Hastelloy C276 Springs

Hastelloy C276 Springs

Hastelloy C276 is a nickel-molybdenum-chromium super alloy with an addition of tungsten and is designed to have excellent corrosion resistance in a wide range of severe environments. The high nickel and molybdenum contents make the nickel steel alloy especially resistant to pitting and crevice corrosion.

Hastelloy C-276 Springs FAQs

What is Hastelloy C-276 and what distinguishes it from other corrosion-resistant alloys?

Hastelloy C-276 (UNS N10276) is a nickel-molybdenum-chromium alloy with tungsten additions, engineered to resist corrosion across the widest possible range of aggressive chemical environments. Unlike stainless steels, which suffer pitting, crevice corrosion, and stress corrosion cracking in chloride-rich or reducing environments, Hastelloy C-276 resists attack in both oxidizing and reducing media simultaneously. Its very low carbon and silicon content minimizes carbide precipitation during welding and heat treatment, preserving corrosion resistance throughout the material—not just at the surface.

What specific chemicals and environments is Hastelloy C-276 resistant to?

Hastelloy C-276 offers outstanding resistance to: concentrated hydrochloric acid across all concentrations at moderate temperatures; sulfuric acid at low-to-moderate concentrations; wet chlorine gas; hypochlorite and chlorine dioxide solutions used in bleaching and water treatment; ferric chloride and other oxidizing chloride solutions; phosphoric acid; reducing and oxidizing mixed-acid environments; seawater and brine; and many organic acids. This broad resistance profile makes it uniquely suited for chemical processing environments where a single spring may contact multiple aggressive media or where the specific chemistry is variable.

What is the maximum operating temperature for Hastelloy C-276 springs?

For spring applications where both mechanical strength and full corrosion resistance must be maintained, Hastelloy C-276 is most reliably specified for service up to approximately 750°F (400°C). Above this temperature, the alloy can begin to sensitize through carbide precipitation in certain environments, which may reduce corrosion resistance in some media. Applications above 750°F should be reviewed against the specific corrosive environment and sensitization behavior before committing to a material specification.

How does Hastelloy C-276 compare to Inconel 625 for spring applications in corrosive environments?

Both are nickel-based superalloys with strong corrosion resistance, but with different performance profiles depending on the specific corrosive agent. C-276's higher molybdenum content (approximately 15–17% Mo vs. 8–10% in Inconel 625) gives it a meaningful advantage in reducing acid environments—hydrochloric acid, sulfuric acid, and mixed reducing-acid service—and in crevice corrosion resistance under chloride exposure. Inconel 625 is often favored for seawater applications and chloride-ion stress corrosion cracking resistance, and is generally somewhat easier to cold form for complex spring geometries. For applications involving concentrated reducing acids or aggressive mixed-acid environments, C-276 is typically the first-choice specification; for high-strength requirements combined with seawater or oxidizing acid exposure, Inconel 625 may be preferred.

What industries most commonly use Hastelloy C-276 springs?

Primary industries include: chemical processing (reactor internals, heat exchanger components, agitator springs, valve actuators), pharmaceutical manufacturing (process equipment subjected to aggressive sterilization and cleaning chemicals), pollution control equipment (flue gas desulfurization systems, acid scrubbers), pulp and paper processing (bleach plant equipment with chlorine dioxide and hypochlorite exposure), oil and gas (sour service valve and actuator springs, production equipment with H₂S and CO₂), and marine applications involving prolonged seawater exposure at elevated temperatures.

What is the minimum wire diameter available for Hastelloy C-276 springs?

Coiling Technologies manufactures Hastelloy C-276 springs starting at a minimum wire diameter of approximately 0.031 inches (0.78 mm), with larger diameters available up to heavy-duty industrial spring sizes. This minimum size supports precision instrument and valve springs in chemical processing and pharmaceutical equipment.

What should engineers specify when ordering Hastelloy C-276 springs for chemical processing applications?

Engineers should provide: the specific chemical environment (reagent identities, concentrations, pH, temperature, presence of oxidizing or reducing agents, and whether chloride ions are present); maximum operating temperature; required spring type and geometry; wire diameter and coil dimensions; spring load, rate, and deflection requirements; quantity; and any applicable design or material standards. ASTM B626 is the standard specification for Hastelloy C-276 (UNS N10276) wire. Material certifications with chemistry and mechanical property test reports are typically required for chemical processing programs and should be requested at order placement.