PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

MS21921-4Nut,tube Coupling

Marshall of Cambridge Aerospace Limited · NSN 4730-00-554-8015 · FSC 4730 · No Item Name Available
Verified by PartsTable
NSN 4730-00-554-8015 — this item is cataloged by the U.S. Government under National Stock Number 4730-00-554-8015. Primary manufacturer part number: MS21921-4.
Features
  • Nut,tube Coupling — FSC 4730
  • Nut Height: 0.720 INCHES NOMINAL IN
  • Nut Style: TUBE COUPLING
  • Length to Shoulder: 0.537 INCHES MINIMUM AND 0.557 INCHES MAXIMUM IN
  • Width Across Flats: 0.562 INCHES NOMINAL IN
  • Nominal Tube Outside Diameter: 0.250 INCHES IN
  • Seat Angle: 45.00 DEGREES NOMINAL
  • Material: STEEL OVERALL
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 4730-00-554-8015, 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 Marshall of Cambridge Aerospace Limited. Government technical data includes 13 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 7 commercial cross-references from 4 manufacturers, enabling identification through both NSN and commercial part number lookups. 2 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Cancelled.

Technical Specifications
ParameterValue
NSN4730-00-554-8015
Primary Part NumberMS21921-4
Item NameNut,tube Coupling
FSC / FSG4730 / 47 — No Item Name Available
ManufacturerMarshall of Cambridge Aerospace Limited
StatusCANCELLED
Nut Height0.720 INCHES NOMINAL IN
Nut StyleTUBE COUPLING
Length to Shoulder0.537 INCHES MINIMUM AND 0.557 INCHES MAXIMUM IN
Width Across Flats0.562 INCHES NOMINAL IN
Nominal Tube Outside Diameter0.250 INCHES IN
Seat Angle45.00 DEGREES NOMINAL
MaterialSTEEL OVERALL
Nominal Thread Size0.438 INCHES IN
Thread Quantity Per Inch20
Smallest Inside Diameter0.300 INCHES MINIMUM AND 0.305 INCHES MAXIMUM IN
Thread SeriesUNF
Thread Class3B
Thread DirectionRIGHT-HAND
Lifecycle & Compliance
Acquisition StatusCANCELLED
HAZMATNo
Verified Substitutes 2
4730-00-222-8636MS21921W4 INTERCHANGEABLE
Nut,tube Coupling
Sae International Dba Sae International
4730-00-555-8203AS21921-4D INTERCHANGEABLE
Nut,tube Coupling
Sae International Dba Sae International
Cross-Reference Index
Part NumberManufacturer
MS21921-4 Marshall of Cambridge Aerospace Limited (GBR)
4730-554-8015 E.c.a Etablissement Centrald'approvisionnement Des Forces Armee
4730005548015 E.c.a Etablissement Centrald'approvisionnement Des Forces Armee
MS21921-4 Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
MS21921D4 Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
AP2109T04 Sps Technologies, Llc Dba Airdrome Precision Components (USA)
AP2109T4 Sps Technologies, Llc Dba Airdrome Precision Components (USA)
Related Parts
4730-00-222-8636INTERCHANGEABLE
NUT,TUBE COUPLING
MS21921W4
4730-00-555-8203INTERCHANGEABLE
NUT,TUBE COUPLING
AS21921-4D

Frequently Asked Questions

What is NSN 4730-00-554-8015?

NSN 4730-00-554-8015 is a Nut,tube Coupling, manufactured by Marshall of Cambridge Aerospace Limited, classified under FSC 4730 (No Item Name Available). Status: cancelled.

What are the part numbers for NSN 4730-00-554-8015?

NSN 4730-00-554-8015 has 7 cross-referenced part numbers: MS21921-4 (Marshall of Cambridge Aerospace Limited), 4730-554-8015 (E.c.a Etablissement Centrald'approvisionnement Des Forces Armee), 4730005548015 (E.c.a Etablissement Centrald'approvisionnement Des Forces Armee), MS21921-4 (Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M), MS21921D4 (Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M) and 2 more.

What NSN replaces 4730-00-554-8015?

There are 2 known substitutes for 4730-00-554-8015: 4730-00-222-8636, 4730-00-555-8203. Verify interchangeability with system specifications before substitution.

What are the specifications of MS21921-4?

Key specifications for MS21921-4: Nut Height: 0.720 INCHES NOMINAL IN; Nut Style: TUBE COUPLING; Length to Shoulder: 0.537 INCHES MINIMUM AND 0.557 INCHES MAXIMUM IN; Width Across Flats: 0.562 INCHES NOMINAL IN. 14 total characteristics are documented in the Federal Logistics Information System.

Is NSN 4730-00-554-8015 still in active supply?

NSN 4730-00-554-8015 is currently cancelled. Check with the Defense Logistics Agency for current availability and authorized substitutes.

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