The Valve,safety Relief, cataloged under National Stock Number 4820-01-346-6201, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Naval Sea Systems Command. Government technical data includes 15 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-346-6201 |
| Primary Part Number | 6511599-1 |
| Item Name | Valve,safety Relief |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Naval Sea Systems Command |
| Status | ACTIVE |
| Flow Control Device | DISK |
| Connection Style | PLAIN,OPTIONAL END(PIPE) ALL ENDS |
| Connection Type | THREADED INTERNAL PIPE ALL ENDS |
| Style Designator | STRAIGHT THRU |
| Operating Pressure | 200.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Thread Direction | RIGHT-HAND ALL ENDS |
| Nominal Thread Size | 0.250 INCHES ALL ENDS IN |
| Media for Which Designed | ACETYLENE SECOND RESPONSE |
| Media for Which Designed | GAS, INERT THIRD RESPONSE |
| Media for Which Designed | HYDROGEN FOURTH RESPONSE |
| Media for Which Designed | REFRIGERANT 12 FIFTH RESPONSE |
| Media for Which Designed | AIR FIRST RESPONSE |
| Material | STEEL COMP 316 BODY |
| Thread Series Designator | NPT ALL ENDS |
| Valve Operation Method | AUTOMATIC |
| 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 |
|---|---|
| 6511599-1 PRIMARY | Naval Sea Systems Command (USA) |
| Reference | Meaning |
|---|---|
| 559T1-2MP-150 | 5/2 Secondary reference U.S. Government activity |
| 6511599 | 7/1 Vendor item drawing reference Naval Sea Systems Command |
NSN 4820-01-346-6201 is a Valve,safety Relief, manufactured by Naval Sea Systems Command, classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-346-6201 has 1 manufacturer part number on file: 6511599-1 (Naval Sea Systems Command).
1 possible match (shared part number, not a government interchangeability claim): 4820-01-346-6202. Verify interchangeability with system specifications before substitution.
Key specifications for 6511599-1: Flow Control Device: DISK; Connection Style: PLAIN,OPTIONAL END(PIPE) ALL ENDS; Connection Type: THREADED INTERNAL PIPE ALL ENDS; Style Designator: STRAIGHT THRU. 15 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.