The Seat,valve, cataloged under National Stock Number 4820-01-104-6770, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Rolls-Royce Corporation. Government technical data includes 12 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-104-6770 |
| Primary Part Number | 6859371 |
| Item Name | Seat,valve |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Rolls-Royce Corporation |
| Status | ACTIVE |
| Flange Seat to Disk End Height | 0.259 INCHES NOMINAL IN |
| Flange Diameter | 1.122 INCHES MINIMUM AND 1.123 INCHES MAXIMUM IN |
| Body Outside Diameter | 1.008 INCHES MINIMUM AND 1.012 INCHES MAXIMUM IN |
| Hardness Rating | 32.0 ROCKWELL C MINIMUM AND 36.0 ROCKWELL C MAXIMUM OVERALL |
| Body Stepped Inside Diameter | 0.500 INCHES MINIMUM AND 0.505 INCHES MAXIMUM FIRST STEP IN |
| Body Stepped Inside Diameter | 0.920 INCHES NOMINAL SECOND STEP IN |
| Body Stepped Inside Diameter | 0.978 INCHES MINIMUM AND 0.983 INCHES MAXIMUM THIRD STEP IN |
| Style Designator | PLAIN FLANGED |
| Seat Radius | 0.030 INCHES MINIMUM AND 0.040 INCHES MAXIMUM IN |
| Under Flange Height | 0.165 INCHES MINIMUM AND 0.170 INCHES MAXIMUM IN |
| Material | STEEL OVERALL |
| Seating Surface Shape | RADIAL |
| 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 |
|---|---|
| 6859371 PRIMARY | Rolls-Royce Corporation (USA) |
| 6859371 | Space Age Engineering, Inc (USA) |
| Reference | Meaning |
|---|---|
| 6859371 | D/9 Drawing number reference only Allison Transmission Inc Dba Allison Transmission, Inc |
| 6859371 | 5/9 Secondary reference U.S. Government activity |
NSN 4820-01-104-6770 is a Seat,valve, manufactured by Rolls-Royce Corporation, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-104-6770 has 2 manufacturer part numbers on file: 6859371 (Rolls-Royce Corporation), 6859371 (Space Age Engineering, Inc).
Key specifications for 6859371: Flange Seat to Disk End Height: 0.259 INCHES NOMINAL IN; Flange Diameter: 1.122 INCHES MINIMUM AND 1.123 INCHES MAXIMUM IN; Body Outside Diameter: 1.008 INCHES MINIMUM AND 1.012 INCHES MAXIMUM IN; Hardness Rating: 32.0 ROCKWELL C MINIMUM AND 36.0 ROCKWELL C MAXIMUM OVERALL. 12 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.