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NT637 ✓ 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 NUT,PLAIN,ROUND is a the manufacturer industrial component. Key specifications include material: STEEL COMP 303 OVERALL, nut_style: ROUND, nut_diameter: 0.250 INCHES NOMINAL IN, thread_class: 2B, nut_thickness: 0.188 INCHES NOMINAL IN, thread_series: UNF. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-00-208-9080, 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
NT637
NSN: 5310-00-208-9080
FSC: 5310
CAGE: 80249 — BAE SYSTEMS INFORMATION AND ELECTRONIC SYSTEMS INTEGRATION INC. (USA)
SPECIFICATIONS
materialSTEEL COMP 303 OVERALL
nut_styleROUND
nut_diameter0.250 INCHES NOMINAL IN
thread_class2B
nut_thickness0.188 INCHES NOMINAL IN
thread_seriesUNF
thread_directionRIGHT-HAND
drive_point_depth0.062 INCHES NOMINAL IN
drive_point_width0.062 INCHES NOMINAL IN
nominal_thread_size0.112 INCHES IN
drive_point_quantity2
thread_quantity_per_inch48
NSN5310-00-208-9080
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: NT637 · 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
•
THREAD QUANTITY PER INCH: 48
•
THREAD SERIES: UNF
•
THREAD CLASS: 2B
•
NOMINAL THREAD SIZE: 0.112 INCHES IN
•
NUT DIAMETER: 0.250 INCHES NOMINAL IN
•
NUT THICKNESS: 0.188 INCHES NOMINAL IN
•
DRIVE POINT QUANTITY: 2
•
DRIVE POINT DEPTH: 0.062 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS (FLIS)
THREAD QUANTITY PER INCH48
THREAD SERIESUNF
THREAD CLASS2B
NOMINAL THREAD SIZE0.112 INCHES IN
NUT DIAMETER0.250 INCHES NOMINAL IN
NUT THICKNESS0.188 INCHES NOMINAL IN
DRIVE POINT QUANTITY2
DRIVE POINT DEPTH0.062 INCHES NOMINAL IN
DRIVE POINT WIDTH0.062 INCHES NOMINAL IN
MATERIAL DOCUMENT AND CLASSIFICATIONMIL-)-A))" ,7,TYPE C MIL SPEC SINGLE MATERIAL RESPONSE OVERALL
VERIFIED SUBSTITUTES & CROSS-REFERENCES 8
S119Interchangeable
interchangeable cross-reference
interchangeable
S159Interchangeable
interchangeable cross-reference
interchangeable
FFS85Interchangeable
interchangeable cross-reference
interchangeable
M457Interchangeable
interchangeable cross-reference
interchangeable
330C889D5018C20Interchangeable
interchangeable cross-reference
interchangeable
S-40Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is NT637?
NT637 is a NUT,PLAIN,ROUND.
What parts can replace NT637?
There are 8 known substitutes for NT637: S119, S159, FFS85 and 5 more. Substitute compatibility should be verified for your specific system.
What is the NSN for NT637?
NT637 is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-00-208-9080. 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