Hollow Plugs | McMaster-Carr

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5,212 Products

Building and Machinery Hardware

Protective Plugs

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

93 products

Protective Caps

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

1,045 products

Press-Fit Framing Caps

Push into press-fit rails for a finished look that keeps out debris

2 products

Bolt-Together Framing and Fittings

Fasten through equally spaced holes to build and adjust guards, tables, and racks

1 product

Strut Channel Framing and Fittings

Secure fittings in the U-shaped channel to route conduit and pipe or build other structures

78 products

Slip-On Framing and Fittings

Insert rails into fittings and tighten screws to make guards, railings, and racks

25 products

Clamp-On Framing and Fittings

Two-piece fittings let you modify assembly stations, conveyors, and racks without dismantling them

1 product

Locking-Slotted Framing and Fittings

Make platforms, bases, and other structures that stand up to more movement than T-slotted framing

1 product

Lockouts

Ensure that machines stay turned off to prevent accidents during maintenance work

4 products

Protective Feet

Add to furniture and light equipment to protect floors from scratches and wear

73 products

Hand Grips

Cover handles so they're more comfortable and secure to hold

168 products

Keyhead Covers

Color-code your keys for easy identification

2 products

Fluid Handling

Pipe Plugs

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

299 products

Pipe Caps

Cover the ends of pipe to keep out dirt and debris

606 products

Hose and Hose Fittings

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

894 products

Tube and Tube Fittings

Typically more flexible than pipe for carrying liquids and gases in short runs around equipment

241 products

Sights

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

231 products

Pressure-Relief Valves

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

17 products

Breather Vents

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

147 products

Expansion Plugs

Seal pipe and tubing lines when checking for leaks

259 products

Heat Exchanger Plugs

Plug leaky internal tubes in heat exchangers

17 products

Air Vent Valves

Eliminate air pockets from fluid lines to maintain consistent flow and prevent surges

38 products

Electrical

Heat-Shrink Tubing End Caps

Seal moisture out of crimped electrical connections

26 products

Electrical Enclosure Drains

Release moisture to keep components dry

4 products

Electrical Enclosure Plugs

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

77 products

Electrical Enclosure Vents

Attach to sealed enclosures so air can flow to equalize temperature and pressure

10 products

Electrical Enclosure Drain Vents

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

6 products

Weatherheads

Bring power into buildings and protect the entry point from rain and snow

10 products

Electrical-Insulating Wire Caps

Cover live wire ends to protect against shock from accidental contact

3 products

DIN Rail Caps

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

2 products

Cold-Shrink Tubing End Caps

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

4 products

Terminal Covers

Block out dirt and corrosion to protect battery terminals

20 products

Electrical Connector Seals

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

5 products

Battery Vent Caps

Flip open to check water levels and fill wet-cell batteries

1 product

Fuse Block Safety Covers

Prevent accidental shocks when handling fuse blocks and fuses

8 products

Electrical Connector Caps

Protect data connectors when not in use

78 products

Capacitor Boots

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

3 products

Fastening and Joining

Press-Fit Nuts

Push into drilled or punched holes to add threads to thin panels

2 products

Cartridge Sealing Caps

Slip over the tips of adhesive and sealant cartridges to keep contents from hardening

1 product

Measuring and Inspecting

Variance Indicator Caps

Cover and color-code the spindle on your variance indicator

1 product

Fabricating and Machining

Clamp Holding Screw Tips

Cover metal holding screws to protect workpieces from scratches

12 products

Tweezer Tip Caps

Protect tweezer tips from damage

1 product

Lubricating

Grease Fitting Caps

Protect grease fittings from dirt, debris, and moisture

14 products

Material Handling

Valve Stem Caps

Keep dust and debris out of tire valves

2 products

Conveyor Guide Mounting Rod Caps

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

7 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 Covers

Protect drum lids from damage and rust

10 products

Vial Caps

Take samples from vials without removing the cap

3 products

Fuel Caps

Seal fuel tanks on trailers, compressors, and other equipment

2 products

Drum Lids

Replace the lid on your drum

16 products

Pail Lids

Replace the lid on your pail with one that quickly screws open and closed

2 products

Drums

Ship and store large volumes of liquid or dry materials

2 products

Gas Tank Safety Caps

Protect valves on high-pressure gas tanks without having to remove the regulator

Facility and Grounds Maintenance

Sink Drain Stoppers

Plug drains to fill up sinks and tubs

5 products

Chain Link Fencing

Everything you need to build or repair a chain link fence, from posts to gates

16 products

Rebar Caps

Brightly colored to alert workers to exposed rebar and pipe

4 products

Heating, Ventilation, and Air Conditioning

Duct and Duct Fittings

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

145 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 Plugs

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

3 products

Fire Hydrant Caps

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

4 products

Bearing Guards

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

20 products

Toe and Foot Guards

Slip over shoes or boots to shield feet and toes from impact

16 products