Steel tubes and steel pipes.
They seem like they should be the same thing, right? They’re both tube-shape, generally speaking, and they’re both made of steel. What more is there to say?
Well, quite a bit, actually.
Steel tubes and steel pipes may seem similar, but in fact, their uses and properties have some very key differences.
For starters, tubes are used primarily for structural purposes. This is especially true for steel tubes, which are much more sturdy and rigid than copper or brass tubes.
Steel pipes, on the other hand, are used as vessels for moving things fluids or gases from one place to another.
Since tubes are structural in nature, they can be made into whatever shape is required, whether it’s square, rectangular, or circular. Pipes, however, are almost exclusively round.
Because of their different uses, the way tubes and pipes are measured is also different.
When measuring a steel tube, the most important measurement is the “outside diameter.” This refers to the distance between opposite ends of the outside of the tube.
Since pipes are used as vessels, the “inside diameter” is much more important. This is the distance between two points on the opposite ends of the hollow center of the pipe.
Also, while the outside diameter of a pipe will remain constant for a specific size, the inside diameter will vary based on the “schedule,” or thickness of the pipe. A pipe’s thickness is extremely important, seeing as it is used for transport.
Working with steel pipe and steel tubing are also very different. While tubes can be attached to each other through simple couplings, pipes must be welded and sealed to prevent leaks.
This is why tubes are much more structurally sound than pipes, but are not useful as vessels.
So remember, if you need something structural, you need a steel tube. But if you need something strong and functional, you need steel pipe.