Thread Protector Caps | McMaster-Carr

	REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration, Evaluation, Authorization and Restriction of Chemicals)

REACH Compliant

	For Pipe Size For Pipe Size

1/16
1/8
1/4
3/8
1/2
3/4
1
1 1/4
1 1/2
2
2 1/2
3
3 1/2
4
5
6
8
10
12
14
16
18
20

	Height Height

	Nut Type Nut Type


Cap	Hex

Locknut

	For Connection Type For Connection Type

	For Thread Diameter For Thread Diameter

	Cap Nut Profile Cap Nut Profile


Low	Standard

Extra-Wide High	High

Open End

	For Surface Type For Surface Type

2,311 Products

Caps

Round Caps

Slide these flexible vinyl caps on and they conform for a snug fit.

Heavy Duty Round Caps

Made of rigid plastic, these caps are more wear resistant than vinyl caps but not as flexible.

Metal Round Caps

More durable than plastic caps, these provide the most protection from abrasion and impact.

Domed Round Caps

The large domed head extends beyond the diameter of your pipe, rod, or tubing for added protection.

Sure-Grip Round Caps

A long, textured pull tab provides a sure grip for quick removal even when wearing gloves.

Tethered Round Caps

The tethered design allows frequent access to the ends of pipe, tubing, and other round objects without ever misplacing the cap.

Hanging Round Caps

Slide these caps over a tool handle or other round object and use the eye to hang it.

Roll-Resistant Round Caps

Commonly used on shipping tubes, these caps have a square head to prevent round objects from rolling during shipping and storage.

Chemical-Resistant Round Caps

These caps have excellent chemical resistance for masking parts during chemical finishing applications such as plating and anodizing.

High-Temperature Round Caps

Good for electroplating, paint baking, and powder-coating applications, these caps withstand temperatures up to 440° F or 570° F.

Food Industry Round Caps

Made of FDA listed materials, these caps are suitable for food contact.

Antistatic Round Caps

Keep equipment safe from electrical currents with these caps that have a surface resistivity of less than 10¹² ohms.

Conductive Round Caps

With a surface resistivity of less than 10⁵ ohms, these caps not only dissipate electrical charges, but can be used as an electrical shield.

Tapered Caps

These flexible plastic caps are tapered to fit a variety of unthreaded and threaded objects.

Tapered Cap Assortments

Keep tapered caps of various sizes on hand to solve whatever problems arise. These flexible plastic caps are tapered to fit a variety of unthreaded and threaded objects.

High-Temperature Tapered Caps

Made of silicone, these caps withstand temperatures of 450° F for electroplating, paint-baking, and powder-coating applications. All of these flexible caps are tapered to fit a variety of unthreaded and threaded objects.

Threaded Caps

Protect externally threaded components from contaminants during fabrication and storage.

Tear-Tab Caps

Push these caps onto pipe and fittings, then tear their tab to break the seal for easy removal.

Propane Tank Tear-Tab Caps

Designed for propane tanks such as those on forklifts and grills, these caps protect tank valves during storage and transit. Push the caps onto the valves, then tear their tab to break the seal for easy removal.

Flexible Pull-Tab Caps

Slide these flexible vinyl caps on and they conform for a snug fit. Pull the tab for easy removal.

High-Visibility Pull-Tab Caps

A vibrant yellow color makes these caps stand out. They are made of flexible rubber that conforms for a snug fit. Pull the tab for easy removal.

Squeeze Top Caps

Squeeze the dome top to remove these caps. They're commonly used as thread protectors.

Heat-Shrink Round Caps

Permanently seal pipe, tubing, conduit, and even crimped electrical connections. Slide these flexible caps on and use a heat gun to tightly shrink them to the shape of whatever they are covering. Their outer surface shrinks while the inner wall flows into voids to create a sealed connection.

Stretchable Elastic Caps

Similar to a shower cap, these caps have an elastic band that allows them to stretch and cover a variety of shapes in a range of sizes.

Stretchable Sealing Caps

Tug on the pull tabs to stretch these caps onto the tips of bottles, beakers, flasks, and cylinders, creating an airtight seal.

Fastener Caps

Hex Nut Caps

Sized to fit hex nuts, these caps snap on for a tight hold and provide protection from corrosion.

