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6558521-3 — COUPLING HALF,QUICK DISCONNECT

✓ Government record, cited
— · HOSE FITTING
PRODUCT OVERVIEW

6558521-3: COUPLING HALF,QUICK DISCONNECT.

The COUPLING HALF,QUICK DISCONNECT is a the manufacturer industrial component. Key specifications include material: STEEL BODY, exterior_color: PURPLE, overall_length: 2.470 INCHES NOMINAL IN, connection_type: THREADED EXTERNAL PIPE FIRST FLUID END CONNECTION, connection_style: PLAIN ALL ENDS, style_designator: MALE COUPLING HALF. This part is cataloged in the U.S.

Government catalog under NSN 4730-01-372-9720, 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
6558521-3
NSN: 4730-01-372-9720
FSC: 4730 — Hose, Pipe, Tube, Lubrication, and Railing Fittings
CAGE: 53711 — NAVAL SEA SYSTEMS COMMAND (USA)
SPECIFICATIONS
materialSTEEL BODY
exterior_colorPURPLE
overall_length2.470 INCHES NOMINAL IN
connection_typeTHREADED EXTERNAL PIPE FIRST FLUID END CONNECTION
connection_stylePLAIN ALL ENDS
style_designatorMALE COUPLING HALF
nominal_thread_size0.375 INCHES ALL ENDS IN
quick_disconnect_methodPUSH-PULL ALL ENDS
thread_series_designatorNPT ALL ENDS
quick_disconnect_nominal_size0.750 INCHES ALL ENDS IN
NSN4730-01-372-9720
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: 6558521-3 · 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
•
CONNECTION STYLE: PLAIN ALL ENDS
•
CONNECTION TYPE: THREADED EXTERNAL PIPE FIRST FLUID END CONNECTION
•
STYLE DESIGNATOR: MALE COUPLING HALF
•
QUICK DISCONNECT NOMINAL SIZE: 0.750 INCHES ALL ENDS IN
•
NOMINAL THREAD SIZE: 0.375 INCHES ALL ENDS IN
•
EXTERIOR COLOR: PURPLE
•
MATERIAL: STEEL BODY
TECHNICAL CHARACTERISTICS
CONNECTION STYLEPLAIN ALL ENDS
CONNECTION TYPETHREADED EXTERNAL PIPE FIRST FLUID END CONNECTION
STYLE DESIGNATORMALE COUPLING HALF
OVERALL LENGTH2.470 INCHES NOMINAL IN
QUICK DISCONNECT NOMINAL SIZE0.750 INCHES ALL ENDS IN
NOMINAL THREAD SIZE0.375 INCHES ALL ENDS IN
EXTERIOR COLORPURPLE
MATERIALSTEEL BODY
QUICK DISCONNECT METHODPUSH-PULL ALL ENDS
THREAD SERIES DESIGNATORNPT ALL ENDS
SUBSTITUTES & CROSS-REFERENCES 1
6558521Reference document
Same NSN cross-reference
Reference document — Vendor item drawing reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Insurance item — stocked against contingency demandNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 6558521-3?
6558521-3 is a COUPLING HALF,QUICK DISCONNECT.
What parts can replace 6558521-3?
There is 1 known substitute for 6558521-3: 6558521. Substitute compatibility should be verified for your specific system.
What is the NSN for 6558521-3?
6558521-3 is cataloged in the U.S. Government catalog under NSN 4730-01-372-9720. 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.