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803-63974-009 — NUT,UNION

✓ Government record, cited
— · HOSE FITTING
PRODUCT OVERVIEW

803-63974-009: NUT,UNION.

The NUT,UNION is a the manufacturer industrial component. Key specifications include material: NICKEL ALLOY OVERALL, nut_style: HEXAGON, thread_class: 3B, thread_series: UN, shoulder_width: 0.270 INCHES NOMINAL IN, thread_direction: RIGHT-HAND. This part is cataloged in the U.S.

Government catalog under NSN 4730-01-421-5218, 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
803-63974-009
NSN: 4730-01-421-5218
FSC: 4730 — Hose, Pipe, Tube, Lubrication, and Railing Fittings
CAGE: 53711 — NAVAL SEA SYSTEMS COMMAND (USA)
SPECIFICATIONS
materialNICKEL ALLOY OVERALL
nut_styleHEXAGON
thread_class3B
thread_seriesUN
shoulder_width0.270 INCHES NOMINAL IN
thread_directionRIGHT-HAND
width_across_flats3.719 INCHES NOMINAL IN
nominal_thread_size3.375 INCHES IN
shoulder_step_width0.250 INCHES NOMINAL IN
shoulder_seat_diameter1.469 INCHES NOMINAL IN
end_item_identificationSEAWOLF CLASS SSN
smallest_inside_diameter2.762 INCHES NOMINAL IN
NSN4730-01-421-5218
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: 803-63974-009 · 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: 3.719 INCHES NOMINAL IN
•
SHOULDER STEP WIDTH: 0.250 INCHES NOMINAL IN
•
SHOULDER WIDTH: 0.270 INCHES NOMINAL IN
•
THREAD SERIES: UN
•
MATERIAL DOCUMENT AND CLASSIFICATION: ASTM B150 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL
•
THREAD DIRECTION: RIGHT-HAND
•
NOMINAL THREAD SIZE: 3.375 INCHES IN
•
NUT STYLE: HEXAGON
TECHNICAL CHARACTERISTICS
WIDTH ACROSS FLATS3.719 INCHES NOMINAL IN
SHOULDER STEP WIDTH0.250 INCHES NOMINAL IN
SHOULDER WIDTH0.270 INCHES NOMINAL IN
THREAD SERIESUN
MATERIAL DOCUMENT AND CLASSIFICATIONASTM B150 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL
THREAD DIRECTIONRIGHT-HAND
NOMINAL THREAD SIZE3.375 INCHES IN
NUT STYLEHEXAGON
THREAD CLASS3B
END ITEM IDENTIFICATIONSEAWOLF CLASS SSN
SUBSTITUTES & CROSS-REFERENCES 2
803-6397434-X6XXXX-009Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
6397434Reference document
Same NSN cross-reference
Reference document — Drawing number reference only
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 803-63974-009?
803-63974-009 is a NUT,UNION.
What parts can replace 803-63974-009?
There are 2 known substitutes for 803-63974-009: 803-6397434-X6XXXX-009, 6397434. Substitute compatibility should be verified for your specific system.
What is the NSN for 803-63974-009?
803-63974-009 is cataloged in the U.S. Government catalog under NSN 4730-01-421-5218. 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.