5/16-18x1-1/4" Hex Head Cap Screws Grade 8 Zinc Yellow

Product Description

Part Number: 31C125HCS8Y
Diameter/Pitch: 5/16"-18
Grade: Grade 8
Length Under Head: 1-1/4"
Finish: Zinc Yellow
Thread Series: Coarse (UNC)
Threading: Fully threaded
Wrench Size: 1/2"

BoltsandNuts.com

5/16-18x1-1/4" Hex Head Cap Screws Grade 8 Zinc Yellow

SKU: 31C125HCS8Y

Product Description

Part Number: 31C125HCS8Y
Diameter/Pitch: 5/16"-18
Grade: Grade 8
Length Under Head: 1-1/4"
Finish: Zinc Yellow
Thread Series: Coarse (UNC)
Threading: Fully threaded
Wrench Size: 1/2"

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Thread Size	5/16"-18
Material	Medium carbon alloy steel, quenched and tempered
Wrench Size	1/2"
Head Height	0.195" – 0.211"
Tensile Strength (min)	150,000 psi
Specifications Met	ASME B18.2.1, SAE J429 Grade 8

Length	1-1/4"
Finish	Zinc Yellow
Thread Series	Coarse (UNC)
Head Marking	Six radial lines on head
Proof Load (min)	6,290 lbf

Grade	Grade 8
Head Type	Hex Cap
Threading	Fully threaded
Thread Class	2A
Hardness	Rockwell C33–C39

Technical Drawing

Not to scale · ASME B18.2.1 · See table for exact dimensions

Technical Dimensions

Length Under Head	1-1/4"
Major Thread Dia.	0.312"
Head Height	0.195" – 0.211"
Width Across Flats	0.500" (1/2")
Width Across Corners	0.577" max
Threads Per Inch	18 TPI
Thread Length	Fully threaded
Thread Class	2A
Proof Load	6,290 lbf
Clamp Load	4,720 lbf
Min. Tensile Strength	150,000 psi
Yield Strength	130,000 psi
Hardness	Rockwell C33–C39

Hex cap screw with a hexagonal head for external wrench engagement and a chamfered point for easier starting. The flat bearing surface distributes clamp load across the joint. Fully threaded shank, with unified coarse (UNC) threads.

Dimensions conform to ASME B18.2.1 and may vary within specified manufacturing tolerances.