1/2"-20 Jam Nuts | McMaster-Carr

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Cadmium Yellow-Chromate Plated

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MS21083C8

MS21083N8

MS35691-39

Insert Maximum Temperature

35 Products

About Hex Nuts

Choose a hex nut with the right profile, material, and strength for your application.

Thin-Profile Hex Nuts

About half the height of standard-profile nuts, these fit in spaces with low clearance. You can also use them as jam nuts by threading them against another hex nut to hold it in place.

Medium-Strength Steel

These Grade 5 or Class 04 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

Steel—Best for dry environments since moisture will cause these nuts to rust.

	Wd.	Ht.	Fastener Strength Grade/Class	Specs. Met	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	1/2"-20	3/4"	5/16"	SAE Grade 5	ASME B18.2.2	50	94846A525	000000


	Steel



			1/2"-20	3/4"	5/16"	SAE Grade 5	ASME B18.2.2	25	94846A210	0000

High-Strength Steel

Rated Grade 8, Grade C, or Class 10, these nuts are about 25% stronger than medium-strength steel nuts. They are commonly used to fasten components in valves, pumps, motors, and other high-stress applications. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

Zinc-Yellow-Chromate-Plated Steel—With a more durable finish than clear zinc plating, these nuts are suitable for most wet and outdoor environments. However, they won't hold up to the harsh chemicals that stainless steel can.

Steel—Best for dry environments since moisture will cause these nuts to rust.

	Wd.	Ht.	Fastener Strength Grade/Class	Specs. Met	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	1/2"-20	3/4"	5/16"	SAE Grade 8	ASME B18.2.2	10	92053A130	00000


	Zinc-Yellow-Chromate-Plated Steel



			1/2"-20	3/4"	5/16"	SAE Grade 8	ASME B18.2.2	25	93839A825	00000


			Steel



					1/2"-20	3/4"	5/16"	SAE Grade 8	ASME B18.2.2	10	92052A210	0000

Low-Strength Steel

Rated Grade 2, Class 6, or lower, these nuts are about half as strong as medium-strength nuts. They are suitable for light duty fastening applications, such as securing access panels. Use them with screws that have a similar strength rating to avoid stripping threads during installation.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

Black-Oxide Steel—Typically chosen for their appearance, these nuts have a dark, matte coating to create a finished look. They offer minimal corrosion resistance, so they're best for dry environments.

Steel—Best for dry environments since moisture will cause these nuts to rust.

	Wd.	Ht.	Fastener Strength Grade/Class	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	1/2"-20	3/4"	5/16"	SAE Grade 2	50	91078A225	00000


	Black-Oxide Steel



			1/2"-20	3/4"	3/16"	—	1	90475A033	0000


			Steel



					1/2"-20	3/4"	5/16"	SAE Grade 2	100	90494A233	00000

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

Black-Oxide 18-8 Stainless Steel—Typically chosen for their appearance, these nuts have a dark, matte coating to create a finished look. They resist rust in wet and outdoor environments, but won't hold up to the harsh chemicals that 316 stainless steel can.

Highly Corrosion-Resistant 316 Stainless Steel—Superior to 18-8 stainless steel, these nuts won't degrade when exposed to harsh weather, salt water, and most chemicals.

Highly Corrosion-Resistant Black-Oxide 316 Stainless Steel—Combines a finished appearance with the rust resistance of 316 stainless steel. Even if the coating wears off, these nuts will hold up in just about any environment, including salt water and most chemicals.

	Wd.	Ht.	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	1/2"-20	3/4"	5/16"	25	91847A525	00000


	Black-Oxide 18-8 Stainless Steel



			1/2"-20	3/4"	5/16"	10	98514A140	00000


			Highly Corrosion-Resistant 316 Stainless Steel



					1/2"-20	3/4"	5/16"	10	94805A224	0000


					Highly Corrosion-Resistant Black-Oxide 316 Stainless Steel



							1/2"-20	3/4"	5/16"	5	90831A180	00000

Brass

Brass—Conductive and nonmagnetic, brass nuts are commonly used to secure electrical equipment, such as circuit board assemblies and mounting brackets, inside enclosures. They're also softer than most metals, so they won't damage other fastening components.

