McMaster-Carr logo
    Forward
    Enter e-mail addresses in the fields below
    Message
    Cancel
    Print
    How can we improve?
    Comments
    E-mail address (if you would like a response)
    27 Products

    Cap Nut Profile

    Cap Nut Profile

    Cap Nuts

    Conceal and protect protruding screw threads while fastening parts together. These nuts help prevent damage to surrounding materials and reduce injuries. Also known as acorn nuts, they have a smooth, rounded head that creates a finished look.
    Stainless Steel
    Image of Product. Front orientation. Cap Nuts. Cap Nuts.
    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. 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—Our most corrosion-resistant cap nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.
    Pkg.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Pkg.
    Qty.
    1-9
    10-49
    50-Up
    18-8 Stainless Steel
    1/2"-13
    		3/8"3/4"9/16"1000000000000000000000000
    1/2"-13
    		1/2"3/4"13/16"1000000000000000000000
     
    Black-Oxide 18-8 Stainless Steel
    1/2"-13
    		1/2"3/4"13/16"1000000000000000000000
     
    Highly-Corrosion-Resistant 316 Stainless Steel
    1/2"-13
    		1/2"3/4"13/16"1000000000000000000000
     
    Low-Strength Steel
    Image of Product. Front orientation. Cap Nuts. Cap Nuts.
    Rated Grade 2, Class 6, or lower, these nuts are about half as strong as medium-strength steel 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 Corrosion-Resistant-Coated Steel—Combines a finished appearance with the rust resistance of stainless steel. The coating has been tested to extreme standards, including 1,000 hours of salt spray resistance, to hold up in wet and outdoor environments. Also known as black luster.
    Nickel-Plated Steel—This plating resists salt water and chemicals better than zinc plating and is less likely to wear off. It also has a bright, polished appearance.
    Pkg.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Pkg.
    Qty.
    1-9
    10-49
    50-Up
    Zinc-Plated Steel
    1/2"-13
    		1/2"3/4"13/16"100000000000000000000000000
     
    Black Corrosion-Resistant-Coated Steel
    1/2"-13
    		1/2"3/4"13/16"1000000000000000000000
     
    Nickel-Plated Steel
    1/2"-13
    		1/2"3/4"9/16"25000000000000000000000000
     
    Medium-Strength Steel
    Image of Product. Front orientation. Cap Nuts. Cap Nuts.
    About twice as strong as low-strength steel, these Grade 5 nuts fasten 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.
    Black Corrosion-Resistant-Coated Steel—Combines a finished appearance with the rust resistance of stainless steel. The coating has been tested to extreme standards, including 1,000 hours of salt spray resistance, to hold up in wet and outdoor environments. Also known as black luster.
    Pkg.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Fastener Strength
    Grade/Class
    Pkg.
    Qty.
    1-9
    10-49
    50-Up
    Zinc-Plated Steel
    1/2"-13
    		1/2"3/4"13/16"SAE Grade 5
    		5000000000000000000000000000
     
    Black Corrosion-Resistant-Coated Steel
    1/2"-13
    		1/2"3/4"13/16"SAE Grade 5
    		100000000000000000000000
     
    High-Strength Steel
    Image of Product. Front orientation. Cap Nuts. Cap Nuts.
    Rated Grade 8 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.
    Black Corrosion-Resistant-Coated Steel—Combines a finished appearance with the rust resistance of stainless steel. The coating has been tested to extreme standards, including 1,000 hours of salt spray resistance, to hold up in wet and outdoor environments. Also known as black luster.
    Pkg.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Fastener Strength
    Grade/Class
    Pkg.
    Qty.
    1-9
    10-49
    50-Up
    Zinc-Plated Steel
    1/2"-13
    		1/2"3/4"13/16"SAE Grade 8
    		1000000000000000000000000
     
    Black Corrosion-Resistant-Coated Steel
    1/2"-13
    		1/2"3/4"13/16"SAE Grade 8
    		100000000000000000000000
     
    Plastic
    Image of Product. Front orientation. Cap Nuts. Cap Nuts.
    Nylon 6/6—Slippery and abrasion resistant, these nuts thread on smoothly and stand up to daily wear and tear. Nylon will swell and weaken when exposed to moisture, so it's best for dry environments.
    Pkg.
    Thread
    Size
    Wd.
    Ht.
    Temp. Range,
    ° F
    Choose a Color
    Pkg.
    Qty.
    1-9
    10-49
    50-Up
    Nylon 6/6
    1/2"-13
    		3/4"13/16"-40 to 185
    Black
    ,
    Off-White
    		25000000000000000000000000000
     
    Brass
    Image of Product. Front orientation. Cap Nuts. Cap Nuts.
    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.
    Chrome-Plated Brass—The brightest, shiniest finish we offer, this plating has a mirror-like appearance that's often used in decorative applications. It has better corrosion resistance than plain brass to stand up to solvents and mild chemicals.
    Pkg.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Pkg.
    Qty.
    1-9
    10-49
    50-Up
    Brass
    1/2"-13
    		5/16"3/4"9/16"10000000000000000000000000000
     
