The confusion and misunderstanding around round pipe and round tube is incredibly common—even in metal shops. Many professionals still don’t understand the differences between the two, which leads to a shocking number of quality issues, missed callouts, inaccurate specifications, and ultimately, costly mistakes in production.
Pipe was originally developed for plumbing applications. As early as 4000 B.C. in Babylonia, baked clay and straw were used, and by 3000 A.D., Egyptians had transitioned to copper piping. Historical accounts suggest ancient China even used piping systems to transport natural gas. In North America, pipe infrastructure dates back to early 1600s Boston, where hollowed-out logs were used before materials like cast iron and, eventually, stainless steel and steel became mainstream.
Pipe started in the early 1600s in Boston, well before flushable toilets, and was often manufactured from wood. Wooden pipes, started from logs, of course, were hollowed out and then joined together.
A few centuries later, other materials started making their way to the market—Orangeburg pipe was popular as late as 1970 but was soon replaced by cast iron which had a much longer life expectancy. Cast iron was then replaced by materials we are more familiar with today: steel, stainless steel and copper.
Tube, though similar in shape, has always had a different role. While pipe is designed to transport fluids, tubing evolved to become a structural component. At All Metals Fabrication, we often say: “Pipe is for plumbing and tube is for tumbling.” In other words, tube is built for structural integrity—supporting architectural builds, automotive frames, and industrial systems.
Unlike pipe, tubing is used in building structures, bridges, automotive frames and support skeletons—anything basically driven by structural integrity. Because tubing is so key in developing support and structural integrity, manufacturing standards are usually much more stringent, which leads to higher priced goods; which is, in fact, where the crossover and misunderstandings begin to materialize.
Generally speaking, round pipe can be safely substituted for round tube on smaller-sized structural applications. Because pipe is usually cheaper than tube, manufacturers started making substitutions or even specifying substitutions to, of course, save money.
Guardrail is a good example. Most of the common-budget guardrail is manufactured from pipe. This product is extremely common and something that you see nearly every day. In this type of product, structural integrity from pipe is sufficiently able to ensure the railing does its job—keep people from falling, in this example, off the concrete platform and stairs.
But here is the confusion: pipe railing is manufactured from two pipe sizes. The larger pipe is 1.25″ Schedule 40 pipe and the smaller pickets are fabricated from .75″ Schedule 40 pipe. Most architects are unaware of the difference between pipe and tube, so they likely use specifications that are inaccurate. Take guardrails for example: while they often use pipe for budget reasons, some manufacturers unknowingly specify “1–1⁄2” Pipe-Tube”—a term that technically doesn’t exist. Here’s why:
Round tubing is called out by Outside Diameter and then wall thickness. For example:
Pipe is defined by the nominal size of the ID (inside dimension). We are trying to figure out how much fluid can move through the inside of the pipe, if that makes sense.
Wall thickness is defined by a term called, Schedule.
This is confusing because Scheduled thickness changes based on pipe size. For example, 1.00″ Schedule 40 pipe has a thinner wall than 2.00″ Schedule 40 pipe.
There is no easy way to remember all the sizes and schedules. We recommend using a chart to track pipe sizes and schedules.
Pipe and tube do not engineer or calculate the same! That is important to remember. Another way of saying this is 1–1⁄2″ Schedule 40 Pipe and 1–1⁄2″ x .125 Wall Tube do not engineer equivalently. This becomes more important if you are designing and fabricating items with larger-size diameters or where the structural integrity is paramount. Railing, for example, is a completely different animal than rail cars. Having said that, we have definitely seen pipe specifications that do not actually meet code, but fabricators and designers alike are incorrectly informed and/or simply ignorant to the difference.
A few other informational items that may be obvious, but just to make sure everyone has a better understanding of the difference between pipe and tube, we include the following:
Despite their differences, both pipe and tube can be cut, welded, formed, and rolled. This is where modern cutting machines and laser tube cutting services make a significant impact.
At All Metals Fabrication, we’ve developed our own 60-foot fiber laser tube cutting machine, capable of cutting and tapping both pipe and tube with incredible precision. Laser tube cutting machines offer a major advantage in speed, accuracy, and maximum productivity, especially when fabricating laser cut parts with complex holes, through holes, or detailed features.
This technology drastically improves lead times and ensures accurate fit-up for weld applications. Once a welder has used parts prepared on a tube laser, it’s nearly impossible to go back to saw-cut methods. The laser cut finish is clean, repeatable, and ideal for high-quality, repeatable fabrication.
We support our customers with high-performance laser tube capabilities, aiming to eliminate common pipe vs. tube mistakes and improve production outcomes. Whether you’re working with round tube, square, or rectangular tube, our laser systems are designed for optimal capacity and flexibility.
All Metals Fabrication specializes in both architectural and light industrial work. We’re ISO 9001 certified and committed to delivering support through our specialized expertise and high-end laser cutting capabilities.
To learn more about our laser tube cutting services, visit All Metals Fabrication. For detailed specs on our tube laser cutting machine, go to Tube Laser Cutting.
Rich Marker is an 18 year, skilled professional in metal fabrication and manufacturing. Co-founder, owner and principal of All Metals Fabrication, Rich has helped to sustain the company’s success over a variety of economic conditions. He has extensive background in continuous improvement, training and process improvement, and emotional intelligence—among other specialized proficiencies. He loves to learn, fly fish, watch college football and devour NY style pizza! He has the best family on earth, loves a good plan, great teaching and the opportunity to get better.
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