Metal Caps | McMaster-Carr

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For Use With

Alcohol-Based Solvents

Deutsch Style Connectors

Grinders for Bits and Burs

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Chicago Fire Department

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Adjustable-Angle Elbow

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Compliant with Exemptions

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Chromate Conversion Coated

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Molybdenum Disulfide Coated

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11,393 Products

Fluid Handling

Pipe and Fittings

Generally thicker and more rigid than tubing for distributing liquids and gases

2,650 products

Tube End Caps

Cover the ends of tube to keep out dirt and debris

342 products

Tube End Plugs

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

122 products

Tube Fittings

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

207 products

Tubing Flow Stops

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

9 products

Hose End Caps

Cover the ends of hose to keep out dirt and debris

129 products

Hose Fittings

Create threaded, barbed, quick-disconnect, and other types of connections between lengths of hose

1,340 products

Hose End Plugs

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

9 products

Hose

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

62 products

Expansion Plugs

Seal pipe and tubing lines when checking for leaks

281 products

Bore Sealing Plugs

Permanently seal unthreaded holes in pneumatic and hydraulic components

69 products

Air Vent Valves

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

32 products

Breather Vents

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

96 products

Pressure-Relief Valves

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

17 products

Sights

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

203 products

Heat Exchanger Plugs

Plug leaky internal tubes in heat exchangers

17 products

Building and Machinery Hardware

Protective Caps

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

84 products

Protective Plugs

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

198 products

Knobs

Position, tighten, and secure fixtures and equipment

437 products

Slip-On Framing and Fittings

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

14 products

T-Slotted Framing and Fittings

The most versatile system, attach fittings along the continuous slots to build virtually anything

