ASTM B464 UNS N08020 / 2.4660 / Alloy20 Nickel Alloy Welded Pipe For Petrochemical Industry
UNS N08020, commonly known as Alloy 20 (also called Carpenter 20), is an austenitic iron-nickel-chromium alloy with deliberate copper and molybdenum additions. ASTM B464 UNS N08020 welded pipe refers to longitudinally welded pipe manufactured from UNS N08020 alloy sheet/strip, produced under the requirements of ASTM B464. It is designed for corrosive service environments, especially sulfuric acid, mixed acid media and general chemical process corrosion. ASTM B464 UNS N08020 Nickel Alloy Welded Pipes are widely used in chemical processing, petrochemical, pharmaceutical, power, marine, and other corrosive-service piping systems.
Chemical Composition (wt%):
| Element |
Min |
Max |
| Ni |
32.0 |
38.0 |
| Cr |
19.0 |
21.5 |
| Fe |
31.0 |
38.0 |
| Cu |
3.0 |
4.0 |
| Mo |
2.0 |
3.0 |
| C |
— |
0.07 |
| Mn |
— |
2.0 |
| Si |
— |
1.0 |
| P |
— |
0.045 |
| S |
— |
0.035 |
| Cb(Nb) |
8×C min |
1.0 max |
Mechanical Properties:
| Property |
Requirement |
| Tensile Strength, Rm |
≥ 550 MPa (≥ 80 ksi) |
| Yield Strength (0.2% offset), Rp0.2 |
≥ 240 MPa (≥ 35 ksi) |
| Elongation (50 mm gauge length) |
≥ 30% |
| Hardness |
≤ 215 HB / ≤ 95 HRB |
Main Features of ASTM B464 UNS N08020 Welded Pipes:
Excellent resistance to sulfuric acid at various concentrations and temperatures.
Good resistance to phosphoric acid, nitric acid, and mixed acids.
Resistant to chloride stress corrosion cracking, pitting, and crevice corrosion.
Niobium-stabilized for resistance to intergranular corrosion after welding.
Good mechanical properties at ambient and elevated temperatures.
Good weldability and formability.
Austenitic, generally non-magnetic in the annealed condition.
Suitable for both oxidizing and reducing environments.
Good performance in chemical process and petrochemical environments.
Typical Applications:
Chemical processing: reactors, heat exchangers, condensers, piping, valves, pumps.
Sulfuric acid, phosphoric acid, and nitric acid production.
Petrochemical and refining: alkylation, hydrodesulfurization, process piping.
Pharmaceutical and food processing: high-purity and sanitary piping.
Power generation and flue gas desulfurization systems.
Marine and offshore: seawater piping, offshore platforms.
Pulp and paper: digesters, bleach plants.
Nuclear fuel processing and related chemical service.
Storage tanks, columns, fittings, and other corrosion-resistant equipment.
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