The Seat,valve, cataloged under National Stock Number 4820-01-421-2566, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Twc-Thevalve Company. Government technical data includes 3 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through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-421-2566 |
| Primary Part Number | 639589 |
| Item Name | Seat,valve |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Twc-Thevalve Company |
| Status | ACTIVE |
| Style Designator | THREADED FLANGED |
| Material | STEEL SEAT |
| Seating Surface Shape | FLAT |
| 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 |
|---|---|
| 639589 PRIMARY | Twc-Thevalve Company (USA) |
| Reference | Meaning |
|---|---|
| 5275F 4.00IN IT3 | 5/9 Secondary reference The Walworth Company |
| 639589 | 3/9 Design control — primary reference The Walworth Company |
| WALWORTH 5275F 4.00IN IT3 | 5/9 Secondary reference Valve Automation and Control of San Diego Dba Valve Automation & Control of San Diego Div Valve Automation and Controls of |
NSN 4820-01-421-2566 is a Seat,valve, manufactured by Twc-Thevalve Company, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-421-2566 has 1 manufacturer part number on file: 639589 (Twc-Thevalve Company).
Key specifications for 639589: Style Designator: THREADED FLANGED; End Item Identification: STRATEGIC SEALIFT CONVERSION SHIPS CLASS; Material: STEEL SEAT; Seating Surface Shape: FLAT. 3 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.