PartsTable
Technical Data Sheet
21FK830 ✓ Verified by PartsTable
· NUT WASHER
WHAT YOU NEED TO KNOW
Match nut grade to bolt grade for full strength Lock nuts prevent loosening under vibration
Don't mix grades — weakens the joint
PRODUCT OVERVIEW

The NUT,SELF-LOCKING,HEXAGON is a the manufacturer industrial component. Key specifications include material: STEEL OVERALL, nut_style: HEXAGON, nut_height: 0.328 INCHES MAXIMUM IN, lubrication: SOLUBLE LUBRICANT, thread_class: 3B, thread_series: UNIFIED NATIONAL JOINT FINE (UNJF). This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-01-081-4690, 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
21FK830
NSN: 5310-01-081-4690
FSC: 5310
CAGE: 56878 — SPS TECHNOLOGIES, LLC DBA PB FASTENERS (USA)
SPECIFICATIONS
materialSTEEL OVERALL
nut_styleHEXAGON
nut_height0.328 INCHES MAXIMUM IN
lubricationSOLUBLE LUBRICANT
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
NSN5310-01-081-4690
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 21FK830 · 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
NUT HEIGHT: 0.328 INCHES MAXIMUM IN
THREAD QUANTITY PER INCH: 20
THREAD SERIES: UNIFIED NATIONAL JOINT FINE (UNJF)
BEARING SURFACE TYPE: CHAMFERED
NOMINAL THREAD SIZE: 0.500 INCHES IN
MATERIAL: STEEL OVERALL
SURFACE TREATMENT: CADMIUM OVERALL
LOCKING FEATURE: PREVAILING TORQUE ALL METAL DESIGN
TECHNICAL CHARACTERISTICS (FLIS)
NUT HEIGHT0.328 INCHES MAXIMUM IN
THREAD QUANTITY PER INCH20
THREAD SERIESUNIFIED NATIONAL JOINT FINE (UNJF)
BEARING SURFACE TYPECHAMFERED
NOMINAL THREAD SIZE0.500 INCHES IN
MATERIALSTEEL OVERALL
SURFACE TREATMENTCADMIUM OVERALL
LOCKING FEATUREPREVAILING TORQUE ALL METAL DESIGN
THREAD DIRECTIONRIGHT-HAND
WIDTH ACROSS FLATS0.741 INCHES MINIMUM AND 0.752 INCHES MAXIMUM IN
VERIFIED SUBSTITUTES & CROSS-REFERENCES 17
1913Interchangeable
interchangeable cross-reference
interchangeable
S6835Interchangeable
interchangeable cross-reference
interchangeable
323-94Interchangeable
interchangeable cross-reference
interchangeable
011-1711Interchangeable
interchangeable cross-reference
interchangeable
HK08RA024Interchangeable
interchangeable cross-reference
interchangeable
251291Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 21FK830?
21FK830 is a NUT,SELF-LOCKING,HEXAGON.
What parts can replace 21FK830?
There are 17 known substitutes for 21FK830: 1913, S6835, 323-94 and 14 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 21FK830?
21FK830 is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-01-081-4690. This indicates validated use in U.S. government and defense supply chains.
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