PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

21549-1Seat,valve

Defense & Development Enterprises Llc · NSN 4820-00-031-7453 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-00-031-7453 — this item is cataloged by the U.S. Government under National Stock Number 4820-00-031-7453. Primary manufacturer part number: 21549-1.
Features
  • Seat,valve — FSC 4820
  • Body Outside Diameter: 0.495 INCHES NOMINAL IN
  • Hardness Rating: 28.0 ROCKWELL C MINIMUM AND 34.0 ROCKWELL C MAXIMUM OVERALL
  • Material Document and Classification: QQ-S-763 CL 6 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
  • Material: STEEL COMP 416 OVERALL
  • FSC Application Data: VALVE
  • Style Designator: PLAIN FLANGED
  • Under Flange Height: 0.232 INCHES NOMINAL IN
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Steel Comp 416 Overall construction
General Description

The Seat,valve, cataloged under National Stock Number 4820-00-031-7453, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Defense & Development Enterprises Llc. Government technical data includes 10 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 3 commercial cross-references from 3 manufacturers, enabling identification through both NSN and commercial part number lookups. 3 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-00-031-7453
Primary Part Number21549-1
Item NameSeat,valve
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerDefense & Development Enterprises Llc
StatusACTIVE
Body Outside Diameter0.495 INCHES NOMINAL IN
Hardness Rating28.0 ROCKWELL C MINIMUM AND 34.0 ROCKWELL C MAXIMUM OVERALL
Material Document and ClassificationQQ-S-763 CL 6 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
MaterialSTEEL COMP 416 OVERALL
FSC Application DataVALVE
Style DesignatorPLAIN FLANGED
Under Flange Height0.232 INCHES NOMINAL IN
Flange Diameter0.656 INCHES NOMINAL IN
Flange Seat to Disk End Height0.048 INCHES NOMINAL IN
Body Inside Diameter0.315 INCHES NOMINAL IN
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 3
1650-00-992-3676215491 INTERCHANGEABLE
Cup,valve,brake Power or Manual
Hydro-Aire Aerospace Corp
6130-01-137-128621549-1 INTERCHANGEABLE
Panel,bottom,rear
Smiths Aerospace, Inc., Electronic Systems-Grand Rapids
3040-01-317-749121549-1 INTERCHANGEABLE
Gearshaft Sector,spur
Aerosonic Llc
Cross-Reference Index
Part NumberManufacturer
21549-1 Defense & Development Enterprises Llc (USA)
KC4070 Kendall Controls Corp (USA)
21549-1 Triumph Thermal Systems - Maryland, Inc. (USA)
Related Parts
1650-00-992-3676INTERCHANGEABLE
CUP,VALVE,BRAKE POWER OR MANUAL
215491
6130-01-137-1286INTERCHANGEABLE
PANEL,BOTTOM,REAR
21549-1
3040-01-317-7491INTERCHANGEABLE
GEARSHAFT SECTOR,SPUR
21549-1

Frequently Asked Questions

What is NSN 4820-00-031-7453?

NSN 4820-00-031-7453 is a Seat,valve, manufactured by Defense & Development Enterprises Llc, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-00-031-7453?

NSN 4820-00-031-7453 has 3 cross-referenced part numbers: 21549-1 (Defense & Development Enterprises Llc), KC4070 (Kendall Controls Corp), 21549-1 (Triumph Thermal Systems - Maryland, Inc.).

What NSN replaces 4820-00-031-7453?

There are 3 known substitutes for 4820-00-031-7453: 1650-00-992-3676, 6130-01-137-1286, 3040-01-317-7491. Verify interchangeability with system specifications before substitution.

What are the specifications of 21549-1?

Key specifications for 21549-1: Body Outside Diameter: 0.495 INCHES NOMINAL IN; Hardness Rating: 28.0 ROCKWELL C MINIMUM AND 34.0 ROCKWELL C MAXIMUM OVERALL; Material Document and Classification: QQ-S-763 CL 6 FED SPEC SINGLE MATERIAL RESPONSE OVERALL; Material: STEEL COMP 416 OVERALL. 11 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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