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PartsTable / COMPONENT / 8991-1378AS
8991-1378AS ✓ 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 WASHER,LOCK is a the manufacturer industrial component. Key specifications include material: COPPER ALLOY OVERALL, hole_diameter: 0.469 INCHES NOMINAL IN, style_designator: FLAT INTERNAL TEETH, surface_treatment: TIN OVERALL. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-01-175-5716, 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
8991-1378AS
NSN: 5310-01-175-5716
FSC: 5310
CAGE: 04009 — COOPER INDUSTRIES INC COOPER DISTRIBUTION EQUIPMENT DIV (USA)
SPECIFICATIONS
materialCOPPER ALLOY OVERALL
hole_diameter0.469 INCHES NOMINAL IN
style_designatorFLAT INTERNAL TEETH
surface_treatmentTIN OVERALL
NSN5310-01-175-5716
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 8991-1378AS · 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
•
MATERIAL: COPPER ALLOY OVERALL
•
SURFACE TREATMENT: TIN OVERALL
•
STYLE DESIGNATOR: FLAT INTERNAL TEETH
•
HOLE DIAMETER: 0.469 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS (FLIS)
MATERIALCOPPER ALLOY OVERALL
SURFACE TREATMENTTIN OVERALL
STYLE DESIGNATORFLAT INTERNAL TEETH
HOLE DIAMETER0.469 INCHES NOMINAL IN
VERIFIED SUBSTITUTES & CROSS-REFERENCES 5
163557Interchangeable
interchangeable cross-reference
interchangeable
BC6673Interchangeable
interchangeable cross-reference
interchangeable
06-0287Interchangeable
interchangeable cross-reference
interchangeable
4854Interchangeable
interchangeable cross-reference
interchangeable
FIGURE 10-2 ITEM NO. 1Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 8991-1378AS?
8991-1378AS is a WASHER,LOCK.
What parts can replace 8991-1378AS?
There are 5 known substitutes for 8991-1378AS: 163557, BC6673, 06-0287 and 2 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 8991-1378AS?
8991-1378AS is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-01-175-5716. 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