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) |
Product-form note: ASTM B127 covers Monel 400 (UNS N04400) plate, sheet and strip; ASTM B564 covers nickel-alloy forgings including N04400. ASTM B865 belongs to Monel K500 (UNS N05500) and is not a Monel 400 purchasing specification. See the grade designation and product-form reference.
Purchasing Specifications by Form
For Monel 400 / UNS N04400, plate / sheet / strip purchasing leads with ASTM B127. Forgings including N04400 are covered under ASTM B564. Do not use ASTM B865 (Monel K500) as a Monel 400 purchasing specification.
| Element | Reference |
|---|---|
| Common name | Monel 400 |
| UNS | N04400 |
| Plate / sheet / strip | ASTM B127 (SB-127 where applicable) — lead for plate TS |
| Forging | ASTM B564 (SB-564 where applicable) |
| ASTM B865 | Not for Monel 400 — belongs to Monel K500 / N05500 |
Confirm ASME SB-* adoption and Code edition where applicable. Listing a specification is not a certification claim. Age-hardenable counterpart: Monel K500 purchasing specs (B865).
Useful information to include in an RFQ (not mandatory for every enquiry):
- Alloy / grade (Monel 400) and UNS (N04400)
- Product form path (B127 plate vs B564 forging)
- Tube-sheet OD / dimensions / thickness
- Tube OD, pitch, hole diameter and pattern
- Drawing + revision, quantity, machining tolerance, inspection / testing
Continue from grade identity into product form and machining:
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.