A tube is a tube is a tube.
Maybe for the layman. For manufacturers and their clients who require steel tubing, it's important to note the differences and understand which tubes work best for which projects. The kind of tubing you choose for your project will depend on factors such as corrosion resistance, stress of the application, cost vs. strength, and more.
One way to avoid hiccups in the design process is to understand seamless vs. welded tubing -- they're far from the same products!
What Is Seamless Vs. Welded Tubing?
Welded tubes are made from long, skinny sheets of metal that are rolled into a tube shape and machine welded at the seam, as seen here:
Seamless tubes, on the other hand, start out as solid metal bars. The bars are hollowed out through piercing or extrusion.
At one time, all functional metal tubing was seamless. In the past, the lower quality and strength of the weld seam meant welded tubing was inherently, weaker, less attractive, and less durable. As manufacturing processes and machinery evolved, welded steel tubing became a viable alternative to seamless.
Today, both welded and seamless tubing offer:
- High corrosion resistance
- A long life span
So, what's the difference between welded and seamless tubing these days? The vast majority of industries use welded tubing due to its cost efficiency.
Welded vs. Seamless Applications
Seamless Steel Tubing
Seamless steel tube is falling by the wayside, except for a few very specific applications. Seamless tubing is very difficult to find above a 1" diameter, and is almost nonexistent above 2". The seamless steel tube manufacturing process is also remarkably expensive. Its much higher cost combined with its small range of sizes is rendering it obsolete.
Today, seamless tubing is more often found in microelectronics and semiconductors -- applications where it's difficult to roll a welded tube small enough with a heavy wall thickness. Aside from that, there are still some standards that require seamless tubing. However, industry experts expect to see updates across the board to allow for welded tubes in those applications.
Welded Steel Tubing
Welding steel tube together is much more common in general. Due to the low cost and modern welding technology, welding tube steel is slowly, but surely, replacing seamless entirely.
Welded steel tubing can be found in almost every industry:
- Home & garden
- Industrial machinery
- Much more
Welded tubing is less expensive overall and meets stricter requirements than its seamless counterpart. Welded tubes allow for:
- Tighter tolerances
- Thinner nominal wall thickness
- Better concentricity
- Higher internal surface quality
It can be produced in longer lengths with larger diameters, and it's more readily available and workable for manufacturers.
We especially recommend welded vs. seamless stainless steel tubing. Stainless steel welded tubes meet the requirements for just about everything. You can also go cheaper if corrosion resistance isn't a top priority.
Welded steel tubing is the future of metal tube manufacturing.
For your projects, welded tubing will almost certainly be the most appropriate option. It's more affordable, more precise, and more diverse in its shapes and sizes.
There are still a few applications where seamless is more appropriate, but it seems those will also be overtaken by welded tubing as manufacturing technology continues to advance. Seamless tubing is slowly being eliminated from the manufacturing repertoire -- it's costly, and only viable for a small range of applications.
Whether we find a way to produce seamless tubing cheaply or turn to micro welded tubing, we're excited to see what the future of tube manufacturing and design will bring. If you'd like to learn more ways to optimize your tube design, check out the free download below.
(This article was originally published in February 2016 and was recently updated.)