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Technical Data Sheet
PartsTable / COMPONENT / 181D1-8
181D1-8 ✓ Verified by PartsTable
— · HOSE FITTING
WHAT YOU NEED TO KNOW
PTFE tape on tapered threads (NPT/BSPT) JIC/AN flare connections seal metal-to-metal — no tape
NPT != BSPT — look identical, NOT interchangeable
PRODUCT OVERVIEW

The INVERTED NUT,TUBE COUPLING is a the manufacturer industrial component. Key specifications include material: COPPER ALLOY, seat_radius: 0.219 INCHES NOMINAL IN, thread_size: 5/16-24, thread_class: 2A A, overall_length: 0.500 INCHES NOMINAL IN, special_features: WEAPON SYSTEM ESSENTIAL. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-00-278-5490, 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
181D1-8
NSN: 4730-00-278-5490
FSC: 4730
CAGE: 30327 — IMPERIAL (USA)
SPECIFICATIONS
materialCOPPER ALLOY
seat_radius0.219 INCHES NOMINAL IN
thread_size5/16-24
thread_class2A A
overall_length0.500 INCHES NOMINAL IN
special_featuresWEAPON SYSTEM ESSENTIAL
style_designatorINVERTED NUT, TUBE, COMPRESSION
thread_directionRIGHT-HAND
width_across_flats0.313 INCHES NOMINAL IN
casehardening_indicatorNOT CASEHARDENED
end_item_identificationSUPPORT EQUIPMENT--C-5 AIRCRAFT, T-38 AIRCRAFT, B-52 AIRCRAFT, T-37 AIRCRAFT, OV-10A AIRCRAFT; AIRCRAFT, F-16; SHOP EQUIPMENT, CONTACT MAINT, TRK-MTD, SET 3, TAM B19457; TRACTOR, FLIGHTLINE TOWING A
smallest_inside_diameter0.128 INCHES NOMINAL IN
NSN4730-00-278-5490
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: 181D1-8 · 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
•
STYLE DESIGNATOR: INVERTED NUT, TUBE, COMPRESSION
•
CRITICALITY CODE JUSTIFICATION: FEAT
•
THREAD SIZE: 5/16-24
•
SMALLEST INSIDE DIAMETER: 0.128 INCHES NOMINAL IN
•
WIDTH ACROSS FLATS: 0.313 INCHES NOMINAL IN
•
CASEHARDENING INDICATOR: NOT CASEHARDENED
•
SEAT RADIUS: 0.219 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS (FLIS)
STYLE DESIGNATORINVERTED NUT, TUBE, COMPRESSION
CRITICALITY CODE JUSTIFICATIONFEAT
THREAD SIZE5/16-24
OVERALL LENGTH0.500 INCHES NOMINAL IN
SMALLEST INSIDE DIAMETER0.128 INCHES NOMINAL IN
WIDTH ACROSS FLATS0.313 INCHES NOMINAL IN
CASEHARDENING INDICATORNOT CASEHARDENED
SEAT RADIUS0.219 INCHES NOMINAL IN
SPECIAL FEATURESWEAPON SYSTEM ESSENTIAL
END ITEM IDENTIFICATIONSUPPORT EQUIPMENT--C-5 AIRCRAFT, T-38 AIRCRAFT, B-52 AIRCRAFT, T-37 AIRCRAFT, OV-10A AIRCRAFT; AIRCRAFT, F-16; SHOP EQUIPMENT, CONTACT MAINT, TRK-MTD, SET 3, TAM B19457; TRACTOR, FLIGHTLINE TOWING A
VERIFIED SUBSTITUTES & CROSS-REFERENCES 11
WInterchangeable
interchangeable cross-reference
interchangeable
1061-0002Interchangeable
interchangeable cross-reference
interchangeable
121634Interchangeable
interchangeable cross-reference
interchangeable
20501-10Interchangeable
interchangeable cross-reference
interchangeable
358BXInterchangeable
interchangeable cross-reference
interchangeable
8-3-4INX5-32INInterchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 181D1-8?
181D1-8 is a INVERTED NUT,TUBE COUPLING.
What parts can replace 181D1-8?
There are 11 known substitutes for 181D1-8: W, 1061-0002, 121634 and 8 more. Substitute compatibility should be verified for your specific system.
Is 181D1-8 still available?
181D1-8 is currently cancelled.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026