PartsTable
Technical Data Sheet
MS51521B4 ✓ 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,TUBE TO BOSS is a the manufacturer industrial component. Key specifications include material: STEEL OVERALL, flow_angle: 90.0 DEGREES, leg_length: 0.940 INCHES MINIMUM AND 1.060 INCHES MAXIMUM FIRST END IN, seat_angle: 37.0 DEGREES ALL ENDS, thread_class: 2B FIRST END, connection_type: THREADED EXTERNAL TUBE SECOND END. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-00-618-5370, 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
MS51521B4
NSN: 4730-00-618-5370
FSC: 4730
CAGE: 96906 — MILITARY STANDARDS PROMULGATED BY MILITARY DEPARTMENTS UNDER AUTHORITY OF DEFENSE STANDARDIZATION MANUAL 4120 3-M
SPECIFICATIONS
materialSTEEL OVERALL
flow_angle90.0 DEGREES
leg_length0.940 INCHES MINIMUM AND 1.060 INCHES MAXIMUM FIRST END IN
seat_angle37.0 DEGREES ALL ENDS
thread_class2B FIRST END
connection_typeTHREADED EXTERNAL TUBE SECOND END
connection_styleFLARED (TUBE) SECOND END
operating_pressure3000.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS
nominal_thread_size0.438 INCHES ALL ENDS IN
end_item_identificationUSED ON AIRPLANE, UTILITY, U-21 (BEECH) AND AIRPLANE, RECONNAISSANCE, UTILITY; ARMORED MULTI-PURPOSE VEHICLE (AMPV); A4 BRADLEY FIGHTING VEHICLE; A3 BRADLEY FIGHTING VEHICLE
thread_series_designatorUNF ALL ENDS
nondefinitive_spec/std_data8C FIGURE
NSN4730-00-618-5370
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: MS51521B4 · 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
THREAD CLASS: 2B FIRST END
OPERATING PRESSURE: 3000.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS
NONDEFINITIVE SPEC/STD DATA: 8C FIGURE
MATERIAL: STEEL OVERALL
FURNISHED ITEMS AND QUANTITY: 1 FLARED SLEEVE AND 1 SHORT COUPLING NUT
NOMINAL OUTSIDE DIAMETER TUBE ACCOMMODATED: 0.250 INCHES ALL ENDS IN
FLOW ANGLE: 90.0 DEGREES
NOMINAL THREAD SIZE: 0.438 INCHES ALL ENDS IN
TECHNICAL CHARACTERISTICS (FLIS)
THREAD CLASS2B FIRST END
OPERATING PRESSURE3000.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS
NONDEFINITIVE SPEC/STD DATA8C FIGURE
MATERIALSTEEL OVERALL
FURNISHED ITEMS AND QUANTITY1 FLARED SLEEVE AND 1 SHORT COUPLING NUT
NOMINAL OUTSIDE DIAMETER TUBE ACCOMMODATED0.250 INCHES ALL ENDS IN
FLOW ANGLE90.0 DEGREES
NOMINAL THREAD SIZE0.438 INCHES ALL ENDS IN
LEG LENGTH0.860 INCHES MINIMUM AND 0.920 INCHES MAXIMUM SECOND END IN
CONNECTION TYPETHREADED EXTERNAL TUBE SECOND END
VERIFIED SUBSTITUTES & CROSS-REFERENCES 24
AS4842/1Interchangeable
interchangeable cross-reference
interchangeable
AN816-4Interchangeable
interchangeable cross-reference
interchangeable
476 686Interchangeable
interchangeable cross-reference
interchangeable
24044Interchangeable
interchangeable cross-reference
interchangeable
6198566Interchangeable
interchangeable cross-reference
interchangeable
15680Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is MS51521B4?
MS51521B4 is a ADAPTER,STRAIGHT,TUBE TO BOSS.
What parts can replace MS51521B4?
There are 24 known substitutes for MS51521B4: AS4842/1, AN816-4, 476 686 and 21 more. Substitute compatibility should be verified for your specific system.
Is MS51521B4 still available?
MS51521B4 is currently cancelled.
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