PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

MS21921-4DNut,tube Coupling

Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M · NSN 4730-01-254-9841 · FSC 4730 · No Item Name Available
Verified by PartsTable
NSN 4730-01-254-9841 — this item is cataloged by the U.S. Government under National Stock Number 4730-01-254-9841. Primary manufacturer part number: MS21921-4D.
Features
  • Nut,tube Coupling — FSC 4730
  • Surface Treatment: ANODIZE OVERALL
  • Thread Quantity Per Inch: 20
  • Thread Series: UNF
  • Smallest Inside Diameter: 0.300 INCHES NOMINAL IN
  • Nominal Tube Outside Diameter: 0.250 INCHES IN
  • Nut Style: TUBE COUPLING
  • Seat Angle: 45.0 DEGREES NOMINAL
Applications
  • Structural fastening and assembly
  • Equipment mounting
  • Panel and housing attachment
  • Fluid conveyance
  • Hydraulic system plumbing
General Description

The Nut,tube Coupling, cataloged under National Stock Number 4730-01-254-9841, is classified within Federal Supply Class 4730 (No Item Name Available) of the Pipe, Tubing, Hose, and Fittings group. The primary manufacturer of record is Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M. Government technical data includes 15 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. 1 verified substitute exists in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4730-01-254-9841
Primary Part NumberMS21921-4D
Item NameNut,tube Coupling
FSC / FSG4730 / 47 — No Item Name Available
ManufacturerMilitary Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
StatusACTIVE
Surface TreatmentANODIZE OVERALL
Thread Quantity Per Inch20
Thread SeriesUNF
Smallest Inside Diameter0.300 INCHES NOMINAL IN
Nominal Tube Outside Diameter0.250 INCHES IN
Nut StyleTUBE COUPLING
Seat Angle45.0 DEGREES NOMINAL
Nut Height0.719 INCHES NOMINAL IN
Length to Shoulder0.547 INCHES NOMINAL IN
Nominal Thread Size0.437 INCHES IN
Width Across Flats0.562 INCHES NOMINAL IN
Specification/standard Data96906-MS21921 GOVERNMENT STANDARD
MaterialALUMINUM ALLOY 2014 OVERALL
Thread Class3B
Thread DirectionRIGHT-HAND
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 1
4730-00-555-8203AS21921-4D INTERCHANGEABLE
Nut,tube Coupling
Sae International Dba Sae International
Cross-Reference Index
Part NumberManufacturer
MS21921-4D Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
Related Parts
4730-00-555-8203INTERCHANGEABLE
NUT,TUBE COUPLING
AS21921-4D

Frequently Asked Questions

What is NSN 4730-01-254-9841?

NSN 4730-01-254-9841 is a Nut,tube Coupling, manufactured by Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M, classified under FSC 4730 (No Item Name Available). Status: active.

What are the part numbers for NSN 4730-01-254-9841?

NSN 4730-01-254-9841 has 1 cross-referenced part number: MS21921-4D (Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M).

What NSN replaces 4730-01-254-9841?

There is 1 known substitute for 4730-01-254-9841: 4730-00-555-8203. Verify interchangeability with system specifications before substitution.

What are the specifications of MS21921-4D?

Key specifications for MS21921-4D: Surface Treatment: ANODIZE OVERALL; Thread Quantity Per Inch: 20; Thread Series: UNF; Smallest Inside Diameter: 0.300 INCHES NOMINAL IN. 15 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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