Monel 400 UnionASTM B564 · MSS SP-83 · Manufacturer, trader & exporter, India
Alloy 400 · UNS N04400
A Monel 400 union is a three-piece forged fitting that joins pipes and can be taken apart, made from Monel 400 to ASTM B564. Unions let a small-bore line be disconnected for maintenance without cutting. Made to MSS SP-83 in threaded or socket-weld ends.
- ASTM B564
- MSS SP-83
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is a Monel 400 Union?
- What it is
- A three-piece forged fitting that joins pipes and can be taken apart
- Material
- ASTM B564
- Dimensions
- MSS SP-83
- Grade
- Monel 400 · UNS N04400
- Best at
- Seawater, hydrofluoric acid and marine service
Monel 400 Union Specification
| Product | Monel 400 Union |
|---|---|
| Material standard | ASTM B564 |
| Dimensional standard | MSS SP-83 |
| Sizes | ⅛" – 4" (ASME B16.11) |
| Wall / class | Class 2000 / 3000 / 6000 / 9000 |
| Ends | Socket weld · NPT threaded |
| Testing | PMI (as specified in the PO) · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 or 3.2 on request / as specified in the PO |
When to Choose an Union
Unions let a small-bore line be disconnected for maintenance without cutting. Made to MSS SP-83 in threaded or socket-weld ends.
- Three pieces: nut, male and female ends
- Threaded or socket weld
- Class 3000 / 6000
More on choosing: Union guide.
Monel 400 Union: Why 400 for unions
Unions let a small-bore line be disconnected for maintenance without cutting. Made to MSS SP-83 in threaded or socket-weld ends. In Monel 400, the choice usually comes down to the medium and temperature — the rows here are the points buyers check for this exact combination.
| Why this grade | Nickel-alloy fittings match nickel-alloy pipe in aggressive media. Monel 400 is picked for seawater, hydrofluoric acid and marine service. |
|---|---|
| Typical service | Marine — Pump shafts, valves and seawater piping. |
| Welding to carbon steel | A nickel-base filler such as ERNiCr-3 (or ERNiCrMo-3) is used when joining it to carbon steel |
| Matching filler | ERNiCu-7 (AWS A5.14) |
| Sour service | Listed in NACE MR0175 / ISO 15156-3 within its limits — state it on the order |
Monel 400 Union Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Nickel (+Co) | As specified |
| Copper | As specified |
| Iron | As specified |
| Manganese | As specified |
| Carbon | As specified |
| Silicon | As specified |
| Sulphur | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM B127 for UNS N04400.
Monel 400 Union Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM B127 for UNS N04400 — Annealed plate.
Full chemistry, properties and equivalents are on the Monel 400 grade page.
Standards on this page
Other Monel 400 pipe fittings
Monel 400 Union — questions buyers ask
Can unions be used in high-pressure lines?
Class 3000 and 6000 unions are rated for high pressure on small bores, but many codes limit their use in hazardous service.
Can Monel 400 unions be welded to carbon steel?
Yes — a nickel-base filler such as ERNiCr-3 (or ERNiCrMo-3) is used when joining it to carbon steel.
Which standard covers Monel 400 unions?
The material is ASTM B564; dimensions follow MSS SP-83. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a Monel 400 union?
The alloy price, the size and schedule or class, quantity, and the testing and documents required. Send your list and we quote the same working day.
Can you supply Monel 400 unions to NACE MR0175?
Yes. Monel 400 is listed in NACE MR0175 / ISO 15156-3 within its limits; state NACE compliance on the order and it is confirmed on the certificate.
What documents do you supply?
EN 10204 3.1 or 3.2 certificates available on request / as specified in the PO; dimensional reports as required. PMI can be arranged depending on product and requirements, as specified in the PO.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026