The Nut,union, cataloged under National Stock Number 4730-01-421-8421, 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 1 manufacturer part number 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through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. 2 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4730-01-421-8421 |
| Primary Part Number | 803-5959306-1XX-003 |
| 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 | 1.880 INCHES NOMINAL IN |
| Shoulder Step Width | 0.120 INCHES NOMINAL IN |
| Shoulder Width | 0.120 INCHES NOMINAL IN |
| Thread Series | UN |
| Thread Direction | RIGHT-HAND |
| Nominal Thread Size | 1.5625 INCHES IN |
| Nut Height | 0.780 INCHES NOMINAL IN |
| Nut Style | HEXAGON |
| Thread Class | 3B |
| Thread Quantity Per Inch | 12 |
| Material | NICKEL ALLOY OVERALL |
| Smallest Inside Diameter | 1.141 INCHES NOMINAL IN |
| Shoulder Seat Diameter | 1.610 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 |
|---|---|
| 803-5959306-1XX-003 PRIMARY | Naval Sea Systems Command (USA) |
| Reference | Meaning |
|---|---|
| 5959306 | D/9 Drawing number reference only Naval Sea Systems Command |
NSN 4730-01-421-8421 is a Nut,union, manufactured by Naval Sea Systems Command, classified under FSC 4730, Hose, Pipe, Tube, Lubrication, and Railing Fittings. Status: active.
NSN 4730-01-421-8421 has 1 manufacturer part number on file: 803-5959306-1XX-003 (Naval Sea Systems Command).
2 possible matches (shared part number, not a government interchangeability claim): 4820-01-483-7795, 4820-01-534-6864. Verify interchangeability with system specifications before substitution.
Key specifications for 803-5959306-1XX-003: Width Across Flats: 1.880 INCHES NOMINAL IN; Shoulder Step Width: 0.120 INCHES NOMINAL IN; Shoulder Width: 0.120 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.