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20FK-720 — NUT,SELF-LOCKING,CASTELLATED,HEX

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

20FK-720: NUT,SELF-LOCKING,CASTELLATED,HEX.

NUT,SELF-LOCKING,CASTELLATED,HEX. Key specifications include material: STEEL OVERALL, nut_style: CASTELLATED, HEXAGON, nut_height: 0.313 INCHES NOMINAL IN, lubrication: DRY FILM LUBRICANT, thread_class: 3B, thread_series: UNF. This part is cataloged in the U.S.

Government catalog under NSN 5310-00-071-5521, 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
20FK-720
NSN: 5310-00-071-5521
NIINs: 000715521, 009336356
FSC: 5310 — Nuts and Washers
CAGE: D9182 — ZF INDUSTRIEANTRIEBE WITTEN GMBH (DEU)
SPECIFICATIONS
materialSTEEL OVERALL
nut_styleCASTELLATED, HEXAGON
nut_height0.313 INCHES NOMINAL IN
lubricationDRY FILM LUBRICANT
thread_class3B
thread_seriesUNF
locking_featurePREVAILING TORQUE ALL METAL DESIGN
thread_directionRIGHT-HAND
width_across_flats0.625 INCHES NOMINAL IN
nominal_thread_size0.438 INCHES IN
thread_quantity_per_inch20
NSN5310-00-071-5521
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 20FK-720 · 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
SUBSTITUTES & CROSS-REFERENCES 1
0FK-720Reference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 20FK-720?
20FK-720 is a NUT,SELF-LOCKING,CASTELLATED,HEX.
What parts can replace 20FK-720?
There is 1 known substitute for 20FK-720: 0FK-720. Substitute compatibility should be verified for your specific system.
What is the NSN for 20FK-720?
20FK-720 is cataloged in the U.S. Government catalog under NSN 5310-00-071-5521. 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.