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 great alternative when super austenitic stainless steels (AL-6XN®, 904L, and 254 SMO®) and duplex stainless steels (2205 and 2507) will not withstand extremely aggressive media.

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. Hastelloy C-22 alloy composition has many benefits that help enhance resistance to pitting, crevice corrosion, and stress corrosion cracking. It has excellent resistance to oxidizing aqueous media including wet chlorine and mixtures containing nitric acid or oxidizing acids with chlorine ions.

C-22 is widely used in the biotech and pharmaceutical, personal care, and home care. This alloy 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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ElementComposition

(%)

Nickel56.00 (As Balanced)
Cobalt2.5 max.
Chromium20-22.5
Molybdenum12.5-14.5
Tungsten3.5
Iron2.0-6.0
Silicon0.08 max.
Manganese0.50 max.
Carbon0.015 max.
Copper0.5 max.
Vanadium0.35 max.
Phosphorous0.02 max.
Sulfur0.02 max.

Alloy Chemical Comparison

Hastelloy C22

(UNS N06022)

C-276

(UNS N10276)

C-4

(UNS N06455)

Alloy 625

(UNS N06625)

% Nickel56.00 (As Balance)57.00 (As Balance)65.00 (As Balance)62.00 (As Balance)
% Cobalt2.5 max.2.5 max.2 max.1 max.
% Chromium20.0-22.516.016.021.0
% Molybdenum12.5-14.516.016.09.0
% Tungsten34--
% Iron (Fe)2.0-6.053.05 max.
% Silicon0.08 max.0.08 max.0.08 max.0.5 max.
% Manganese0.5 max.1.0 max.1.0 max0.5 max.
% Carbon0.015 max.0.01 max.0.01 max.0.1 max.
% Vanadium0.35 max.0.35 max.--
% Phosphorous0.02 max.0.0250.025-
% Sulfur0.02 max.0.010 max.0.01 max.-
% Niobium---3.7
% Titanium--0.7 max.0.4 max.
% Aluminum---0.4 max.
% Copper0.5 max.0.5 max.0.5 max.-

Physical Properties of Hastelloy C-22

Superior physical properties such as ductility, durability, thermal conductivity, and hardness make Hastelloy C-22 a prime choice for fabrication.

PropertyValue
Density0.314 lb/in
8.69 g/cm3
Modulus of Elasticity30.3 x 106 psi
209 GPa
Melting Range2475 – 2550°F
1357 – 1399°C
Thermal Conductivity
212°F
100°C

7.7 Btu/hr • ft • °F
11.1 W/mK
Mean Coefficient of Thermal Expansion
75 to 200°F
24 to 93°C

6.9 μm/in.-°F
12.4 μm/m.°C
Specific Heat Capacity0.099 Btu/lb.-°F
414 J/Kg-K
Electrical Resistivity730.7 µΩm•circ mil/ft
1.215 µΩm
Magnetic Permeability
at 200 oersted (15.9 kA/m)
≤1.001
Alloy/FormASMEASTMAWS
Plate, Sheet & StripSB575B575-
Wire, Rod, Round BarSB574B574-
Nickel Alloy ForgingsSB564B564
B462
B472
-
Seamless Pipe & TubeSB622B622-
Welded PipeSB619B619-
Wrought Nickel Alloy Welded FittingsSB366B366-
Welded TubeSB626B626-
Forged Pipe Flanges, Fittings. and ValvesSB462B462-
Covered Welding ElectrodesSFA5.11
(ENiCrMo-10)
-A5.11
(ENiCrMo-10)
CastingsSA494
CX2MW
NS N26022
A494-
Bare Welded Rods and WireERNiCrMo-10
UNS N06022
-A5.14
(ERNiCrMo-10)

Advantage #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. 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
AlloyCPT*

(°C)

CPT*

(°F)

CCCT**

(°C)

CCCT**

(°F)

Hastelloy C-22> 150> 302102212
C-27615030280176
C-414028450122
Alloy 6259019450122

*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

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.

Critical Pitting and Critical Crevice Temperature Nickel Alloys Hastelloy C-22
Pitting Resistance Equivalent Number - Hastelloy C-22 AL-6XN

Advantage #2 Product Availability

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

Advantage #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.

