Stainless Steel 316L vs. Super Duplex vs. Hastelloy
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Home navigate_next knowledge base navigate_next Stainless Steel 316L vs. Super Duplex vs. Hastelloy

Knowledge base · Material selection

316L stainless steel, super duplex or Hastelloy:
which material should you choose?

Three materials, three price classes, three fields of application. We compare them on corrosion resistance, strength, machinability and cost — so you can make the right choice for your process.

Corrosion index PREN 24 → 70 Yield strength 220 → 550 MPa Price index 1× → 10× Food & pharma EC 1935/2004

The three materials up close

From the hygienic standard to the nickel alloy for the harshest chemistry. Below, for each material: the properties, the pros and cons, and when it is the right choice.

316L stainless steel hygienic coupling

316L stainless steel (1.4404)

Austenitic stainless steel · ±17% Cr, 12% Ni, 2–2.5% Mo · C ≤ 0.03%

316L stainless steel is the standard in the food, dairy and pharmaceutical industries. The low carbon content (the “L” for low carbon) prevents intergranular corrosion after welding — ideal for welded piping systems, couplings and fittings. The molybdenum provides clearly better corrosion resistance than 304 stainless steel.

Advantages

  • Excellent value for money; widely available from stock
  • Food-safe: complies with EC 1935/2004 and FDA requirements
  • Very good weldability and machinability (low carbon)
  • Polishes to a smooth finish (Ra ≤ 0.8 µm) — ideal for CIP/SIP
  • Good resistance to acids, alkalis and cleaning agents

Disadvantages

  • Prone to pitting corrosion at high chloride concentrations (seawater, brine)
  • Risk of stress corrosion cracking (SCC) with chlorides above ±50 °C
  • Relatively low yield strength — thicker walls required at high pressure
  • PREN ±24–26: not suitable for aggressive chloride environments

When to choose 316L? Food, dairy, beverages, pharma and general industry — dairy couplings (DIN 11851), Tri-Clamp, hose tails and piping. The right choice for 90% of hygienic applications, as long as there is no high chloride load or extreme process media.

Super duplex coupling, maritime setting

Super duplex (1.4410 / SAF 2507)

Duplex (austenite + ferrite) · ±25% Cr, 7% Ni, 4% Mo + nitrogen

Super duplex combines an austenitic and a ferritic structure and gets the best of both worlds: roughly twice the strength of 316L and far higher resistance to chloride corrosion. The material of choice for the maritime sector, offshore and desalination plants.

Advantages

  • ±2× as strong as 316L — thinner walls and lighter construction
  • PREN > 40: excellent resistance to pitting and crevice corrosion
  • Very high resistance to chloride stress corrosion cracking
  • Suitable for seawater, brackish water and brine
  • Good fatigue strength under dynamic loads

Disadvantages

  • Harder to weld: requires precise heat input
  • Harder to machine than 316L — higher machining costs
  • Limited service range: embrittlement above ±250 °C, loss of toughness below −50 °C
  • More expensive than 316L and less widely stocked

When to choose super duplex? Maritime and offshore, desalination, brine lines, chemical processes with high chloride concentrations, and structures where high strength saves weight. The logical step up when 316L corrodes away in your environment.

Hastelloy coupling, chemical process plant

Hastelloy (C-276 / C-22)

Nickel-based alloy · ±57% Ni, 16% Cr, 16% Mo — not a stainless steel

Hastelloy is not a stainless steel but a nickel alloy, and plays in a different league. Where 316L and even super duplex give up — hot hydrochloric acid, sulphuric acid, wet chlorine gas — Hastelloy keeps standing. It withstands both oxidising and reducing media, a unique combination.

Advantages

  • Virtually unbeatable corrosion resistance in aggressive chemistry
  • Withstands hot hydrochloric acid, sulphuric acid and wet chlorine gas
  • Performs in both oxidising and reducing environments
  • Retains its properties at high temperatures
  • Virtually immune to pitting, crevice and stress corrosion

Disadvantages

  • Price: 5–10× that of 316L stainless steel
  • Long lead times — rarely available from stock
  • Heavy and costly machining (tough nickel alloy)
  • Overkill for standard food and water applications

When to choose Hastelloy? Chemical and petrochemical industry, flue gas cleaning, acid production and processes with aggressive or varying media where no stainless steel holds up. Choose Hastelloy only when 316L and duplex demonstrably fall short — otherwise you pay far too much.

