Cap Plugs | McMaster-Carr

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10,581 Products

Building and Machinery Hardware

Protective Plugs

Insert into holes in pipe, containers, panels, and parts to keep out debris

1,010 products

Protective Caps

Protect just about anything, including pipe, flanges, screws, and posts

1,045 products

Fluid Handling

Tube End Caps

Cover the ends of tube to keep out dirt and debris

396 products

Tube End Plugs

Insert into the ends of tube to keep out dirt and debris

251 products

Tube Fittings

Make threaded, push to connect, barbed, and other types of connections between lengths of tube

363 products

Tubing Flow Stops

Temporarily block water flow to make soldering repairs without waiting for your line to drain

9 products

Pipe Plugs

Insert into the ends of pipe to keep out dirt and debris

1,389 products

Pipe Caps

Cover the ends of pipe to keep out dirt and debris

606 products

Pipe Flanges

Create an access point in a line by bolting two same-size flanges together with a gasket

209 products

Pipe Fittings

Form threaded, barbed, flanged, and other types of connections between lengths of pipe

4 products

Hose and Hose Fittings

Flexible and stronger than tubing; often used to convey liquids and gases under pressure

279 products

Expansion Plugs

Seal pipe and tubing lines when checking for leaks

354 products

Bore Sealing Plugs

Permanently seal unthreaded holes in pneumatic and hydraulic components

69 products

Thermocouple Connector Covers

Shield thermocouple connectors from dust and debris

1 product

Sights

Observe and monitor the contents of pipes, tanks, and other containers

231 products

Breather Vents

Maintain even pressure and vacuum as temperatures change by allowing airflow in tanks and enclosures

14 products

Pressure Test Fittings

Create a temporary connection point for gauges and other testing equipment

28 products

Pressure-Relief Valves

Protect equipment by opening at a set pressure and closing when the pressure drops; for repeated use

17 products

Heat Exchanger Plugs

Plug leaky internal tubes in heat exchangers

17 products

Electrical

Electrical Plugs

Pair with sockets or receptacles to transmit power or data

1,074 products

Electrical Receptacles

Install in a wall or panel to transmit power or data to plugs or sockets

599 products

Electrical Sockets

Pair with plugs or receptacles to transmit power or data

425 products

Electrical Adapters

Change electrical connectors to another type, size, or gender

102 products

Electrical Connector Caps

Protect data connectors when not in use

78 products

Electrical Connector Seals

Add to the front or back of connectors to block out dust, debris, and weather

5 products

Data Port Plugs

Keep dust, debris, and moisture out of unused computer ports

3 products

Electrical Connector Thread Adapters

Join two connectors that both have internal threads

6 products

Data Port Locks

Block USB or Ethernet ports from unauthorized use

9 products

Electrical Connector Contacts

Crimp wire into pins and sleeves to create custom Molex or Amphenol connectors

10 products

Electrical Enclosure Plugs

Block or seal holes in outlet boxes and enclosures to keep out debris, dust, and moisture

77 products

Electrical Enclosure Drains

Release moisture to keep components dry

4 products

Electrical Enclosure Drain Vents

Prevent moisture from getting trapped inside enclosures while letting air flow through

5 products

Heat-Shrink Tubing End Caps

Seal moisture out of crimped electrical connections

26 products

Cold-Shrink Tubing End Caps

Seal crimped electrical connections without heat or tools to protect against moisture

4 products

DIN Rail Caps

Guard the edges of DIN rail from damage and create a finished look

2 products

Light Switch/Receptacles

Combine a switch and receptacle into a single outlet box for a small footprint

1 product

Circuit Breaker Box Filler Plates

Conceal live electrical components in circuit breaker boxes to prevent injury and damage

2 products

Capacitor Boots

Shield capacitors and wire connections to extend their service life and reduce accidental shocks

3 products

Fabricating and Machining

Fixture Plate Plugs

Keep chips and shavings from clogging or damaging unused holes on fixture plates in milling machines

