Introduction

Inconel 690 (UNS N06690 / Alloy 690 / W.Nr. 2.4642) is a high-chromium nickel alloy developed specifically to resist stress corrosion cracking in high-temperature aqueous environments. The alloy contains a minimum of 58% nickel, 27–31% chromium—significantly higher than Inconel 600's 14–17%—and 7–11% iron. This elevated chromium content provides superior resistance to oxidizing chemicals and hot gases, while the high nickel content ensures protection against chloride-induced stress corrosion cracking and caustic environments. Defined by ASTM B167 for seamless pipe and tube, ASTM B168 for plate and sheet, and ASTM B166 for bar, Inconel 690 is the preferred material for nuclear steam generators, chemical processing, heat exchangers, power generation, and petrochemical industry applications. Available in a full range of product forms including Inconel 690 seamless pipe, tube, plate, sheet, round bar, wire, and forgings.

Chemical components

Mechanical properties

Physical properties

Inconel 690 Available Products and Standard

1. GB/T 15007 (Nickel and Nickel Alloy Plate, Strip, and Foil)

Domestic Grade: NS3105 (GB/T 15007) / Inconel 690 equivalent

Type: Sheet / Plate / Strip / Wire / Tube / Bar

Size Range:

• Inconel 690 Wire: 0.1 – 15.0 mm dia

• Inconel 690 Strip: 0.05 – 5.0 mm thick × 5 – 500 mm wide

• Inconel 690 Round Bar: 8 – 355 mm dia

• Inconel 690 Sheet / Plate: 0.5 – 180 mm thick

• Inconel 690 Seamless Tube / Pipe: Custom sizes available

Surface: Annealed, Bright, Pickled, Ground

Testing: Chemical analysis, mechanical test (tensile strength, yield strength, elongation), hardness test, intergranular corrosion test, dimensional inspection

2. ASTM B168 (Standard Specification for Nickel‑Chromium Alloy Plate, Sheet, and Strip)

Grade: UNS N06690 / Inconel 690 / Alloy 690 / W. Nr. 2.4642

Type: Sheet / Plate / Strip

Size Range:

• Inconel 690 Sheet / Plate: 0.5 – 180 mm thick (hot rolled or cold rolled)

• Inconel 690 Strip: 0.05 – 5.0 mm thick × up to 500 mm wide (coils)

Surface: Annealed, Pickled, Bright, Polished

Testing: Chemical analysis, mechanical test (tensile, yield, elongation), hardness test, intergranular corrosion test, dimensional inspection

3. ASTM B166 (Standard Specification for Nickel‑Chromium Alloy Rod and Bar)

Grade: UNS N06690 / Inconel 690 / Alloy 690

Type: Round Bar / Rod / Wire

Size Range:

• Inconel 690 Round Bar: 8 – 355 mm dia (hot rolled or cold drawn)

• Inconel 690 Wire: 0.1 – 15.0 mm dia (coils or straight)

Surface: Annealed, Pickled, Ground, Turned, Bright

Testing: Chemical analysis, mechanical test (tensile, yield, elongation), hardness test, ultrasonic test, dimensional inspection

4. ASTM B167 (Standard Specification for Nickel‑Chromium Alloy Seamless Pipe and Tube)

Grade: UNS N06690 / Inconel 690 / Alloy 690

Type: Seamless Pipe / Seamless Tube

Size Range:

• Inconel 690 Seamless Pipe: 6 – 610 mm OD × 1 – 50 mm wall thickness

• Inconel 690 Seamless Tube: Custom sizes

Surface: Annealed, Pickled, Bright

Testing: Chemical analysis, mechanical test (tensile, yield, elongation), hydrostatic test, eddy current test, dimensional inspection

Applications

1. Nuclear Power & Steam Generators

• For pressurized water reactor (PWR) steam generator tubing, Inconel 690 seamless tube is the industry standard. Its high chromium content (27–31%) provides superior resistance to stress corrosion cracking in high-temperature, high-purity water environments—the primary failure mode that affected its predecessor, Inconel 600.

• For reactor coolant piping and pressurizer components, Alloy 690 pipe maintains mechanical integrity under neutron irradiation and high-temperature water conditions.

• For nuclear fuel reprocessing equipment handling nitric and nitric/hydrofluoric acid solutions, Inconel 690 sheet and plate resist the aggressive chemicals used in spent fuel processing.

• For control rod drive mechanisms and reactor internal fasteners, UNS N06690 round bar delivers the combination of corrosion resistance and mechanical strength required for safety‑critical nuclear applications.

