PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

20677Seat,valve

Schneider Electric Systems Usa Inc · NSN 4820-00-343-6040 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-00-343-6040 — this item is cataloged by the U.S. Government under National Stock Number 4820-00-343-6040. Primary manufacturer part number: 20677.
Features
  • Seat,valve — FSC 4820
  • Thread Quantity Per Inch: 15 SINGLE THREADED PORTION
  • Style Designator: THREADED FLANGED
  • Thread Series Designator: UNS SINGLE THREADED PORTION
  • Material: COPPER ALLOY OVERALL
  • Seating Surface Shape: ANGULAR
  • Body Inside Diameter: 1.875 INCHES NOMINAL IN
  • Thread Class: 2A SINGLE THREADED PORTION A
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Copper Alloy Overall construction
General Description

The Seat,valve, cataloged under National Stock Number 4820-00-343-6040, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Schneider Electric Systems Usa Inc. Government technical data includes 13 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 1 commercial cross-reference from 1 manufacturer, enabling identification through both NSN and commercial part number lookups. 5 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-00-343-6040
Primary Part Number20677
Item NameSeat,valve
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerSchneider Electric Systems Usa Inc
StatusACTIVE
Thread Quantity Per Inch15 SINGLE THREADED PORTION
Style DesignatorTHREADED FLANGED
Thread Series DesignatorUNS SINGLE THREADED PORTION
MaterialCOPPER ALLOY OVERALL
Seating Surface ShapeANGULAR
Body Inside Diameter1.875 INCHES NOMINAL IN
Thread Class2A SINGLE THREADED PORTION A
Flange Seat to Disk End Height0.185 INCHES NOMINAL IN
Flange Diameter2.500 INCHES NOMINAL IN
Under Flange Height0.395 INCHES NOMINAL IN
Nominal Thread Size2.312 INCHES SINGLE THREADED PORTION IN
Thread Length0.345 INCHES NOMINAL SINGLE THREADED PORTION IN
Seat Angle in Deg45.000 NOMINAL
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 5
4210-00-136-466720-677 INTERCHANGEABLE
Valve Assembly,fire
Kidde Technologies, Inc Div Kidde Aerospace and Defense
5133-00-189-9280 INTERCHANGEABLE
Drill,twist
5330-00-640-9344 INTERCHANGEABLE
Gasket
1040-00-938-374854A50C98-2 INTERCHANGEABLE
Cover,regulator
Navair and Navsea Managed Original Design Activity Dwg Not Material/parts Supplier
5910-01-025-540820677 INTERCHANGEABLE
Capacitor Leaf
Mirion Technologies (canberra), Inc.
Cross-Reference Index
Part NumberManufacturer
20677 PRIMARY Schneider Electric Systems Usa Inc (USA)
Related Parts
4210-00-136-4667INTERCHANGEABLE
VALVE ASSEMBLY,FIRE
20-677
5133-00-189-9280INTERCHANGEABLE
DRILL,TWIST
5330-00-640-9344INTERCHANGEABLE
GASKET
1040-00-938-3748INTERCHANGEABLE
COVER,REGULATOR
54A50C98-2
5910-01-025-5408INTERCHANGEABLE
CAPACITOR LEAF
20677

Frequently Asked Questions

What is NSN 4820-00-343-6040?

NSN 4820-00-343-6040 is a Seat,valve, manufactured by Schneider Electric Systems Usa Inc, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-00-343-6040?

NSN 4820-00-343-6040 has 1 cross-referenced part number: 20677 (Schneider Electric Systems Usa Inc).

What NSN replaces 4820-00-343-6040?

There are 5 known substitutes for 4820-00-343-6040: 4210-00-136-4667, 5133-00-189-9280, 5330-00-640-9344 and 2 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 20677?

Key specifications for 20677: Thread Quantity Per Inch: 15 SINGLE THREADED PORTION; Style Designator: THREADED FLANGED; Thread Series Designator: UNS SINGLE THREADED PORTION; Material: COPPER ALLOY OVERALL. 14 total characteristics are documented in the Federal Logistics Information System.

Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
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