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5B1921 — NUT,TUBE COUPLING

✓ Government record, cited
— · HOSE FITTING
PRODUCT OVERVIEW

5B1921: NUT,TUBE COUPLING.

The NUT,TUBE COUPLING is a the manufacturer industrial component. Key specifications include material: STEEL COMP 1115 OVERALL, nut_style: TUBE COUPLING, nut_height: 1.500 INCHES NOMINAL IN, thread_class: 3B, thread_series: UNF, thread_direction: RIGHT-HAND. This part is cataloged in the U.S.

Government catalog under NSN 4730-00-423-9536, 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
5B1921
NSN: 4730-00-423-9536
FSC: 4730 — Hose, Pipe, Tube, Lubrication, and Railing Fittings
CAGE: 11083 — CATERPILLAR INC DIV CATERPILLAR DEFENSE (USA)
SPECIFICATIONS
materialSTEEL COMP 1115 OVERALL
nut_styleTUBE COUPLING
nut_height1.500 INCHES NOMINAL IN
thread_class3B
thread_seriesUNF
thread_directionRIGHT-HAND
length_to_shoulder1.125 INCHES NOMINAL IN
width_across_flats1.312 INCHES NOMINAL IN
nominal_thread_size1.125 INCHES IN
smallest_inside_diameter0.906 INCHES NOMINAL IN
thread_quantity_per_inch12
nominal_tube_outside_diameter0.875 INCHES IN
NSN4730-00-423-9536
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: 5B1921 · 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
•
LENGTH TO SHOULDER: 1.125 INCHES NOMINAL IN
•
WIDTH ACROSS FLATS: 1.312 INCHES NOMINAL IN
•
THREAD SERIES: UNF
•
MATERIAL DOCUMENT AND CLASSIFICATION: 66 FED STD SINGLE MATERIAL RESPONSE OVERALL
•
THREAD DIRECTION: RIGHT-HAND
•
NOMINAL THREAD SIZE: 1.125 INCHES IN
•
NUT HEIGHT: 1.500 INCHES NOMINAL IN
•
NUT STYLE: TUBE COUPLING
TECHNICAL CHARACTERISTICS
LENGTH TO SHOULDER1.125 INCHES NOMINAL IN
WIDTH ACROSS FLATS1.312 INCHES NOMINAL IN
THREAD SERIESUNF
MATERIAL DOCUMENT AND CLASSIFICATION66 FED STD SINGLE MATERIAL RESPONSE OVERALL
THREAD DIRECTIONRIGHT-HAND
NOMINAL THREAD SIZE1.125 INCHES IN
NUT HEIGHT1.500 INCHES NOMINAL IN
NUT STYLETUBE COUPLING
THREAD CLASS3B
THREAD QUANTITY PER INCH12
OTHER ITEMS IN FSC 4730 — Hose, Pipe, Tube, Lubrication, and Railing Fittings
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
4730-00-000-1895 4730-00-000-4289 4730-00-000-4445 4730-00-000-8373 4730-00-000-8897 4730-00-001-0007 4730-00-001-0008
SUBSTITUTES & CROSS-REFERENCES

No substitute or cross-reference records for this part.

LIFECYCLE
NSN statusActive· U.S. Government catalog
No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 5B1921?
5B1921 is a NUT,TUBE COUPLING.
What is the NSN for 5B1921?
5B1921 is cataloged in the U.S. Government catalog under NSN 4730-00-423-9536. 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.