PartsTable
Technical Data Sheet
21FA420 ✓ 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: 0.270 INCHES MINIMUM AND 0.290 INCHES MAXIMUM IN, thread_class: 2B, thread_series: UNIFIED NATIONAL COARSE (UNC), locking_feature: PREVAILING TORQUE ALL METAL DESIGN. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-00-575-5628, 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
21FA420
NSN: 5310-00-575-5628
FSC: 5310
CAGE: 56878 — SPS TECHNOLOGIES, LLC DBA PB FASTENERS (USA)
SPECIFICATIONS
materialSTEEL OVERALL
nut_styleHEXAGON
nut_height0.270 INCHES MINIMUM AND 0.290 INCHES MAXIMUM IN
thread_class2B
thread_seriesUNIFIED NATIONAL COARSE (UNC)
locking_featurePREVAILING TORQUE ALL METAL DESIGN
thread_directionRIGHT-HAND
surface_treatmentCADMIUM OVERALL
width_across_flats0.430 INCHES MINIMUM AND 0.439 INCHES MAXIMUM IN
nominal_thread_size0.250 INCHES IN
bearing_surface_typeCHAMFERED
thread_quantity_per_inch20
NSN5310-00-575-5628
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 21FA420 · 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 CLASS: 2B
BEARING SURFACE TYPE: CHAMFERED
NOMINAL THREAD SIZE: 0.250 INCHES IN
MATERIAL: STEEL OVERALL
NUT STYLE: HEXAGON
LOCKING FEATURE: PREVAILING TORQUE ALL METAL DESIGN
LUBRICATION: SOLUBLE LUBRICANT
THREAD SERIES: UNIFIED NATIONAL COARSE (UNC)
TECHNICAL CHARACTERISTICS (FLIS)
THREAD CLASS2B
BEARING SURFACE TYPECHAMFERED
NOMINAL THREAD SIZE0.250 INCHES IN
MATERIALSTEEL OVERALL
NUT STYLEHEXAGON
LOCKING FEATUREPREVAILING TORQUE ALL METAL DESIGN
LUBRICATIONSOLUBLE LUBRICANT
THREAD SERIESUNIFIED NATIONAL COARSE (UNC)
THREAD QUANTITY PER INCH20
THREAD DIRECTIONRIGHT-HAND
VERIFIED SUBSTITUTES & CROSS-REFERENCES 21
80-007Interchangeable
interchangeable cross-reference
interchangeable
80-007-16-4AInterchangeable
interchangeable cross-reference
interchangeable
1854Interchangeable
interchangeable cross-reference
interchangeable
21FA420Interchangeable
interchangeable cross-reference
interchangeable
5310PL0625588Interchangeable
interchangeable cross-reference
interchangeable
220100-16Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 21FA420?
21FA420 is a NUT,SELF-LOCKING,HEXAGON.
What parts can replace 21FA420?
There are 21 known substitutes for 21FA420: 80-007, 80-007-16-4A, 1854 and 18 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 21FA420?
21FA420 is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-00-575-5628. This indicates validated use in U.S. government and defense supply chains.
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