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PartsTable / COMPONENT / MIL-F-5509
MIL-F-5509 ✓ 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 ADAPTER,STRAIGHT,PIPE TO BOSS is a the manufacturer industrial component. Key specifications include material: STEEL COMP 316 OVERALL, body_style: STEPPED, leg_length: 3.375 INCHES MINIMUM AND 3.469 INCHES MAXIMUM ALL ENDS IN, seat_angle: 37.0 DEGREES, reducer_type: CONCENTRIC, thread_class: 3A FIRST END A. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-00-001-3957, 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
MIL-F-5509
NSN: 4730-00-001-3957
FSC: 4730
CAGE: 81348 — FEDERAL SPECIFICATIONS PROMULGATED BY GENERAL SERVICES ADMINISTRATION WASHINGTON DC (USA)
SPECIFICATIONS
materialSTEEL COMP 316 OVERALL
body_styleSTEPPED
leg_length3.375 INCHES MINIMUM AND 3.469 INCHES MAXIMUM ALL ENDS IN
seat_angle37.0 DEGREES
reducer_typeCONCENTRIC
thread_class3A FIRST END A
overall_length2.250 INCHES NOMINAL IN
connection_typeTHREADED EXTERNAL BOSS ALL ENDS
connection_styleFLARED W/ GASKET SEAL (BOSS) ALL ENDS
special_featuresCAP DRILLER FOR ATTACHMENT FO SAFETY CHAIN
style_designatorINSERT AND THREADED INTERNAL
thread_directionRIGHT-HAND INTERNAL
NSN4730-00-001-3957
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: MIL-F-5509 · 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
VERIFIED SUBSTITUTES & CROSS-REFERENCES 4
AS4842/1/5-4KInterchangeable
Same NIIN cross-reference
interchangeable
2021-4-5CInterchangeable
Same NIIN cross-reference
interchangeable
AN816-5-4KInterchangeable
Same NIIN cross-reference
interchangeable
0103-4-5CInterchangeable
Same NIIN cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is MIL-F-5509?
MIL-F-5509 is a ADAPTER,STRAIGHT,PIPE TO BOSS.
What parts can replace MIL-F-5509?
There are 4 known substitutes for MIL-F-5509: AS4842/1/5-4K, 2021-4-5C, AN816-5-4K and 1 more. Substitute compatibility should be verified for your specific system.
Is MIL-F-5509 still available?
MIL-F-5509 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