	Wd.	Ht.	Pkg. Qty.		Pkg.
Brass



	1/2"-20	3/4"	5/16"	10	92174A440	000000

Left-Hand-Thread Hex Nuts

These nuts tighten when turned to the left. Use them with left-hand rods and screws to prevent counterclockwise-moving parts from loosening.

Corrosion-Resistant Stainless Steel

Highly Corrosion-Resistant 316 Stainless Steel—Superior to 18-8 stainless steel, these nuts won't degrade when exposed to harsh weather, salt water, and most chemicals.

	Wd.	Ht.	Pkg. Qty.		Pkg.
Highly Corrosion-Resistant 316 Stainless Steel



	1/2"-20	3/4"	7/16"	1	95355A251	000000

Left-Hand-Thread Thin-Profile Hex Nuts

These nuts tighten when turned to the left. Use them with left-hand rods and screws to prevent counterclockwise-moving parts from loosening. About half the height of standard-profile nuts, these fit in spaces with low clearance. You can also use them as jam nuts by threading them against another hex nut to hold it in place.

Medium-Strength Steel

These Grade 5 or Class 04 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

	Wd.	Ht.	Fastener Strength Grade/Class	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	1/2"-20	3/4"	5/16"	SAE Grade 5	25	99612A136	000000

Low-Strength Steel

Steel—Best for dry environments since moisture will cause these nuts to rust.

	Wd.	Ht.	Fastener Strength Grade/Class	Specs. Met	Pkg. Qty.		Pkg.
Black-Oxide Steel



	1/2"-20	3/4"	5/16"	SAE Grade 2	ASTM A108	1	90519A872	00000


	Steel



			1/2"-20	3/4"	5/16"	SAE Grade 2	—	25	90083A225	00000

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

Highly Corrosion-Resistant 316 Stainless Steel—Superior to 18-8 stainless steel, these nuts won't degrade when exposed to harsh weather, salt water, and most chemicals.

	Wd.	Ht.	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	1/2"-20	3/4"	5/16"	5	94450A280	000000


	Highly Corrosion-Resistant 316 Stainless Steel



			1/2"-20	3/4"	5/16"	1	93031A172	0000

Thin-Profile Nylon-Insert Locknuts

About half the height of standard-profile locknuts, these fit in spaces with low clearance. You can also use them as jam nuts by threading them against a hex nut to hold it in place. The nylon insert grips the screw to prevent loosening from moderate vibration without damaging threads. However, the insert may become brittle if exposed to high temperatures. These locknuts are reusable a handful of times, but the holding power decreases with each use.

High-Strength Steel

Rated Grade 8, Grade C, or Class 10, these locknuts are about 25% stronger than medium-strength steel nuts. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

	Wd.	Ht.	Fastener Strength Grade/Class	Insert Max. Temp., ° F	Pkg. Qty.		Pkg.
Zinc-Yellow-Chromate-Plated Steel



	1/2"-20	3/4"	5/16"	SAE Grade 8	250	5	94945A121	00000


	Zinc-Plated Steel



			1/2"-20	3/4"	5/16"	SAE Grade 8	220	5	94945A225	0000


			Black-Oxide Steel



					1/2"-20	3/4"	5/16"	SAE Grade 8	250	5	94945A112	0000

Low-Strength Steel

Rated Grade 2, Class 6, or lower, these locknuts are about half as strong as medium-strength steel nuts. Use them with screws that have a similar strength rating to avoid stripping threads during installation.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

	Wd.	Ht.	Insert Max. Temp., ° F	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	1/2"-20	3/4"	5/16"	220	100	90566A230	000000

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

316 Stainless Steel—Our most corrosion-resistant nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.

	Wd.	Ht.	Insert Max. Temp., ° F	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	1/2"-20	3/4"	5/16"	220	5	90101A255	00000


	Black-Oxide 18-8 Stainless Steel



			1/2"-20	3/4"	5/16"	220	5	90101A126	0000


			316 Stainless Steel



					1/2"-20	3/4"	5/16"	220	10	97367A137	00000

Shock Absorber Mounting Nuts

Hex Nuts

Use Mounting Blocks for Shock Absorbers (not included) to mount and secure threaded-body shock absorbers.

