They seem the same.
In: Engineering
I used to work in both a pipe factory and a tubing factory at different times, when I was a younger man.
They made CLEAR distinctions, though I think it was out of hubris. The pipe factory was in Wisconsin, and they cast large diameter pipe from bronze and steel, as I recall. They had large cylindrical molds, with a gear ring about the middle. The whole thing was set in a machine by something that looked like a front loader with a big rod as the attachment on the front, and this was machine just a pair of roller wheels on either end. The middle set into a drive gear. The whole thing was spun like an axle.
On one end, another big loader came by with a crucible of molten metal. While the mold was spinning, they poured it in, where it splayed out, cooled, and shrunk enough for the first loader to come and pull the pipe out.
I worked next to the x-ray pit, which was long enough to hold a whole cast pipe. They checked it for cracks and faults. Workers would grind the ends and weld flanges. My job was to wrap the welds in thermal blankets and heat them to 1,750 F to temper them. The process took about 8 hours. We’d rig up a dozen pipes to two transformers wired in series, the transformers were each on their own 12′ trailer. I’ve no idea how much power I was in charge of or how much danger I was in. I can’t believe they hired me. I can’t believe I took the job, but fuck the money was good for a kid and it’s gotta beat hookin’.
Pipe holds pressure. That’s the big stink they made about it, what distinguished them from tubing.
Now, my father works in steel. These days, it’s steel stamping, though it used to be in the mills in Chicago, before they all shut down. So sheet steel I understand. The stuff comes in rolls, like tape. It’ll be ~3′ wide and the roll will weigh between 1 to 4 tons, and be as thin as paper. As they unrolled it, they sliced it into several narrower rolls. These would be fed into the line, where it would be uncoiled, then gradually rolled into a continuous cylinder, welded along the seam, and then cut, all in a continuous process. When the cutter would come down, it would shake the floor. The whole factory was several football fields long. They would use this green coolant stuff that would flow like a fire hydrant out of the pipe as it went through this part of the process.
The tubing would be covered in a caustic oil. The stuff would eat through anything not steel, eventually. It corroded my work boots eventually, they literally just crumbled to grime and grit after I stopped working there.
I pressed one end of the tubing in a dye, a cylinder with a reduction. Hardened steel. I was weight lifting like an animal at the time but GOD DAMN were those things heavy. What this did was reduce the diameter of one end so they could thread a rod with a ball on the end through the tube, and then grab onto that and pull the tubing through a stretcher, which thinned out the tube and increased it’s length.
Let me tell you about the furnaces. They were a football field by themselves. They burned a special filtered natural gas. The VERY purple flames burned “cold”, in that you could stick your hand in it and not be hurt, or you could throw greasy cardboard in it and it wouldn’t catch. I don’t understand what I saw, either, but that was part of the pre-heat. Inside the furnace was all ceramic lined, with little peep holes all along so you could see in. The ceramic was so hot inside it glowed almost white. I learned from my dad about molten steel, and knew well enough to not look directly into the furnace without eye protection, similar to welding goggles. We heat treated the tubing.
That caustic oil would be cooked off, and you couldn’t see one end of the factory from the other. And we breathed that shit in. We were saturated in it. I went to college afterward and got into software development, but I had to throw away all my clothes, everything stunk of that caustic oil shit.
Tubing is structural, or doesn’t hold pressure. We made tubing for dish washers, hospital beds, cars, god knows what else. Wire might be routed through it. You were “educated” (RE: chewed the fuck out) if you called any of their product “pipe”.
Are these definitions rigid? No! We use the words tubing and pipe interchangeably, so long as it’s use is consistent.
A tube is any hollow, open-ended cylinder-shaped object, it doesn’t matter what it is being used for.
A pipe is a kind of tube. It directs a continuous flow of some substance from one location to another and is usually rigid.
A toilet paper roll isn’t a pipe, because it doesn’t transport anything. A subway tunnel isn’t a pipe because while it does transport, it doesn’t do so in a continuous flow.
Very little.
The term tube is usually used for something with a bit more flex, whereas a pipe is most often rigid.
A tube and a pipe perform more or less the same function, but pipe vs tube is primarily dependent on where you’re building something or what materials you need to move through it.
Pipes generally have threads on their ends, and you connect them using those threads. Tubes generally don’t have threads, and you connect them using compression. There are plastic pipes, that use glue to pretend to be threads, so that’s another case.
Tube is also used in cases there the effect isn’t to move a liquid. The round forms you put concrete in are tubes, because the concrete turns solid and holds something up. Similarly, tubes can be used to give more cross sectional area, to reduce flex, that a solid structural member of the same mass.
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