Welding Hastelloy Bar C-22 UNS N06022 W.Nr.2.4602 Suitable For Environments With Alternating Oxidizing And Reducing Conditions

Hastelloy C-22 is a highly versatile nickel-chromium-molybdenum-tungsten alloy known for its outstanding resistance to a wide range of corrosive environments. This alloy is particularly valued for its ability to withstand both oxidizing and reducing conditions, making it ideal for use in various demanding industries.

Hastelloy C-22 exhibits excellent resistance to pitting, crevice corrosion, and stress corrosion cracking. It is highly resistant to both oxidizing and reducing media, which makes it suitable for environments where such conditions may alternate. The alloy performs exceptionally well in a variety of aggressive chemical environments, including chlorides, wet chlorine, hypochlorite, and chlorine dioxide solutions. It also resists the corrosive effects of sulfuric, acetic, formic, and phosphoric acids. Hastelloy C-22 maintains its mechanical properties and corrosion resistance at elevated temperatures, making it suitable for high-temperature applications. The alloy can be readily fabricated using conventional methods, including welding, which does not significantly degrade its corrosion resistance.

Welding Hastelloy C-22 (UNS N06022, W.Nr. 2.4602) requires special considerations due to its unique properties. Here are the key features and guidelines:

Key Features of Hastelloy C-22 Welding

• Excellent Corrosion Resistance

Superior resistance to oxidizing and reducing environments, including chlorides, sulfuric acid, nitric acid, and seawater.

Resists pitting, crevice corrosion, and stress corrosion cracking.

• High-Temperature Performance

Retains mechanical strength and corrosion resistance at high temperatures.

Suitable for applications in extreme chemical processing environments.

• Weldability

Good weldability using common welding methods (GTAW/TIG, GMAW/MIG, SMAW, and PAW).

Avoids carbide precipitation and intermetallic phases that could degrade corrosion resistance.

• Low Thermal Conductivity

Requires controlled heat input to prevent excessive distortion and cracking.

• Matching Filler Materials

ERNiCrMo-10 (AWS A5.14) or ENiCrMo-10 (AWS A5.11) recommended for best corrosion resistance.

• Preheating and Post-Weld Treatment

No preheating required.

Post-weld heat treatment (PWHT) is usually not necessary, but solution annealing (2050°F/1120°C) may be used for stress relief.

• Precautions During Welding

Keep interpass temperature below 200°F (93°C).

Avoid contamination from iron, carbon steel, or other reactive materials.

Use clean, non-contaminated shielding gas (argon or argon-helium mix).

These characteristics make Hastelloy C-22 ideal for harsh chemical processing, marine, aerospace, and power plant applications.

Applications:

Hastelloy C-22 is used across a wide range of industries due to its exceptional resistance to corrosion and versatility:

• Chemical Processing:

Reactors, heat exchangers, and other equipment exposed to aggressive chemicals.

Components handling acidic solutions and mixed acid environments.

• Pollution Control:

Flue gas desulfurization systems, scrubbers, and ducting.

Equipment for controlling emissions in waste processing.

• Oil and Gas:

Downhole tubing and components exposed to sour gas environments.

Offshore platforms and subsea equipment.

• Pharmaceutical and Food Processing:

Vessels, piping, and equipment requiring high purity and resistance to contamination.

Systems handling bioactive and corrosive media.

• Aerospace and Marine:

Components exposed to harsh marine environments.

High-strength fasteners and fittings in aerospace applications.

Hastelloy C-22 is a highly reliable and robust alloy designed to withstand the most challenging corrosive environments. Its excellent resistance to both oxidizing and reducing conditions, coupled with its thermal stability and ease of fabrication, make it a preferred material for critical applications in chemical processing, pollution control, oil and gas, and other demanding sectors.