloy pipe and tube, including UNS N07740. The purchase order should also state the required edition, dimensions, condition and supplementary testing.
Is Alloy 740H the same as UNS N07740?
UNS N07740 is the formal UNS designation associated with INCONEL alloy 740H. Use both the UNS designation and ASTM B983 on the RFQ to prevent ambiguity.
What information is needed for quotation?
Send the standard and edition, pipe or tube designation, outside diameter, wall thickness, length, quantity, condition, heat treatment, NDE, certificate and delivery destination. Add the applicable code case and drawing for code construction.
Request an Alloy 740H Seamless Pipe Review
Send your ASTM B983 / UNS N07740 requirement with OD, wall, length, condition, quantity, testing and code documentation. We will review the product form and heat-treatment route before quotation.
