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21FC-820 — NUT,SELF-LOCKING,HEXAGON

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

21FC-820: NUT,SELF-LOCKING,HEXAGON.

The NUT,SELF-LOCKING,HEXAGON is a the manufacturer industrial component. Key specifications include material: STEEL OVERALL, nut_style: HEXAGON, nut_height: 0.602 INCHES MAXIMUM IN, temp_rating: 800.0 FAHRENHEIT MAXIMUM DEGF, thread_class: 3B, thread_series: UNIFIED NATIONAL JOINT FINE (UNJF). This part is cataloged in the U.S.

Government catalog under NSN 5310-01-241-6351, 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
21FC-820
NSN: 5310-01-241-6351
NIINs: 012416351, 014229917
FSC: 5310 — Nuts and Washers
CAGE: 56878 — SPS TECHNOLOGIES, LLC DBA PB FASTENERS (USA)
SPECIFICATIONS
materialSTEEL OVERALL
nut_styleHEXAGON
nut_height0.602 INCHES MAXIMUM IN
temp_rating800.0 FAHRENHEIT MAXIMUM DEGF
thread_class3B
thread_seriesUNIFIED NATIONAL JOINT FINE (UNJF)
locking_featurePREVAILING TORQUE ALL METAL DESIGN
thread_directionRIGHT-HAND
surface_treatmentCADMIUM OVERALL
width_across_flats0.741 INCHES MINIMUM AND 0.752 INCHES MAXIMUM IN
nominal_thread_size0.500 INCHES IN
bearing_surface_typeCHAMFERED
NSN5310-01-241-6351
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 21FC-820 · OEM ⚠ VERIFY BEFORE ORDERING Grade matters for torque spec — don't mix grades. A Grade 5 nut on a Grade 8 bolt weakens the joint. Lock nuts, wing nuts, and castle nuts are NOT interchangeable with standard hex ✓ BROKER TIP Match nut to bolt thread class and material. Stainless bolt + zinc nut = galvanic corrosion. Always verify finish matches (plain, zinc, hot-dip galvanized) PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
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CRITICALITY CODE JUSTIFICATION: ZZZY
•
REFERENCE NUMBER DIFFERENTIATING CHARACTERISTICS: MATERIAL WILL BE IN ACCORDANCE WITH SHIPS PARTS CONTROL CENTER ACTIVITY HX QUALITY CONTROL,MANUFACTURING AND TESTING SPECIFICATIONS
TECHNICAL CHARACTERISTICS
CRITICALITY CODE JUSTIFICATIONZZZY
REFERENCE NUMBER DIFFERENTIATING CHARACTERISTICSMATERIAL WILL BE IN ACCORDANCE WITH SHIPS PARTS CONTROL CENTER ACTIVITY HX QUALITY CONTROL,MANUFACTURING AND TESTING SPECIFICATIONS
SUBSTITUTES & CROSS-REFERENCES 1
LLCZ25494Reference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 21FC-820?
21FC-820 is a NUT,SELF-LOCKING,HEXAGON.
What parts can replace 21FC-820?
There is 1 known substitute for 21FC-820: LLCZ25494. Substitute compatibility should be verified for your specific system.
What is the NSN for 21FC-820?
21FC-820 is cataloged in the U.S. Government catalog under NSN 5310-01-241-6351. 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.