Threaded Standoff Caps

Give open-ended standoffs a finished look and protect them from dirt and debris.

Screw Caps

Conceal and protect the tops of socket head or button head screws.

Hinged Fastener Caps

A one-piece hinged design allows frequent access to screw heads without misplacing the top. To conceal and protect the entire screw head, insert your screw through the hole in the base and flip the hinged top over.

Snap-On Fastener Caps

To conceal and protect the entire screw head, insert your screw through the hole in the base and snap on the top.

Flange Caps

Adhesive-Back Flange Caps

Stick these caps on the raised surfaces of flanges or other flat surfaces for extra protection during transport and storage.

Flange Caps

Snap these caps into flange bolt holes to safeguard pipe flanges during shipping, storing, and finishing applications. They all have a thick center pad to protect the flange opening and pipe threads from damage.

SAE Flange Caps

Protect SAE hydraulic flanges during shipping, storing, and finishing applications.

Rebar Caps

Keep personnel safe from protruding rebar and pipe. Made of rigid plastic, these durable safety caps are bright orange or yellow for excellent visibility.

Tapered Plugs

Hollow Tapered Plugs

The hollow construction allows these plugs to compress for a snug fit in threaded and unthreaded holes of varying diameters.

Hollow Tapered Plug Assortments

Keep hollow tapered plugs of various sizes on hand to solve whatever problems arise. The hollow construction allows these plugs to compress for a snug fit in threaded and unthreaded holes of varying diameters.

Miniature Tapered Plugs

Sized to fit small openings, these tiny plugs fit snugly but can be removed easily using the flange. Their tapered design fits a range of hole diameters.

Pull-Ring Tapered Plugs

Pull the two built-in rings to quickly remove these plugs. All are tapered to fit a range of hole diameters.

Corks

Lightweight and moisture resistant, these plugs are laboratory-grade 100% natural cork. They’re tapered to fit a range of hole diameters.

Tapered Plugs

Often used as laboratory stoppers, these rubber plugs have good impact and abrasion resistance. They’re tapered to fit a range of hole diameters.

Expandable Tapered Plugs

Place a plug into an opening and tighten the wing nut—the sides expand to create a seal in holes of varying diameters.

Hollow High-Temperature Tapered Plugs

The hollow construction allows these plugs to compress for a snug fit in threaded and unthreaded holes of varying diameters. Good for electroplating, paint baking, and powder-coating applications, they withstand temperatures up to 450° F.

High-Temperature Tapered Plugs

Good for electroplating, paint baking, and powder-coating applications, these plugs withstand temperatures up to 570° F. All are tapered to fit a range of hole diameters.

Expandable High-Temperature Tapered Plugs

Place a plug into an opening and tighten the wing nut—the sides expand to create a seal in holes of varying diameters. Good for paint baking and powder-coating applications, these plugs withstand temperatures up to 450° F.

Miniature High-Temperature Tapered Plugs

Sized to fit small openings, these tiny plugs fit snugly but can be removed easily using the flange. They withstand temperatures up to 470° F, which makes them good for electroplating, paint baking, and powder-coating applications. All are tapered to fit a range of hole diameters.

Chemical-Resistant Tapered Plugs

These plugs have excellent chemical resistance for masking parts during chemical finishing applications such as plating and anodizing. Their tapered design fits a range of hole diameters.

Food Industry Tapered Plugs

Made of FDA listed materials, these plugs are suitable for food contact. They're tapered to fit a range of hole diameters.

Round Plugs

Threaded Round Plugs for 37° Flared Tube

Designed to fit into 37° flared connections such as those found on JIC and SAE fittings, these plugs protect internally threaded connections from contaminants during fabrication and storage.

Threaded Round Plugs for Straight-Thread Pipe

Seal tube and hose fittings to keep their straight threads protected from contaminants during fabrication and storage.

Threaded Round Plugs for NPT Pipe

Protect internally threaded NPT connections from contaminants during fabrication and storage.

High-Temperature Round Plugs for NPT Pipe

These plugs withstand temperatures up to 600° F to protect internally threaded NPT connections from contaminants during electropainting, paint baking, and powder coating applications.

Threaded Round Plugs for BSPT Pipe

Safeguard internally threaded BSPT connections from contaminants during fabrication and storage.

