The Valve,safety Relief, cataloged under National Stock Number 4820-01-256-0662, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 16 specifications, cited from the U.S. Government catalog. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-256-0662 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Status | ACTIVE |
| Flow Control Device | PLUG |
| Flange Shape | ROUND WITH HOLES ALL ENDS |
| Flange Face Design | PLAIN ALL ENDS |
| Bolt Circle Nominal Diameter | 5.500 INCHES ALL ENDS IN |
| Connection Type | FLANGE ALL ENDS |
| Style Designator | ANGLE FLANGED ENDS |
| Bolt Hole Nominal Diameter | 0.562 INCHES ALL ENDS IN |
| Valve Size | 3.000 INCHES IN |
| Second Connection Face to Centerline Distance | 5.250 INCHES IN |
| Nominal Outside Diameter | 6.625 INCHES ALL ENDS IN |
| Bolt Hole Quantity | 8 ALL ENDS |
| First Connection Face to Centerline Distance | 5.250 INCHES IN |
| Material | STEEL BODY |
| Opening Pressure Setting | 20.0 POUNDS PER SQUARE INCH LBS |
| Valve Operation Method | AUTOMATIC |
| Nominal Thickness | 0.188 INCHES ALL ENDS IN |
| 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 |
|---|---|
| 2973AFBAC | 3/9 Design control — primary reference U.S. Government activity |
| 2973AFBAC | C/1 Advisory reference — outside the item-of-supply concept Fairbanks Morse, Llc |
NSN 4820-01-256-0662 is a Valve,safety Relief, classified under FSC 4820, Valves, Nonpowered. Status: active.
Key specifications for 4820-01-256-0662: Flow Control Device: PLUG; Flange Shape: ROUND WITH HOLES ALL ENDS; Flange Face Design: PLAIN ALL ENDS; Bolt Circle Nominal Diameter: 5.500 INCHES ALL ENDS IN. 16 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.