The three materials side by side

Property316L stainlessSuper duplexHastelloy C-276
TypeAustenitic stainlessDuplex stainlessNickel alloy
PREN (pitting corrosion index)±24–26> 40±65–70
Yield strength (Rp0.2)±220 MPa±550 MPa±310 MPa
Chloride resistanceLimitedVery goodExcellent
SeawaterNot suitableSuitableSuitable
Aggressive acids (HCl, H₂SO₄)Not suitableLimitedExcellent
WeldabilityVery goodRequires expertiseGood, but costly
Food contact (EC 1935/2004)Standard choicePossibleRarely needed
Relative price1×±2–3×±5–10×
AvailabilityWidely stockedLimitedMade to order

Quick selection guide

316L

Food, dairy, beverages, pharma and general industry. No high chloride load? Then 316L is almost always the right — and most economical — choice.

Super duplex

Seawater, brine, maritime and offshore. Or when high strength allows thinner walls and saves weight.

Hastelloy

Aggressive chemistry where nothing else survives: hot hydrochloric acid, sulphuric acid, chlorine gas. Only when 316L and duplex demonstrably fall short.

In doubt? The right material depends on the medium, concentration, temperature, pressure and cleaning process. Our specialists are happy to think along with you.

In depth: Hastelloy® C-276 (Alloy C-276)

C-276 almost always refers to Hastelloy® C-276, a premium nickel-molybdenum-chromium alloy known for its exceptional corrosion resistance. The material is used worldwide in the chemical industry, offshore, oil & gas and other environments where standard stainless steel is not sufficiently resistant.

Chemical composition (approximate)

ElementPercentage
Nickel (Ni)approx. 57%
Molybdenum (Mo)15–17%
Chromium (Cr)14.5–16.5%
Tungsten (W)3–4.5%
Iron (Fe)4–7%
Other elementsSmall amounts of Co, Mn, V, Si and C

Key properties

  • Excellent corrosion resistance
  • Resistant to both oxidising and reducing chemicals
  • Very high resistance to pitting and crevice corrosion
  • Good resistance to stress corrosion cracking
  • Suitable for applications at elevated temperatures
  • Long service life under severe chemical conditions

Typical applications

  • Chemical process industry
  • Offshore installations
  • Oil and gas industry
  • Pharmaceutical industry
  • Chlorine and bleaching plants
  • Flue gas desulphurisation (FGD) plants
  • Chemical pumps, valves and fittings
  • Heat exchangers
  • Instrumentation and process piping

Chemical resistance — resistant to, among others

  • Hydrochloric acid (HCl)
  • Sulphuric acid (H₂SO₄)
  • Phosphoric acid
  • Formic acid
  • Acetic acid
  • Sodium hypochlorite
  • Chlorine and chlorine dioxide
  • Wet chlorine gases
  • Seawater
  • Many organic solvents

Please note: the actual chemical resistance depends on the concentration, temperature, pressure and any impurities in the medium. For critical applications, always consult a chemical resistance table or the manufacturer.

Comparison: Hastelloy C-276 vs. 316 stainless steel

Property316 stainlessHastelloy C-276
General corrosion resistanceGoodExcellent
Hydrochloric acidPoorExcellent
Sodium hypochloritePoorVery good
ChlorinePoorVery good
SeawaterGoodExcellent
Price level€€€€€€

When to choose C-276? Hastelloy C-276 is typically used when 316 stainless steel is not sufficiently resistant to aggressive chemicals or severe corrosive conditions. Although considerably more expensive than stainless steel, it offers far higher chemical resistance and a longer service life.

Applications within industry

C-276 is widely used for:

Products in C-276

  • Chemical couplings
  • Hose couplings
  • Valves
  • Pump components
  • Instrumentation
  • Fittings
  • Process piping for highly corrosive media

Need help choosing your material?

NexaParts supplies couplings, hoses and fittings in 316L stainless steel and advises you on the right material for your application. Call or email us — you’ll always get a technically substantiated answer.

Contact us

The values stated (PREN, yield strength, price indications) are indicative and may vary by alloy, supplier and product form. Always consult the material certificates and your process conditions for a final material selection.