PartsTable
Technical Data Sheet
Download PDF

B3878-1 — WASHER,KEY

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

B3878-1: WASHER,KEY.

The WASHER,KEY is a the manufacturer industrial component. Key specifications include material: STEEL COMP 4130 OVERALL, hole_diameter: 0.640 INCHES NOMINAL IN, surface_treatment: CADMIUM AND CHROMATE OVERALL, material_thickness: 0.040 INCHES NOMINAL IN, minimum_tensile_strength: 180000 POUNDS PER SQUARE INCH LBS, external_prebent_key_width: 0.400 INCHES NOMINAL IN. This part is cataloged in the U.S.

Government catalog under NSN 5310-01-265-9333, 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
B3878-1
NSN: 5310-01-265-9333
FSC: 5310 — Nuts and Washers
CAGE: 54184 — ARA, INC (USA)
SPECIFICATIONS
materialSTEEL COMP 4130 OVERALL
hole_diameter0.640 INCHES NOMINAL IN
surface_treatmentCADMIUM AND CHROMATE OVERALL
material_thickness0.040 INCHES NOMINAL IN
minimum_tensile_strength180000 POUNDS PER SQUARE INCH LBS
external_prebent_key_width0.400 INCHES NOMINAL IN
external_prebent_key_length0.125 INCHES NOMINAL IN
overall_distance_including_keys1.325 INCHES NOMINAL IN
material_document_and_classificationMIL-S-18729 MIL SPEC SINGLE MATERIAL RESPONSE OR AMS 6350 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
distance_from_centerline_to_end_of_key0.825 INCHES NOMINAL IN
surface_treatment_document_and_classificationQQ-P-416,TY 2,CL 1 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
distance_from_centerline_to_inside_of_prebent_key0.785 INCHES NOMINAL IN
NSN5310-01-265-9333
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: B3878-1 · 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
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416,TY 2,CL 1 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
•
DISTANCE FROM CENTERLINE TO INSIDE OF PREBENT KEY: 0.785 INCHES NOMINAL IN
•
EXTERNAL PREBENT KEY LENGTH: 0.125 INCHES NOMINAL IN
•
OVERALL DISTANCE INCLUDING KEYS: 1.325 INCHES NOMINAL IN
•
MATERIAL DOCUMENT AND CLASSIFICATION: MIL-S-18729 MIL SPEC SINGLE MATERIAL RESPONSE OR AMS 6350 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
•
MATERIAL THICKNESS: 0.040 INCHES NOMINAL IN
•
DISTANCE FROM CENTERLINE TO END OF KEY: 0.825 INCHES NOMINAL IN
•
SURFACE TREATMENT: CADMIUM AND CHROMATE OVERALL
TECHNICAL CHARACTERISTICS
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416,TY 2,CL 1 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
DISTANCE FROM CENTERLINE TO INSIDE OF PREBENT KEY0.785 INCHES NOMINAL IN
EXTERNAL PREBENT KEY LENGTH0.125 INCHES NOMINAL IN
OVERALL DISTANCE INCLUDING KEYS1.325 INCHES NOMINAL IN
MATERIAL DOCUMENT AND CLASSIFICATIONMIL-S-18729 MIL SPEC SINGLE MATERIAL RESPONSE OR AMS 6350 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
MATERIAL THICKNESS0.040 INCHES NOMINAL IN
DISTANCE FROM CENTERLINE TO END OF KEY0.825 INCHES NOMINAL IN
SURFACE TREATMENTCADMIUM AND CHROMATE OVERALL
MINIMUM TENSILE STRENGTH180000 POUNDS PER SQUARE INCH LBS
EXTERNAL PREBENT KEY WIDTH0.400 INCHES NOMINAL IN
OTHER ITEMS IN FSC 5310 — Nuts and Washers
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5310-00-000-0040 5310-00-000-0077 5310-00-000-0079 5310-00-000-1146 5310-00-000-3815 5310-00-000-4532 5310-00-000-4540
SUBSTITUTES & CROSS-REFERENCES

No substitute or cross-reference records for this part.

LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Insurance item — stocked against contingency demandNo demilitarization required
Ready to buy B3878-1?
Compare prices from verified sellers on eBay
Buy on eBay →
As an eBay Partner, PartsTable may earn a commission. Your price is not affected.
FREQUENTLY ASKED QUESTIONS
What is B3878-1?
B3878-1 is a WASHER,KEY.
What is the NSN for B3878-1?
B3878-1 is cataloged in the U.S. Government catalog under NSN 5310-01-265-9333. This indicates validated use in U.S. government and defense supply chains.
Community Feedback
Leave a Comment
Comments are reviewed before appearing. You will receive an email to verify before your comment appears.

Request a Quote — B3878-1

✓ 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.