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661642 — NUT,SELF-LOCKING,HEXAGON

✓ Government record, cited
Legrand · NUT WASHER
PRODUCT OVERVIEW

661642: NUT,SELF-LOCKING,HEXAGON.

The NUT,SELF-LOCKING,HEXAGON is a Legrand industrial component. Key specifications include material: IRON ALLOY 660 OVERALL, nut_style: INTERNAL OR EXTERNAL WRENCHING HEXAGON, nut_height: 0.188 INCHES MAXIMUM IN, thread_class: 3B, thread_series: UNIFIED NATIONAL JOINT FINE (UNJF), hardness_rating: 38.0 ROCKWELL C MINIMUM AND 48.0 ROCKWELL C MAXIMUM. This part is cataloged in the U.S.

Government catalog under NSN 5310-00-168-2978, 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
661642
NSN: 5310-00-168-2978
FSC: 5310 — Nuts and Washers
CAGE: 77445 — RTX CORPORATION DBA PRATT & WHITNEY DIV PRATT &WHITNEY (USA)
SPECIFICATIONS
materialIRON ALLOY 660 OVERALL
nut_styleINTERNAL OR EXTERNAL WRENCHING HEXAGON
nut_height0.188 INCHES MAXIMUM IN
thread_class3B
thread_seriesUNIFIED NATIONAL JOINT FINE (UNJF)
hardness_rating38.0 ROCKWELL C MINIMUM AND 48.0 ROCKWELL C MAXIMUM
locking_featurePREVAILING TORQUE ALL METAL DESIGN
thread_directionRIGHT-HAND
surface_treatmentSILVER OVERALL
width_across_flats0.365 INCHES MINIMUM AND 0.377 INCHES MAXIMUM IN
nominal_thread_size0.190 INCHES IN
bearing_surface_typeCHAMFERED
NSN5310-00-168-2978
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 661642 · Legrand ⚠ 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
•
WIDTH ACROSS FLATS: 0.365 INCHES MINIMUM AND 0.377 INCHES MAXIMUM IN
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: AMS 2411 ASSN STD SINGLE TREATMENT RESPONSE OVERALL
•
THREAD SERIES: UNIFIED NATIONAL JOINT FINE (UNJF)
•
HARDNESS RATING: 38.0 ROCKWELL C MINIMUM AND 48.0 ROCKWELL C MAXIMUM
•
MATERIAL DOCUMENT AND CLASSIFICATION: AMS 5525 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
•
THREAD DIRECTION: RIGHT-HAND
•
NOMINAL THREAD SIZE: 0.190 INCHES IN
•
LOCKING FEATURE: PREVAILING TORQUE ALL METAL DESIGN
TECHNICAL CHARACTERISTICS
WIDTH ACROSS FLATS0.365 INCHES MINIMUM AND 0.377 INCHES MAXIMUM IN
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONAMS 2411 ASSN STD SINGLE TREATMENT RESPONSE OVERALL
THREAD SERIESUNIFIED NATIONAL JOINT FINE (UNJF)
HARDNESS RATING38.0 ROCKWELL C MINIMUM AND 48.0 ROCKWELL C MAXIMUM
MATERIAL DOCUMENT AND CLASSIFICATIONAMS 5525 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
THREAD DIRECTIONRIGHT-HAND
NOMINAL THREAD SIZE0.190 INCHES IN
LOCKING FEATUREPREVAILING TORQUE ALL METAL DESIGN
NUT HEIGHT0.188 INCHES MAXIMUM IN
SURFACE TREATMENTSILVER OVERALL
SUBSTITUTES & CROSS-REFERENCES 6
661640Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
540625Reference document
Same NSN cross-reference
Reference document — Advisory reference — outside the item-of-supply concept
H49044-3Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
5310PL0633370Reference document
Same NSN cross-reference
Reference document — Informative reference only
661641Reference document
Same NSN cross-reference
Reference document — Advisory reference — outside the item-of-supply concept
H31-3Reference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusCancelled· U.S. Government catalog
Acquisition advice: Insurance item — stocked against contingency demandNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 661642?
661642 is a NUT,SELF-LOCKING,HEXAGON manufactured by Legrand.
What parts can replace 661642?
There are 6 known substitutes for 661642: 661640, 540625, H49044-3 and 3 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 661642?
661642 is cataloged in the U.S. Government catalog under NSN 5310-00-168-2978. 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.