At first glance, tube, pipe and conduit look similar. But if you use pipe when you need tube, or vice versa, your project could go sideways. And if you use a different type of tube when you should use conduit (a specific type of tube used to protect wire), you could have wiring problems and may create a fire hazard.

Understanding pipe vs. tube and conduit vs. pipe may help you order the right material for your job and prevent future leaks, weather damage and safety or structural hazards.

Differences between pipe and tube

The terms “pipe” and “tube” are often used interchangeably by DIYers and even construction professionals. That’s not surprising, since they look similar and can be made from the same materials, such as steel or PVC. But they aren’t really the same at all.

In short, a pipe is a round hollow structure used to transport flowing material, typically under pressure. Most often, a pipe carries a liquid or gas, but it can also be used to carry pellets, powder or other materials that flow. Plumbing and HVAC systems use pipe. Tube is used to provide structure, stability and/or protection in a range of applications, from setting concrete to building a handrail.

Here’s a rundown of the main differences between pipe and tube.

Pipes: Thicker walls and pressure tested

Pipes typically have thicker walls than tubes and have been pressure tested to prevent leaks. A pipe’s pressure rating lets you know how much pressure it can withstand. Residential plumbing systems or vents can use pipe with a lower pressure rating than larger projects such as city-wide sewer or gas lines.

There are two sets of standards used to order pipe. Both are guidelines, not precise measurements:

• Schedule: Schedule refers to the pipe’s wall thickness, which correlates with its pressure rating. A pipe with a higher schedule has a higher pressure rating.
• Nominal pipe size (NPS): NPS correlates to the internal diameter of the pipe. Pipe with a higher nominal pipe size has greater internal and outside diameters

Tubes: Strong, but not designed to withstand internal pressure

Tube, measured by its outside diameter, is a hollow structure used to provide protection and/or stability. It’s not designed to withstand internal pressure, and it generally has thinner walls than pipe. Most tube is rigid, but some tubes can be bent or shaped.

Tubes are versatile and used in countless applications. A telescoping tube might hold up your shower curtain or extend your selfie stick. Structural steel tubes are used for everything from bridge and fence construction to securing the foundation of new buildings and docks. Many tubes are designed to stand up to the elements and resist damage from UV light.

What is conduit?

Conduit, also known as electrical conduit, is a type of tube used to protect wires or cables. It also makes it easier to pull and place (or replace) wires. It can shelter internet wires running along a home’s exterior from moisture and UV light, or shield electrical wires in the basement or attic from rodents. On industrial and commercial sites, it can seal wiring away from heat, hazardous material or water to reduce the risk of fire or malfunction.

This durable tubing can be made from aluminum, steel, plastic or PVC. When choosing conduit, consider whether you need flexible or rigid conduit and whether it will be exposed to the elements.

Like other tubes, conduit is measured by outside diameter. That diameter affects the internal diameter, which influences how much wire you’ll be able to run through it.

PVC pipe vs. PVC conduit

PVC pipe and PVC conduit look nearly identical: They’re both lightweight, hollow, rigid cylinders made from the same material. However, they can’t be used interchangeably. They are manufactured using different processes and have the same differences outlined in the “Differences between pipe and tube” section above, including the ability to withstand internal pressure (pipe can, conduit cannot).

Here’s an outline of similarities and main distinctions between PVC pipe and PVC conduit.

Pipe, tube and conduit have many similarities, but as with everything related to construction, the devil is in the details, and that’s where the differences between these materials show up. For plumbing or HVAC projects, you should consider getting pressure-tested pipe. If you need stability or protection, there’s a tube or conduit that’s likely right for your job. You should always consult with an expert regarding the specific circumstances, applicable rules and regulations related to your site and to your situation.

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