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FN04-56 — NUT,TUBE COUPLING

✓ Government record, cited
— · HOSE FITTING
PRODUCT OVERVIEW

FN04-56: NUT,TUBE COUPLING.

The NUT,TUBE COUPLING is a the manufacturer industrial component. Key specifications include material: COPPER ALLOY OVERALL, nut_style: TUBE COUPLING, nut_height: 0.500 INCHES NOMINAL IN, thread_class: 2B, thread_series: UNEF, thread_direction: RIGHT-HAND. This part is cataloged in the U.S.

Government catalog under NSN 4730-00-065-8678, 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
FN04-56
NSN: 4730-00-065-8678
FSC: 4730 — Hose, Pipe, Tube, Lubrication, and Railing Fittings
CAGE: 30327 — IMPERIAL (USA)
SPECIFICATIONS
materialCOPPER ALLOY OVERALL
nut_styleTUBE COUPLING
nut_height0.500 INCHES NOMINAL IN
thread_class2B
thread_seriesUNEF
thread_directionRIGHT-HAND
width_across_flats0.750 INCHES NOMINAL IN
nominal_thread_size0.625 INCHES IN
smallest_inside_diameter0.438 INCHES NOMINAL IN
thread_quantity_per_inch24
nominal_tube_outside_diameter0.438 INCHES IN
NSN4730-00-065-8678
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: FN04-56 · 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: 0.750 INCHES NOMINAL IN
•
THREAD SERIES: UNEF
•
THREAD DIRECTION: RIGHT-HAND
•
NOMINAL THREAD SIZE: 0.625 INCHES IN
•
NUT HEIGHT: 0.500 INCHES NOMINAL IN
•
NUT STYLE: TUBE COUPLING
•
THREAD CLASS: 2B
•
THREAD QUANTITY PER INCH: 24
TECHNICAL CHARACTERISTICS
WIDTH ACROSS FLATS0.750 INCHES NOMINAL IN
THREAD SERIESUNEF
THREAD DIRECTIONRIGHT-HAND
NOMINAL THREAD SIZE0.625 INCHES IN
NUT HEIGHT0.500 INCHES NOMINAL IN
NUT STYLETUBE COUPLING
THREAD CLASS2B
THREAD QUANTITY PER INCH24
MATERIALCOPPER ALLOY OVERALL
SMALLEST INSIDE DIAMETER0.438 INCHES NOMINAL IN
SUBSTITUTES & CROSS-REFERENCES 1
9995431Reference document
Same NSN cross-reference
Reference document — Drawing number reference only
LIFECYCLE
NSN statusActive· U.S. Government catalog
No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is FN04-56?
FN04-56 is a NUT,TUBE COUPLING.
What parts can replace FN04-56?
There is 1 known substitute for FN04-56: 9995431. Substitute compatibility should be verified for your specific system.
What is the NSN for FN04-56?
FN04-56 is cataloged in the U.S. Government catalog under NSN 4730-00-065-8678. 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.