Hastelloy C-22, C-4 and C-2000 Low-Carbon Ni-Cr-Mo Butt Weld Fittings

Hastelloy C-22 (N06022), C-4 (N06455) and C-2000 (N06200) butt weld fittings to ASME SB-366 and B16.9. Low-C Ni-Cr-Mo for scrubbers, pulp bleach and sour gas.

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The Hastelloy C family is defined by low carbon plus a controlled addition of copper or tungsten, and it occupies the middle ground between C-276 and the more corrosion-exotic alloys. C-22 raises chromium and adds tungsten for oxidising and reducing balance; C-4 trades some of that for a lower-cost, high-chromium-low-nickel variant; C-2000 adds copper for broader acid coverage. All three are low-carbon Ni-Cr-Mo alloys, and all three are specified where C-276 alone leaves a gap.

Product range

90° and 45° elbows, 180° returns, equal and reducing tees, concentric and eccentric reducers, caps and lap-joint stub ends to ASME B16.9, in solution-annealed condition with bevelled ends. Socket weld and threaded fittings to B16.11 on request. MSS SP-43 and SP-95 geometries available. Companion forged flanges to SB-462 and B16.47 are quoted alongside.

Material specifications and grades

ASME specProduct formGrades (UNS)
SB-366 / SB-366MWrought BW & SW fittingsN06022, N06455, N06200
SB-462Forged flanges, forged fittingsN06022, N06200
SB-574RodN06022, N06455, N06200
SB-575Plate, sheet, stripN06022, N06455, N06200
SB-626Welded tubeN06022, N06455, N06200

Composition, ASME SB-575 Table 1 (% by weight)

ElementC-22 (N06022)C-4 (N06455)C-2000 (N06200)
NickelRemainderRemainderRemainder
Chromium20.0–22.514.0–18.022.0–24.0
Molybdenum12.5–14.514.0–17.015.0–17.0
Iron2.0–6.03.0 max3.0 max
Copper——0.50 max
Tungsten2.5–3.5——
Carbon, max0.0150.0150.010
Cobalt, max2.52.00.3

C-22 carries tungsten (2.5–3.5%) that neither C-4 nor C-2000 contains. If your datasheet cites tungsten, the grade is C-22 — this is a fast way to catch a mislabelled heat.

Mechanical properties, ASME SB-575 Table 2

PropertyC-22C-4C-2000
Tensile strength, min100,000 psi (690 MPa)100,000 psi (690 MPa)100,000 psi (690 MPa)
Yield strength (0.2% offset), min45,000 psi (310 MPa)40,000 psi (276 MPa)45,000 psi (310 MPa)
Elongation in 2 in., min45%40%45%

Solution annealing, ASME SB-366 Table 3

GradeTemperatureQuenchFootnote
C-22 (N06022)2050 °F [1121 °C]Rapid air/waterD
C-4 (N06455)1950 °F [1065 °C]Rapid air/waterD
C-2000 (N06200)2075–2125 °F [1135–1163 °C]Rapid air/water—

Both C-22 and C-4 carry footnote D in SB-366 Table 3, which reads “Minimum temperature.” Where a lower-temperature variant of these alloys is required for a given service condition, that minimum must be agreed with the manufacturer rather than assumed. C-2000 carries no footnote.

Applications

C-22 for flue-gas desulphurisation scrubbers, wet chlorine, hypochlorite and bleach handling, seawater and aggressive chemical environments, and sour gas where chloride stress-corrosion cracking is a concern. C-4 for hydrochloric and sulphuric acid service, pulp bleaching, and general acid handling. C-2000 for reducing and oxidising acid mixes including nitric-hydrofluoric blends, and for seawater where higher copper improves acid resistance.

Inspection and certification

EN 10204 3.1 certificates standard; 3.2 and customer-specific MTR formats on request. Available inspection: PMI, tensile and hardness per lot, ASTM G-28 intergranular corrosion, ferrite checks, and third-party witness by SGS, BV or Lloyd’s Register.

Ordering information

Please specify grade (N06022 / N06455 / N06200), NPS size, wall thickness or schedule, quantity, end preparation and certification level. Send the process media and operating temperature if the grade is not yet fixed — we will confirm suitability before pricing.

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