1 product

Fastening and Joining

Retaining Rings

Hold components on a shaft

25 products

Standoff Caps

Create a finished look on standoffs and protect them from dirt and debris

66 products

Quick-Release Pin Receptacles

Secure quick-release pins when you don’t have a through hole

35 products

Quick-Release Pin Retaining Caps

Hold quick-release pins in holes that are oversized or out of round

23 products

Lubricating

Grease Fittings

Create an inlet on equipment and machinery for injecting lubricant; also known as Zerk fittings

365 products

Grease Fitting Caps

Protect grease fittings from dirt, debris, and moisture

14 products

Grease Fitting Adapters

Mate grease fittings when the sizes and thread types don't match

41 products

Grease Fitting Manifolds

Lubricate multiple points with the same amount and type of grease using one grease fitting

3 products

Grease Fitting Repair Tools

Remove and repair broken or clogged grease fittings and re-tap threaded holes

2 products

Grease Fitting Cleaning Tools

Flush out old grease, dirt, and debris from clogged fittings

2 products

Grease Fitting Junction Blocks

Send different types and amounts of grease from multiple grease fittings to lubricate several points

9 products

Grease Fitting Installation Tools

Tap to insert grease fittings in unthreaded holes

2 products

Oil Fittings

Install in engine blocks and other machinery to pour in oil while keeping dust out

36 products

Containers, Storage, and Furniture

Drum Plugs

Seal drum lid openings

19 products

Drum Plug Caps

Access inside drums to fill them

4 products

Drum Locks

Secure drum lids and openings to prevent tampering

3 products

Dust Covers

Stretch over drums, pails, and other objects to keep out dust and debris

16 products

Syringe Caps

Cover syringe tips when not in use to protect them and prevent leaks

13 products

Stacking Caps and Targets

Turn the ends of posts into stackable shelving and rack systems

6 products

Measuring and Inspecting

Hose Coupling Size-Identification Kits

Match your hose coupling to one of the plugs to determine its size without measuring

1 product

Facility and Grounds Maintenance

Sink Drain Stoppers

Plug drains to fill up sinks and tubs

5 products

Sink Drains

Empty liquids from sinks into sewer lines

17 products

Faucet Hole Covers

Close off unused faucet holes intended for soap dispensers and side sprayers

2 products

Floor Drain Trap Seals

Stop sewer gases from escaping through rarely used floor drains if the P-trap dries out

4 products

Drain Cleanouts

Create an access point to inspect and clean floor drain pipelines

3 products

Rebar Caps

Brightly colored to alert workers to exposed rebar and pipe

4 products

Material Handling

Conveyor Guide Mounting Rod Caps

Cover the ends of conveyor guide mounting rods for a finished look

7 products

Heating, Ventilation, and Air Conditioning

Duct and Duct Fittings

Circulate air through HVAC systems using round, rectangular, and fabric duct

36 products

Chimney Pipe and Fittings

Exhaust hot air and fumes from boilers, furnaces, and stoves

21 products

Air Conditioner Service Valve Caps

Seal off AC service valves to prevent refrigerant from leaking out

2 products

Safety Equipment

Fire Hydrant Caps

Pair with a hook-style spanner wrench to quickly cover and uncover fire hydrants

4 products

Fire Hydrant Plugs

Pair with a hook-style spanner wrench to quickly seal fire hydrants and washdown equipment

3 products

Floor Drain Plugs

Prevent oil and other spills from going down your floor drain

3 products

Spill-Control Drain Covers

Block grates and manholes so liquid can't get in and odors can't get out

6 products

Bearing Guards

Shield bearings from dirt, and protect fingers and tools from moving parts

14 products

Power Transmission

Die Spring Screw Caps

Brace springs and control tension in die sets while simplifying maintenance

10 products

Communication

Tamper-Evident Seals

Secure hasps, latches, and other connections to visibly indicate tampering

2 products

Sealing

Drum Plug Gaskets

Form a tighter seal in drum openings than with a drum plug alone

7 products