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PartsTable / COMPONENT / NAS594-6
NAS594-6 ✓ 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: STEEL COMP 431, thread_size: 0.562-18, thread_class: 3A A, overall_length: 0.610 INCHES NOMINAL IN, strength_rating: ERR-060, style_designator: INVERTED NUT, TUBE, FLARE. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-00-990-8908, 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
NAS594-6
NSN: 4730-00-990-8908
FSC: 4730
CAGE: 80205 — NATIONAL AEROSPACE STANDARDS COMMITTEE AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA INC NOT FOR RFQ OR SOLICITATION USE (USA)
SPECIFICATIONS
materialSTEEL COMP 431
thread_size0.562-18
thread_class3A A
overall_length0.610 INCHES NOMINAL IN
strength_ratingERR-060
style_designatorINVERTED NUT, TUBE, FLARE
thread_directionRIGHT-HAND
seat_angle_in_deg33.0
surface_treatmentPASSIVATE
fabrication_methodBAR STOCK, MACHINED
width_across_flats0.465 INCHES NOMINAL IN
casehardening_indicatorNOT CASEHARDENED
NSN4730-00-990-8908
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: NAS594-6 · 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
•
MATERIAL DOCUMENT AND CLASSIFICATION: MIL-S-18732, COND HT-200 MIL SPEC SINGLE MATERIAL RESPONSE
•
SEAT ANGLE IN DEG: 33.0
•
MATERIAL HARDNESS RATING: 20.0 ROCKWELL C MINIMUM AND 32.0 ROCKWELL C MAXIMUM
•
STYLE DESIGNATOR: INVERTED NUT, TUBE, FLARE
•
SURFACE TREATMENT: PASSIVATE
•
MATERIAL: STEEL COMP 431
•
CASEHARDENING INDICATOR: NOT CASEHARDENED
TECHNICAL CHARACTERISTICS (FLIS)
MATERIAL DOCUMENT AND CLASSIFICATIONMIL-S-18732, COND HT-200 MIL SPEC SINGLE MATERIAL RESPONSE
SEAT ANGLE IN DEG33.0
MATERIAL HARDNESS RATING20.0 ROCKWELL C MINIMUM AND 32.0 ROCKWELL C MAXIMUM
STYLE DESIGNATORINVERTED NUT, TUBE, FLARE
SURFACE TREATMENTPASSIVATE
MATERIALSTEEL COMP 431
OVERALL LENGTH0.610 INCHES NOMINAL IN
CASEHARDENING INDICATORNOT CASEHARDENED
SMALLEST INSIDE DIAMETER0.380 INCHES NOMINAL IN
SCREW THREAD SERIES DESIGNATORUNF
VERIFIED SUBSTITUTES & CROSS-REFERENCES 7
5856Interchangeable
interchangeable cross-reference
interchangeable
BB22188Interchangeable
interchangeable cross-reference
interchangeable
9041846Interchangeable
interchangeable cross-reference
interchangeable
QQA282872Interchangeable
interchangeable cross-reference
interchangeable
172-225Interchangeable
interchangeable cross-reference
interchangeable
GQA282872Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is NAS594-6?
NAS594-6 is a INVERTED NUT,TUBE COUPLING.
What parts can replace NAS594-6?
There are 7 known substitutes for NAS594-6: 5856, BB22188, 9041846 and 4 more. Substitute compatibility should be verified for your specific system.
Is NAS594-6 still available?
NAS594-6 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