Thread Length: 0.745 INCHES NOMINAL SINGLE THREADED PORTION IN
Style Designator: PLAIN
Body Inside Diameter: 17.880 INCHES NOMINAL IN
Nominal Thread Size: 19.625 INCHES SINGLE THREADED PORTION IN
Thread Class: 2A SINGLE THREADED PORTION A
Thread Quantity Per Inch: 12 SINGLE THREADED PORTION
Material: NICKEL ALLOY OVERALL
Identification
NSN: 4820-01-440-3994
NIIN: 014403994
FSC: 4820 — Valves, Nonpowered
FSG: 48 — Valves
General Description
The Seat,valve, cataloged under National Stock Number 4820-01-440-3994, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. Government technical data includes 8 specifications, cited from the U.S. Government catalog. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 8 items share a part number with this NSN in the catalog (possible match — not a government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
4820-01-440-3994
Item Name
Seat,valve
FSC / FSG
4820 / 48 — Valves, Nonpowered
Status
ACTIVE
Thread Length
0.745 INCHES NOMINAL SINGLE THREADED PORTION IN
Style Designator
PLAIN
Body Inside Diameter
17.880 INCHES NOMINAL IN
Nominal Thread Size
19.625 INCHES SINGLE THREADED PORTION IN
Thread Class
2A SINGLE THREADED PORTION A
Thread Quantity Per Inch
12 SINGLE THREADED PORTION
Material
NICKEL ALLOY OVERALL
Thread Series Designator
UN SINGLE THREADED PORTION
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 Items8
Each row states its source: a government interchangeability/replacement code, or a possible match on a shared part number.
4820-01-440-4049POSSIBLE MATCH
STEM,FLUID VALVE
Possible match (shared part number)
4820-01-440-4079POSSIBLE MATCH
VALVE,CHECK
Possible match (shared part number)
4820-01-440-4103POSSIBLE MATCH
DISK,VALVE
Possible match (shared part number)
4820-01-440-4521POSSIBLE MATCH
SEAT,VALVE
Possible match (shared part number)
4820-01-440-4548POSSIBLE MATCH
STEM,FLUID VALVE
Possible match (shared part number)
4820-01-440-4605POSSIBLE MATCH
DISK,VALVE
Possible match (shared part number)
4820-01-440-4832POSSIBLE MATCH
SEAT,VALVE
Possible match (shared part number)
4820-01-440-4895POSSIBLE MATCH
STEM,FLUID VALVE
Possible match (shared part number)
Cross-Reference Index
No manufacturer part numbers on file in the U.S. Government catalog.
Reference documents
Reference
Meaning
TDCV-016095
5/9Secondary reference
C M Industries Inc Dba Custom Marine Sales
TDCV-016095-20 PIECE 3
3/9Design control — primary reference
C M Industries Inc Dba Custom Marine Sales
TDCV-016095-20-03
5/9Secondary reference
C M Industries Inc Dba Custom Marine Sales
Related Parts
4820-01-440-4049POSSIBLE MATCH
STEM,FLUID VALVE
4820-01-440-4079POSSIBLE MATCH
VALVE,CHECK
4820-01-440-4103POSSIBLE MATCH
DISK,VALVE
4820-01-440-4521POSSIBLE MATCH
SEAT,VALVE
4820-01-440-4548POSSIBLE MATCH
STEM,FLUID VALVE
4820-01-440-4605POSSIBLE MATCH
DISK,VALVE
4820-01-440-4832POSSIBLE MATCH
SEAT,VALVE
4820-01-440-4895POSSIBLE MATCH
STEM,FLUID VALVE
Frequently Asked Questions
What is NSN 4820-01-440-3994?
NSN 4820-01-440-3994 is a Seat,valve, classified under FSC 4820, Valves, Nonpowered. Status: active.
What NSN replaces 4820-01-440-3994?
8 possible matches (shared part number, not a government interchangeability claim): 4820-01-440-4049, 4820-01-440-4079, 4820-01-440-4103. Verify interchangeability with system specifications before substitution.
What are the specifications of 4820-01-440-3994?
Key specifications for 4820-01-440-3994: Overall Height: 0.875 INCHES NOMINAL IN; Thread Length: 0.745 INCHES NOMINAL SINGLE THREADED PORTION IN; Style Designator: PLAIN; Body Inside Diameter: 17.880 INCHES NOMINAL IN. 8 specifications are documented in the U.S. Government catalog.
Is NSN 4820-01-440-3994 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.