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Inconel 690 (UNS N06690) Seamless Pipe, Plate and Sheet
Inconel 690 (UNS N06690) is a nickel-chromium-iron alloy with 27.0-31.0% chromium, supplied as SB-167 seamless pipe and tube, SB-168 plate, sheet and strip, and SB-564 bar. It is the standard selection for high-temperature sulphur-bearing process gas, combustion atmospheres and nuclear steam service.
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Inconel 690 is the high-chromium member of the 600series nickel-iron-chromium alloys. Where Inconel 600 relies on moderate chromium for general corrosion resistance, Inconel 690 raises chromium to 27.0 to 31.0% and thereby delivers markedly better resistance to oxidising acid media and to sulphur-bearing atmospheres at elevated temperature.
Specification Coverage
| Product Form | ASME Specification | UNS Designation |
|---|---|---|
| Seamless pipe and tube | SB-167 | N06690 |
| Plate, sheet and strip | SB-168 | N06690 |
| Bar, rod and wire | SB-166 | N06690 |
| Bar and forging stock | SB-564 | N06690 |
| Forged flanges | SB-462 | N06690 |
UNS N06690 is not listed in ASME SB-366 Table 2 for wrought fittings. If your project requires forged elbows, tees or reducers in 690, contact us so we can confirm the applicable manufacturing route and specification.
Grade Comparison
| Grade | UNS | Cr | Distinguishing Position |
|---|---|---|---|
| Inconel 600 | N06600 | 14.0–17.0 | General purpose corrosion and heat resistance |
| Inconel 601 | N06601 | 21.0–25.0 | Aluminium addition for furnace oxidation |
| Inconel 690 | N06690 | 27.0–31.0 | High chromium for sulphur and oxidising service |
| Inconel 617 | N06617 | 20.0–24.0 | Cobalt-molybdenum for creep and ammonia |
For a sulphur-bearing process gas at elevated temperature — for example hydroprocessing reformer furnace coils, sulphuric acid plant, or combustion gases containing sulphur — 690 is the correct selection and 600 will suffer sulphidation attack. For nitrogen-bearing and carburising conditions, review 601 or 617 instead.
Chemical Composition
Per SB-167 Table 1, Alloy N06690:
| Element | Composition Limit, % |
|---|---|
| Nickel | remainder |
| Chromium | 27.0–31.0 |
| Iron | 7.0–11.0 |
| Manganese | 0.5 max |
| Copper | 0.5 max |
| Carbon | 0.05 max |
Mechanical Properties
| Specification | Condition | Tensile min. | Yield min. | Elongation min. |
|---|---|---|---|---|
| SB-168 plate, sheet, strip | Annealed H | 95,000 psi (655 MPa) | 35,000 psi (240 MPa) | — |
| SB-168 plate, sheet, strip | Annealed | 86,000 psi (590 MPa) | 34,000 psi (235 MPa) | — |
| SB-167 pipe and tube | Hot-worked annealed, 5 in. (127 mm) OD and under | 86,000 psi (590 MPa) | per SB-167 Table 2 | per SB-167 |
| SB-167 pipe and tube | Hot-worked annealed, over 5 in. OD | 85,000 psi (586 MPa) | per SB-167 Table 2 | per SB-167 |
| SB-167 pipe and tube | Cold-worked annealed, over 5 in. OD | 75,000 psi (515 MPa) | per SB-167 Table 2 | per SB-167 |
Note the strength falls as size increases: SB-167 requires 86,000 psi (590 MPa) for hot-worked annealed material up to 5 in. outside diameter, dropping to 85,000 psi (586 MPa) above that, and to 75,000 psi (515 MPa) for cold-worked annealed material over 5 in. Specify the outside diameter band if it matters to your design.
Size Range and Condition
| Parameter | Basis | Typical Supply Range |
|---|---|---|
| Pipe OD and wall | ASME B36.19M | 1/8 in. to 4 in. OD; confirm larger sizes |
| Plate thickness | SB-168 Table 1 | 3/16 in. and over hot-rolled |
| Sheet thickness | SB-168 Table 1 | 0.018 in. to 0.250 in. (0.46 to 6.35 mm) |
| Strip thickness | SB-168 Table 1 | 0.005 in. to 0.250 in. (0.13 to 6.35 mm) |
| Condition | SB-167 / SB-168 | Annealed (standard), annealed H, hot-rolled, cold-worked |
Applications
- Reformer and hydrocracker furnace coils and headers handling sulphur-bearing process gas
- Sulphuric acid production and acid handling equipment
- Combustion gas turbines and industrial combustion systems with sulphur in the fuel
- Nuclear steam generators and primary circuit components
- High-temperature heat exchangers and furnace internals
- Oxidising acid processing where 600 and 601 are inadequate
Inspection and Testing
- EN 10204 3.1 certification, 3.2 available on request
- Annealing and solution treatment with heat-treatment records issued
- Intercrystalline corrosion testing to ASTM G28 where specified
- Ultrasonic or eddy-current testing to ASTM A993, or the standard cited on your order
- Hydrostatic testing available on pipe orders
- PMI verification and full heat-number traceability on every lot
- Dimensional inspection against ASME B36.19M and the cited product specification
Ordering Information
To receive an accurate quotation, please advise:
- Product form — pipe, plate, sheet, strip, bar or rod
- Grade — Inconel 690 / UNS N06690, and which specification applies (SB-167, SB-168, SB-166 or SB-564)
- Dimensions — OD and wall thickness, or thickness, width and length
- Condition — annealed, annealed H, or cold worked
- Quantity and required delivery date
- Certification — EN 10204 3.1 or 3.2
- Any NACE MR0175 / MR0103, PED or IBR documentation requirements
Send your enquiry to our sales team and we will respond with a full specification and commercial offer.
