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MS21921-20K — NUT,TUBE COUPLING

✓ Government record, cited
— · HOSE FITTING
PRODUCT OVERVIEW

MS21921-20K: NUT,TUBE COUPLING.

The NUT,TUBE COUPLING is a the manufacturer industrial component. Key specifications include material: STEEL CORROSION RESISTING NUT, nut_style: TUBE COUPLING, nut_height: 1.05 INCHES NOMINAL IN, thread_class: 3B, thread_series: UNIFIED NATIONAL JOINT (UNJ), thread_direction: RIGHT-HAND. This part is cataloged in the U.S.

Government catalog under NSN 4730-01-660-1400, indicating validated use in U.S. government and defense logistics supply chains. Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels.

Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
MS21921-20K
NSN: 4730-01-660-1400
FSC: 4730 — Hose, Pipe, Tube, Lubrication, and Railing Fittings
CAGE: 0U583 — SAE INTERNATIONAL DBA SAE INTERNATIONAL (USA)
SPECIFICATIONS
materialSTEEL CORROSION RESISTING NUT
nut_styleTUBE COUPLING
nut_height1.05 INCHES NOMINAL IN
thread_class3B
thread_seriesUNIFIED NATIONAL JOINT (UNJ)
thread_directionRIGHT-HAND
fabrication_methodMACHINED
width_across_flats2.0 INCHES NOMINAL IN
nominal_thread_size1.625 INCHES IN
smallest_inside_diameter1.33 INCHES NOMINAL IN
thread_quantity_per_inch12
nominal_tube_outside_diameter1.25 INCHES IN
NSN4730-01-660-1400
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: MS21921-20K · OEM ⚠ VERIFY BEFORE ORDERING NPT ≠ BSPT — tapered threads look identical but are NOT interchangeable. Wrong thread = leak. JIC (37°) ≠ AN (37°) ≠ SAE 45° — flare angles must match exactly. Measure thread pitch with gauge — visual identification is unreliable ✓ BROKER TIP Always use thread sealant (PTFE tape or pipe compound) on tapered threads (NPT/BSPT). JIC/AN flare fittings seal metal-to-metal — never use tape on flare connections PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
WIDTH ACROSS FLATS: 2.0 INCHES NOMINAL IN
•
THREAD SERIES: UNIFIED NATIONAL JOINT (UNJ)
•
THREAD DIRECTION: RIGHT-HAND
•
NOMINAL THREAD SIZE: 1.625 INCHES IN
•
NUT HEIGHT: 1.05 INCHES NOMINAL IN
•
NUT STYLE: TUBE COUPLING
•
THREAD CLASS: 3B
TECHNICAL CHARACTERISTICS
WIDTH ACROSS FLATS2.0 INCHES NOMINAL IN
THREAD SERIESUNIFIED NATIONAL JOINT (UNJ)
THREAD DIRECTIONRIGHT-HAND
NOMINAL THREAD SIZE1.625 INCHES IN
NUT HEIGHT1.05 INCHES NOMINAL IN
PART NAME ASSIGNED BY CONTROLLING AGENCYNUT, TUBE COUPLING
NUT STYLETUBE COUPLING
THREAD CLASS3B
THREAD QUANTITY PER INCH12
MATERIALSTEEL CORROSION RESISTING NUT
SUBSTITUTES & CROSS-REFERENCES 2
SAE-AS21921Reference document
Same NSN cross-reference
Reference document — Secondary reference
SAE-AS18280Reference document
Same NSN cross-reference
Reference document — Design control — primary reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Insurance item — stocked against contingency demandNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is MS21921-20K?
MS21921-20K is a NUT,TUBE COUPLING.
What parts can replace MS21921-20K?
There are 2 known substitutes for MS21921-20K: SAE-AS21921, SAE-AS18280. Substitute compatibility should be verified for your specific system.
What is the NSN for MS21921-20K?
MS21921-20K is cataloged in the U.S. Government catalog under NSN 4730-01-660-1400. This indicates validated use in U.S. government and defense supply chains.
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✓ PartsTable — the parts reference. Every fact cited to its source.
PartsTable Design LLC · partstable.com
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.
PartsTable commercial catalog: edition Unified commercial catalog snapshot through 2026-09-28, edition date not on file, retrieved 2026-09-28.