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1S221 — WASHER,FLAT

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

1S221: WASHER,FLAT.

The WASHER,FLAT is a the manufacturer industrial component. Key specifications include material: STEEL OVERALL, thickness: 0.250 INCHES NOMINAL IN, hole_diameter: 1.031 INCHES MINIMUM AND 1.062 INCHES MAXIMUM IN, overall_diameter: 3.344 INCHES MINIMUM AND 3.375 INCHES MAXIMUM IN, peripheral_shape_style: ROUND, center_hole_shape_style: ROUND. This part is cataloged in the U.S.

Government catalog under NSN 5310-01-218-3209, 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
1S221
NSN: 5310-01-218-3209
FSC: 5310 — Nuts and Washers
CAGE: 2Y614 — LINK-BELT CRANES, L.P., LLLP (USA)
SPECIFICATIONS
materialSTEEL OVERALL
thickness0.250 INCHES NOMINAL IN
hole_diameter1.031 INCHES MINIMUM AND 1.062 INCHES MAXIMUM IN
overall_diameter3.344 INCHES MINIMUM AND 3.375 INCHES MAXIMUM IN
peripheral_shape_styleROUND
center_hole_shape_styleROUND
cross-sectional_shape_styleRECTANGULAR
NSN5310-01-218-3209
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 1S221 · 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: 3.344 INCHES MINIMUM AND 3.375 INCHES MAXIMUM IN
•
CROSS-SECTIONAL SHAPE STYLE: RECTANGULAR
•
PERIPHERAL SHAPE STYLE: ROUND
•
MATERIAL: STEEL OVERALL
•
CENTER HOLE SHAPE STYLE: ROUND
•
HOLE DIAMETER: 1.031 INCHES MINIMUM AND 1.062 INCHES MAXIMUM IN
•
THICKNESS: 0.250 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS
OVERALL DIAMETER3.344 INCHES MINIMUM AND 3.375 INCHES MAXIMUM IN
CROSS-SECTIONAL SHAPE STYLERECTANGULAR
PERIPHERAL SHAPE STYLEROUND
MATERIALSTEEL OVERALL
CENTER HOLE SHAPE STYLEROUND
HOLE DIAMETER1.031 INCHES MINIMUM AND 1.062 INCHES MAXIMUM IN
THICKNESS0.250 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: Semi-active item — no replacement plannedNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 1S221?
1S221 is a WASHER,FLAT.
What is the NSN for 1S221?
1S221 is cataloged in the U.S. Government catalog under NSN 5310-01-218-3209. 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.