High-Temperature Pull-Through Round Plugs

Good for electroplating, paint baking, and powder-coating applications, these plugs withstand temperatures up to 600° F. To form a tight seal, use the smaller end of the plug to pull the larger end into a through hole.

Flanged Pull-Through Round Plugs

Designed with a flange, these plugs protect countersunk holes during anodizing, electroplating, paint baking, and powder-coating applications. All withstand temperatures up to 600° F. Use the smaller end of the plug to pull the larger end into a through hole to form a tight seal.

Chemical-Resistant Pull-Through Round Plugs

These plugs have excellent chemical resistance for masking parts during chemical finishing applications such as plating and anodizing. Use the smaller end of the plug to pull the larger end into a through hole to form a tight seal.

Miniature Pull-Through Round Plugs

Also known as mouse tails, these tiny plugs fit through-hole IDs as small as 0.022”, 0.025", or 0.03”.

Round Plugs

The hollow construction allows these plugs to compress for a snug fit in threaded and unthreaded holes.

Sealing Plugs

With a compressible flanged top, these plugs are designed to seal the ends of copper tubing often used in water supply lines, refrigerant lines, and HVAC compressors. All are sized to fit standard copper tube dimensions.

Antistatic Round Plugs

Keep equipment safe from electrical currents with these plugs that have a surface resistivity of less than 10¹² ohms.

Conductive Round Plugs

With a surface resistivity of less than 10⁵ ohms, these plugs not only dissipate electrical charges, but can be used as an electrical shield.

Snap-In Round Plugs

Flexible ridges or straps hold these plugs in place and allow them to fit a range of hole diameters.

Pull-Tab Round Plugs

A time-saving alternative to threaded plugs, these plugs press in place and have an ergonomic pull tab for quick and easy removal. Use them to temporarily protect holes in objects from contaminants during storage, painting, and light fabrication.

Square Plugs

Push-In Square Plugs

Push these plugs into an opening and friction holds them in place.

Snap-In Square Plugs

Flexible ridges or straps hold these plugs in place.

Metal Square Plugs

More durable than plastic plugs, these provide the most protection from abrasion and impact. Use them to eliminate sharp edges and create a finished look on metal fence and machine-guard posts. Drive them in place with a hammer for a secure fit.

Domed Square Plugs

Often used on metal furniture, these plugs provide a finished look on posts and tubes. Snap them into place and their flexible ridges will provide a secure grip.

Rectangular Plugs

Snap-In Rectangular Plugs

Flexible ridges securely hold these plugs in place and allow them to fit a range of hole sizes.

Push-In Rectangular Plugs

Push these plugs into an opening and friction holds them in place.

Panel Plugs

Plastic Snap-In Panel Plugs

Tapered prongs or a snap-in ring securely hold these plugs in place.

Metal Snap-In Panel Plugs

Made of steel, these are our most durable plugs for panels. Tapered prongs snap into the hole to securely hold them in place.

Metal Snap-In Panel Plug Assortments

Keep metal snap-in plugs of various sizes on hand to solve whatever problems arise. Made of steel, these plugs are our most durable plugs for panels. Their tapered prongs snap into holes to securely hold them in place.

Vented Snap-In Panel Plugs

Vents in the top allow air circulation and permit heat and fumes to escape. These plugs have tapered prongs that snap into the hole to securely hold them in place.

Push-In Panel Plugs

Push these plugs into place for a finished appearance on both sides of a panel.

Vented Locking Panel Plugs

Vents in the top allow air circulation and permit heat and fumes to escape. All of these plugs have wings that expand against the sides of the hole to lock them in place.

Locking Panel Plugs

The wings on these plugs expand against the sides of a hole to lock them in place.

Clear Locking Panel Plugs

These plugs are see-through to provide visibility and light transmission. They have wings that expand against the sides of the hole to lock them in place.

Sealing Panel Plugs

The wings on these plugs expand against the sides of a hole to form a liquid-tight seal. Pierce the plugs with round wire, cable, or tubing and they function as a grommet to create insulated holes.

Hydraulic Sealing Plugs

Permanently seal unthreaded holes in pneumatic and hydraulic components.

