In any project that requires tubing, having the right tube size is crucial. Tube dimensions need to be very precise because they hold together important structural elements. At the same time, tubes are different from pipes and hoses, so knowing the differences between these products will help you make good buying decisions. 

Here we’ll explain the differences between tubes and pipes, common tubing applications, and the importance of selecting the right tubing dimensions.

Tubes vs. Pipes

The terms “tubes” and “pipes” might be used interchangeably because of how similar they look, but they have different functions. Pipes usually transport fluid, such as municipal water, so it’s important to keep track of flow volume and pressure using the inside diameter. Tubes also convey substances, but their structural applications—such as medical devices—require precise outside diameter measurements.

Also note that, while both tubes and pipes are hollow cylinders made of rigid, uniform material, hoses are flexible and layered with different materials. What all these products have in common, however, is a wide variety of applications. 

In this blog, we’ll focus on the most popular applications for tubes.

Hydraulic Applications

Some tubing systems can handle hydraulic applications. They transfer chemicals, solvents, and water. The tubes must be matched with hydraulic fittings that can create a strong enough seal to eliminate the risk of leaks and resist rust or chemical degradation.

Pneumatic Applications

Tubes can also belong in pneumatic systems, which transfer gases. Like hydraulic systems, the tubes must be matched with precise, noncorrodible fittings. However, these fittings need to have even more reliable seals to prevent gas leaks.

Structural Applications

Tubes can also be used for railings, decorative architectural elements, and structural reinforcements. While these assemblies also have fittings to cap the tubes or secure them in place, they don’t need to be sealed to prevent leaks.

Understanding Tubing Dimensions

When you’re handling tubing orders, it’s essential to understand how to measure and identify tubes of different dimensions. Tubes are measured by outside diameter—that is, how wide across the tube is, including the thickness of the walls. For example, if a tube is classified as one inch, then its outside diameter is exactly one inch. 

On the other hand, pipes are measured by nominal pipe size, which correlates to the inside diameter. (For pipes larger than 12 inches, the nominal pipe size corresponds to the outside diameter.) For instance, a one-inch pipe can have an outside diameter of 1.25 inches, whereas a 13-inch pipe is truly 13 inches, counting wall thickness. 

To effectively measure tube sizes, you need to determine four different dimensions:

  1. The outside diameter of the tube (from the outside edge of the tube wall to the outside edge of the opposing side)
  2. The inside diameter of the tube (the diameter of the hollow portion within the tube walls)
  3. The roundness of the tube. Tubes can flatten or slightly deform during storage or installation, so assessing the tube’s roundness is critical.
  4. The wall thickness, also called the tube gauge. Common gauge sizes range from 7 and 22, with each number referring to a specific measurement. The higher the gauge number, the thinner the wall. For example, a 1.5-inch 10 gauge steel tube refers to a tube with an outside diameter of 1.5 inches and wall thickness of 0.134 inch. A 3-inch 18 gauge tube has a wall thickness of 0.049 inch.

Tubes and More From E Tube & Wire

Now that you know the distinctions between tubes and pipes, different tubing applications, and how to measure tubes properly, you can make a more informed decision about your next tubing or piping purchase.

At E Tube & Wire, we produce precision tubing products. Since 1978, we’ve been providing our clients with high-quality parts and excellent customer service. Contact us today to learn more about our capabilities or request a quote for pricing details.

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