The Seat,valve, cataloged under National Stock Number 4820-01-256-9873, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 17 specifications, cited from the U.S. Government catalog. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-256-9873 |
| Item Name | Seat,valve |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flange Seat to Disk End Height | 0.229 INCHES MINIMUM AND 0.239 INCHES MAXIMUM IN |
| Flange Diameter | 1.104 INCHES MINIMUM AND 1.114 INCHES MAXIMUM IN |
| Thread Length | 0.172 INCHES NOMINAL SINGLE THREADED PORTION IN |
| Seal Accommodation Type | GROOVED |
| Criticality Code Justification | ZZZY |
| Style Designator | THREADED FLANGED |
| Material Document and Classification | QQ-N-288 FED SPEC SINGLE MATERIAL RESPONSE OVERALL |
| Body Inside Diameter | 1.105 INCHES MINIMUM AND 1.113 INCHES MAXIMUM IN |
| Nominal Thread Size | 1.188 INCHES SINGLE THREADED PORTION IN |
| Under Flange Height | 0.105 INCHES MINIMUM AND 0.115 INCHES MAXIMUM IN |
| Thread Class | 3A SINGLE THREADED PORTION A |
| Thread Quantity Per Inch | 20 SINGLE THREADED PORTION |
| Material | NICKEL ALLOY OVERALL |
| Seat Angle in Deg | 45.000 NOMINAL |
| Thread Series Designator | UN SINGLE THREADED PORTION |
| Reference Number Differentiating Characteristics | MATERIAL WILL BE IN ACCORDANCE WITH SHIPS PARTS CONTROL CENTER ACTIVITY HX QUALITY CONTROL,MANUFACTURING AND TESTING SPECIFICATIONS |
| Seating Surface Shape | ANGULAR |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL F — Mutilate — Cut |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | C |
| Reference | Meaning |
|---|---|
| 803-4384536-4XXX-13(SPCLN) | 3/1 Design control — primary reference U.S. Government activity |
NSN 4820-01-256-9873 is a Seat,valve, classified under FSC 4820, Valves, Nonpowered. Status: active.
Key specifications for 4820-01-256-9873: Flange Seat to Disk End Height: 0.229 INCHES MINIMUM AND 0.239 INCHES MAXIMUM IN; Flange Diameter: 1.104 INCHES MINIMUM AND 1.114 INCHES MAXIMUM IN; Thread Length: 0.172 INCHES NOMINAL SINGLE THREADED PORTION IN; Seal Accommodation Type: GROOVED. 17 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.
NSN 4820-01-256-9873 has DEMIL Code F. Demilitarization may be required before disposal or transfer to non-military entities.
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.