2. Chemical Processing & Acid Handling

• For nitric acid production tail-gas reheaters, Inconel 690 pipe provides excellent resistance to oxidizing acid environments at elevated temperatures.

• For heating coils and tanks in stainless steel pickling operations using nitric/hydrofluoric acid solutions, Alloy 690 tube withstands the corrosive effects of mixed acid service.

• For heat exchangers in chemical plants handling sulfuric acid, hydrochloric acid, and other aggressive chemicals, Inconel 690 plate and sheet deliver low corrosion rates and excellent resistance to localized attack.

• For waste incineration and pollution control equipment, UNS N06690 welded pipe offers good oxidation resistance and protection against high-temperature corrosive gases.

3. Heat Exchangers & Power Generation

• For shell-and-tube heat exchangers in high-temperature corrosive service, Inconel 690 seamless pipe provides excellent resistance to stress corrosion cracking and good thermal stability.

• For boiler components and superheater tubing in power generation facilities, Alloy 690 tube maintains mechanical properties at elevated temperatures with good oxidation resistance.

• For furnace equipment and thermal processing systems, Inconel 690 plate and sheet offer durability in high-temperature oxidizing atmospheres.

• For condenser tubes and feedwater heaters in conventional power plants, UNS N06690 tube combines corrosion resistance with good fabricability.

4. Petrochemical Industry & Furnace Equipment

• For petrochemical reformer components and process furnace hardware, Inconel 690 pipe withstands high-temperature oxidation and carburization in aggressive process environments.

• For furnace muffles, retorts, and radiant tubes in heat-treating equipment, Alloy 690 sheet provides good oxidation resistance and thermal stability at elevated temperatures.

• For high-temperature ducting and exhaust systems, Inconel 690 welded pipe delivers resistance to hot gas corrosion and thermal cycling.

5. Aerospace & High-Temperature Equipment

• For gas turbine exhaust ducting and high-temperature airframe components, Inconel 690 plate and sheet offer oxidation resistance and structural stability in demanding aerospace environments.

• For high-temperature fasteners and structural components, UNS N06690 bar provides the combination of strength and corrosion resistance required for critical applications.

FAQ – Inconel 690 Alloy

Q: What is the difference between Inconel 690 and Inconel 600?

A: The primary difference is chromium content. Inconel 690 contains 27–31% chromium, compared to Inconel 600's 14–17%. This higher chromium content gives Inconel 690 significantly superior resistance to stress corrosion cracking in high-temperature aqueous environments—the key reason it replaced Inconel 600 as the standard material for PWR steam generator tubing. Inconel 690 was specifically developed as a high-chromium modification of Inconel 600 to address stress corrosion cracking failures in nuclear steam generators.

Q: What is the maximum operating temperature for Inconel 690?

A: Inconel 690 is suitable for continuous service up to approximately 1000°F (540°C) in aqueous environments and offers good oxidation resistance at higher temperatures in dry atmospheres. It is designed for high-temperature applications including furnace equipment, gas turbine components, and heat treatment systems where both corrosion resistance and thermal stability are required.

Q: What are the key ASTM standards for Inconel 690?

A: ASTM B167 covers seamless pipe and tube (with ASME SB167 for pressure vessel applications); ASTM B168 covers plate, sheet, and strip (with ASME SB168); ASTM B166 covers bar; ASTM B564 covers forgings. For welding, AWS A5.14 ERNiCrFe-7 and AWS A5.11 ENiCrFe-7 are the matching filler metal specifications.

Q: Is Inconel 690 suitable for nitric acid service?

A: Yes. Inconel 690 has excellent resistance to nitric acid and nitric/hydrofluoric acid solutions. It is widely used in nitric acid production tail-gas reheaters, heating coils and tanks for stainless steel pickling operations, and nuclear fuel reprocessing equipment. This high chromium nickel alloy provides outstanding performance in oxidizing acid environments where other alloys would rapidly corrode.

We are a trusted Inconel 690 Supplier and Inconel 690 Manufacturer, China‑based, serving nuclear power plant builders, chemical processors, heat exchanger fabricators, and petrochemical equipment manufacturers worldwide. All products comply with ASTM B167 / ASTM B168 / ASME SB167 with EN 10204 3.1 mill certificates, PMI verification, hydrostatic and eddy current test reports. We offer Inconel 690 seamless pipe, tube, plate, sheet, round bar, wire, strip, forgings, flanges, and pipe fittings in custom sizes, with cut‑to‑length, precision machining, and solution annealing services. Schedule 40, Schedule 80, and heavy wall options available. Contact us at info@monokj.com for size chart, pricing, or custom requirements.