Hastelloy® C-22®

Lower Your Downtime, Not Your Standards

Solves Serious Corrosion Problems

Central States Industrial (CSI) keeps a complete line of Hastelloy® C-22® (UNS N06022) tubing and fittings in-stock, allowing for a quick turn-around. C-22 is a nickel-chromium-molybdenum-tungsten alloy with better overall resistance to uniform and localized corrosion than any other Ni-Cr-Mo alloy, like Hastelloy C-276, C-4, and alloy 625. 

C-22 is a great alternative when superaustenitic stainless steels (AL-6XN®, 904L, and 254 SMO®) and duplex stainless steels (2205 and 2507) will not withstand extremely aggressive media. Hastelloy C-22 has excellent resistance to oxidizing aqueous media including wet chlorine and mixtures containing nitric acid or oxidizing acids with chlorine ions.

C-22 is included in the metallic materials committee (MM) under BPE. Unified Numbering System (UNS) designation N06022, Werkstoff's number 2.4602, and NiCr21Mo14W. UNS number N06022 incorporates Inconel Alloy 22, Inconel 622, ATI’s Alloy 22, and AL 22.

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  • Hastelloy C-22 Tubing

  • Hastelloy C-22 Adapters

  • Hastelloy® C-22® Elbows

  • Hastelloy C-22 End Caps

  • Hastelloy® C-22® Ferrules

  • Hastelloy C-22 Reducers

  • Hastelloy C-22 Tees and Crosses

  • Hastelloy® C-22® True Wyes & Laterals

Hastelloy C-22 Family Shot

CSI Standards

All Hastelloy C-22 tubing and fittings supplied by CSI will meet the following criteria:

Surface Finish Designations

The finish designator is indicated in the CSI item number as a suffix. The suffix will define the finishing requirements for that process component. Each item number can have several different finish designators applied to it.

View Surface Finish Designations

CSI Part Number Designator

Hastelloy Advantages

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.

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1. 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. 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
Controlled tests that produce pits and crevice corrosion

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.


2. Product Availability

Product Forms

  • Plate
  • Sheet
  • Strip
  • Billet
  • Round bar
  • Wire
  • Covered electrodes
  • Sanitary tubing
  • Pipe


3. Interchangeability

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.

Welding Hastelloy C-22

Nickel-based alloys generally exhibit sluggish welding and shallow penetration characteristics; so, the possibility of incomplete fusion increases. Care must be used to ensure that sound welds are achieved. If orbital or automatic welding equipment is used, programs should utilize a pulsed current. Pulsed current inputs can help control weld penetration without exclusive heat input. Pulsing also helps control weld pool, improving the uniformity of weld bead appearance.

Cleanliness is critical when welding nickel-based alloys. Contamination by grease, oil, lead, sulfur, or other low melting point elements can lead to severe cracking problems. The welding surface and adjacent areas should be cleaned thoroughly with an appropriate solvent such as 99.9% isopropanol (IPA). Prior to any welding, all foreign matter—lubricates, cutting chips, burrs, crayon markings— should be removed.

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In the majority of corrosive environments, C-22 products are used in the as-welded condition. Post-weld heat treatment such as full solution annealing or stress relief annealing is usually not required.

Welding to dissimilar metals

Orbital welding C-22 to other alloys such as AL-6XN or 316L can be done autogenously; however, performance expectations in corrosive environments should be kept low. Welding procedure development and mechanical testing should follow the requirements set by the applicable code or standard. Additional test methods should also be considered when evaluating corrosion. It is advisable to consult a metallurgist with corrosion experience to assess the service requirements for the specified application.

Weld Appearance

Weld appearance can be somewhat misleading when visually compared with any hygienic welds made in 316L stainless steel. A typical Hastelloy C-22 weld will have oxide islands in the weld bead. These films that form in the weld pool and solidify on the weld have been identified as high-melting-point nonmetallic oxides. Oxide islands are common and the appearance is permitted in standards such as the ASME BPE. 

Discoloration in the heat affected zone (HAZ) is also common and is not necessarily the result of improper gas shielding. Discoloration in the HAZ can also be caused by tube mill surface conditioning processes such as pickling, passivation, mechanical polishing, cleaning and/or annealing furnace atmosphere. Discoloration in the HAZ from these processes are generally darker than seen in traditional stainless steel materials, but it does not indicate an improper weld.

Hastelloy C-22 Weld ID

Hastelloy C-22 Weld OD

316L Weld ID

316L Weld OD

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