Rectangular tubing is primarily measured by its outside dimensions and its wall thickness. This standard method ensures consistency for manufacturing, design, and procurement purposes.
When you encounter specifications for rectangular steel or aluminum tubing, for instance, they will typically be presented as three numbers:
- The measurement of one outside side (e.g., width).
- The measurement of the adjacent outside side (e.g., height).
- The thickness of the material forming the walls of the tube.
These measurements are crucial because they determine how the tube will fit with other components, its weight, and contribute to its structural properties.
Understanding the Dimensions
Let's break down what these measurements signify:
- Outside Dimensions: These are the measurements across the widest points of the tube's exterior cross-section. For rectangular tubing, this involves measuring the length of the two different sides that form the rectangle. For example, a tube might be described as 2 inches by 4 inches. This refers to the outside width and outside height.
- Wall Thickness: This is the distance between the outer surface and the inner surface of the tube's material. It is uniform around the perimeter of the tube. Wall thickness is often specified in inches, millimeters, or by a gauge number, although using decimal thickness (like 0.120 inches) is more precise than gauge.
Why Outside Dimensions and Wall Thickness?
Measuring by outside dimensions is standard across the industry for various tubing and piping products. This is essential for:
- External Fit: Ensuring the tube fits into or alongside other components, brackets, or structures.
- Calculating Internal Dimensions: While not the primary measurement used for ordering, the inside dimensions can be easily calculated by subtracting twice the wall thickness from each outside dimension.
Example Measurement Specification:
A common way to specify rectangular tubing is like this:
4" x 2" x 0.120" Rectangular Tube
This means the tube has:
- An outside dimension of 4 inches (one side).
- An outside dimension of 2 inches (the adjacent side).
- A wall thickness of 0.120 inches.
Using a table format helps visualize this:
| Measurement Type | Value | Description |
|---|---|---|
| Outside Width | 4 inches | Measurement of one exterior side |
| Outside Height | 2 inches | Measurement of the adjacent exterior side |
| Wall Thickness | 0.120 inches | Thickness of the tube's material |
This clear, three-part measurement system allows manufacturers and users to accurately identify and order the correct size rectangular tubing for their specific needs.