    Chrome-Plated Brass
    1/2"-13
    		5/16"3/4"9/16"5000000000000000000000
     

    High-Profile Cap Nuts

    Image of Product. Front orientation. Cap Nuts. High-Profile Cap Nuts.
    Three times the thread depth of standard cap nuts, these cover and protect extra-long, protruding screws, so you don't have to cut them when fastening parts together. They help prevent damage to surrounding materials and reduce injuries. Also known as acorn nuts, they have a smooth, rounded head that creates a finished look.
    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.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Each
    18-8 Stainless Steel
    1/2"-13
    		1"3/4"1 7/16"000000000000000
    1/2"-13
    		1 1/4"3/4"1 3/4"00000000000000
    1/2"-13
    		1 1/2"3/4"2"00000000000000
     

    High-Heavy-Profile Cap Nuts

    Image of Product. Bottom orientation. Cap Nuts. High-Heavy-Profile Cap Nuts.
    20% wider and taller than standard cap nuts, these have high, flat sides so your wrench won't slip off as you tighten. They cover screws to protect the threads and to prevent damage to surrounding materials. Also known as acorn nuts, they have a smooth, rounded head to create a finished look.
    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.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Each
    18-8 Stainless Steel
    1/2"-13
    		19/32"7/8"15/16"000000000000000
     
    Steel
    Black-Oxide Steel—Typically chosen for their appearance, these nuts have a dark, matte coating. They offer minimal corrosion resistance, so they're best for dry environments.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Each
    Black-Oxide Steel
    1/2"-13
    		19/32"7/8"15/16"00000000000000
     

    Sanitary Cap Nuts

    With extremely smooth sides and rounded edges, these nuts are free of crevices where bacteria can grow. Use them to cover and protect exposed threads while fastening parts together. Nuts are certified by EHEDG to meet sanitary design standards. They have a Buna-N seal on the base that keeps liquid, debris, and other contaminants off the threads. The seal is made with metal and chemical additives, so you can find it with a metal detector or X-ray machine if it falls into your line. Also known as acorn nuts, these have a domed head to create a finished look.
    Stainless Steel
    Image of Product. Front orientation. Cap Nuts. Sanitary Cap Nuts.
    Highly-Corrosion-Resistant 316 Stainless Steel—Won't corrode from frequent washdowns and can stand up to the harshest cleaners and detergents.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Seal
    Material
    Certification
    Food Industry Std.
    Each
    Highly-Corrosion-Resistant 316 Stainless Steel
    1/2"-13
    		11/32"3/4"35/64"Buna-N
    		EHEDG Certified
    		FDA Compliant 21 CFR 177.2600
    		000000000000000
     

    Open-End Cap Nuts

    Image of Product. Front orientation. Cap Nuts. Open-End Cap Nuts.
    The open top allows threads to stick out slightly, so you don't have to worry about picking the wrong thread depth. These nuts also engage more threads than standard nuts for a tighter hold. The smooth, curved head creates a finished look, while still partially concealing and protecting the sides of the screw from damage.
    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.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Each
    18-8 Stainless Steel
    1/2"-13
    		1/2"3/4"1/2"00000000000000
     

    Cap Nuts with Threadlocker

    Image of Product. Front orientation. Contains Annotated, Border. Cap Nuts. Cap Nuts with Threadlocker.
    These nuts not only conceal and protect protruding screw threads, they also resist loosening from mild vibration. They have a nylon patch bonded to their threads that grips screws for a tighter hold than standard cap nuts. They’re reusable a handful of times, but the patch’s holding power decreases with each use. Also known as acorn nuts, they have a smooth, rounded head that creates a finished look.
    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—Our most corrosion-resistant cap nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    1/2"-13
    		1/2"3/4"13/16"100000000000000
     
    Highly-Corrosion-Resistant 316 Stainless Steel
    1/2"-13
    		1/2"3/4"13/16"100000000000000
     

    Sealing Cap Nuts

    Image of Product. Bottom orientation. Cap Nuts. Sealing Cap Nuts.
    Keep liquid, gas, debris, and other contaminants from seeping into or out of machinery, with no need for a separate O-ring. These nuts are often used outdoors to protect enclosures and other equipment from harsh weather. They also withstand high pressure, so they are useful for sealing pneumatic pumps and pressure valves. Also known as acorn nuts, they conceal protruding screw threads while fastening parts together and have a smooth, rounded head for a finished look.
    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.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Seal Material
    Seal Temp.
    Range, ° F
    Max. Pressure,
    psi
    Each
    18-8 Stainless Steel
    1/2"-13
    		1/2"3/4"13/16"Silicone Rubber
    		-80 to 4001,20000000000000000
     

    Distorted-Thread Cap Nuts

    Image of Product. Bottom orientation. Cap Nuts. Distorted-Thread Cap Nuts.
    For a stronger hold than nylon-insert cap nuts, these have irregularly shaped threads that grip the screw to resist loosening. The threads prevent the nut from backing out in high-vibration applications, but they also increase the effort to install and remove. To get these nuts off, you may need special tools, such as an impact wrench or propane torch. They have a smooth, rounded head that conceals and protects protruding screw threads while creating a finished look. Nuts are not reusable.
    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—Our most corrosion-resistant cap nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    1/2"-13
    		1/2"3/4"13/16"1000000000000000
     
    Highly-Corrosion-Resistant 316 Stainless Steel
    1/2"-13
    		1/2"3/4"13/16"100000000000000
     
    Low-Strength Steel
    Rated Grade 2, Class 6, or lower, these nuts 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.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Fastener Strength
    Grade/Class
    Pkg.
    Qty.
    Pkg.
    Zinc-Plated Steel
    1/2"-13
    		1/2"3/4"13/16"SAE Grade 2
    		5000000000000000
     
    back to top