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PartsTable / COMPONENT / 278953R91
278953R91 ✓ 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, thread_size: 9/16-20, thread_class: 2A A, overall_length: 0.844 INCHES NOMINAL IN, special_features: WEAPON SYSTEM ESSENTIAL, style_designator: INVERTED NUT, TUBE, DOUBLE COMPRESSION. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-00-288-9391, 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
278953R91
NSN: 4730-00-288-9391
FSC: 4730
CAGE: 29510 — KOMATSU AMERICAN INTL CO (USA)
SPECIFICATIONS
materialCOPPER ALLOY
thread_size9/16-20
thread_class2A A
overall_length0.844 INCHES NOMINAL IN
special_featuresWEAPON SYSTEM ESSENTIAL
style_designatorINVERTED NUT, TUBE, DOUBLE COMPRESSION
thread_directionRIGHT-HAND
fabrication_methodBAR STOCK, MACHINED
width_across_flats0.625 INCHES NOMINAL IN
casehardening_indicatorNOT CASEHARDENED
smallest_inside_diameter0.380 INCHES MINIMUM AND 0.382 INCHES MAXIMUM IN
criticality_code_justificationFEAT
NSN4730-00-288-9391
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: 278953R91 · 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
•
TUBE OUTSIDE DIAMETER FOR WHICH DESIGNED: 0.375 INCHES NOMINAL IN
•
THREAD DIRECTION: RIGHT-HAND
•
SMALLEST INSIDE DIAMETER: 0.380 INCHES MINIMUM AND 0.382 INCHES MAXIMUM IN
•
WIDTH ACROSS FLATS: 0.625 INCHES NOMINAL IN
•
CRITICALITY CODE JUSTIFICATION: FEAT
•
STYLE DESIGNATOR: INVERTED NUT, TUBE, DOUBLE COMPRESSION
•
MATERIAL: COPPER ALLOY
TECHNICAL CHARACTERISTICS (FLIS)
TUBE OUTSIDE DIAMETER FOR WHICH DESIGNED0.375 INCHES NOMINAL IN
THREAD DIRECTIONRIGHT-HAND
SMALLEST INSIDE DIAMETER0.380 INCHES MINIMUM AND 0.382 INCHES MAXIMUM IN
WIDTH ACROSS FLATS0.625 INCHES NOMINAL IN
CRITICALITY CODE JUSTIFICATIONFEAT
STYLE DESIGNATORINVERTED NUT, TUBE, DOUBLE COMPRESSION
SPECIAL FEATURESWEAPON SYSTEM ESSENTIAL
MATERIALCOPPER ALLOY
THREAD CLASS2A A
CASEHARDENING INDICATORNOT CASEHARDENED
VERIFIED SUBSTITUTES & CROSS-REFERENCES 21
28737Interchangeable
interchangeable cross-reference
interchangeable
QD572Interchangeable
interchangeable cross-reference
interchangeable
C8421Interchangeable
interchangeable cross-reference
interchangeable
T304Interchangeable
interchangeable cross-reference
interchangeable
P8391Interchangeable
interchangeable cross-reference
interchangeable
47047Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 278953R91?
278953R91 is a INVERTED NUT,TUBE COUPLING.
What parts can replace 278953R91?
There are 21 known substitutes for 278953R91: 28737, QD572, C8421 and 18 more. Substitute compatibility should be verified for your specific system.
Is 278953R91 still available?
278953R91 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