POST-WELD ANNEALING

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 metalsOrbital welding C-22 to AL-6XN or 316L can be done autogenously but considerations should be made about performance expectations in corrosive environments. Welding procedure development and mechanical testing should follow the requirements of the applicable code or standard. To evaluate corrosion resistance, additional test methods should be considered. It is advisable to consult a metallurgist with corrosion experience to evaluate the service requirements for the applied 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 Inside Diameter

Hastelloy C-22 Weld OD

Hastelloy C-22 Weld Outside Diameter

316L Weld ID

316L Weld Inside Diameter

316L Weld OD

316L Weld Outside Diameter

Industries & Applications

Pharmaceutical & Biotech
  • Active pharmaceutical ingredients (API)
  • Buffer lines
  • Pharmaceutical water systems
  • Pesticide production
Personal Care
  • Cosmetic products
  • Beauty products
  • Health care
Beverages
  • Breweries
  • Hot water systems
Food Processing
  • Cellophane
  • Food packaging
  • Fermentation
Chemical
  • SO2
  • Phosphoric acid
  • Acetic acid/acetic anhydride
  • Acid etching
  • Chlorination systems
  • Sulfonation systems
Other Applications
  • Chlorination systems
  • Nuclear fuel processing
  • Semi-conductors
  • Aerospace
  • Pulp and paper
  • Power generation
  • Marine and offshore
  • Construction
  • Oil and gas
Industries

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.

Finish CodeProduct Contact Surface

(Max Ra)*

Product Contact Surface Finish Treatment

(ID)

Non-Product Contact Surface

(Max Ra)

Non-Product Contact Surface Finish Treatment

(OD)

BPE SF Code Ref.Dimensions & Tolerances (BPE) or (CSI)
PL20 µ-inch
(0.51 µm)
Polished or Drawn32 µ-inch
(0.81 µm)
Mechanical PolishSF1BPE
P2525 µ-inch
(0.64 µm)
Electropolished**32 µ-inch
(0.81 µm)
Mechanical PolishSF6BPE
7
32 µ-inch
(0.81 µm)
Polished or Drawn32 µ-inch
(0.81 µm)
Mechanical PolishN/ACSI
PUN/AUnpolished (Mill)N/AUnpolished (Mill)N/ACSI

*20/32 µ-inch Max Ra is an approximate value and is not guaranteed. Surface finish roughness shall be physically examined for “P25” using a profilometer calibrated to standards traceable to NIST. Surface finish roughness shall not be subject to physical examination for “P7” or “7”

**The interior surfaces shall be mechanically polished or as drawn to a 25 Ra µ-inch (0.64 µm) maximum finish for sizes ½” to 4” diameter. The electropolishing process may increase the Ra values post electropolishing and have areas of preferential etching (e.g. frosting, shadowing, ect). Final Ra values for electropolished tubing and fitting shall not be used as criteria of acceptance for this product.

PROCESS CONTACT SURFACE FINISH

UNPOLISHED TUBING & FITTINGS (PU)

The interior of the tube/fitting shall be mill finish. Roughness requirements are not applied to this material.

MECHANICALLY POLISHED TUBING & FITTINGS (7)

The interior of the tube/fitting shall be drawn or mechanically polished to a 32 μ-inch (0.81 μm) maximum finish. No interior surface finish reading above 32 μ-inch is acceptable.

MECHANICALLY POLISHED TUBING & FITTINGS (PL)

The interior of the tube/fitting shall be drawn or mechanically polished to a 20 μ-inch (0.51 μm) maximum finish and meets the requirements of ASME BPE for a SF1 surface finish designation. No interior surface finish reading above 20 μ-inch is acceptable.

ELECTROPOLISHED TUBING & FITTINGS (PM)

The interior of the fittings is electropolished to a 15 μ-inch (0.64 μm) maximum finish and meets the requirements of ASME BPE for a SF4 surface finish designation No interior surface reading above 15 μ-inch is acceptable

ELECTROPOLISHED TUBING & FITTINGS (P25)

The interior of the fittings is electropolished to a 25 μ-inch (0.64 μm) maximum finish and meets the requirements of ASME BPE for a SF6 surface finish designation. No interior surface reading above 25 μ-inch is acceptable.

NON-PROCESS CONTACT SURFACE FINISH

MECHANICALLY POLISHED TUBING & FITTINGS (32 μ-inch/0.81 μm)

The exterior of the tube/fitting shall be mechanically polished to a surface finish comparable to a 150 grit or better and considered to be equivalent to a No. 4 finish as defined by 3-A Sanitary Standards. Rough- ness of less than 32 μ-inch (0.81 μm) is typical but cannot be guaranteed.

UNPOLISHED (MILL)

The exterior of the tube/fitting shall be mill finish or as machined. Roughness requirements are not applied to this material.

