Nickel Alloys for Corrosion Resistance
January 07, 2015 in Pipe by Tim Walshauser
If you need pipes that can withstand acidic corrosion, nickel alloys may be a good choice.
Nickel alloys like alloy 625, alloy 825 and alloy 400 fall between stainless steel and the exotic materials, such as tantalum, in terms of resistance to corrosion. They’re often used in environments where aggressive inorganic acids are present, where stainless steels would be susceptible to stress-corrosion pitting, cracking and crevice attack.
Nickel alloys have a variety of corrosion-resistant attributes, including:
- Most are very resistant to chloride-induced stress corrosion cracking
- Many can resist aggressive reducing acids, including hydrochloric and low-to-medium concentrations of sulfuric acid
- A number of nickel alloys can endure both strong reducing acids and strong oxidizing acids
- Many have high resistance to alkalis
- Some have high resistance to localized attack (pitting and crevice corrosion)
Types of Nickel Alloys
There are six main types of nickel alloy, each with its own recommended use case:
- Pure nickel is often used for caustic service
- Nickel-copper is used in reducing acids
- Nickel-molybdenum is also used in reducing acids
- Nickel-iron-chromium is used in oxidizing acids
- Nickel-chromium-silicon is used in superoxidizing acids
- Nickel-chromium-molybdenum performs well in a variety of acids
Some of the most popular grades of nickel alloy include:
- Alloy 400. Comprised of around 23% copper, it performs well in alkaline salt and salt water. It’s often used in marine projects and oil towers.
- Alloy 625. It’s comprised of 20 to 30 percent chromium, a greater amount than many other nickel alloys, and it’s often used in engine exhaust systems.
- Alloy 825. Made of around 20% chromium and 20% iron, this alloy is often used in chemical processing, pollution control and oil and gas recovery.
Get a Quote Today
As you can see, Nickel alloys have many advantages in corrosive environments. If you need pipes that can withstand corrosion in your next project, contact us for a quote today. We’ll help you find the right nickel alloy (or other material) for your job.