The Seat,valve, cataloged under National Stock Number 4820-01-057-2128, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 14 specifications, cited from the U.S. Government catalog. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 3 items share a part number with this NSN in the catalog (possible match — not a government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 | 4820-01-057-2128 |
| Item Name | Seat,valve |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flange Seat to Disk End Height | 0.188 INCHES NOMINAL IN |
| Flange Diameter | 1.750 INCHES NOMINAL IN |
| Thread Length | 0.625 INCHES NOMINAL SINGLE THREADED PORTION IN |
| Style Designator | THREADED FLANGED |
| Material Document and Classification | STELLITE MFR REF SINGLE MATERIAL RESPONSE FACE |
| Body Inside Diameter | 1.000 INCHES NOMINAL IN |
| Nominal Thread Size | 1.625 INCHES SINGLE THREADED PORTION IN |
| Under Flange Height | 0.781 INCHES NOMINAL IN |
| Thread Class | 2A SINGLE THREADED PORTION A |
| Thread Quantity Per Inch | 12 SINGLE THREADED PORTION |
| Material | COBALT ALLOY FACE |
| Material | STEEL COMP 303 BODY |
| Thread Series Designator | UN SINGLE THREADED PORTION |
| 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 |
| Reference | Meaning |
|---|---|
| B4659 | 3/2 Design control — primary reference U.S. Government activity |
| 4547-2 | 5/2 Secondary reference U.S. Government activity |
NSN 4820-01-057-2128 is a Seat,valve, classified under FSC 4820, Valves, Nonpowered. Status: active.
3 possible matches (shared part number, not a government interchangeability claim): 4140-01-470-2599, 6525-01-501-5948, 2910-01-537-0758. Verify interchangeability with system specifications before substitution.
Key specifications for 4820-01-057-2128: Flange Seat to Disk End Height: 0.188 INCHES NOMINAL IN; Flange Diameter: 1.750 INCHES NOMINAL IN; Thread Length: 0.625 INCHES NOMINAL SINGLE THREADED PORTION IN; Style Designator: THREADED FLANGED. 14 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.