Monel 400 Tube Sheet
A nickel-copper alloy developed specifically for resistance to hydrofluoric acid and flowing seawater — two services where even duplex and standard stainless struggle, making Monel 400 a specialist rather than a general-purpose upgrade.
Chemical Composition
| Element | Min % | Max % |
|---|---|---|
| Nickel (Ni) | 63.0 | — |
| Copper (Cu) | 28.0 | 34.0 |
| Iron (Fe) | — | 2.5 |
| Manganese (Mn) | — | 2.0 |
| Carbon (C) | — | 0.30 |
Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength | 480–620 MPa (annealed) |
| Yield Strength (0.2% offset) | 170–280 MPa (annealed) |
| Elongation | 35–60% |
| Max. Practical Service Temp. | ~480°C |
Equivalent Grades
| Standard | Designation |
|---|---|
| ASTM / UNS | N04400 |
| EN / DIN | 2.4360 |
| Trade Name | Monel® 400 (Special Metals) |
Why Monel Over Duplex or Stainless
Available Product Forms
Monel 400 is most commonly ordered as Fixed or Floating Tube Sheets, and occasionally as a Clad Tube Sheet face on a lower-cost base to control cost on large-diameter parts.
Applications
Refinery HF alkylation units, marine and offshore seawater cooling, and select chemical processing services involving hydrofluoric or sulfuric acid at concentrations that would attack stainless or duplex.
Advantages & Limitations
Advantages
- Resists hydrofluoric acid where stainless and duplex cannot
- Good resistance to flowing seawater and biofouling
- Retains ductility across a wide temperature range
Limitations
- Significant cost premium over stainless and duplex
- Not the best choice for oxidizing acids (Hastelloy or titanium instead)
- Machining requires specific tooling due to work-hardening behaviour
FAQ
No — K500 is a precipitation-hardenable variant with added aluminum and titanium, giving significantly higher strength than standard 400. K500 is used where higher strength is needed alongside Monel's corrosion resistance; 400 is the standard grade for general HF and seawater service.
Nickel forms a protective fluoride film in HF service that resists further attack, a mechanism that stainless steel's chromium oxide passive layer doesn't replicate in this specific chemical environment. This is why HF alkylation units are one of the classic Monel applications in refining.
Monel 400 is typically sourced to order given lower demand volume compared to stainless or duplex — send your specification and quantity for a confirmed lead time.