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31251H — BOLT,MACHINE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

31251H: BOLT,MACHINE.

The BOLT,MACHINE is a the manufacturer industrial component. Key specifications include material: STEEL COMP 1340 OVERALL, head_style: HEXAGON, head_height: 0.365 INCHES MINIMUM AND 0.385 INCHES MAXIMUM IN, thread_class: 3A A, thread_length: 1.240 INCHES MINIMUM AND 1.260 INCHES MAXIMUM IN, fastener_length: 2.490 INCHES MINIMUM AND 2.510 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5306-00-350-2874, 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
31251H
NSN: 5306-00-350-2874
FSC: 5306 — Bolts
CAGE: 56442 — DIAMOND REO TRUCK CO (USA)
SPECIFICATIONS
materialSTEEL COMP 1340 OVERALL
head_styleHEXAGON
head_height0.365 INCHES MINIMUM AND 0.385 INCHES MAXIMUM IN
thread_class3A A
thread_length1.240 INCHES MINIMUM AND 1.260 INCHES MAXIMUM IN
fastener_length2.490 INCHES MINIMUM AND 2.510 INCHES MAXIMUM IN
hardness_rating25.0 ROCKWELL C MINIMUM AND 34.0 ROCKWELL C MAXIMUM OVERALL
thread_directionRIGHT-HAND
features_providedFINISHED HEAD
width_between_flats0.740 INCHES MINIMUM AND 0.760 INCHES MAXIMUM IN
nominal_thread_diameter0.500 INCHES IN
thread_quantity_per_inch20
NSN5306-00-350-2874
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 31251H · OEM ⚠ VERIFY BEFORE ORDERING Verify thread pitch before ordering — metric (M8×1.25) ≠ imperial (5/16-18). Wrong thread = wrong part. Grade/class stamped on bolt head determines tensile strength ✓ BROKER TIP Grade/class stamped on head determines tensile strength. Grade 8 > Grade 5 > Grade 2. Always confirm head marking matches specification requirement PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
HEAD HEIGHT: 0.365 INCHES MINIMUM AND 0.385 INCHES MAXIMUM IN
•
FASTENER LENGTH: 2.490 INCHES MINIMUM AND 2.510 INCHES MAXIMUM IN
•
THREAD LENGTH: 1.240 INCHES MINIMUM AND 1.260 INCHES MAXIMUM IN
•
HARDNESS RATING: 25.0 ROCKWELL C MINIMUM AND 34.0 ROCKWELL C MAXIMUM OVERALL
•
MATERIAL DOCUMENT AND CLASSIFICATION: ASTM A322 ASSN STD SINGLE MATERIAL RESPONSE OR ASTM A331 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
•
NOMINAL THREAD DIAMETER: 0.500 INCHES IN
•
FEATURES PROVIDED: FINISHED HEAD
•
HEAD STYLE: HEXAGON
TECHNICAL CHARACTERISTICS
HEAD HEIGHT0.365 INCHES MINIMUM AND 0.385 INCHES MAXIMUM IN
FASTENER LENGTH2.490 INCHES MINIMUM AND 2.510 INCHES MAXIMUM IN
THREAD LENGTH1.240 INCHES MINIMUM AND 1.260 INCHES MAXIMUM IN
HARDNESS RATING25.0 ROCKWELL C MINIMUM AND 34.0 ROCKWELL C MAXIMUM OVERALL
MATERIAL DOCUMENT AND CLASSIFICATIONASTM A322 ASSN STD SINGLE MATERIAL RESPONSE OR ASTM A331 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
NOMINAL THREAD DIAMETER0.500 INCHES IN
FEATURES PROVIDEDFINISHED HEAD
HEAD STYLEHEXAGON
THREAD DIRECTIONRIGHT-HAND
WIDTH BETWEEN FLATS0.740 INCHES MINIMUM AND 0.760 INCHES MAXIMUM IN
SUBSTITUTES & CROSS-REFERENCES 2
380018Reference document
Same NSN cross-reference
Reference document — Secondary reference
86228Reference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 31251H?
31251H is a BOLT,MACHINE.
What parts can replace 31251H?
There are 2 known substitutes for 31251H: 380018, 86228. Substitute compatibility should be verified for your specific system.
What is the NSN for 31251H?
31251H is cataloged in the U.S. Government catalog under NSN 5306-00-350-2874. 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.