The Nut,union, cataloged under National Stock Number 4730-01-421-5218, is classified within Federal Supply Class 4730 (Hose, Pipe, Tube, Lubrication, and Railing Fittings) of the Pipe, Tubing, Hose, and Fittings group. The manufacturer of record is Naval Sea Systems Command. Government technical data includes 13 specifications, cited from the U.S. Government catalog. The record lists 2 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4730-01-421-5218 |
| Primary Part Number | 803-63974-009 |
| Item Name | Nut,union |
| FSC / FSG | 4730 / 47 — Hose, Pipe, Tube, Lubrication, and Railing Fittings |
| Manufacturer | Naval Sea Systems Command |
| Status | ACTIVE |
| Width Across Flats | 3.719 INCHES NOMINAL IN |
| Shoulder Step Width | 0.250 INCHES NOMINAL IN |
| Shoulder Width | 0.270 INCHES NOMINAL IN |
| Thread Series | UN |
| Material Document and Classification | ASTM B150 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL |
| Thread Direction | RIGHT-HAND |
| Nominal Thread Size | 3.375 INCHES IN |
| Nut Style | HEXAGON |
| Thread Class | 3B |
| Thread Quantity Per Inch | 12 |
| Material | NICKEL ALLOY OVERALL |
| Smallest Inside Diameter | 2.762 INCHES NOMINAL IN |
| Shoulder Seat Diameter | 1.469 INCHES NOMINAL IN |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| 803-63974-009 PRIMARY | Naval Sea Systems Command (USA) |
| 803-6397434-X6XXXX-009 | Naval Sea Systems Command (USA) |
| Reference | Meaning |
|---|---|
| 6397434 | D/9 Drawing number reference only Naval Sea Systems Command |
NSN 4730-01-421-5218 is a Nut,union, manufactured by Naval Sea Systems Command, classified under FSC 4730, Hose, Pipe, Tube, Lubrication, and Railing Fittings. Status: active.
NSN 4730-01-421-5218 has 2 manufacturer part numbers on file: 803-63974-009 (Naval Sea Systems Command), 803-6397434-X6XXXX-009 (Naval Sea Systems Command).
Key specifications for 803-63974-009: Width Across Flats: 3.719 INCHES NOMINAL IN; Shoulder Step Width: 0.250 INCHES NOMINAL IN; Shoulder Width: 0.270 INCHES NOMINAL IN; Thread Series: UN. 13 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.