ASTM B725 UNS N04400 Welded Nickel Alloy Pipe Monel 400 Welded Pipe
ASTM B725 Monel 400 / UNS N04400 / 2.4360 Welded Pipe Nickel Alloy Pipe
Welded pipe under ASTM B725 means the longitudinal seam is fusion welded without the addition of filler metal (autogenous welding), and the entire pipe is subsequently annealed to optimize performance. ASTM B725 UNS N04400 welded pipe is a standard‑grade, seam‑welded tube made of Monel 400 alloy, used primarily in marine, chemical, and HF acid services where corrosion resistance is critical and seamless pipe is not economically required.
Monel 400 is renowned for:
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Excellent resistance to seawater and marine atmospheres (low corrosion rate, no stress corrosion cracking).
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Resistance to hydrofluoric acid (all concentrations up to boiling point) and sulfuric/hydrochloric acids in reducing conditions.
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Good resistance to neutral and alkaline salt solutions.
Equivalent Grade of ASTM B725 Welded Monel 400 Nickel Alloy Pipe
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Materials |
Trademark | UNS | Werkst. Nr. | Density (g/cm3) | BS | ASTM Standard |
|---|---|---|---|---|---|---|
| Alloy 400 | Monel 400 | N04400 | 2.4360 | 8,83 | 3072-6 NA13 | ASME SB/ASTM B163, B165, B725, B730, B127, B164, B366, B164 |
Chemical Properties % of ASTM B725 UNS N04400 Welded Nickel Alloy Pipe Monel 400 Welded Pipe
| Monel 400 | Ni | C | Al | Mn | Si | Fe | Cu | S | Cr |
| 63.0 min | 0.3 max | 0.50 max | 2.0 max | 0.5 max | 1.0 – 2.5 | 28.0 – 34.0 | 0.02 max | – |
Mechanical Characteristics of ASTM B725 UNS N04400 Welded Nickel Alloy Pipe Monel 400 Welded Pipe
| Density | Melting Point | Yield Strength (0.2%Offset) | Tensile Strength | Elongation |
| 8.8 g/cm3 | 1350 °C (2460 °F) | Psi - 35,000 , MPa - 240 | Psi - 80,000 , MPa - 550 | 40 % |
Manufacturing Differences of Welded Pipe: One Seam vs. Two Seams
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One‑Seam Pipe (Standard)
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Two‑Seam Pipe (Large Diameter, by agreement) |
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Application
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Marine engineering (seawater piping, heat exchangers)
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Chemical and petrochemical plants (hydrofluoric acid alkylation, HF service)
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Oil & gas (sour gas handling, downhole equipment)
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Power generation (feedwater heaters, condenser tubes)
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