PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

42974Seat,valve

Spirax Sarco Inc Dba Spirax Sarco · NSN 4820-00-399-2877 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-00-399-2877 — this item is cataloged by the U.S. Government under National Stock Number 4820-00-399-2877. Primary manufacturer part number: 42974.
Features
  • Seat,valve — FSC 4820
  • Seating Surface Shape: FLAT
  • Thread Series Designator: UNEF SINGLE THREADED PORTION
  • Flange Diameter: 1.878 INCHES NOMINAL IN
  • Material: STEEL CORROSION RESISTING OVERALL
  • Flange Seat to Disk End Height: 0.170 INCHES NOMINAL IN
  • Thread Length: 0.312 INCHES NOMINAL SINGLE THREADED PORTION IN
  • Style Designator: THREADED FLANGED
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Steel Corrosion Resisting Overall construction
General Description

The Seat,valve, cataloged under National Stock Number 4820-00-399-2877, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Spirax Sarco Inc Dba Spirax Sarco. Government technical data includes 11 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. 2 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-00-399-2877
Primary Part Number42974
Item NameSeat,valve
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerSpirax Sarco Inc Dba Spirax Sarco
StatusACTIVE
Seating Surface ShapeFLAT
Thread Series DesignatorUNEF SINGLE THREADED PORTION
Flange Diameter1.878 INCHES NOMINAL IN
MaterialSTEEL CORROSION RESISTING OVERALL
Flange Seat to Disk End Height0.170 INCHES NOMINAL IN
Thread Length0.312 INCHES NOMINAL SINGLE THREADED PORTION IN
Style DesignatorTHREADED FLANGED
Body Inside Diameter0.960 INCHES NOMINAL IN
Thread Class2A SINGLE THREADED PORTION A
Nominal Thread Size1.625 INCHES SINGLE THREADED PORTION IN
Under Flange Height0.375 INCHES NOMINAL IN
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 2
5950-01-123-1478986279-1B INTERCHANGEABLE
Reactor
Raytheon Company Dba Raytheon
5365-01-290-631942974 INTERCHANGEABLE
Spacer,ring
Ingersoll-Rand Company Dba Ingersoll-Rand Div Tool & Hoist Division
Cross-Reference Index
Part NumberManufacturer
42974 PRIMARY Spirax Sarco Inc Dba Spirax Sarco (USA)
Related Parts
5950-01-123-1478INTERCHANGEABLE
REACTOR
986279-1B
5365-01-290-6319INTERCHANGEABLE
SPACER,RING
42974

Frequently Asked Questions

What is NSN 4820-00-399-2877?

NSN 4820-00-399-2877 is a Seat,valve, manufactured by Spirax Sarco Inc Dba Spirax Sarco, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-00-399-2877?

NSN 4820-00-399-2877 has 1 cross-referenced part number: 42974 (Spirax Sarco Inc Dba Spirax Sarco).

What NSN replaces 4820-00-399-2877?

There are 2 known substitutes for 4820-00-399-2877: 5950-01-123-1478, 5365-01-290-6319. Verify interchangeability with system specifications before substitution.

What are the specifications of 42974?

Key specifications for 42974: Seating Surface Shape: FLAT; Thread Series Designator: UNEF SINGLE THREADED PORTION; Flange Diameter: 1.878 INCHES NOMINAL IN; Material: STEEL CORROSION RESISTING OVERALL. 12 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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