Seawater eats through most metals eventually. Monel 400 does not: this nickel-copper alloy, a minimum of 63% nickel with 28 to 34% copper, has been the standard choice for marine and hydrofluoric acid service since long before newer nickel alloys came along. USA Piping Solution stocks Monel 400 pipe and tube in the USA, seamless to ASTM B165 and welded to ASTM B725, in round, square, and rectangular profiles. Every order, whichever construction you need, ships with full material certification. For the wider Monel range, see our Monel Pipes & Tubes page, and for other alloys built for the same kind of corrosive service, browse Exotic Alloy Pipes & Tubes.
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What Is Monel 400 Pipe?
Monel 400 is a solid-solution nickel-copper alloy, a minimum of 63% nickel with 28 to 34% copper, valued for its resistance to seawater, brine, hydrofluoric acid, and sulfuric acid across a wide temperature range. It also welds and fabricates well, which is why it shows up in corrosion-critical piping where both durability and workability matter.
Specifications
| Property | Details |
|---|---|
| Specifications | ASTM B165, ASTM B829, ASTM B775, ASTM B725, ASTM B163, ASTM B730, ASTM B751, AMS 4574 |
| Dimension Standards | ANSI B36.19M, ANSI B36.10 |
| Form | Round pipe, square pipe, rectangular pipe |
| Schedule Range | 0.3 mm - 50 mm; SCH 5, 10, 40, 80, 80S, 160, XXS |
| Length | Single random, double random, cut length |
| Ends | Plain, beveled, or threaded |
| Finish | Annealed & pickled, bright annealed, polished, cold drawn |
| External Coating | 3LPE / 3LPP / FBE / DFBE / PP |
Types
- Seamless Pipe: the standard form for pressure and process piping, to ASTM B165.
- Welded Pipe: cost-effective option for larger sizes, to ASTM B725.
- ERW Pipe: electric-resistance-welded, an economical route for straight-run piping.
- Alloy 400 Tubing: seamless tube for heat exchanger and instrumentation use.
- Clad Pipe: Monel 400 cladding over a steel substrate for cost-sensitive corrosive applications.
Applications
- Offshore & Marine Engineering: seawater piping and structural components on platforms and vessels.
- Heat Exchangers: tube and pipe in corrosive process-side service.
- Chemical Processing: hydrofluoric and sulfuric acid handling equipment.
- Oil & Gas Pipelines: piping exposed to sour and corrosive well fluids.
- Desalination Plants: seawater intake and process piping.
Monel 400 vs Copper Nickel Alloys
Monel 400 is not automatically the better choice. It offers higher strength and broader corrosion resistance, including in hydrofluoric acid service that copper-nickel alloys don't handle, but it comes at a higher cost. For moderate marine and seawater duty without a hydrofluoric acid or high-strength requirement, Copper Nickel 90/10 or Copper Nickel 70/30 is often the more economical choice. Material selection should come down to pressure, temperature, and the specific corrosive media in your system, not alloy reputation alone.
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Testing, Certification & Availability
Every order ships with mill test certification and full material traceability. See our Quality Policy page for the full testing program we run across all grades. Monel 400 pipe price depends on size, schedule, construction method, and order quantity; send us your OD, wall thickness or schedule, and length requirement and we'll confirm current availability and pricing. International shipment is available on request.
Related Products
- Monel Pipes & Tubes
- Monel Flanges
- Hastelloy C276 Tubing
- Inconel 625 Pipes & Tubes
- Inconel 600 Pipes & Tubes
- Copper Nickel 90/10 Pipes & Tubes
- Copper Nickel 70/30 Pipes & Tubes
Frequently Asked Questions
Is Monel 400 available as both seamless and welded pipe?
Yes. Seamless pipe and tube are supplied to ASTM B165; welded pipe is supplied to ASTM B725, both in the same UNS N04400 chemistry.
How does Monel 400 compare to copper nickel alloys for marine piping?
Monel 400 offers higher strength and broader corrosion resistance, including hydrofluoric acid service that copper-nickel alloys don't handle. For moderate marine seawater duty without that requirement, a copper-nickel alloy is often the more economical choice; see our Copper Nickel 90/10 and Copper Nickel 70/30 pages for that comparison.
What certifications are supplied with Monel 400 pipe?
Every order ships with mill test certification and full material traceability. See our Quality Policy page for the full program.
What sizes and schedules are available in Monel 400 pipe?
We stock standard NPS sizes across common schedules. Send us your OD, wall thickness or schedule, and length requirement and we'll confirm current availability.
Can Monel 400 pipe be supplied with an external coating?
Yes, 3LPE, 3LPP, FBE, DFBE, and PP coatings are available on request for buried or subsea service.