How to choose caps and plugs

Range of different sized, coloured and shaped caps and plugs

Choosing the right cap or plug to protect your application can be challenging. Our caps & plugs application guide provides an easy way to choose the perfect solution by thread or hole size. Start by determining whether you need a cap or a plug, identify your application’s thread or hole size, then use the charts to select the Essentra product that will work best for you.

Our application guide will provide multiple solutions for your needs, so if you’re not sure which one will work best, request free samples today to ensure proper fit and function.

How to choose the right cap or plug

Consider your environment

There are various environmental factors to consider when protecting your application:

  • Contamination - Are dirt and dust present?
  • Temperature - At what temperature range is your application operating?
  • Vibration - Is your application exposed to vibration or movement?
  • Pressure – Are there any type of air or fluid pressure testing requirements?

Understand your application

Working with multiple applications can bring different variables. First, think about whether you need to protect or mask:

  • Protection – Consider what part requires protecting and how the cap or plugs needs to perform. For example, if you are protecting a profile with an interior thread, you may select a threaded plug or if the application requires shielding against entry or escape of liquids, then an o-ring could be applied.
  • Masking – Consider the surface area and the complexities of the masking process, which can include painting, blasting or high-temperature drying. For example, if you are masking a number of holes in a high-temperature environment, you may select a high-temperature flangeless silicone plug that includes tapered rings to allow a variety of hole diameters to be masked.

Identify the right material

One of the most critical environmental factors to consider is whether or not your application is exposed to heat. If heat tolerance is required, consider a high temp vinyl, EPDM or silicone cap or plug which can operate safely from 425° F up to 600° F.

Another consideration is whether or not the cap or plug is required to withstand a high impact environment. Softer materials such as PVC and EPDM are more flexible to impact versus LDPE or HDPE.

Think about your production process

Understanding your production process allows you to consider how caps and plugs can be applied. These can vary from manual to tool-based processes.

A push fit cap or flanged plug can be applied to fit multiple profiles. This allows for fast hand application, which is essential if you are looking to save time. For tool based processes, a cross head threaded plug can be used.

Consider the removal process

Ease and speed of removal might be a factor for your production environment. Protection for threads or profiles must be carefully removed, which may take time. Using a push fit product versus a threaded one can save time on removal, which saves time in your production schedule. To increase ease of removal, consider a cap or plug with an ergonomic pull tab or flange, which can inject speed and efficiency of the removal process.
 

Do I need a cap or a plug?

  • Caps fit snugly on the outside of a component to protect external threaded and non-threaded ends
  • Plugs grip the inside of a component to protect internal threads or holes
  • Both protect against dirt and dust from entering your component
Caps on production line

Caps and Plugs applications

Caps and plugs prevent dirt, dust, moisture, liquids and any other contaminants from entering the opening during manufacturing, masking, storage and transportation. Some can be used multiple times and many are versatile enough for different stages in processes. We recommend that you try before you buy – ask us for free samples.

Caps and Plugs for protection during storage and transportation

Tapered Cap and Tapered Plug
  1. Recommended: Tapered Cap and Tapered Plug
  2. Common uses: Storage and transportation
  3. Other reasons why:
  • Plugs multiple inner diameters
  • Caps multiple outside diameters
  • Tapered caps and plugs made of Low Density Polyethylene (LDPE), a rigid, yet soft material
Parallel Protection Plugs
  1. Recommended: Parallel Protection Plugs
  2. Common uses: Manufacturing, storage and transportation
  3. Other reasons why:
  • Resists shredding
  • Ideal for threaded applications
  • Protects against dirt, moisture and corrosion
  • Made of Low Density Polyethylene (LDPE), a rigid, yet soft material
Standard Size Pipe Caps
  1. Recommended: Standard Size Pipe Caps
  2. Common uses: Assembly, storage and transportation
  3. Other reasons why:
  • Low cost and high quality
  • Internal ribs ensure a tight fit and release after pressure build up
  • Made of Low Density Polyethylene (LDPE), a rigid, yet soft material
Finned Stud Caps
  1. Recommended: Finned Stud Caps
  2. Common uses: Manufacturing, storage and transportation
  3. Other reasons why:
  • Protects a wide range of studs
  • Internal fins provide a strong hold and are flexible for use on various diameters
  • Comes with grip to ease removal and without grip
  • Made of Low Density Polyethylene (LDPE), a rigid, yet soft material

Caps and Plugs for protection against liquid ingress

Threaded O-Ring Plugs
  1. Recommended: Threaded O-Ring Plugs
  2. Common uses: Hydraulics
  3. Other reasons why:
  • Can be applied or removed by hand, hex wrench or screwdriver
  • Compressing flange lip and O-Ring provide water tight seal for superior leakage protection
  • Available in a variety of threads
  • Available in: Polypropylene (PP) for good chemical resistance, High Density Polyethylene (HDPE) with serrated grip or Nylon for strength, abrasion resistance
Grease Fitting Caps
  1. Recommended: Grease Fitting Caps
  2. Common uses: Mechanical systems
  3. Other reasons why:
  • Protects critical components from dirt and moisture
  • Easy to apply
  • Inner lip provides secure fit
  • Made of flexible PVC, which stands up to high temperatures

