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Technical Data Sheet
PartsTable / COMPONENT / 121637
121637 ✓ 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: STEEL CORROSION RESISTING OVERALL, thickness: 0.008 INCHES MINIMUM AND 0.012 INCHES MAXIMUM IN, hole_diameter: 0.255 INCHES MINIMUM AND 0.259 INCHES MAXIMUM IN, hardness_rating: 94.0 ROCKWELL B NOMINAL, overall_diameter: 0.440 INCHES NOMINAL IN, surface_treatment: PASSIVATE OVERALL. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-00-012-1637, 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
121637
NSN: 5310-00-012-1637
FSC: 5310
CAGE: 56442 — DIAMOND REO TRUCK CO (USA)
SPECIFICATIONS
materialSTEEL CORROSION RESISTING OVERALL
thickness0.008 INCHES MINIMUM AND 0.012 INCHES MAXIMUM IN
hole_diameter0.255 INCHES MINIMUM AND 0.259 INCHES MAXIMUM IN
hardness_rating94.0 ROCKWELL B NOMINAL
overall_diameter0.440 INCHES NOMINAL IN
surface_treatmentPASSIVATE OVERALL
peripheral_shape_styleROUND
center_hole_shape_styleROUND
cross-sectional_shape_styleRECTANGULAR
material_document_and_classificationQQ-S-766 CLASS 304,COND A FED SPEC SINGLE MATERIAL RESPONSE OVERALL
surface_treatment_document_and_classificationMIL-F-14072 E300 MIL SPEC SINGLE TREATMENT RESPONSE OVERALL
NSN5310-00-012-1637
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 121637 · 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
•
HOLE DIAMETER: 0.255 INCHES MINIMUM AND 0.267 INCHES MAXIMUM IN
•
MATERIAL THICKNESS: 0.047 INCHES MINIMUM AND 0.057 INCHES MAXIMUM IN
•
NONDEFINITIVE SPEC/STD DATA: 1 STYLE AND A CLASS
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416 FED SPEC 1ST TREATMENT RESPONSE OR QQ-Z-325 FED SPEC 2ND TREATMENT RESPONSE OVERALL
•
SURFACE TREATMENT: CADMIUM OR ZINC OVERALL
•
MATERIAL DOCUMENT AND CLASSIFICATION: 66 FED STD ALL MATERIAL RESPONSES OR AISI NATIONAL SPEC ALL MATERIAL RESPONSES OR SAE NATIONAL SPEC ALL MATERIAL RESPONSES OVERALL
•
HARDNESS RATING: 45.0 ROCKWELL C MINIMUM AND 53.0 ROCKWELL C MAXIMUM
•
OUTSIDE DIAMETER: 0.489 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS (FLIS)
HOLE DIAMETER0.255 INCHES MINIMUM AND 0.267 INCHES MAXIMUM IN
MATERIAL THICKNESS0.047 INCHES MINIMUM AND 0.057 INCHES MAXIMUM IN
NONDEFINITIVE SPEC/STD DATA1 STYLE AND A CLASS
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416 FED SPEC 1ST TREATMENT RESPONSE OR QQ-Z-325 FED SPEC 2ND TREATMENT RESPONSE OVERALL
SURFACE TREATMENTCADMIUM OR ZINC OVERALL
MATERIAL DOCUMENT AND CLASSIFICATION66 FED STD ALL MATERIAL RESPONSES OR AISI NATIONAL SPEC ALL MATERIAL RESPONSES OR SAE NATIONAL SPEC ALL MATERIAL RESPONSES OVERALL
HARDNESS RATING45.0 ROCKWELL C MINIMUM AND 53.0 ROCKWELL C MAXIMUM
OUTSIDE DIAMETER0.489 INCHES MAXIMUM IN
STYLE DESIGNATORSPLIT HELICAL-RIGHT HAND
VERIFIED SUBSTITUTES & CROSS-REFERENCES 18
A2500Interchangeable
interchangeable cross-reference
interchangeable
6220-21Interchangeable
interchangeable cross-reference
interchangeable
132634Interchangeable
interchangeable cross-reference
interchangeable
2300169Interchangeable
interchangeable cross-reference
interchangeable
A775Interchangeable
interchangeable cross-reference
interchangeable
8158030Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 121637?
121637 is a WASHER,LOCK.
What parts can replace 121637?
There are 18 known substitutes for 121637: A2500, 6220-21, 132634 and 15 more. Substitute compatibility should be verified for your specific system.
Is 121637 still available?
121637 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