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4900278 — NUT,SELF-LOCKING,EXTENDED WASHER

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

4900278: NUT,SELF-LOCKING,EXTENDED WASHER.

NUT,SELF-LOCKING,EXTENDED WASHER. Key specifications include material: NICKEL ALLOY OVERALL, nut_style: DOUBLE HEXAGON, thread_class: 3B, thread_series: UNIFIED NATIONAL JOINT FINE (UNJF), overall_height: 0.396 INCHES MINIMUM AND 0.411 INCHES MAXIMUM IN, locking_feature: PREVAILING TORQUE ALL METAL DESIGN. This part is cataloged in the U.S.

Government catalog under NSN 5310-00-989-5079, 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
4900278
NSN: 5310-00-989-5079
FSC: 5310 — Nuts and Washers
CAGE: 53375 — SSANFORD TOOL & DESIGN INC (USA)
SPECIFICATIONS
materialNICKEL ALLOY OVERALL
nut_styleDOUBLE HEXAGON
thread_class3B
thread_seriesUNIFIED NATIONAL JOINT FINE (UNJF)
overall_height0.396 INCHES MINIMUM AND 0.411 INCHES MAXIMUM IN
locking_featurePREVAILING TORQUE ALL METAL DESIGN
thread_directionRIGHT-HAND
washer_thickness0.060 INCHES MINIMUM AND 0.080 INCHES MAXIMUM IN
precious_materialSILVER
surface_treatmentSILVER OVERALL
width_across_flats0.367 INCHES MINIMUM AND 0.376 INCHES MAXIMUM IN
nominal_thread_size0.250 INCHES IN
NSN5310-00-989-5079
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 4900278 · 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
•
WASHER OUTSIDE DIAMETER: 0.433 INCHES MINIMUM AND 0.443 INCHES MAXIMUM IN
•
WIDTH ACROSS FLATS: 0.367 INCHES MINIMUM AND 0.376 INCHES MAXIMUM IN
•
THREAD SERIES: UNIFIED NATIONAL JOINT FINE (UNJF)
•
PRECIOUS MATERIAL: SILVER
•
WASHER THICKNESS: 0.060 INCHES MINIMUM AND 0.080 INCHES MAXIMUM IN
•
THREAD DIRECTION: RIGHT-HAND
•
NOMINAL THREAD SIZE: 0.250 INCHES IN
TECHNICAL CHARACTERISTICS
OVERALL HEIGHT0.396 INCHES MINIMUM AND 0.411 INCHES MAXIMUM IN
WASHER OUTSIDE DIAMETER0.433 INCHES MINIMUM AND 0.443 INCHES MAXIMUM IN
WIDTH ACROSS FLATS0.367 INCHES MINIMUM AND 0.376 INCHES MAXIMUM IN
THREAD SERIESUNIFIED NATIONAL JOINT FINE (UNJF)
PRECIOUS MATERIALSILVER
WASHER THICKNESS0.060 INCHES MINIMUM AND 0.080 INCHES MAXIMUM IN
THREAD DIRECTIONRIGHT-HAND
NOMINAL THREAD SIZE0.250 INCHES IN
LOCKING FEATUREPREVAILING TORQUE ALL METAL DESIGN
SURFACE TREATMENTSILVER OVERALL
SUBSTITUTES & CROSS-REFERENCES 5
490278Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
59854-428Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
ST1180-10Reference document
Same NSN cross-reference
Reference document — Secondary reference
ST1325-10Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
B00101-4Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Terminal item — stock exhausted; no further procurementNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 4900278?
4900278 is a NUT,SELF-LOCKING,EXTENDED WASHER.
What parts can replace 4900278?
There are 5 known substitutes for 4900278: 490278, 59854-428, ST1180-10 and 2 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 4900278?
4900278 is cataloged in the U.S. Government catalog under NSN 5310-00-989-5079. This indicates validated use in U.S. government and defense supply chains.
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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.