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PartsTable / COMPONENT / 21FK632
21FK632 ✓ 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, lubrication: SOLUBLE LUBRICANT, temp_rating: 450.0 FAHRENHEIT NOMINAL DEGF, thread_class: 3B, thread_series: UNJC. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-00-731-3564, 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
21FK632
NSN: 5310-00-731-3564
FSC: 5310
CAGE: 56878 — SPS TECHNOLOGIES, LLC DBA PB FASTENERS (USA)
SPECIFICATIONS
materialSTEEL OVERALL
nut_styleHEXAGON
lubricationSOLUBLE LUBRICANT
temp_rating450.0 FAHRENHEIT NOMINAL DEGF
thread_class3B
thread_seriesUNJC
overall_height0.115 INCHES MINIMUM AND 0.141 INCHES MAXIMUM IN
hardness_rating49.0 ROCKWELL C MAXIMUM
locking_featurePREVAILING TORQUE ALL METAL DESIGN
thread_directionRIGHT-HAND
washer_thickness0.010 INCHES MINIMUM IN
surface_treatmentCADMIUM OVERALL
NSN5310-00-731-3564
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 21FK632 · 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
•
THREAD DIRECTION: RIGHT-HAND
•
LOCKING FEATURE: PREVAILING TORQUE ALL METAL DESIGN
•
BEARING SURFACE TYPE: FLAT
•
NOMINAL THREAD SIZE: 0.138 INCHES IN
•
THREAD QUANTITY PER INCH: 32
•
THREAD SERIES: UNIFIED NATIONAL COARSE (UNC)
•
NUT HEIGHT: 0.121 INCHES MINIMUM AND 0.141 INCHES MAXIMUM IN
•
SURFACE TREATMENT: CADMIUM OVERALL
TECHNICAL CHARACTERISTICS (FLIS)
THREAD DIRECTIONRIGHT-HAND
LOCKING FEATUREPREVAILING TORQUE ALL METAL DESIGN
BEARING SURFACE TYPEFLAT
NOMINAL THREAD SIZE0.138 INCHES IN
THREAD QUANTITY PER INCH32
THREAD SERIESUNIFIED NATIONAL COARSE (UNC)
NUT HEIGHT0.121 INCHES MINIMUM AND 0.141 INCHES MAXIMUM IN
SURFACE TREATMENTCADMIUM OVERALL
WIDTH ACROSS FLATS0.313 INCHES MAXIMUM IN
THREAD CLASS2B
VERIFIED SUBSTITUTES & CROSS-REFERENCES 12
80103Interchangeable
interchangeable cross-reference
interchangeable
7367747Interchangeable
interchangeable cross-reference
interchangeable
96P-62WInterchangeable
interchangeable cross-reference
interchangeable
MN16-06Interchangeable
interchangeable cross-reference
interchangeable
MS21042-06Interchangeable
interchangeable cross-reference
interchangeable
80092Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 21FK632?
21FK632 is a NUT,SELF-LOCKING,HEXAGON.
What parts can replace 21FK632?
There are 12 known substitutes for 21FK632: 80103, 7367747, 96P-62W and 9 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 21FK632?
21FK632 is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-00-731-3564. This indicates validated use in U.S. government and defense supply chains.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026