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ST52781 — WASHER,FLAT

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

ST52781: WASHER,FLAT.

The WASHER,FLAT is a the manufacturer industrial component. Key specifications include thickness: 0.051 INCHES MINIMUM AND 0.080 INCHES MAXIMUM IN, hole_diameter: 0.281 INCHES NOMINAL IN, heat_treatment: QUENCHED AND TEMPERED, hardness_rating: 35.0 ROCKWELL C MINIMUM AND 45.0 ROCKWELL C MAXIMUM, overall_diameter: 0.625 INCHES NOMINAL IN, special_features: OPTIONAL HARDNESS ROCKWELL 15N SCALE 77.0 MIN AND ROCKWELL 15N SCALE 85.0 MAX. This part is cataloged in the U.S.

Government catalog under NSN 5310-01-092-5496, 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
ST52781
NSN: 5310-01-092-5496
FSC: 5310 — Nuts and Washers
CAGE: K0680 — ROLLS-ROYCE AIRLINES (GBR)
SPECIFICATIONS
materialSTEEL COMP 1008 OR STEEL COMP 1009 OR STEEL COMP 1015 OR STEEL COMP 1018 OR STEEL COMP 1020 OR STEEL COMP 1035 OR STEEL COMP 1040 OR STEEL COMP 1045 OVERALL
thickness0.051 INCHES MINIMUM AND 0.080 INCHES MAXIMUM IN
hole_diameter0.281 INCHES NOMINAL IN
heat_treatmentQUENCHED AND TEMPERED
hardness_rating35.0 ROCKWELL C MINIMUM AND 45.0 ROCKWELL C MAXIMUM
overall_diameter0.625 INCHES NOMINAL IN
special_featuresOPTIONAL HARDNESS ROCKWELL 15N SCALE 77.0 MIN AND ROCKWELL 15N SCALE 85.0 MAX
features_providedCASEHARDENED
peripheral_shape_styleROUND
center_hole_shape_styleROUND
cross-sectional_shape_styleRECTANGULAR
NSN5310-01-092-5496
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: ST52781 · 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
•
OVERALL DIAMETER: 0.625 INCHES NOMINAL IN
•
HEAT TREATMENT: QUENCHED AND TEMPERED
•
HARDNESS RATING: 35.0 ROCKWELL C MINIMUM AND 45.0 ROCKWELL C MAXIMUM
•
CROSS-SECTIONAL SHAPE STYLE: RECTANGULAR
•
FEATURES PROVIDED: CASEHARDENED
•
PERIPHERAL SHAPE STYLE: ROUND
•
MATERIAL: STEEL COMP 1008 OR STEEL COMP 1009 OR STEEL COMP 1015 OR STEEL COMP 1018 OR STEEL COMP 1020 OR STEEL COMP 1035 OR STEEL COMP 1040 OR STEEL COMP 1045 OVERALL
TECHNICAL CHARACTERISTICS
OVERALL DIAMETER0.625 INCHES NOMINAL IN
HEAT TREATMENTQUENCHED AND TEMPERED
HARDNESS RATING35.0 ROCKWELL C MINIMUM AND 45.0 ROCKWELL C MAXIMUM
CROSS-SECTIONAL SHAPE STYLERECTANGULAR
FEATURES PROVIDEDCASEHARDENED
SPECIAL FEATURESOPTIONAL HARDNESS ROCKWELL 15N SCALE 77.0 MIN AND ROCKWELL 15N SCALE 85.0 MAX
PERIPHERAL SHAPE STYLEROUND
MATERIALSTEEL COMP 1008 OR STEEL COMP 1009 OR STEEL COMP 1015 OR STEEL COMP 1018 OR STEEL COMP 1020 OR STEEL COMP 1035 OR STEEL COMP 1040 OR STEEL COMP 1045 OVERALL
CENTER HOLE SHAPE STYLEROUND
HOLE DIAMETER0.281 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 3
5310010925496Reference document
Same NSN cross-reference
Reference document — Informative reference only
8356625-1Reference document
Same NSN cross-reference
Reference document — Secondary reference
9422845Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Insurance item — stocked against contingency demandNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is ST52781?
ST52781 is a WASHER,FLAT.
What parts can replace ST52781?
There are 3 known substitutes for ST52781: 5310010925496, 8356625-1, 9422845. Substitute compatibility should be verified for your specific system.
What is the NSN for ST52781?
ST52781 is cataloged in the U.S. Government catalog under NSN 5310-01-092-5496. 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.