Caps and Plugs for easy application and removal

Pull-Tab Caps
  1. Recommended: Pull-Tab Caps
  2. Common uses: Storage and transportation – PVC / Hydraulic hoses – EVA
  3. Other reasons why:
  • Large pull tab for easy removal
  • Available in PVC for flexibility and airtight seal
  • Available in Ethylene Vinyl Acetate (EVA) for tensile strength, toughness and flexibility
Side Pull Plugs
  1. Recommended: Side Pull Plugs
  2. Common uses: Manufacturing, storage and transportation
  3. Other reasons why:
  • Protects threaded or non-threaded components
  • Pull tab feature designed for easy removal
  • Available in Thermoplastic Rubber (TPR)
  • Available in Low Density Polyethylene (LDPE)
  • Resists acid
Tear Tab Caps
  1. Recommended: Tear Tab Caps
  2. Common uses: Manufacturing, storage and transportation
  3. Other reasons why:
  • When tab is pulled, cap splits open for quick removal
  • Suitable as NPT thread plug, and UNF
  • Made of Low Density Polyethylene (LDPE) to protect from damage
Tapered Round Plugs with Flange
  1. Recommended: Tapered Round Plugs with Flange
  2. Common uses: Storage and transportation
  3. Other reasons why:
  • Excellent protection from damage, dirt, moisture and corrosion
  • Designed as both a cap and a plug
  • Wide flange keeps plug from being accidentally pushed down through the mating part
  • Flange enables easy removal
  • Tapered design can plug or cap multiple diameters
  • Made of Low Density Polyethylene (LDPE) to protect from damage
Snap Fit Plugs
  1. Recommended: Snap Fit Plugs
  2. Common uses: Manufacturing, storage and transportation
  3. Other reasons why:
  • Centre tab allows for a strong grip for easy tightening and removal
  • Suitable as a metric threaded cap, and for BSP and UNF threads
  • Made of Low Density Polyethylene (LDPE) to protect from damage

Caps and Plugs for end use

Sheet Metal Plugs
  1. Recommended: Sheet Metal Plugs
  2. Common uses: Automotive, specialist vehicles
  3. Other reasons why:
  • Push in plugs for panels designed to cover holes in sheet metal
  • Easy to fit with simple push and remove
  • No fastening required
  • Secure fit
  • Attractive finish
  • Made of hard, long-lasting Nylon
Secure Cover Caps
  1. Recommended: Secure Cover Caps
  2. Common uses: Furniture, outdoor equipment
  3. Other reasons why:
  • Snaps securely into place with ease
  • Conceals and protects bolt head or nut
  • Available in different colours and can be mixed and matched
  • Made of Polypropylene (PP) for good impact strength and pliability
Bolt Protection Caps
  1. Recommended: Bolt Protection Caps
  2. Common uses: Furniture, outdoor equipment
  3. Other reasons why:
  • Protects washers, bolts and nuts against weathering and tampering
  • Gives application finished appearance
  • Available with extended head for large studs
  • Protects washers, bolts and nuts against weathering and tampering
  • Gives application finished appearance
  • Available with extended head for large studs
  • Available in Polyethylene (PE) and Low Density Polyethylene (LDPE)
Banjo Union Plugs
  1. Recommended: Banjo Union Plugs
  2. Common uses: Automotive – protection of banjo unions
  3. Other reasons why:
  • Prevents dirt and moisture ingress
  • Made of Low Density Polyethylene (LDPE), a rigid, yet soft material

Caps and Plugs for masking

Materials react differently to processes, so before you actually start masking, request a free sample of the plug or masking cap for painting or for any masking process that you’re interested in. This will allow you to test it. Find out more about masking materials in our guide, Masking Materials Selection Guide.

You’ll also find masking tape convenient for areas that caps or plugs can’t cover. Find out more in our guide, How to choose the right high-temperature masking tape.

High-Temperature Silicone Tapered Plugs
  1. Recommended: High-Temperature Silicone Tapered Plugs
  2. Material: Silicone / EPDM
  3. Other reasons why:
  • Available as a solid plug or with a hollow core to aid in compression
  • Excellent chemical resistance
  • Reusable
Masking Washer Caps
  1. Recommended: Masking Washer Caps
  2. Material: EPDM / Silicone
  3. Other reasons why:
  • Protects threaded and non-threaded end tips
  • Washer seals the edge to protect from contaminant
Masking Pull Plugs
  1. Recommended: Masking Pull Plugs
  2. Material: Silicone / EPDM
  3. Other reasons why:
  • Masks threaded or unthreaded through holes
  • Fast, easy removal
Easy Pull Masking Caps
  1. Recommended: Easy Pull Masking Caps
  2. Material: Silicone / EPDM
  3. Other reasons why:
  • Protects end tip profiles
  • Internal seal prevents paint ingress
  • Flange provides easy removal
Masking Flangeless Plugs
  1. Recommended: Masking Flangeless Plugs
  2. Material: TPR / EPDM
  3. Other reasons why:
  • Masks holes without masking surrounding areas
  • Protects multiple diameters
  • Masking pull plug with tab for easy installation and removal
Paper Caps
  1. Recommended: Paper Caps
  2. Material: Paper
  3. Other reasons why:
  • Easy application
  • Environmentally friendly and economical solution

Download free CADs and try before you buy

Free CADs are available for most solutions, which you can download. You can also request free samples to make sure you’ve chosen exactly what you need. If you’re not quite sure which solution will work best for your application, our experts are always happy to advise you.

Whatever your requirements, you can depend on fast despatch. Request your free samples or download free CADs now.

Questions?

Email us at sales@essentracomponents.com or speak to one of our experts for further information on the ideal solution for your application 800-847-0486.