		Steel
	Thread Size		Each
Hex Nuts



		1/2"-20	6600K75	00000

Mil. Spec. Thin-Profile Hex Nuts

These nuts are manufactured and tested to strict U.S. military standards for material and construction. About half the height of standard-profile nuts, they fit in spaces with low clearance. You can also use them as jam nuts by threading them against another hex nut to hold it in place.

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

	Wd.	Ht.	Mil. Spec.	Specs. Met	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	1/2"-20	3/4"	5/16"	MS35691-39	Fed. Spec. FF-N-836	1	92101A980	00000

Thin-Profile Flex-Top Locknuts for Heavy Vibration

About two-thirds the height of standard flex-top nuts, these fit in spaces with low clearance. You can also use them as jam nuts by threading them against a hex nut to hold it in place. The top section expands to grip the screw on all sides for a stronger hold than both nylon-insert and distorted-thread locknuts. As a result, they're suitable for use in equipment with constant, vigorous vibration, such as engines. These locknuts are reusable a handful of times, but the holding power decreases with each use.

Steel

These locknuts have equivalent strength to Grade 8 and Class 10 steel nuts. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Cadmium-Plated Steel—These locknuts have good lubricity to thread on smoothly and ease installation. The plating also creates a barrier against rust that's comparable to zinc-yellow-chromate plating.

Steel—Best for dry environments since moisture will cause these nuts to rust.

	Wd.	Ht.	Pkg. Qty.		Pkg.
Cadmium-Plated Steel



	1/2"-20	3/4"	21/64"	5	94830A550	00000


	Steel



			1/2"-20	3/4"	21/64"	1	94830A135	0000

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

	Wd.	Ht.	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	1/2"-20	3/4"	21/64"	1	94140A159	000000

Mil. Spec. Thin-Profile Nylon-Insert Locknuts

These locknuts are manufactured and tested to strict U.S. military standards for material and construction. They are about half the height of standard-profile locknuts to fit in spaces with low clearance. You can also use them as jam nuts by threading them against a hex nut to hold it in place. The nylon insert grips the screw to prevent loosening from moderate vibration without damaging threads. However, the insert may become brittle if exposed to high temperatures. These locknuts are reusable a handful of times, but the holding power decreases with each use.

Low-Strength Steel

Cadmium Yellow-Chromate-Plated Steel—These locknuts have good lubricity to thread on smoothly and ease installation. The plating also creates a barrier against rust that's comparable to zinc-yellow-chromate plating.

Certificates with a traceable lot number are available for these products. Download certificates from ORDER HISTORY after your order ships.

	Wd.	Ht.	Mil. Spec.	Insert Max. Temp., ° F	Specs. Met	Pkg. Qty.		Pkg.
Cadmium Yellow-Chromate-Plated Steel



	1/2"-20	3/4"	5/16"	MS21083N8	250	NASM21083	1	95496A380	00000

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

	Wd.	Ht.	Mil. Spec.	Insert Max. Temp., ° F	Specs. Met	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	1/2"-20	3/4"	5/16"	MS21083C8	250	NASM21083	1	97231A490	000000

Knurled-Head Thumb Nuts

Get a good grip on these nuts, even with oily fingers. They have a raised, slip-resistant head, so you can tighten them by hand and make controlled adjustments. Knurled-head nuts have a smaller profile than wing nuts, so they fit in tighter spots.

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

		Collar
	Thread Size	Dia.	Ht.	Head Dia.	Ht.	Threading	Pkg. Qty.		Pkg.
18-8 Stainless Steel



		1/2"-20	5/8"	3/4"	1 1/8"	15/16"	Fully Threaded	1	91833A147	000000


		Black-Oxide 18-8 Stainless Steel



				1/2"-20	5/8"	3/4"	1 1/8"	15/16"	Fully Threaded	1	92088A133	00000