24 products

Strut Channel Framing and Fittings

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

47 products

Press-Fit Framing and Fittings

Set up temporary partitions, guards, and displays using only a hammer

1 product

Leveling Mount Inserts

Slip onto equipment and furniture to add threaded-stud leveling feet

97 products

Protective Feet

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

26 products

Door Drip Guards

Divert rain and snow away from door openings

10 products

Lockouts

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

4 products

Electrical

Electrical Connector Caps

Protect data connectors when not in use

35 products

Latching Connectors

Protect connections in wet or harsh environments while keeping them accessible

161 products

Coaxial Connectors

Plugs, sockets, and receptacles to make coaxial connections

52 products

Power Connectors

Plugs, sockets, receptacles, and other connectors for powering equipment

371 products

USB Connectors

Plugs, sockets, and receptacles to make USB connections

17 products

Audio Connectors

Plugs, sockets, receptacles, and adapters to make audio connections

22 products

Metric Circular Connectors

Plugs, sockets, receptacles, and adapters for equipment with metric connections

57 products

RJ45 Plugs

Pair with sockets or receptacles to make Ethernet connections

11 products

Mil. Spec. Connectors

Meet strict military standards or are compatible with Mil. Spec. connectors

94 products

Sure Seal Connectors

A PVC housing keeps out liquids and dust and resists chemicals

6 products

Amphenol Connectors

Attach wires to a circuit board

15 products

CB Radio Sockets

Pair with receptacles to connect CB radios

1 product

Breakaway Connectors

If pulled or stressed, these disconnect without damaging cables and equipment

3 products

Ecomate Connectors

Connect machine tools, robots, and other vibrating equipment

14 products

Ballast Connectors

Avoid exposure to live wires when replacing fluorescent ballasts

2 products

ix Industrial Sockets

Pair with plugs to add ix Industrial connections to printed circuit boards

6 products

Welding Cable Connectors

Plugs and sockets to deliver power to welding cable

9 products

AMP Connectors

Build-your-own and ready-to-use AMP connectors

38 products

Circuit Board Connectors

Connect flat flexible cable to circuit boards

10 products

Molex Connectors

Plugs, sockets, and housings for making Molex connections

105 products

DMX Connectors

Replace damaged plugs and sockets on lighting cables

2 products

Micro 360 Connectors

Plugs and sockets to make signal and data connections in tight spaces

20 products

D-Sub Connectors

Plugs, sockets, and receptacles for connecting computers, monitors, and printers

82 products

Han Connectors

Stackable plugs and sockets to make Han connections

6 products

Wire Splices, Connectors, and Taps

Join wire and protect the connection

377 products

Terminal Covers

Block out dirt and corrosion to protect battery terminals

2 products

USB Cords

Transfer data between computers, printers, and mobile devices

12 products

Metric Circular Cords

Send power and signal to equipment with metric connections

117 products

Electrical Enclosure Plugs

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

55 products

Electrical Enclosure Vents

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

5 products

Electrical Enclosure Drain Vents

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

5 products

Electrical Enclosure Drains

Release moisture to keep components dry

2 products

Outlet Box Covers

Enclose wiring for outlets and switches or block off unused components

68 products

Outlet Boxes

House electrical components such as on-off switches, receptacles, and dimmer knobs

5 products

Weatherheads

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

10 products

Fastening and Joining

Cap Nuts

Cover and protect threads while adding a finished look; also known as acorn nuts

402 products

Retaining Rings

Hold components on a shaft

305 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

36 products

Quick-Release Pin Retaining Caps

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

23 products

Press-Fit Nuts

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

2 products

Threaded Inserts

Create new threads or repair stripped threads

1 product

Socket Retaining Rings

Secure sockets and adapters to impact tools

3 products

Containers, Storage, and Furniture

Drum Plug Caps

Access inside drums to fill them

4 products

Drum Plugs

Seal drum lid openings

13 products

Drum Locks

Secure drum lids and openings to prevent tampering

3 products

Drum Lids

Replace the lid on your drum

16 products

Drum Covers

Protect drum lids from damage and rust

2 products

Drum Locking Rings

Clamp lids onto drums for a tight seal

7 products

Fuel Caps

Seal fuel tanks on trailers, compressors, and other equipment

2 products

Gas Tank Safety Caps

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

1 product

Gas Tank Safety Collars

Protect valves on acetylene tanks without having to remove the regulator

1 product

Hard Hat Racks

Keep hard hats close at hand, but out of the way

5 products

Stacking Caps and Targets

Turn the ends of posts into stackable shelving and rack systems

6 products

Heating, Ventilation, and Air Conditioning

Duct and Fittings

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

133 products

Chimney Pipe and Fittings

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

20 products

Air Conditioner Service Valves

Tap into refrigerant lines to drain and fill your system

18 products

Safety Equipment

Fire Hydrant Caps

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

6 products

Fire Hydrant Plugs

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

3 products

Toe and Foot Guards

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

14 products

Earmuffs

Dampen loud noises to protect hearing

6 products

Hard Hats

Protect your head from falling objects

1 product

Bearing Guards

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

6 products

Floor Drain Plugs

Prevent oil and other spills from going down your floor drain

3 products

Lubricating

Grease Fitting Adapters

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

41 products

Grease Fittings

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

361 products

Grease Fitting Manifolds

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

3 products

Grease Fitting Junction Blocks

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

9 products

Grease Fitting Repair Tools

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

2 products

Grease Fitting Installation Tools

Tap to insert grease fittings in unthreaded holes

2 products

Grease Fitting Cleaning Tools

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

2 products

Facility and Grounds Maintenance

Drain Cleanouts

Create an access point to inspect and clean floor drain pipelines

3 products

Faucet Hole Covers

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

1 product

Sink Drain Strainers

Catch debris to prevent clogs and plug drains to fill sinks

6 products

Sink Drains

Empty liquids from sinks into sewer lines

34 products

Chain Link Fencing

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

5 products

Fence Posts

Secure and hold up fencing

10 products

Rebar Caps

Brightly colored to alert workers to exposed rebar and pipe

2 products

Fabricating and Machining

Clamp Holding Screws

Replace worn holding screws in clamps or customize with different sizes or styles

52 products

Vise Jaw Liners

Place over vise jaws to protect workpieces from marring

46 products

Fixture Plate Plugs

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

6 products

Tooling Ball Covers

Protect tooling balls when not in use

1 product

Sanding Bits

Smooth out small, recessed, and hard-to-reach areas, and also remove paint and rust

206 products

Power Transmission

Die Spring Screw Caps

Brace springs and control tension in die sets while simplifying maintenance

10 products

Material Handling

Valve Stem Caps

Keep dust and debris out of tire valves

1 product

Sealing

Drum Gaskets

Seal lids onto steel and stainless steel drums

6 products