Project Description
Inconel 690 (UNS N06690 / W. Nr. 2.4642 / NiCr29Fe) is a high-chromium nickel-iron alloy engineered specifically for resistance to oxidizing corrosion, stress corrosion cracking, and carburization at elevated temperatures. With a chromium content of 27–31 % — the highest of any standard INCONEL® grade — Alloy 690 delivers outstanding performance in highly oxidizing environments such as nitric acid, sulfuric acid at high concentrations, and high-temperature flue gases containing sulfur dioxide. In the oil and gas sector the alloy is specified for H₂S-bearing sour service, desulfurization units, refinery furnace components, and offshore process equipment where both corrosion resistance and sustained high-temperature strength are mandatory. SHUNFU METAL produces N06690 bar from vacuum-induction-melted heats with full composition verification by OES and mechanical testing per ASTM B166, supplying EN 10204 3.1 / 3.2 MTR with every order.
Inconel 690 / N06690 — Introduction
Alloy 690 emerged as the preferred replacement for Inconel 600 in pressurized water reactor (PWR) steam generators after extensive research showed its superior resistance to intergranular stress corrosion cracking in high-purity water at 300 °C. The fundamental advantage is its elevated chromium level: at 27–31 % Cr, the passive oxide film is thermodynamically stable under oxidizing conditions where the 15 % Cr of Alloy 600 becomes vulnerable. This same mechanism benefits the oil and gas industry — wherever hot oxidizing process streams, flue gases with SO₂, or high-concentration acid solutions are present, Alloy 690 outperforms lower-chromium nickel grades.
SHUNFU METAL melts N06690 in a VIF, hot-forges or hot-rolls to bar, and applies a controlled anneal at 1065–1120 °C to produce a uniform grain structure (ASTM No. 5 or finer). Each bar lot is 100 % ultrasonically tested per ASTM E114, and hardness survey is performed along the length to confirm heat-treatment uniformity. Optional thermal-stability tests and IGC-evaluation per ASTM A262 Practice C are available on request for critical sour-service orders.
Equivalent Grades & Applicable Standards
| Standard Body | Designation / Grade | Specification / Form |
|---|---|---|
| ASTM | N06690 | B166 (bar & rod), B168 (plate/sheet), B167/B829 (tube), B564 (forgings), B366 (fittings) |
| ASME | N06690 | SB-166 (bar), SB-168 (plate), SB-167 (tube), SB-564 (forgings) |
| EN / DIN | NiCr29Fe / 2.4642 | EN 10095 (heat-resistant strip/bar), DIN 17744 (composition), DIN 17752 (bar) |
| ISO | NiCr29Fe | ISO 9723 (bar & rod), ISO 6208 (strip) |
| Trade / Brand | INCONEL® 690 / Nicrofer® 6030 | Special Metals / Thyssenkrupp VDM trade names |
| Chinese GB / YB | NS3304 / GH690 | GB/T 14992, YB/T 5257 (heat-resistant alloys) |
| NACE / ISO 15156 | N06690 | ISO 15156-3 Annex A (sour service qualification) |
Oil & Gas Applications — N06690 Bar Components
Reactor internals, catalyst retainer rods, and valve stems in hydrodesulfurization (HDS) columns handling H₂S at 300–450 °C.
Agitator shafts, packing support rods, and nozzle flanges in amine treating units and Claus sulfur recovery reactors.
Burner blocks, flue-gas baffle rods, and tube-support hangers in direct-fired crude and vacuum distillation heaters.
Seawater injection pump shafts, heat exchanger channel heads, and valve bodies in chloride-laden topside environments.
Reformer radiant-section support pins, castings, and thermowell bars in steam methane reforming (SMR) units at 800–900 °C.
Pilot burner assemblies, flare tip retaining rings, and ignition electrode bars exposed to SO₂-laden flame gases.
Wellhead body forgings, tubing hangers, and downhole mandrels for CO₂/H₂S co-injection applications.
Shell-and-tube exchanger tie rods, baffles, and tube sheets in service with hot oxidizing process streams and sulfur compounds.
Supply Forms & Size Range — Inconel 690 Bar
| Form | Size Range | Applicable Standard | Condition |
|---|---|---|---|
| Hot-Rolled Round Bar | Ø 6 mm – Ø 250 mm | ASTM B166 | Annealed (hot-finished) |
| Hot-Rolled Flat Bar | Thickness 6–100 mm × Width 20–400 mm | ASTM B166 | Annealed |
| Cold-Drawn Round Bar | Ø 3 mm – Ø 80 mm | ASTM B166 | Annealed or cold-drawn |
| Forged Round Bar | Ø 80 mm – Ø 800 mm | ASTM B564 / EN 10269 | Forged + annealed |
| Forged Flat / Block | Thickness 50–400 mm × Width up to 1,200 mm | ASTM B564 / EN ISO 9723 | Forged + annealed |
Standard lengths: 1,000–6,000 mm; cut-to-length available. SHUNFU METAL maintains stock of common diameters (Ø 12–Ø 150 mm) for prompt delivery. Oversized forgings are made to order with typical lead time 8–14 weeks. All surfaces can be supplied black (as-forged/as-rolled), turned (peeled), or ground to h9/h11 tolerance.
Chemical Composition — ASTM B166 / N06690
| Element | Ni | Cr | Fe | C | Mn | Si | Cu | S |
|---|---|---|---|---|---|---|---|---|
| Content (%) | ≥ 58.0 | 27.0–31.0 | 7.0–11.0 | ≤ 0.05 | ≤ 0.50 | ≤ 0.50 | ≤ 0.50 | ≤ 0.015 |
Balance: Nickel (including Cobalt). Composition per ASTM B166 / UNS N06690. SHUNFU METAL targets mid-range chemistry with Cr at 28.5–30.5 % and C ≤ 0.03 % to maximize intergranular corrosion resistance. Full 12-element chemistry report (including P, Al, Ti, Co) is provided on every heat’s MTR.
Mechanical Properties — Inconel 690 Bar
| Condition | Tensile Strength Rm (MPa) |
Yield Strength Rp0.2 (MPa) |
Elongation A₅ (%) |
Hardness HB / HRB |
|---|---|---|---|---|
| Annealed (hot-finished) 1,065–1,120 °C, rapid cool |
≥ 586 | ≥ 240 | ≥ 30 | ≤ 200 HB / ≤ 93 HRB |
| Annealed (cold-finished) Annealed after cold draw |
≥ 620 | ≥ 275 | ≥ 30 | ≤ 210 HB / ≤ 96 HRB |
| Cold-Drawn (as-drawn) No anneal after drawing |
690–860 | 415–620 | ≥ 20 | 200–260 HB |
| Forged + Annealed 1,065–1,120 °C, air cool or water quench |
≥ 586 | ≥ 240 | ≥ 30 | ≤ 200 HB |
Test temperature: 20 °C. Standard: ASTM B166 / EN 10095. Modulus of elasticity: 215 kN/mm². Density: 8.19 g/cm³. SHUNFU METAL performs room-temperature tensile tests and hardness survey on each lot; elevated-temperature tensile data (300 °C, 500 °C, 700 °C) available on request for critical pressure-retaining applications per ASME BPVC.