To an outsider, pipes and tubes may seem like they should be synonymous. To a marine engineer, the measurements, standards and language used to distinguish the two couldn’t be more different. In fact, differences in nomenclature and measurements could cause quite the headache if tubes and pipes were mistakenly assumed to be interchangeable.
The 8 Main Differences Between Pipes and Tubes
- Tubes can come in different shapes like square, rectangular and cylindrical. Pipe is always cylindrical or round.
- While rigid tubes are frequently used in structural applications, copper and brass tubes can be rather flexible. Pipes are typically always rigid and resistant to bending.
- When it comes to classification, pipes use schedule and nominal diameter. For example, a pipe could have a 250mm nominal diameter and a schedule of 80. Tubes are classified by their outside diameter measurement and thickness. A copper tube, for instance, could be 10 mm with a 2 mm thickness.
- Pipes accommodate larger applications with sizes that range from a half-inch to several feet. Tubes are generally used in applications that require smaller diameters. While 10-inch pipes are common, it’s rare that you will come across a 10-inch tube.
- Tubes are often put to use in applications that require precise outside diameters, like with cooler tubes, heat exchanger tubes and boiler tubes.
- Pipes have a pressure rating and are schedule, which is why they are often used to carry fluids that must be contained.
- The thickness of tubes increases in standard increments such as 1 mm or 2 mm. Pipe thickness depends on the schedule, so there is no fixed increment.
- Joining pipes is more labor intensive as it requires welding, threading or flanges. Tubes can be joined quickly and easily with flaring, brazing or couplings, but for this reason, they don’t offer the same stability.
