Hastelloy Alloys: Grades, Properties & Supply

HASTELLOY is a registered trademark of Haynes International. Sagiant Piping Industries is an independent supplier and stockist, not the alloy producer. Corrosion grades (C/B series) and the high-temperature grade X serve different duties — identify the exact UNS number, specification edition and condition on enquiry.

Producer/specification reference limits; “bal” denotes balance and is not a fixed value — X nickel is the balance (about 47%), not a demonstrated contractual minimum. A dash means not separately specified, not zero. B-2 and B-3 are distinct grades with different chromium, iron and stabilising additions. These are not full heat analyses — the purchase specification edition and heat/product certificate control acceptance.

“Core” grades have completed records; “Reference” names are documented in producer literature and quoted until chemistry, form, specification and availability are confirmed — a listing is not a stock statement. Historical names (B, C, G, A, D) are tracked in a separate research register. Do not treat other brands (alloy 59, 686, Haynes 188/230/242) as HASTELLOY grades; cast grades, filler classifications and powder forms are separate from wrought base metal. UNS cross-references are not substitution approvals.

Indicative solution-annealed plate values against the referenced specification; requirements differ by product form (plate/sheet, bar, pipe/tube, forgings), size and route, and typical data are separate from guaranteed minima. Confirm grade, UNS, form, size interval, condition, specification edition and test method on the certificate. C-22HS solution-treated, cold-worked and aged conditions are kept distinct (with hydrogen-embrittlement cautions). For X, add elevated-temperature tensile, creep, stress-rupture and thermal-stability data with time/stress/test basis; weld-metal, HAZ and base-metal properties are separated where claimed. Pressure-code allowable stresses reference the code, edition, form and temperature — not tensile strength.

Producer reference densities near ambient. Melting ranges are not service temperatures. Use the grade-specific density in the weight calculator, not one family value. Young’s and shear modulus, Poisson’s ratio, specific heat, thermal conductivity, mean thermal-expansion coefficient (with its interval), electrical resistivity and permeability are provided per grade on enquiry with temperature/condition. Do not publish a single family “non-magnetic” value as a precision property; distinguish mean expansion over an interval from instantaneous expansion.

A routing matrix for specification review, not a universal certification. General-requirement standards B829 (seamless tubular), B751 (welded tube), B775 (welded pipe) and B906 (flat) apply only where invoked. ASTM and ASME SB adoption editions are not automatically identical; an ASTM material specification does not by itself establish pressure-code approval. Rename designation “equivalents” as cross-references: C-276 N10276/2.4819; C-22 N06022/2.4602; C-2000 N06200/2.4675; B-2 N10665/2.4617; B-3 N10675/2.4600; X N06002/2.4665 — matching identifiers do not prove identical limits, condition or code eligibility.

Availability is confirmed per enquiry with stocked / sourced / made-to-order status — the ranges below are indicative, not a statement that every grade is held in every size, schedule and condition.

Class 2500 is a flange pressure class, not “2500 psi”, and B16.5 Class 2500 extends only to NPS 12. STD/XS do not always equal Sch 40/80, and 40S/80S differ from 40/80 at some sizes. Keep dimensional standards (B36.10 / B36.19) separate from material specifications. See the schedule chart and weight calculator.

• B-series (B-2, B-3): excellent in reducing acids such as hydrochloric acid, but they contain little or no chromium, so oxidising contaminants (ferric/cupric ions, aeration, oxidising acids) can cause rapid attack — not for “all concentrations” without purity, temperature and oxidant limits.
• C-series (C-276, C-22, C-2000) and G grades: broad resistance to mixed oxidising and reducing acids and chlorides. C-22 has higher chromium (better in oxidising conditions) and C-276 higher molybdenum/tungsten (strong in reducing conditions) — comparisons are environment-specific, not a universal ranking.
• Distinguish wet (moist) chlorine and hypochlorite from dry chlorine; specify concentration, temperature, aeration, contaminants, crevices and weld condition. Publish corrosion rates only with the test solution, temperature, duration and specimen condition.
• X (high-temperature): selected for strength and oxidation resistance in furnace/combustion service — not an aqueous-corrosion choice. Its high-temperature capability is not an unrestricted load-bearing or pressure-design limit; separate oxidation exposure, creep/rupture life and code limits.
• ASTM G28 detects specific intergranular-corrosion susceptibility for particular alloys and specimen states; it is a test method with named applicability and acceptance, not a blanket guarantee of service resistance. Sour-service (ISO 15156 / NACE MR0175) needs the applicable part/edition, grade, condition, hardness and environmental limits.