Advantages of Hastelloy® C-22®

Need serious corrosion resistance? Hastelloy® C-22® offers superior longevity in the most corrosive environments and boasts an impressively quick lead time.

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Stainless steels like 304L and 316L material, when exposed to high temperatures and chloride environments, face localized corrosion like pitting, crevice corrosion, or stress corrosion cracking. When faced with such problems, the next best material of choice is AL-6XN® alloy. However, every material has a threshold limit, and when AL-6XN's threshold is reached, opting for C-22 is the best option. Hastelloy® C-22® can withstand very aggressive conditions, surpassing the capabilities of AL-6XN and similar alloys.


Hastelloy C-22 is extremely resistant to corrosion in oxidizing and reducing environments. C-22 has shown an outstanding resistance to a wide range of chemicals, including chlorides, organic and inorganic solutions.

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Corrosion Resistance

Hastelloy C-22 has excellent resistance in oxidizing and reducing environments. It consistently shows good results when exposed to strong oxidizers, such as ferric and cupric chlorides, chlorine, organic and inorganic hot contaminated solutions, formic and acetic acids, acetic anhydride, and seawater and brine solutions.

Products that use acidified solutions can introduce a strong risk for corrosion. When traditional 316L has failed, and AL-6XN has reached its material design limit, then Hastelloy C-22 is the best option. Examples of these corrosive environments include:

  • Chlorides
  • Phosphoric acids
  • Acetic acids
  • Sulfuric acids in active pharmaceutical ingredients (API's)
  • Buffer solutions
  • Any other beauty or health product where contamination due to corrosion is an issue
Critical Pitting and Critical Crevice Corrosion Temperatures
Alloy CPT*








Hastelloy C-22 > 150 > 302 102 212
C-276 150 302 80 176
C-4 140 284 50 122
Alloy 625 90 194 50 122

*Critical pitting temperature (CPT) — The lowest temperature at which pitting corrosion begins in a 24-hour immersion.

**Critical crevice corrosion temperature (CCCT) — The lowest temperature at which crevice corrosion begins in a 100-hour immersion.

Controlled tests that produce pits and crevice corrosion can be used to rank the relative performance of alloys. Haynes International has published the following results of laboratory immersion tests using an oxidizing NaCl-HCl solution of 4% sodium chloride, 0.1% ferric sulfate and 0.01% molar hydrochloric acid. The temperature of this solution, containing 24,300 ppm chlorides and pH of 2, was adjusted in 5° C increments to determine the critical pitting temperature and critical crevice corrosion temperature of each alloy.


Pitting Resistance Equivalent Number

Pitting resistance equivalent number (PREN) is a quantitative way of measuring corrosion resistance. The higher the number, the better the corrosion resistance.



Inconel Alloy 22 and Hastelloy C-22 are equivalent and can be used interchangeably as they fall under UNS number N06022. This UNS number is covered by ASTM, ASME, ISO, DIN and other international standards, making it available in many common product forms.

Hastelloy C-276 and C-22 can also be used interchangeably, based on application.

Product Availability

Product Forms
  • Plate
  • Sheet
  • Strip
  • Billet
  • Round bar
  • Wire
  • Covered electrodes
  • Sanitary tubing
  • Pipe
Fabricated Products