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04521-020 — O-RING

✓ Government record, cited
— · ORING SEAL
PRODUCT OVERVIEW

04521-020: O-RING.

The O-RING is a the manufacturer industrial component. Key specifications include center_hole_diameter: 2.589 INCHES MINIMUM AND 2.629 INCHES MAXIMUM IN, cross-sectional_height: 0.135 INCHES MINIMUM AND 0.143 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5331-01-256-0427, 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
04521-020
NSN: 5331-01-256-0427
FSC: 5331 — O-ring
CAGE: 21439 — CURTISS-WRIGHT FLOW CONTROL SERVICE, LLC DBA ENGINEERED ARRESTING SYSTEMS - ESCO DIV CW FLOW CONTROL SVC LLC DBA (USA)
SPECIFICATIONS
center_hole_diameter2.589 INCHES MINIMUM AND 2.629 INCHES MAXIMUM IN
cross-sectional_height0.135 INCHES MINIMUM AND 0.143 INCHES MAXIMUM IN
NSN5331-01-256-0427
COMPONENT DIAGRAM
O-RING / SEAL — MATERIAL DETERMINES APPLICATION ID: — CROSS-SECTION CS: — SPECIFICATION Material: — Durometer: — Temp: — PN: 04521-020 MFR: OEM ⚠ VERIFY BEFORE ORDERING Wrong material = failure. Viton for oil/fuel, EPDM for water/steam, Buna-N for general purpose, Silicone for food-grade. Chemical incompatibility causes swelling, brittleness, or rapid degradation ✓ BROKER TIP Durometer (hardness) affects sealing pressure tolerance. Higher Shore A = harder = higher pressure. Standard durometer is 70A — verify if application requires different hardness PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
CROSS-SECTIONAL HEIGHT: 0.135 INCHES MINIMUM AND 0.143 INCHES MAXIMUM IN
•
CENTER HOLE DIAMETER: 2.589 INCHES MINIMUM AND 2.629 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS
CROSS-SECTIONAL HEIGHT0.135 INCHES MINIMUM AND 0.143 INCHES MAXIMUM IN
CENTER HOLE DIAMETER2.589 INCHES MINIMUM AND 2.629 INCHES MAXIMUM IN
OTHER ITEMS IN FSC 5331 — O-ring
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5331-00-001-1971 5331-00-001-1979 5331-00-001-3904 5331-00-001-3905 5331-00-001-3906 5331-00-001-3908 5331-00-001-3923 5331-00-001-3924
SUBSTITUTES & CROSS-REFERENCES 2
52-D-6012-8Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
2-231Reference document
Same NSN cross-reference
Reference document — Advisory reference — outside the item-of-supply concept
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 04521-020?
04521-020 is a O-RING.
What parts can replace 04521-020?
There are 2 known substitutes for 04521-020: 52-D-6012-8, 2-231. Substitute compatibility should be verified for your specific system.
What is the NSN for 04521-020?
04521-020 is cataloged in the U.S. Government catalog under NSN 5331-01-256-0427. 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.