PartsTable TECHNICAL DATA SHEET

NSN 4820-01-429-0421Government record, cited

Seat, Valve4820-01-429-0421

NSN 4820-01-429-0421 · NIIN 014290421 · Part number 556-6408987-A-5

Naval Sea Systems Command · FSC 4820 — Valves, Nonpowered · FSG 48 — Valves · CAGE 53711

Government record, cited

NSN 4820-01-429-0421 — this item is cataloged by the U.S. Government under National Stock Number 4820-01-429-0421. Manufacturer of record part number: 556-6408987-A-5.

Also searched as 4820-01-429-0421 · 4820014290421 · NIIN 014290421 · 01-429-0421 · FSC 4820 Valves, Nonpowered · CAGE 53711 · 556-6408987-A-5 · 264378701 FIND · 2643-787-01 FN A-5 · 211084951 · 6408987

Nearby stock numbers ← 4820-01-429-0420 Valve, Check · 4820-01-429-0556 Stem, Fluid Valve →

4820-01-429-0421 — Valves, Nonpowered

Features

Seat,valve — FSC 4820
Body Outside Diameter: 1.061 INCHES NOMINAL IN
Style Designator: PLAIN
Body Inside Diameter: 0.563 INCHES NOMINAL IN
Seat Radius: 0.280 INCHES NOMINAL IN
Material: PLASTIC OVERALL
Seating Surface Shape: RADIAL
2 manufacturer part numbers on file

Identification

NSN: 4820-01-429-0421
NIIN: 014290421
FSC: 4820 — Valves, Nonpowered
FSG: 48 — Valves
Primary part number: 556-6408987-A-5
Manufacturer: Naval Sea Systems Command

General Description

The Seat,valve, cataloged under National Stock Number 4820-01-429-0421, 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 6 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through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 7 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.

Technical Specifications

Parameter	Value
NSN	4820-01-429-0421
Primary Part Number	556-6408987-A-5
Item Name	Seat,valve
FSC / FSG	4820 / 48 — Valves, Nonpowered
Manufacturer	Naval Sea Systems Command
Status	ACTIVE
Body Outside Diameter	1.061 INCHES NOMINAL IN
Style Designator	PLAIN
Body Inside Diameter	0.563 INCHES NOMINAL IN
Seat Radius	0.280 INCHES NOMINAL IN
Material	PLASTIC OVERALL
Seating Surface Shape	RADIAL

Lifecycle & Compliance

Acquisition Status	ACTIVE
DEMIL Code	DEMIL A — No Demilitarization Required
Hazard	No hazard code in the DLA record (HMIC N)
Criticality Code	X

⇄ Related Items 7

Each row states its source: a government interchangeability/replacement code, or a possible match on a shared part number.

4820-01-429-0556556-6408987-A-6 POSSIBLE MATCH

STEM,FLUID VALVE

Possible match (shared part number)Naval Sea Systems Command

4820-01-429-1272556-6408987 FIND B-2 POSSIBLE MATCH

CAP,VALVE

Possible match (shared part number)Naval Sea Systems Command

4820-01-429-1273556-6408987 FIND B-5 POSSIBLE MATCH

SEAT,VALVE

Possible match (shared part number)Naval Sea Systems Command

4820-01-429-1276556-6408987 FIND B-6 POSSIBLE MATCH

STEM,FLUID VALVE

Possible match (shared part number)Naval Sea Systems Command

4820-01-429-2492556-6408987 FIND B-4,B-5 POSSIBLE MATCH

PARTS KIT,BALL VALVE

Possible match (shared part number)Naval Sea Systems Command

4730-01-432-9230264378701 FIND AA-1 POSSIBLE MATCH

ADAPTER ASSEMBLY,VALVE

Possible match (shared part number)Naval Sea Systems Command

4820-01-442-3077264378701 FIND B-3 POSSIBLE MATCH

PLUG,ROTARY,VALVE

Possible match (shared part number)Naval Sea Systems Command

Cross-Reference Index

Part Number	Manufacturer
556-6408987-A-5 PRIMARY	Naval Sea Systems Command (USA)
211084951	Naval Sea Systems Command (USA)

Reference documents

Reference	Meaning
264378701 FIND	C/1 Advisory reference — outside the item-of-supply concept Naval Sea Systems Command
2643-787-01 FN A-5	5/9 Secondary reference U.S. Government activity
6408987	D/9 Drawing number reference only Naval Sea Systems Command

Related Parts

4820-01-429-0556POSSIBLE MATCH

STEM,FLUID VALVE

556-6408987-A-6

4820-01-429-1272POSSIBLE MATCH

CAP,VALVE

556-6408987 FIND B-2

4820-01-429-1273POSSIBLE MATCH

SEAT,VALVE

556-6408987 FIND B-5

4820-01-429-1276POSSIBLE MATCH

STEM,FLUID VALVE

556-6408987 FIND B-6

4820-01-429-2492POSSIBLE MATCH

PARTS KIT,BALL VALVE

556-6408987 FIND B-4,B-5

4730-01-432-9230POSSIBLE MATCH

ADAPTER ASSEMBLY,VALVE

264378701 FIND AA-1

4820-01-442-3077POSSIBLE MATCH

PLUG,ROTARY,VALVE

264378701 FIND B-3

Frequently Asked Questions

What is NSN 4820-01-429-0421?

NSN 4820-01-429-0421 is a Seat,valve, manufactured by Naval Sea Systems Command, classified under FSC 4820, Valves, Nonpowered. Status: active.

What part numbers are listed for NSN 4820-01-429-0421?

NSN 4820-01-429-0421 has 2 manufacturer part numbers on file: 556-6408987-A-5 (Naval Sea Systems Command), 211084951 (Naval Sea Systems Command).

What NSN replaces 4820-01-429-0421?

7 possible matches (shared part number, not a government interchangeability claim): 4820-01-429-0556, 4820-01-429-1272, 4820-01-429-1273. Verify interchangeability with system specifications before substitution.

What are the specifications of 556-6408987-A-5?

Key specifications for 556-6408987-A-5: Overall Height: 0.250 INCHES NOMINAL IN; Body Outside Diameter: 1.061 INCHES NOMINAL IN; Style Designator: PLAIN; Body Inside Diameter: 0.563 INCHES NOMINAL IN. 6 specifications are documented in the U.S. Government catalog.

Is NSN 4820-01-429-0421 hazardous material?

No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.

Sources

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.

✓ Data cited from the U.S. Government catalog; commercial cross-references from OEM and certified industry sources.

PartsTable Design LLC · partstable.com