PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

MS21921-10DNut,tube Coupling

Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M · NSN 4730-00-555-8204 · FSC 4730 · No Item Name Available
Verified by PartsTable
NSN 4730-00-555-8204 — this item is cataloged by the U.S. Government under National Stock Number 4730-00-555-8204. Primary manufacturer part number: MS21921-10D.
Features
  • Nut,tube Coupling — FSC 4730
  • Thread Direction: RIGHT-HAND
  • Material: ALUMINUM ALLOY OVERALL
  • Surface Treatment: ANODIZE OVERALL
  • Surface Treatment Document and Classification: MIL-A-8625,TY 2 MIL SPEC SINGLE TREATMENT RESPONSE OVERALL
  • Width Across Flats: 1.000 INCHES NOMINAL IN
  • Nominal Tube Outside Diameter: 0.625 INCHES IN
  • Thread Series: UNF
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 4730-00-555-8204, 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 8 commercial cross-references from 6 manufacturers, enabling identification through both NSN and commercial part number lookups. 12 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Cancelled.

Technical Specifications
ParameterValue
NSN4730-00-555-8204
Primary Part NumberMS21921-10D
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
StatusCANCELLED
Thread DirectionRIGHT-HAND
MaterialALUMINUM ALLOY OVERALL
Surface TreatmentANODIZE OVERALL
Surface Treatment Document and ClassificationMIL-A-8625,TY 2 MIL SPEC SINGLE TREATMENT RESPONSE OVERALL
Width Across Flats1.000 INCHES NOMINAL IN
Nominal Tube Outside Diameter0.625 INCHES IN
Thread SeriesUNF
Nominal Thread Size0.875 INCHES IN
Smallest Inside Diameter0.690 INCHES MINIMUM AND 0.695 INCHES MAXIMUM IN
Nut Height0.970 INCHES MINIMUM AND 0.990 INCHES MAXIMUM IN
Thread Quantity Per Inch14
Seat Angle45.00 DEGREES NOMINAL
Nut StyleTUBE COUPLING
Length to Shoulder0.677 INCHES MINIMUM AND 0.697 INCHES MAXIMUM IN
Thread Class3B
Lifecycle & Compliance
Acquisition StatusCANCELLED
HAZMATNo
Verified Substitutes 12
5365-00-089-4451 INTERCHANGEABLE
Spacer,sleeve
5310-00-297-58931569 INTERCHANGEABLE
Washer,flat
R.w. Fernstrum & Company
2940-00-350-9071309735 INTERCHANGEABLE
Filter Element,fluid
New Holland N.v.nc.
2520-00-393-09071569 INTERCHANGEABLE
Yoke,release Clutch
Dana Off Highway Products, Llc
4730-00-454-7545HP3400 INTERCHANGEABLE
Adapter,straight,pipe to Boss
Baumbach Engineering Co
5120-00-505-5918 INTERCHANGEABLE
Drift Pin
5330-00-599-4748 INTERCHANGEABLE
Gasket
4730-00-821-1824MS21921-10 INTERCHANGEABLE
Nut,tube Coupling
Sae International Dba Sae International
5940-00-823-14101569 INTERCHANGEABLE
Terminal,lug
Halsit Holdings Llc Div Halsit Holdings, Llc Dba Abbatron
4330-00-897-2713922972 INTERCHANGEABLE
Filter Element,fluid
Parker-Hannifin Corporation Dba Hydraulic Filter Division Div Hydraulic & Fuel Filter Division
Cross-Reference Index
Part NumberManufacturer
MS21921-10D Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
C61A2024D10 Parker-Hannifin Corporation Dba Pneutronics Div Corporate Headquarters (USA)
SAE-AS18280 Sae International Dba Sae International (USA)
156/9 Wellman Group (GBR)
MS21921D10 Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
C61A2024D10 Parker Hannifin Corporation Div Aerospace Group Headquarters (USA)
C61A2024D10 Parker Hannifin Corp Stratoflex Div Aircraft Fittings Opn (USA)
MS21917D10 Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
Related Parts
5365-00-089-4451INTERCHANGEABLE
SPACER,SLEEVE
5310-00-297-5893INTERCHANGEABLE
WASHER,FLAT
1569
2940-00-350-9071INTERCHANGEABLE
FILTER ELEMENT,FLUID
309735
2520-00-393-0907INTERCHANGEABLE
YOKE,RELEASE CLUTCH
1569
4730-00-454-7545INTERCHANGEABLE
ADAPTER,STRAIGHT,PIPE TO BOSS
HP3400
5120-00-505-5918INTERCHANGEABLE
DRIFT PIN
5330-00-599-4748INTERCHANGEABLE
GASKET
4730-00-821-1824INTERCHANGEABLE
NUT,TUBE COUPLING
MS21921-10
5940-00-823-1410INTERCHANGEABLE
TERMINAL,LUG
1569
4330-00-897-2713INTERCHANGEABLE
FILTER ELEMENT,FLUID
922972
3120-01-202-2750INTERCHANGEABLE
BUSHING,SLEEVE
1569
5985-01-328-0442INTERCHANGEABLE
CONTROL,ANTENNA
1569AS1800

Frequently Asked Questions

What is NSN 4730-00-555-8204?

NSN 4730-00-555-8204 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: cancelled.

What are the part numbers for NSN 4730-00-555-8204?

NSN 4730-00-555-8204 has 8 cross-referenced part numbers: MS21921-10D (Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M), C61A2024D10 (Parker-Hannifin Corporation Dba Pneutronics Div Corporate Headquarters), SAE-AS18280 (Sae International Dba Sae International), 156/9 (Wellman Group), MS21921D10 (Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M) and 3 more.

What NSN replaces 4730-00-555-8204?

There are 12 known substitutes for 4730-00-555-8204: 5365-00-089-4451, 5310-00-297-5893, 2940-00-350-9071 and 9 more. Verify interchangeability with system specifications before substitution.

What are the specifications of MS21921-10D?

Key specifications for MS21921-10D: Thread Direction: RIGHT-HAND; Material: ALUMINUM ALLOY OVERALL; Surface Treatment: ANODIZE OVERALL; Surface Treatment Document and Classification: MIL-A-8625,TY 2 MIL SPEC SINGLE TREATMENT RESPONSE OVERALL. 16 total characteristics are documented in the Federal Logistics Information System.

Is NSN 4730-00-555-8204 still in active supply?

NSN 4730-00-555-8204 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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