Grade A Bolts | McMaster-Carr

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Low

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Unified Standard Class 2A

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Right Hand

Tensile Strength

30,000 psi to 99,999 psi

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65 Products

Low-Strength ASTM Grade A Steel Square Head Screws


Fully Threaded	Partially Threaded

About half the strength of medium-strength screws, these screws can be used for light duty fastening applications, such as securing access panels. Large flat sides make them easy to grip with a wrench and keep them from rotating in square holes. Material meets ASTM A307 specifications for quality. Length is measured from under the head.

	Square Head Screws											Nuts
					Head
	Lg.	Threading	Min. Thread Lg.	Thread Spacing	Wd.	Ht.	Tensile Strength, psi	Specs. Met	Pkg. Qty.		Pkg.	Pkg. Qty.		Pkg.
Steel





				1/4"-20 Threads
				1"	Fully Threaded	—	Coarse	3/8"	11/64"	60,000	ASTM A307	25	000000000	00000	100	000000000	000000
				1 1/4"	Partially Threaded	3/4"	Coarse	3/8"	11/64"	60,000	ASTM A307	25	000000000	00000	100	000000000	00000
				1 1/2"	Partially Threaded	3/4"	Coarse	3/8"	11/64"	60,000	ASTM A307	50	000000000	00000	100	000000000	00000
				2"	Partially Threaded	3/4"	Coarse	3/8"	11/64"	60,000	ASTM A307	25	000000000	00000	100	000000000	00000



						5/16"-18 Threads
						3/4"	Fully Threaded	—	Coarse	1/2"	13/64"	60,000	ASTM A307	25	000000000	00000	100	000000000	00000
						1"	Fully Threaded	—	Coarse	1/2"	13/64"	60,000	ASTM A307	25	000000000	00000	100	000000000	00000
						1 1/4"	Fully Threaded	—	Coarse	1/2"	13/64"	60,000	ASTM A307	25	000000000	00000	100	000000000	00000
						1 1/2"	Partially Threaded	7/8"	Coarse	1/2"	13/64"	60,000	ASTM A307	10	000000000	0000	100	000000000	00000
						2"	Partially Threaded	7/8"	Coarse	1/2"	13/64"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000
						3"	Partially Threaded	7/8"	Coarse	1/2"	13/64"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000
						4"	Partially Threaded	7/8"	Coarse	1/2"	13/64"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000



								3/8"-16 Threads
								1"	Fully Threaded	—	Coarse	9/16"	1/4"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000
								1 1/4"	Partially Threaded	1"	Coarse	9/16"	1/4"	60,000	ASTM A307	10	000000000	0000	100	000000000	00000
								1 1/2"	Partially Threaded	1"	Coarse	9/16"	1/4"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000
								1 3/4"	Partially Threaded	1"	Coarse	9/16"	1/4"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000
								2"	Partially Threaded	1"	Coarse	9/16"	1/4"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000
								2 1/2"	Partially Threaded	1"	Coarse	9/16"	1/4"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000
								3"	Partially Threaded	1"	Coarse	9/16"	1/4"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000
								3 1/2"	Partially Threaded	1"	Coarse	9/16"	1/4"	60,000	ASTM A307	10	000000000	00000	100	000000000	00000



										1/2"-13 Threads
										1"	Fully Threaded	—	Coarse	3/4"	21/64"	60,000	ASTM A307	10	000000000	00000	50	000000000	00000
										1 1/2"	Fully Threaded	—	Coarse	3/4"	21/64"	60,000	ASTM A307	10	000000000	00000	50	000000000	00000
										1 3/4"	Fully Threaded	—	Coarse	3/4"	21/64"	60,000	ASTM A307	10	000000000	00000	50	000000000	00000
										2"	Partially Threaded	1 1/4"	Coarse	3/4"	21/64"	60,000	ASTM A307	10	000000000	00000	50	000000000	00000
										2 1/4"	Partially Threaded	1 1/4"	Coarse	3/4"	21/64"	60,000	ASTM A307	5	000000000	00000	50	000000000	00000
										2 1/2"	Partially Threaded	1 1/4"	Coarse	3/4"	21/64"	60,000	ASTM A307	5	000000000	00000	50	000000000	00000
										3"	Partially Threaded	1 1/4"	Coarse	3/4"	21/64"	60,000	ASTM A307	5	000000000	00000	50	000000000	00000
										3 1/2"	Partially Threaded	1 1/4"	Coarse	3/4"	21/64"	60,000	ASTM A307	5	000000000	00000	50	000000000	00000
										4"	Partially Threaded	1 1/4"	Coarse	3/4"	21/64"	60,000	ASTM A307	5	000000000	00000	50	000000000	00000
										5"	Partially Threaded	1 1/4"	Coarse	3/4"	21/64"	60,000	ASTM A307	5	000000000	00000	50	000000000	00000
										6"	Partially Threaded	1 1/4"	Coarse	3/4"	21/64"	60,000	ASTM A307	5	000000000	00000	50	000000000	00000
										8"	Partially Threaded	1 1/2"	Coarse	3/4"	21/64"	60,000	ASTM A307	1	000000000	0000	50	000000000	00000



