Locking Caps | McMaster-Carr

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400 Nickel

Acrylic/Cotton Fabric

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Fitting Type

Pipe Size

Shape

Adjustable-Angle Elbow

Color

Brown/Dark Brown/White

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Chicago Fire Department

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Alcohol-Based Solvents

Deutsch Style Connectors

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Adjustable Heel Strap with Buckles

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Band-and-Buckle Clamp

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DFARS Specialty Metals

16,618 Products

Most Likely Products

Protective Caps

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

1,045 products

Pipe Caps

Cover the ends of pipe to keep out dirt and debris

606 products

Tube End Caps

Cover the ends of tube to keep out dirt and debris

396 products

Protective Plugs

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

1,010 products

Pipe Plugs

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

1,389 products

All Results

Fluid Handling

Pipe Caps

Cover the ends of pipe to keep out dirt and debris

606 products

Pipe Plugs

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

1,389 products

Pipe Flanges

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

1,167 products

Pipe Fittings

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

4 products

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

466 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

155 products

Hose Fittings

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

1,387 products

Hose End Plugs

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

41 products

Hose

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

65 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

Air Vent Valves

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

38 products

Breather Vents

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

147 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

231 products

Thermocouple Connector Covers

Shield thermocouple connectors from dust and debris

1 product

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

1,045 products

Protective Plugs

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

1,010 products

T-Slotted Framing and Fittings

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

127 products

Strut Channel Framing and Fittings

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

112 products

Slip-On Framing and Fittings

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

27 products

Bolt-Together Framing and Fittings

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

1 product

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

Press-Fit Framing and Fittings

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

2 products

Knobs

Position, tighten, and secure fixtures and equipment

483 products

Protective Feet

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

153 products

Leveling Mount Inserts

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

113 products

Leveling Mounts

Level machines and workbenches on uneven surfaces, reduce vibration, and protect floors

10 products

Hand Grips

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

183 products

Keyhead Covers

Color-code your keys for easy identification

2 products

Door Drip Guards

Divert rain and snow away from door openings

13 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

78 products

Electrical Plugs

Pair with sockets or receptacles to transmit power or data

1,074 products

Electrical Sockets

Pair with plugs or receptacles to transmit power or data

664 products

Wire Splices, Connectors, and Taps

Join wire and protect the connection

371 products

Wire Splice Covers

Seal out dust and moisture to protect electrical connectors

3 products

Wire Splice Bits

Install twist-on wire splices using a power screwdriver or drill

2 products

Wire Splice Screwdrivers

Install twist-on wire splices

2 products

Electrical Adapters

Change electrical connectors to another type, size, or gender

107 products

Data Port Plugs

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

3 products

Terminal Covers

Block out dirt and corrosion to protect battery terminals

20 products

Terminal and Splice Kits

Maintain a supply of extra terminals and splices to join and terminate wire

17 products

Data Port Locks

Block USB or Ethernet ports from unauthorized use

9 products

Electrical Connector Clips

Attach to data connectors to lock them in place, repair them, or color code them

4 products

Electrical Connector Contacts

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

13 products

Electrical Connector Seals

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

5 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 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

Heat-Shrink Tubing End Caps

Seal moisture out of crimped electrical connections

26 products

Electrical-Insulating Wire Caps

Cover live wire ends to protect against shock from accidental contact

3 products

Cold-Shrink Tubing End Caps

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

4 products

Outlet Boxes

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

7 products

Outlet Box Covers

Enclose wiring for outlets and switches or block off unused components

86 products

DIN Rail Caps

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

2 products

Weatherheads

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

10 products

Battery Vent Caps

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

1 product

Capacitor Boots

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

3 products

Circuit Breaker Box Filler Plates

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

2 products

Fuse Block Safety Covers

Prevent accidental shocks when handling fuse blocks and fuses

8 products

Fastening and Joining

Cap Nuts

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

423 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

35 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

Cartridge Sealing Caps

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

1 product

Socket Retaining Rings

Secure sockets and adapters to impact tools

39 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

Drum Lids

Replace the lid on your drum

16 products

Drum Covers

Protect drum lids from damage and rust

10 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

Dust Covers

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

16 products

Hard Hat Bags

Protect your hard hat from sunlight and other damaging elements to extend its life

