A guide to plastic end caps

Red plastic end caps

Protecting pipes and tubes with end caps

We’ve designed this guide to help you understand end caps and their uses, including:

Damage to pipes threaten safety, the environment and system reliability. When damaged, metal is vulnerable to corrosion from moisture and contaminants, or even extreme temperature changes. Corrosion is also a constant threat even when there is no impact. All it takes is for moisture and debris to enter the pipe.

Tube end caps

End-cap protection is critical, fitting over the outside diameter of your pipe. But pipes aren’t the only applications that need capping. For example, exposed tubes, such as those on scaffolding, need end caps to protect the general public and workers. Tube end caps can prevent serious injuries. Tube caps for packaging are another common need – so are caps for end use.

The plastic end cap: other applications

Damage can also happen during manufacturing processes, specifically masking. High-temperature protective end caps prevent contamination to keep your application’s internal body clean. End caps are also needed to protect electrical connectors from dust and other contaminants. They’re used on rods – caps even have end uses, providing a finishing touch to applications for a neat appearance.

Different shapes are also available, from round to square plastic caps. You can even find rectangular PVC caps.

Why plastics are ideal for end caps

Plastics are the ideal materials for end caps, no matter what the application. They come in a range of materials, from soft and flexible vinyls to impact-resistant LDPE. Threaded pipe caps and plugs are normally for heavier duty applications. Nylon end caps are available, but the material’s rigidity makes it ideal for threaded fittings that need long lasting or permanent protection.

Plastic push caps: types

Most end caps are push fit for both threaded and non-threaded applications. You can learn more about caps, both push fit and threaded, in our Ultimate guide to caps and plugs.

​Round end caps

Round end caps

  • Round pipe end caps also designed for tubes and rods
  • LDPE – durable, lightweight & 100% recyclable
  • Excellent protection for transport and storage
  • Maximum temperature: 79.4˚C (175˚F)

Use for: Protection during transportation and storage

​Circular end cap connector

Circular end cap connector

  • Cost-effective protection
  • Protects against dirt, dust, and moisture during transit and storage
  • LDPE

Use for: Circular connectors with standard threads

​Flexible plastic pipe caps

Flexible plastic pipe caps

  • Protects threaded or non-threaded pipe ends
  • Resistant to cracking or splitting under normal use
  • Outstanding toughness and puncture-resistant
  • PE for good flexibility
  • Easy assembly and removal

Use for: Protection during transportation and storage

​Round vinyl end caps

Round vinyl end caps

  • Flexible PVC can stretch on to larger dimensions for snug fit
  • No tearing, splitting or shredding
  • Airtight seal while also insulating and cushioning
  • Shock resistance – great for protection in transport
  • Maximum temperature: 176.7˚C (350˚F)

Use for: Fence posts and other end uses; all masking processes, except blasting

​Driveshaft protection caps

Driveshaft protection caps

  • Protects driveshafts and the surrounding bearings from oil and chemicals
  • Available for ANSI/SAE, DIN748, IEC 600-72, and ISO R775 driveshafts
  • Impact-resistant LDPE

Use for: Protection during transportation and storage

​Tapered cap & plugs – standard

Tapered cap & plugs – standard

  • Can be used as a cap or plug
  • Caps multiple outer diameters or plugs multiple inner diameters
  • Red or blue LDPE
  • Available with wide flange for added protection on bearing surfaces

Use for: Protection during transportation & storage

​Plastic caps for tubing – packaging

Plastic caps for tubing – packaging

  • Internal rib that provides a quick and tight fit on tube containers
  • LDPE

Use for: Packaging tube I.D.s with 1/4" through 1-3/4" with .045" wall thickness

​Round hanger vinyl caps

Round hanger vinyl caps

  • PVC provides flexibility and snug fit
  • Glossy, attractive finish for decorative end use

Use for: Hanging packaging tubes or tools from a hook

Green end caps on tubes
Inside height

Plastic end caps: sizing

A firm fit is paramount for end caps to ensure they don’t fall off, exposing your application to damage and ingress. If height is relevant, you want to measure the inside height of the area of your application that needs capping.

Depending on the type of cap you plan on using, it’s the outside and inside diameters that you need to match to the manufacturer’s caps.

Tapered cap

Let’s say you want to use a standard tapered cap. Follow these steps to get the dimensions you’ll need.

Outer diameter

Step 1:

Measure the outside diameter of your application, end to end, as shown here.

Inner lips distance

Step 2:

Measure the distance between the inner lips, as shown here.

Note: If you’re using a flexible material such as PVC, you won’t need an exact measurement. PVC can stretch across multiple diameters. Still, it’s best to get the precise measurement so that you can estimate the leeway you have.

Our standard tapered end cap is made of LDPE, so you’ll want the exact inside and outside diameters. Once you have those, you can match your measurements with those on our website for that product. Measurements are available in both imperial and metric units.

Step 3:

Match your measurements online to those of our tapered caps. If you’re looking for say, 5/8" plastic end caps, you’ll find it listed in decimals: 0.625. Or, for example, 2 3/8" plastic pipe caps will be listed as 2.375 and a 1 3/4 plastic cap will appear as 1.75.

Below is a snippet of sizes available for these caps. Notice that sizes are listed within ranges. If your inside and outside diameters fall within a particular range, that’s the size you should use.

Sizes for caps

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 end cap 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.


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.