UNS N08535 Pipes & Tubes are high performance super Austenitic alloy pipes and tubes designed to resist corrosive conditions with high chloride, carbon dioxide (CO₂) and hydrogen sulfide (H₂S) contents. This is an iron-nickel-chromium-molybdenum alloy with high pitting resistance, high resistance to crevice corrosion and high resistance to stress corrosion cracking in harsh corrosive environments of sour service. Seamless pipes and tubes are produced to ASTM B622 / ASME SB622, and oilfield tubing to relevant ISO 13680 specs. The grade is designed for deep sour gas wells, petrochemical equipment and marine heat-exchange systems, with sizes up to 3.5 in (88.9 mm) OD. Material can be provided with the full traceability and EN 10204 3.1 certification. UNS N08535 Pipes & Tubes are manufactured, stocked and exported by Amardeep Steel for critical industrial applications.
Specifications of UNS N08535 Pipes & Tubes
Parameter / Standard Type | Specification Details / Governing Standards |
|---|---|
UNS Number | UNS N08535 |
Industry Designations | Alloy 8535, Alloy8535, Superaustenitic Fe-Ni-Cr-Mo Alloy |
Seamless Pipe & Tube | ASTM B622 / ASME SB-622 (Seamless Nickel and Nickel-Cobalt Alloy Pipe and Tube; covers seamless sizes up to 3.5 in / 88.9 mm OD) |
Pipe Fittings | ASTM B366 / ASME SB-366 (Factory-Made Wrought Nickel and Nickel Alloy Fittings) |
Oil & Gas Downhole Tubing / Casing | ISO 13680 (Petroleum and natural gas industries — Corrosion-resistant alloy seamless tubes for use as casing, tubing, and coupling stock) |
EN / DIN / JIS / BS Equivalents | No direct published equivalent. Specify directly by UNS N08535 or ASTM B622. |
Chemical Compositions of UNS N08535 Pipes & Tubes
Element | Min (%) | Max (%) | Function / Effect |
|---|---|---|---|
Carbon (C) | — | 0.030 | Prevents intergranular carbide precipitation |
Chromium (Cr) | 24.0 | 27.0 | Provides severe oxidizing resistance & passive oxide film |
Nickel (Ni) | 29.0 | 36.5 | Stabilizes austenitic structure & resists chloride SCC |
Molybdenum (Mo) | 2.5 | 4.0 | Resists localized pitting & crevice attack |
Copper (Cu) | — | 1.5 | Enhances corrosion resistance in non-oxidizing acids |
Manganese (Mn) | — | 1.0 | Deoxidizer improving hot-workability |
Silicon (Si) | — | 0.5 | Promotes oxidation resistance |
Phosphorus (P) | — | 0.030 | Restricted to prevent hot tearing during hot processing |
Sulphur (S) | — | 0.030 | Restricted to optimize pitting performance & hot ductility |
Iron (Fe) | 29.4 (Bal.) | 44.5 (Bal.) | Base matrix metal balance |
Mechanical & Elastic Properties of UNS N08535 Pipes & Tubes
Property | ASTM B622 Minimum Requirement | Typical Producer Value (SI Units) | Typical Producer Value (Imperial Units) |
|---|---|---|---|
Ultimate Tensile Strength | 586 MPa / 85 ksi | 570 MPa | 83 ksi |
Yield Strength (0.2% Offset) | 241 MPa / 35 ksi | 240 MPa | 35 ksi |
Elongation at Break | 30% | 46% | 46% |
Fatigue Strength | — | 220 MPa | 32 ksi |
Shear Strength | — | 400 MPa | 58 ksi |
Elastic Modulus (Young's Modulus) | — | 200 GPa | 29.0106psi (29.0Mpsi) |
Shear Modulus | — | 80 GPa | 11.6106psi (11.6Mpsi) |
Poisson's Ratio | — | 0.28 | 0.28 |
Physical Properties of UNS N08535 Pipes & Tubes
Property | Value (SI Units) | Value (Imperial Units) |
|---|---|---|
Density | 8.1 g/cm³ | 505.7 lb/ft³ |
Melting Range | 1370 – 1420 °C | 2500 – 2590 °F |
Specific Heat Capacity | 470 J/(kg·K) at 20°C | 0.112 BTU/(lb·°F) |
Thermal Conductivity | 13 W/(m·K) at 20°C | 7.5 BTU·ft/(h·ft²·°F) |
Coefficient of Thermal Expansion (CTE) | 16 µm/(m·K) at 20–100°C | 8.910-6in/(in·°F) |
Latent Heat of Fusion | 310 J/g | 133.3 BTU/lb |
