PartsTable
Technical Data Sheet
Download PDF

181D 3-8IN. — INVERTED NUT,TUBE COUPLING

✓ Government record, cited
— · HOSE FITTING
PRODUCT OVERVIEW

181D 3-8IN.: INVERTED NUT,TUBE COUPLING.

The INVERTED NUT,TUBE COUPLING is a the manufacturer industrial component. Key specifications include material: COPPER ALLOY 360, seat_radius: 0.219 INCHES NOMINAL IN, thread_size: 9/16-20, thread_class: 2A A, overall_length: 0.609 INCHES NOMINAL IN, special_features: 200PSI. This part is cataloged in the U.S.

Government catalog under NSN 4730-00-278-5553, 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
181D 3-8IN.
NSN: 4730-00-278-5553
FSC: 4730 — Hose, Pipe, Tube, Lubrication, and Railing Fittings
CAGE: 30327 — IMPERIAL (USA)
SPECIFICATIONS
materialCOPPER ALLOY 360
seat_radius0.219 INCHES NOMINAL IN
thread_size9/16-20
thread_class2A A
overall_length0.609 INCHES NOMINAL IN
special_features200PSI
style_designatorINVERTED NUT, TUBE, COMPRESSION
thread_directionRIGHT-HAND
fabrication_methodBAR STOCK, MACHINED OR FORGED
width_across_flats0.563 INCHES NOMINAL IN
casehardening_indicatorNOT CASEHARDENED
smallest_inside_diameter0.378 INCHES NOMINAL IN
NSN4730-00-278-5553
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: 181D 3-8IN. · 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: 0.563 INCHES NOMINAL IN
•
TUBE OUTSIDE DIAMETER FOR WHICH DESIGNED: 0.375 INCHES NOMINAL IN
•
STYLE DESIGNATOR: INVERTED NUT, TUBE, COMPRESSION
•
MATERIAL DOCUMENT AND CLASSIFICATION: SAE CA360 ASSN STD SINGLE MATERIAL RESPONSE
•
THREAD DIRECTION: RIGHT-HAND
•
SEAT RADIUS: 0.219 INCHES NOMINAL IN
•
CASEHARDENING INDICATOR: NOT CASEHARDENED
TECHNICAL CHARACTERISTICS
WIDTH ACROSS FLATS0.563 INCHES NOMINAL IN
TUBE OUTSIDE DIAMETER FOR WHICH DESIGNED0.375 INCHES NOMINAL IN
STYLE DESIGNATORINVERTED NUT, TUBE, COMPRESSION
MATERIAL DOCUMENT AND CLASSIFICATIONSAE CA360 ASSN STD SINGLE MATERIAL RESPONSE
OVERALL LENGTH0.609 INCHES NOMINAL IN
THREAD DIRECTIONRIGHT-HAND
SEAT RADIUS0.219 INCHES NOMINAL IN
CASEHARDENING INDICATORNOT CASEHARDENED
THREAD SIZE9/16-20
SPECIAL FEATURES200PSI
SUBSTITUTES & CROSS-REFERENCES 3
106-10006Reference document
Same NSN cross-reference
Reference document — Secondary reference
6100X6Reference document
Same NSN cross-reference
Reference document — Secondary reference
81TS6Reference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusCancelled· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
Ready to buy 181D 3-8IN.?
Compare prices from verified sellers on eBay
Buy on eBay →
As an eBay Partner, PartsTable may earn a commission. Your price is not affected.
FREQUENTLY ASKED QUESTIONS
What is 181D 3-8IN.?
181D 3-8IN. is a INVERTED NUT,TUBE COUPLING.
What parts can replace 181D 3-8IN.?
There are 3 known substitutes for 181D 3-8IN.: 106-10006, 6100X6, 81TS6. Substitute compatibility should be verified for your specific system.
What is the NSN for 181D 3-8IN.?
181D 3-8IN. is cataloged in the U.S. Government catalog under NSN 4730-00-278-5553. This indicates validated use in U.S. government and defense supply chains.
Community Feedback
Leave a Comment
Comments are reviewed before appearing. You will receive an email to verify before your comment appears.

Request a Quote — 181D 3-8IN.

✓ 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.