Ethernet Port Plugs

Shield unused RJ45 type ports on computers and other electronic equipment from debris and moisture.

Expansion Plugs for Castings

Also known as freeze plugs, these are commonly used to permanently seal the shallow holes left in a component during the casting process.

Cap Nuts

Sanitary Low-Profile Cap Nuts

Certified by EHEDG (European Hygienic Engineering and Design Group) to meet sanitary design standards, these cap nuts fit into tight spaces to cover and seal exposed threads in your food processing facility.

Plastic Cap Nuts

These nylon 6/6 cap nuts are chemical resistant, nonconductive, and lightweight.

Metric Plastic Cap Nuts

These metric nylon 6/6 cap nuts are chemical resistant, nonconductive, and lightweight.

Low-Strength Steel Cap Nuts

About half the strength of medium-strength steel cap nuts, use them in light duty fastening applications, such as securing access panels.

Metric Low-Strength Steel Cap Nuts

These metric nuts are about half the strength of medium-strength steel cap nuts. Use them in light duty fastening applications, such as securing access panels.

Metric High-Strength Steel Cap Nuts—Class 10

Comparable in strength to Class 10.9 bolts, these nuts are about 25% stronger than medium-strength steel cap nuts.

High-Strength Steel Cap Nuts—Grade 8

These nuts are about 25% stronger than medium-strength steel cap nuts.

Medium-Strength Steel Cap Nuts

These Grade 5 cap nuts are suitable for fastening most machinery and equipment.

Metric 18-8 Stainless Steel Cap Nuts

These metric cap nuts have good chemical resistance and may be mildly magnetic.

18-8 Stainless Steel Cap Nuts

These cap nuts have good chemical resistance and may be mildly magnetic.

Metric Super-Corrosion-Resistant
316 Stainless Steel Cap Nuts

These metric cap nuts have excellent resistance to chemicals and salt water.

Super-Corrosion-Resistant
316 Stainless Steel Cap Nuts

These cap nuts have excellent resistance to chemicals and salt water.

Aluminum Cap Nuts

One-third the weight of steel, aluminum cap nuts resist corrosion in wet environments.

Brass Cap Nuts

Brass cap nuts are corrosion resistant in wet environments and electrically conductive.

Steel Extra-Wide High-Hex Cap Nuts

Known for their strength, these steel cap nuts have a black-oxide finish to resist corrosion in dry environments.

Stainless Steel Extra-Wide High-Hex Cap Nuts

Stainless steel cap nuts have excellent corrosion resistance in most environments.

Low-Profile Cap Nuts

Low-profile cap nuts are about 20% shorter than standard cap nuts for use in low-profile applications.

Sanitary Thread Caps

Cover exposed threads with these caps to help prevent bacteria growth in food processing areas and other sanitary environments.

High-Profile Cap Nuts

These cap nuts offer at least three-times the thread depth of standard cap nuts and are about twice the height.

Nylon-Insert Cap Locknuts

The nylon cap covers and grips the threads to resist loosening.

Metric Nylon-Insert Cap Locknuts

A nylon insert on these metric nuts prevents vibration from loosening them, and a domed head protects the threads at the end of the bolt from damage and debris.

Distorted-Thread Cap Locknuts

An irregularly shaped thread grips the bolt for a stronger hold than nylon-insert cap locknuts.

Open-End Cap Nuts

The dome is open so these cap nuts can be used on bolts of any length.

18-8 Stainless Steel Socket Head Screws

Chrome-Plated Plugs for Stainless
Steel Socket Head Screws

Insert these plugs into the drive socket to block debris and provide a finished look.

18-8 Stainless Steel Socket Head Screws

Use these general purpose 18-8 stainless steel screws for a variety of fastening applications. They have good chemical resistance.

Cap Nut Assortments

Cap nuts cover and protect threads while providing a finished appearance.

Storage and Waste Containers

Dust Caps for Drums

Protect contents from dirt, dust, and other contaminants with these caps.

Antistatic Dust Caps for Pails

Caps are made with an additive that prevents static charge from building up on the surface.

Antistatic Dust Caps for Drums

An additive on these caps prevents static charge from building up on the surface.

Dust Caps for Pails

Stretch these plastic caps over the tops of pails to keep out dust, bugs, and other debris.