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Technical Data Sheet
PartsTable / COMPONENT / MIL-F-85731/1B
MIL-F-85731/1B ✓ Verified by PartsTable
— · ORING SEAL
WHAT YOU NEED TO KNOW
Material determines chemical compatibility Standard durometer is 70 Shore A
Wrong material = catastrophic seal failure
PRODUCT OVERVIEW

The MIL-F-85731/1B is a the manufacturer industrial component. This product is currently in active production with full OEM support. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5340-01-088-6303, 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
MIL-F-85731/1B
NSN: 5340-01-088-6303
FSC: 5340
CAGE: 81349 — MILITARY SPECIFICATIONS PROMULGATED BY MILITARY DEPARTMENTS/AGENCIES UNDER AUTHORITY OF DEFENSE STANDARDIZATION MANUAL 4120 3-M
SPECIFICATIONS
Part NumberMIL-F-85731/1B
NSN5340-01-088-6303
COMPONENT DIAGRAM
O-RING / SEAL — MATERIAL DETERMINES APPLICATION ID: — CROSS-SECTION CS: — SPECIFICATION Material: — Durometer: — Temp: — PN: MIL-F-85731/1B 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
•
THREAD DIRECTION: RIGHT-HAND
•
NOMINAL THREAD SIZE: 0.250 INCHES IN
•
THREAD QUANTITY PER INCH: 28
•
MOUNTING METHOD: PIN(S)
•
THREAD LENGTH: 1.375 INCHES NOMINAL IN
•
THREAD SERIES DESIGNATOR: UNF
•
STYLE DESIGNATOR: KNURLED NO. 2
TECHNICAL CHARACTERISTICS (FLIS)
THREAD DIRECTIONRIGHT-HAND
SPECIAL FEATURESINCLUDES SPACER STOP FEATURE
NOMINAL THREAD SIZE0.250 INCHES IN
THREAD QUANTITY PER INCH28
MOUNTING METHODPIN(S)
THREAD LENGTH1.375 INCHES NOMINAL IN
THREAD SERIES DESIGNATORUNF
STYLE DESIGNATORKNURLED NO. 2
THREAD CLASS3A A
MATERIALUNABLE TO DECODE
VERIFIED SUBSTITUTES & CROSS-REFERENCES 6
MIL-F-85731/1Upgraded Successor
successor cross-reference
successor
M85731/1-12Upgraded Successor
successor cross-reference
successor
MIL-DTL-85731/1Interchangeable
interchangeable cross-reference
interchangeable
MIL-F-85731/1BInterchangeable
interchangeable cross-reference
interchangeable
M85731/1-6AInterchangeable
Same NIIN cross-reference
interchangeable
MS14108-6AInterchangeable
Same NIIN cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is MIL-F-85731/1B?
MIL-F-85731/1B is a MIL-F-85731/1B.
What parts can replace MIL-F-85731/1B?
There are 6 known substitutes for MIL-F-85731/1B: MIL-F-85731/1, M85731/1-12, MIL-DTL-85731/1 and 3 more. Substitute compatibility should be verified for your specific system.
What is the NSN for MIL-F-85731/1B?
MIL-F-85731/1B is cataloged in the Federal Logistics Information System (FLIS) under NSN 5340-01-088-6303. This indicates validated use in U.S. government and defense supply chains.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026