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Technical Data Sheet
PartsTable / COMPONENT / B20521-4
B20521-4 ✓ 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 KEY,WOODRUFF is a the manufacturer industrial component. Key specifications include material: STEEL COMP 2330 OR STEEL COMP 4130 OR STEEL COMP 8630 OVERALL, thickness: 0.1250 INCHES MINIMUM AND 0.1260 INCHES MAXIMUM IN, key_height: 0.198 INCHES MINIMUM AND 0.203 INCHES MAXIMUM IN, shear_strength: 100000 SINGLE POUNDS PER SQUARE INCH, circle_diameter: 0.490 INCHES MINIMUM AND 0.500 INCHES MAXIMUM IN, hardness_rating: 40.0 ROCKWELL C MINIMUM AND 50.0 ROCKWELL C MAXIMUM OVERALL. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5315-00-616-5514, 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
B20521-4
NSN: 5315-00-616-5514
FSC: 5315
CAGE: 83298 — ALLIED SIGNAL INC AEROSPACE EQUIPMENT SYSTEMS EATONTOWN SITE (USA)
SPECIFICATIONS
materialSTEEL COMP 2330 OR STEEL COMP 4130 OR STEEL COMP 8630 OVERALL
thickness0.1250 INCHES MINIMUM AND 0.1260 INCHES MAXIMUM IN
key_height0.198 INCHES MINIMUM AND 0.203 INCHES MAXIMUM IN
shear_strength100000 SINGLE POUNDS PER SQUARE INCH
circle_diameter0.490 INCHES MINIMUM AND 0.500 INCHES MAXIMUM IN
hardness_rating40.0 ROCKWELL C MINIMUM AND 50.0 ROCKWELL C MAXIMUM OVERALL
style_designatorROUND BOTTOM
starting_edge_shapeSTRAIGHT
key_size_designationWOODRUFF 3
NSN5315-00-616-5514
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: B20521-4 · 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
•
CIRCLE DIAMETER: 0.490 INCHES MINIMUM AND 0.500 INCHES MAXIMUM IN
•
KEY SIZE DESIGNATION: WOODRUFF 3
•
KEY HEIGHT: 0.198 INCHES MINIMUM AND 0.203 INCHES MAXIMUM IN
•
STYLE DESIGNATOR: ROUND BOTTOM
•
MATERIAL: STEEL COMP 2330 OR STEEL COMP 4130 OR STEEL COMP 8630 OVERALL
•
THICKNESS: 0.1250 INCHES MINIMUM AND 0.1260 INCHES MAXIMUM IN
•
HARDNESS RATING: 40.0 ROCKWELL C MINIMUM AND 50.0 ROCKWELL C MAXIMUM OVERALL
•
STARTING EDGE SHAPE: STRAIGHT
TECHNICAL CHARACTERISTICS (FLIS)
CIRCLE DIAMETER0.490 INCHES MINIMUM AND 0.500 INCHES MAXIMUM IN
KEY SIZE DESIGNATIONWOODRUFF 3
KEY HEIGHT0.198 INCHES MINIMUM AND 0.203 INCHES MAXIMUM IN
STYLE DESIGNATORROUND BOTTOM
MATERIALSTEEL COMP 2330 OR STEEL COMP 4130 OR STEEL COMP 8630 OVERALL
THICKNESS0.1250 INCHES MINIMUM AND 0.1260 INCHES MAXIMUM IN
HARDNESS RATING40.0 ROCKWELL C MINIMUM AND 50.0 ROCKWELL C MAXIMUM OVERALL
STARTING EDGE SHAPESTRAIGHT
SHEAR STRENGTH100000 SINGLE POUNDS PER SQUARE INCH
VERIFIED SUBSTITUTES & CROSS-REFERENCES 33
74142SInterchangeable
interchangeable cross-reference
interchangeable
168JInterchangeable
interchangeable cross-reference
interchangeable
09078Interchangeable
interchangeable cross-reference
interchangeable
0005438Interchangeable
interchangeable cross-reference
interchangeable
7E6309Interchangeable
interchangeable cross-reference
interchangeable
3968-001Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is B20521-4?
B20521-4 is a KEY,WOODRUFF.
What parts can replace B20521-4?
There are 33 known substitutes for B20521-4: 74142S, 168J, 09078 and 30 more. Substitute compatibility should be verified for your specific system.
Is B20521-4 still available?
B20521-4 is currently cancelled.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026