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AS21916D8-4L — REDUCER,BOSS

✓ Government record, cited
— · HOSE FITTING
PRODUCT OVERVIEW

AS21916D8-4L: REDUCER,BOSS.

The REDUCER,BOSS is a the manufacturer industrial component. Key specifications include material: ALUMINUM ALLOY 2024 OVERALL, reducer_type: CONCENTRIC, thread_class: 3A BOTH ENDS A, connection_type: THREADED EXTERNAL BOSS ALL ENDS, connection_style: EXTERNAL SEAT FOR GASKET SEAL (BOSS) ALL ENDS, nominal_thread_size: 0.4375 INCHES SECOND END IN. This part is cataloged in the U.S.

Government catalog under NSN 4730-01-736-2671, 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
AS21916D8-4L
NSN: 4730-01-736-2671
FSC: 4730 — Hose, Pipe, Tube, Lubrication, and Railing Fittings
CAGE: 0U583 — SAE INTERNATIONAL DBA SAE INTERNATIONAL (USA)
SPECIFICATIONS
materialALUMINUM ALLOY 2024 OVERALL
reducer_typeCONCENTRIC
thread_class3A BOTH ENDS A
connection_typeTHREADED EXTERNAL BOSS ALL ENDS
connection_styleEXTERNAL SEAT FOR GASKET SEAL (BOSS) ALL ENDS
nominal_thread_size0.4375 INCHES SECOND END IN
nominal_overall_length1.344 INCHES IN
end_item_identificationC-5
thread_quantity_per_inch16 FIRST END
thread_series_designatorUNIFIED NATIONAL JOINT FINE (UNJF) BOTH ENDS
part_name_assigned_by_controlling_agencyREDUCER, EXTERNAL THREAD, FLARELESS TUBE
NSN4730-01-736-2671
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: AS21916D8-4L · 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: EXTERNAL SEAT FOR GASKET SEAL (BOSS) ALL ENDS
•
NOMINAL OVERALL LENGTH: 1.344 INCHES IN
•
CONNECTION TYPE: THREADED EXTERNAL BOSS ALL ENDS
•
NOMINAL THREAD SIZE: 0.4375 INCHES SECOND END IN
•
THREAD CLASS: 3A BOTH ENDS A
TECHNICAL CHARACTERISTICS
CONNECTION STYLEEXTERNAL SEAT FOR GASKET SEAL (BOSS) ALL ENDS
NOMINAL OVERALL LENGTH1.344 INCHES IN
CONNECTION TYPETHREADED EXTERNAL BOSS ALL ENDS
NOMINAL THREAD SIZE0.4375 INCHES SECOND END IN
NOMINAL THREAD SIZE0.750 INCHES FIRST END IN
PART NAME ASSIGNED BY CONTROLLING AGENCYREDUCER, EXTERNAL THREAD, FLARELESS TUBE
THREAD CLASS3A BOTH ENDS A
END ITEM IDENTIFICATIONC-5
THREAD QUANTITY PER INCH16 FIRST END
THREAD QUANTITY PER INCH20 SECOND END
OTHER ITEMS IN FSC 4730 — Hose, Pipe, Tube, Lubrication, and Railing Fittings
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
4730-00-000-1895 4730-00-000-4289 4730-00-000-4445 4730-00-000-8373 4730-00-000-8897 4730-00-001-0007 4730-00-001-0008
SUBSTITUTES & CROSS-REFERENCES 1
AS21916Reference document
Same NSN cross-reference
Reference document — Secondary 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 AS21916D8-4L?
AS21916D8-4L is a REDUCER,BOSS.
What parts can replace AS21916D8-4L?
There is 1 known substitute for AS21916D8-4L: AS21916. Substitute compatibility should be verified for your specific system.
What is the NSN for AS21916D8-4L?
AS21916D8-4L is cataloged in the U.S. Government catalog under NSN 4730-01-736-2671. 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.