1 product

Vial Caps

Take samples from vials without removing the cap

3 products

Pail Lids

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

2 products

Helmet Bags

Carry your helmet and shield it from scratches, dents, and rain

1 product

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

Hard Hat Racks

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

5 products

Knife Sheaths

Safely store knives while protecting them from damage

7 products

Pegboard Hook End Caps

Slide onto the end of pegboard hooks to protect items from scratches

2 products

Lubricating

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 Fittings

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

365 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

Safety Equipment

Bandanas

Keep sun, dust, and sweat off your face

3 products

Hats

Shield your head from sun, rain, cold, and sparks

28 products

Hard Hat Liners

Layer under your hard hat for extra warmth

16 products

Hard Hats

Protect your head from falling objects

52 products

Hard Hat Windsocks

Stretch over your hard hat to block wind and cold

5 products

Hard Hat Cooling Pads

Soak in water to keep your head cool

5 products

Clothing Kits

Head-to-toe protection from electrical arc flashes, chemical splashes, welding sparks, and more

12 products

Hair Covers

Catch stray hairs before they contaminate food

11 products

Hoods

Shield your head and neck from dirt, heat, cold, and electrical and welding sparks

30 products

Bump Caps

Guard against minor head bumps and scrapes

42 products

Earplugs

Protect your hearing in loud environments without the bulk of earmuffs

82 products

Toe and Foot Guards

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

16 products

Bump Cap Inserts

Tuck inside a baseball cap to protect your head from bumps and scrapes

4 products

Face Shields

Protect your face from dirt, chemical splashes, and electrical and welding sparks

3 products

Ear Warmers

Wrap behind your head to shield your ears from the cold and wind

1 product

Bicycle Helmets

A multi-directional impact protection system (MIPS) reduces injury risk

1 product

Neck Gaiters

Protect your neck and face from cold, heat, flames, and electrical hazards

5 products

Earmuffs

Dampen loud noises to protect hearing

21 products

Sweatbands

Absorb sweat from your head or arms

8 products

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

Bearing Guards

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

20 products

Spill-Control Drain Covers

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

7 products

Floor Drain Plugs

Prevent oil and other spills from going down your floor drain

3 products

Heating, Ventilation, and Air Conditioning

Duct and Duct Fittings

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

145 products

Air Diverters

Guide air toward your workspace or deflect unwanted drafts

9 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

Air Conditioner Service Valves

Tap into refrigerant lines to drain and fill your system

15 products

Fabricating and Machining

Clamp Holding Screw Tips

Cover metal holding screws to protect workpieces from scratches

12 products

Clamp Holding Screws

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

52 products

Tweezer Tip Caps

Protect tweezer tips from damage

1 product

Vise Jaw Liners

Place over vise jaws to protect workpieces from marring

50 products

Jaw Covers for Pliers

Cover the jaws of slip-joint pliers to protect the finish of your workpiece

2 products

Fixture Plate Plugs

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

1 product

Rotary Tool Nose Caps

Attach to the end of Dremel grinders for quick accessory changes without extra tools

1 product

Sanding Bits

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

173 products

Facility and Grounds Maintenance

Flush Valve Replacement Parts

Replace virtually any part in the most common flush valve brands

5 products

Sink Drain Stoppers

Plug drains to fill up sinks and tubs

5 products

Sink Drains

Empty liquids from sinks into sewer lines

40 products

Sink Drain Strainers

Catch debris to prevent clogs and plug drains to fill sinks

6 products

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

2 products

Protective Coatings

Shield surfaces from the surrounding environment

1 product

Chain Link Fencing

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

6 products

Fence Posts

Secure and hold up fencing

7 products

Rebar Caps

Brightly colored to alert workers to exposed rebar and pipe

4 products

Shampoo Caps

Remove contaminants from your hair with no rinsing required

2 products

Material Handling

Conveyor Guide Mounting Rod Caps

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

7 products

Valve Stem Caps

Keep dust and debris out of tire valves

2 products

Ladder Pads

Cushion the top of ladders to protect surfaces

1 product

Pallet Load Covers

Fit over boxes on pallets to shield the tops and edges from strapping gouges and impact

1 product

Power Transmission

Die Spring Screw Caps

Brace springs and control tension in die sets while simplifying maintenance

10 products

Communication

Labels

Stick onto items to identify or convey information about them

17 products

Tamper-Evident Seals

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

2 products

Marking Cones

Designate areas for material identification, inventory control, and pallet staging

6 products

Headsets

Make hands-free calls from your computer, smartphone, or other device

3 products

Measuring and Inspecting

Variance Indicator Caps

Cover and color-code the spindle on your variance indicator

1 product

Caliper Battery Covers

Protect the battery inside your caliper

8 products

Voltage Detectors

Check for voltage in receptacles, cables, and electrical components

3 products

Sealing

Drum Plug Gaskets

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

7 products

Drum Gaskets

Seal lids onto steel and stainless steel drums

6 products