Electrical Conductivity | 1.7 % IACS (Equal Volume) | 1.7 % IACS |
Pitting Resistance Equivalent (PREN) | ~ 36 | ~ 36 |
UNS N08535 Pipes & Tubes Weight Chart
NPS Size | Outside Dia (OD) | Schedule 10S (Wall / Wt) | Schedule 40S (Wall / Wt) | Schedule 80S (Wall / Wt) |
|---|---|---|---|---|
1/8" | 10.3 mm | 1.24 mm / 0.29 kg/m | 1.73 mm / 0.38 kg/m | 2.41 mm / 0.48 kg/m |
1/4" | 13.7 mm | 1.65 mm / 0.51 kg/m | 2.24 mm / 0.65 kg/m | 3.02 mm / 0.82 kg/m |
3/8" | 17.1 mm | 1.65 mm / 0.65 kg/m | 2.31 mm / 0.87 kg/m | 3.20 mm / 1.13 kg/m |
1/2" | 21.3 mm | 2.11 mm / 1.03 kg/m | 2.77 mm / 1.31 kg/m | 3.73 mm / 1.67 kg/m |
3/4" | 26.7 mm | 2.11 mm / 1.32 kg/m | 2.87 mm / 1.74 kg/m | 3.91 mm / 2.27 kg/m |
1" | 33.4 mm | 2.77 mm / 2.16 kg/m | 3.38 mm / 2.58 kg/m | 4.55 mm / 3.34 kg/m |
1-1/4" | 42.2 mm | 2.77 mm / 2.78 kg/m | 3.56 mm / 3.50 kg/m | 4.85 mm / 4.61 kg/m |
1-1/2" | 48.3 mm | 2.77 mm / 3.21 kg/m | 3.68 mm / 4.18 kg/m | 5.08 mm / 5.59 kg/m |
2" | 60.3 mm | 2.77 mm / 4.06 kg/m | 3.91 mm / 5.61 kg/m | 5.54 mm / 7.72 kg/m |
2-1/2" | 73.0 mm | 3.05 mm / 5.43 kg/m | 5.16 mm / 8.91 kg/m | 7.01 mm / 11.77 kg/m |
3" | 88.9 mm | 3.05 mm / 6.66 kg/m | 5.49 mm / 11.65 kg/m | 7.62 mm / 15.76 kg/m |
Wall Thickness Chart of UNS N08535 Pipes & Tubes
Outer Diameter (OD) | Available Wall Thickness Options |
|---|---|
6.35 mm (1/4") | 0.89 mm, 1.24 mm, 1.65 mm |
9.53 mm (3/8") | 0.89 mm, 1.24 mm, 1.65 mm, 2.11 mm |
12.70 mm (1/2") | 1.24 mm, 1.65 mm, 2.11 mm, 2.77 mm |
15.88 mm (5/8") | 1.24 mm, 1.65 mm, 2.11 mm, 2.77 mm |
19.05 mm (3/4") | 1.65 mm, 2.11 mm, 2.77 mm, 3.05 mm |
25.40 mm (1") | 1.65 mm, 2.11 mm, 2.77 mm, 3.40 mm |
31.75 mm (1-1/4") | 2.11 mm, 2.77 mm, 3.40 mm |
38.10 mm (1-1/2") | 2.11 mm, 2.77 mm, 3.40 mm, 4.06 mm |
50.80 mm (2") | 2.77 mm, 3.40 mm, 4.06 mm, 4.85 mm |
Applications and Industrial Uses of UNS N08535 Pipes & Tubes
- Deep Sour Gas Well Tubing
- Oil and Gas Downhole Equipment
- High-Pressure Sour-Service Pipelines
- Petrochemical Processing Equipment
- Marine Heat Exchangers
- Offshore Oil and Gas Systems
- Chemical Processing Plants
- Sour Gas Production Equipment
Frequently Asked Questions
What are UNS N08535 Pipes and Tubes?
UNS N08535 Pipes and Tubes are high-performance Fe-Ni-Cr-Mo alloy products designed for severe corrosive and sour-service environments.
What is UNS N08535 also known as?
UNS N08535 is commercially known as Alloy 8535 or Alloy 2535.
Is UNS N08535 suitable for sour service?
Yes. UNS N08535 is designed for demanding sour-service applications containing hydrogen sulfide (H₂S).
Can UNS N08535 withstand H₂S and CO₂ environments?
Yes. It provides strong resistance to corrosion in environments containing H₂S, CO₂, and chlorides.
Is UNS N08535 suitable for HPHT oil and gas wells?
Yes. It is suitable for selected high-pressure, high-temperature oil and gas well applications, subject to service conditions.
What is the difference between UNS N08535 and Alloy 625?
UNS N08535 is a superaustenitic Fe-Ni-Cr-Mo alloy developed particularly for severe sour-service environments, while Alloy 625 is a nickel-chromium-molybdenum alloy known for high strength and broad corrosion resistance.
Is UNS N08535 resistant to pitting and crevice corrosion?
Yes. Its alloy composition provides strong resistance to pitting and crevice corrosion in aggressive chloride-containing environments.
What is the difference between UNS N08535 and 254 SMO (UNS S31254)?
Both are 6-7% molybdenum superaustenitic grades for chloride service. UNS N08535 carries a wider nickel range (29.0 to 36.5%) for added resistance to chloride stress corrosion cracking, while 254 SMO is more widely stocked as a standard super-duplex alternative.