CSI Part Number Designator

C22 Part Number Designator

Tolerances

Standard Tolerances in Tubing Dimensions
Welded or SeamlessODOD ToleranceApplicable SpecificationWall ThicknessWall Thickness ToleranceCSI Surface Finish Designation
Seamless0.500 in
(12.7 mm)
+/- 0.005 in
(+/- 0.13 mm)
ASTM B6220.065 in
(1.65 mm)
+/- 15% of wall-PL
Seamless0.750 in
(19.1 mm)
+/- 0.075 in
(+/- 0.19 mm)
ASTM B6220.065 in
(1.65 mm)
+/- 10% of wall-PL
Seamless1.000 in
(25.4 mm)
+/- 0.075 in
(+/- 0.19 mm)
ASTM B6220.065 in
(1.65 mm)
+/- 10% of wall-PL
Welded1.500 in
(38.1 mm)
+/- 0.075 in
(+/- 0.19 mm)
ASTM B6260.065 in
(1.65 mm)
+/- 12.5% of wall-PL
Welded2.000 in
(50.8 mm)
+/- 0.010 in
(+/- 0.20 mm)
ASTM B6260.065 in
(1.65 mm)
+/- 12.5% of wall-PL
Welded3.000 in
(76.2 mm)
+/- 0.010 in
(+/- 0.20 mm)
ASTM B6260.065 in
(1.65 mm)
+/- 12.5% of wall-PL
Standard Tolerances in Fitting Dimensions
ODOD ToleranceWall ThicknessWall Thickness ToleranceCSI Surface Finish Designation
0.500 in
(12.7 mm)
+/- 0.010 in
(+/- 0.25 mm)
0.065 in
(1.65 mm)
+/- 15% of wall-PL
0.750 in
(19.1 mm)
+/- 0.010 in
(+/- 0.25 mm)
0.065 in
(1.65 mm)
+/- 10% of wall-PL
1.000 in
(25.4 mm)
+/- 0.010 in
(+/- 0.25 mm)
0.065 in
(1.65 mm)
+/- 10% of wall-PL
1.500 in
(38.1 mm)
+/- 0.016 in
(+/- 0.40 mm)
0.065 in
(1.65 mm)
+/- 12.5% of wall-PL
2.000 in
(50.8 mm)
+/- 0.016 in
(+/- 0.40 mm)
0.065 in
(1.65 mm)
+/- 12.5% of wall-PL
3.000 in
(76.2 mm)
+/- 0.016 in
(+/- 0.40 mm)
0.065 in
(1.65 mm)
+/- 12.5% of wall-PL

The American Society of Mechanical Engineers (ASME) has prepared a standard intended for design, materials, construction, inspection, and testing of vessels, piping, and related accessories such as pumps, valves, and fittings for use in the biopharmaceutical industry, referred to as ASME-BPE. This catalog does not intend to address criteria in the ASME-BPE specification. The items offered within this catalog are in accordance with ASME-BPE dimensions.

PRODUCT MARKING

  • All Hastelloy C-22 tubing will meet dimensional criteria and mechanical properties as set forth per the current ASTM B622 (seamless) or ASTM B626 (welded) specifications. Due to marking/finish/acceptance criteria obtainable in C-22, tubing will not be marked ASME-BPE.
  • All C-22 fittings ending in -PL will be marked with BPE SF1 surface finish reference, UNS number N06022, CSI logo, and alloy lot number.
  • All C-22 fittings ending in -P25 will be marked with BPE SF6 surface finish reference.

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Frequently Asked Questions

Is C-22 the same as C-276?

In many applications Hastelloy C-22 and C-276 can be used interchangeably. However, they are different nickel alloys. Haynes International, the original manufacturer of both materials, states C-22 has “better overall corrosion resistance than other Ni-Cr-Mo alloys available today, including Hastelloy C-276 and C-4 alloys, as well as alloy 625.”

C-22 contains 22% chromium, compared to the 16% in C-276, which is one factor contributing to C-22's improved performance.

Is Inconel Alloy 22 same as Hastelloy C-22?

Inconel Alloy 22 and Hastelloy C-22 are alloys with the same UNS number, N06022. Inconel is a brand name of Special Metals Corporation, and Hastelloy is a brand name of Haynes International. Haynes International is the original inventor of this alloy. Allegheny Ludlum also makes Alloy 22. C-22 is a registered trademark of Haynes.

Are weld insert rings or special welding wires required to join C-22 components?

Due to very low carbon content, welded wrought C-22 alloy does not form the microstructures that are deficient in corrosion-resistant elements typically produced in stainless steel and 6% molybdenum alloys during welding. Therefore, overalloying with weld insert rings or other higher alloy filler material is usually not required.

Can AL-6XN alloy be welded to C-22?

Hastelloy C-22 tubing and fittings can be welded directly to AL-6XN tubing and vessels without weld insert rings. If filler wire is required to make the weld, C-22 filler wire (ER NiCrMo-10) is recommended. If the surface area of the AL-6XN portion of the weldment is much greater than the surface area of the C-22 alloy component, the likelihood of galvanic corrosion attack is minimized.

Is C-22 stainless steel?

Hastelloy C-22 is a nickel alloy with 56% nickel, 13% molybdenum, and 22% chromium. N06022 is the UNS number with other names such as Inconel 22, Alloy 22, AL 22, etc.

Does Hastelloy C-22 exhibit weldability like other nickel alloys?

Hatelloy C-22 exhibits excellent weldability, is ductile, and is easily fabricated into industrial components like the other nickel alloys.