Hastelloy C22 Tube Sheet
Higher chromium than C276, giving improved resistance in certain oxidizing conditions (notably wet chlorine and ferric/cupric chloride) plus better as-welded corrosion resistance without post-weld heat treatment.
Chemical Composition
| Element | Min % | Max % |
|---|---|---|
| Nickel (Ni) | Balance | — |
| Chromium (Cr) | 20.0 | 22.5 |
| Molybdenum (Mo) | 12.5 | 14.5 |
| Tungsten (W) | 2.5 | 3.5 |
| Iron (Fe) | 2.0 | 6.0 |
| Carbon (C) | — | 0.015 |
Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength | 690 MPa min (annealed) |
| Yield Strength (0.2% offset) | 310 MPa min (annealed) |
| Elongation | 45% min |
| Max. Practical Service Temp. | ~550°C |
Equivalent Grades
| Standard | Designation |
|---|---|
| ASTM / UNS | N06022 |
| EN / DIN | 2.4602 |
| Trade Name | Hastelloy® C-22 (Haynes International) |
For UNS N06022, ASTM B575 covers plate, sheet and strip commonly used for tube-sheet stock. ASTM B622 covers seamless pipe and tube of UNS N06022 and does not by itself define a tube-sheet plate purchase requirement — confirm the product form and specification edition against the purchaser specification.
C22 vs. C276 — Which One
See the full Hastelloy C276 datasheet for the broader-spectrum alternative.
Purchasing Specifications by Form
For Hastelloy C22 / UNS N06022, the verified plate path is ASTM B575 and the verified forging path is ASTM B564. ASTM B622 remains seamless pipe/tube — not plate. Distinguish C22 chemistry from C276 on the drawing when both are under consideration.
| Element | Reference |
|---|---|
| Common name | Hastelloy C22 |
| UNS | N06022 |
| Plate / sheet / strip | ASTM B575 (SB-575 where applicable) |
| Forging | ASTM B564 (SB-564 where applicable) |
| Pipe / tube | ASTM B622 — not plate |
Same form discipline as C276: B575 plate / B564 forging / B622 ≠ plate. Confirm ASME SB-* and Code edition where applicable.
| Specification | Product form / role | How to read it for tube sheets |
|---|---|---|
| ASTM B575 / SB-575 | Plate, sheet and strip | Lead plate path for tube-sheet blanks from flat product |
| ASTM B564 / SB-564 | Nickel-alloy forgings (N06022 where listed) | Forged blank path when forging is specified |
| ASTM B622 | Seamless pipe and tube | Not plate. Do not treat B622 as a tube-sheet plate purchasing specification |
Useful information to include in an RFQ (not mandatory for every enquiry):
- Alloy / grade (Hastelloy C22) and UNS (N06022) — distinguish from C276 on the drawing
- Plate (B575) vs forging (B564) — never treat B622 as plate TS
- Tube-sheet OD / dimensions / thickness
- Tube OD, pitch, hole diameter and pattern
- Drawing + revision, quantity, machining tolerance, inspection / testing
Continue from grade identity into product form and machining:
Product Form Considerations
C22 tube sheets are typically machined from plate or forging stock ordered to the product-form specification on the purchase order. Confirm plate/sheet versus forging before treating any single ASTM number as universal for the finished tube sheet.
Applications
Chlorine dioxide bleach plants, wet chlorine processing, ferric and cupric chloride etching solutions, and pharmaceutical processes with aggressive cleaning agents where welded fabrication without PWHT is required.
Advantages & Limitations
Advantages
- Superior as-welded resistance vs. C276, no PWHT required
- Better resistance to wet chlorine and oxidizing chloride solutions
- Excellent resistance to pitting and crevice corrosion
Limitations
- Similar high cost to C276
- Slow, tool-intensive machining
- C276 may be preferred for broader mixed-acid resistance
FAQ
Not exactly an upgrade — the two are optimized for slightly different conditions. C22's higher chromium gives it an edge in wet chlorine and certain oxidizing chloride solutions, while C276 has a longer track record across a broader range of reducing acid conditions.
No — C22's low carbon and high chromium content give it good as-welded corrosion resistance without requiring PWHT, which is one of its key practical advantages over some other corrosion-resistant alloys.
Similar to C276 — typically sourced to order given specialist demand. Send your specification and quantity for a confirmed schedule.