Telling DOM and ERW tubing apart

Ever since we founded the company back in 2004, we have made it our mission to provide clients with top-notch ERW tubes. We don’t just supply a handful of designs however; we have over 200 different shapes and sizes that are appropriate for various applications. Carefully tested and designed to last, ours are is the tubing to choose if you want quality results.

ERW and DOM tubes are similar in some respects but differ in others. It’s important to understand these differences so that you don’t end up with the wrong one by mistake.

With the ERW process, steel strips are unwound from the coils and are side-trimmed in an effort to condition the edges and manage width for welding. Afterwards, the strip moves past a group of contoured rollers that cold-form it into the right shape. The material’s edge sections are brought together as a butt joint under compression and are welded by heating up to 2000°F. The result of this is that the flash weld is detached from the tube’s outer diameter. After the weld has undergone testing, the tubing goes through a number of sizing rolls to obtain its finish size.

Drawn over mandrel (DOM) isn’t actually the tube itself, but rather its finishing procedure. The actual tubing is thought of as first-class and is typically generated from SAE 1026 OR 1020 steel. The initial manufacturing stages are indistinguishable from those used for ERW tubes. What separates them however is that the whole flash weld is confiscated and the tubing is cold-drawn over a mandrel. It’s often the case that DOM is referred to as seamless tube, which is untrue as, while the seam is present, it’s near invisible.

At Union Steel, in addition to the standard seamed rectangular, circular, and square tubes, you also have the option to purchase pre-galvanised and seamless ones. Due to our status as an ISO9001 establishment, we can handle orders of any size and offer exceptional levels of care to customers at the same time.

If there’s something we can help you with, please get in touch. We are friendly and approachable, able to offer support and advice about selecting the perfect tubing for each job.