Exhaust Pipe, Exhaust Tubing – What Does it All Mean?
Whether you’re buying an MRT aftermarket exhaust kit or designing a custom system, you’ve likely heard the words “pipe” and “tube” thrown around a lot. Many people assume the two words are interchangeable and use them as such.
But is there a difference between piping and tubing? Actually, there is – and it’s a bigger deal than it might seem. Ask the wrong person for Mustang exhaust pipes instead of tubes, and you could end up with one messed-up system. Let’s look at the piping and tubing debate with how it relates to exhaust performance.
Differences Between Piping and Tubing
There are a few ways to distinguish pipes and tubes. Pipes are always round while tubes can be round, rectangular or square. Tubes can be made via cold-rolling or hot-rolling while pipe is only made by hot-rolling. A metal tube is stronger overall while also being easier to bend.
The biggest and most important distinction, however, is how they are measured. Different systems are used to measure pipe size material and tube size material, and you don’t want to get them confused. Here’s a basic overview of the measurement systems.
Pipe Size Material
Pipes are measured using the Nominal Pipe Size set by the American Standards Association, which involved a nominal diameter and a schedule number. But just because it’s standardized doesn’t mean it’s clear. To begin with, the nominal diameter never quite matches either the outside diameter (OD) or inside diameter (ID). For example, a 2-inch nominal size pipe has an OD of 2.375 inches.
But if you think that’s confusing, wait until we get to the wall thickness. Also known as the gauge, pipe wall thickness is divided into “schedules” that vary greatly. The 2-inch nominal diameter pipe we mentioned has 0.109-inch thick walls on Schedule 10 and 0.154-inch thick walls on Schedule 40 – and this affects the inner diameter. Even people who work with pipes professionally have trouble keeping track!
Tube Size Material
Thankfully, tubing size material is much easier to understand. The main dimensions are the OD and the gauge – and unlike piping, tube measurements are constant. A 16-gauge pipe always has 0.065-inch thick walls regardless of the OD. This makes it easy to calculate the inner diameter. Furthermore, when you purchase 3-inch tubing, you know it’s referring to the OD, and there aren’t any schedules to keep track of.
It should be noted that tube size gauge and sheet metal gauge aren’t the same. For instance, 16-gauge is 0.065 inches for tubing and 0.060 inches for sheet metal. Make sure you’re using the right size chart when you shop!
Which is Used for Exhaust?
Nearly all car exhaust manufacturers use tube size materials to fabricate their systems. Along with a simpler measurement system, tubing is easier to shape for common exhaust diameters. The main use for pipes in the exhaust industry is non-race turbo systems that benefit from the thicker walls piping can offer. MRT custom exhaust tubing uses the tube size system so you can focus on hearing the performance, feeling the difference and getting noticed.