												5/8"-11 Threads
												2"	Partially Threaded	1 1/2"	Coarse	15/16"	27/64"	60,000	ASTM A307	1	000000000	0000	25	000000000	00000
												2 1/2"	Partially Threaded	1 1/2"	Coarse	15/16"	27/64"	60,000	ASTM A307	5	000000000	00000	25	000000000	00000
												3"	Partially Threaded	1 1/2"	Coarse	15/16"	27/64"	60,000	ASTM A307	1	000000000	0000	25	000000000	00000
												3 1/2"	Partially Threaded	1 1/2"	Coarse	15/16"	27/64"	60,000	ASTM A307	1	000000000	0000	25	000000000	00000
												4"	Partially Threaded	1 1/2"	Coarse	15/16"	27/64"	60,000	ASTM A307	1	000000000	0000	25	000000000	00000
												4 1/2"	Partially Threaded	1 1/2"	Coarse	15/16"	27/64"	60,000	ASTM A307	1	000000000	0000	25	000000000	00000
												5"	Partially Threaded	1 1/2"	Coarse	15/16"	27/64"	60,000	ASTM A307	1	000000000	0000	25	000000000	00000
												6"	Partially Threaded	1 1/2"	Coarse	15/16"	27/64"	60,000	ASTM A307	1	000000000	0000	25	000000000	00000
												7"	Partially Threaded	1 3/4"	Coarse	15/16"	27/64"	60,000	ASTM A307	1	000000000	0000	25	000000000	00000
												11"	Partially Threaded	1 3/4"	Coarse	15/16"	27/64"	60,000	ASTM A307	1	000000000	00000	25	000000000	00000



												3/4"-10 Threads
		2 1/2"										Partially Threaded	1 3/4"	Coarse	1 1/8"	1/2"	60,000	ASTM A307	1	000000000	0000	10	000000000	00000
		3"	Partially Threaded									1 3/4"	Coarse	1 1/8"	1/2"	60,000	ASTM A307	1	000000000	0000	10	000000000	00000
		3 3/4"	Partially Threaded									1 3/4"	Coarse	1 1/8"	1/2"	60,000	ASTM A307	1	000000000	0000	10	000000000	00000
		4"	Partially Threaded									1 3/4"	Coarse	1 1/8"	1/2"	60,000	ASTM A307	1	000000000	0000	10	000000000	00000
		4 1/2"	Partially Threaded									1 3/4"	Coarse	1 1/8"	1/2"	60,000	ASTM A307	1	000000000	0000	10	000000000	00000
		5"	Partially Threaded									1 3/4"	Coarse	1 1/8"	1/2"	60,000	ASTM A307	1	000000000	0000	10	000000000	00000
		5 1/2"	Partially Threaded									1 3/4"	Coarse	1 1/8"	1/2"	60,000	ASTM A307	1	000000000	00000	10	000000000	00000
		6"	Partially Threaded									1 3/4"	Coarse	1 1/8"	1/2"	60,000	ASTM A307	1	000000000	00000	10	000000000	00000
		7"	Partially Threaded	2"								Coarse	1 1/8"	1/2"	60,000	ASTM A307	1	000000000	0000	10	000000000	00000
		8"	Partially Threaded	2"	Coarse							1 1/8"	1/2"	60,000	ASTM A307	1	000000000	00000	10	000000000	00000
		9"	Partially Threaded	2"	Coarse							1 1/8"	1/2"	60,000	ASTM A307	1	000000000	00000	10	000000000	00000
		10"	Partially Threaded	2"	Coarse							1 1/8"	1/2"	60,000	ASTM A307	1	000000000	00000	10	000000000	00000
		12"	Partially Threaded	2"	Coarse							1 1/8"	1/2"	60,000	ASTM A307	1	000000000	00000	10	000000000	00000



				1"-8 Threads
				6"	Partially Threaded							2 1/4"	Coarse	1 1/2"	21/32"	60,000	ASTM A307	1	000000000	00000	5	000000000	00000
				7"	Partially Threaded							2 1/2"	Coarse	1 1/2"	21/32"	60,000	ASTM A307	1	000000000	00000	5	000000000	00000
				9"	Partially Threaded							2 1/2"	Coarse	1 1/2"	21/32"	60,000	ASTM A307	1	000000000	00000	5	000000000	00000
				10"	Partially Threaded	2 1/2"						Coarse	1 1/2"	21/32"	60,000	ASTM A307	1	000000000	00000	5	000000000	00000