Process comparison
DOM vs ERW tubing
DOM is ERW tubing that receives subsequent drawing. The useful comparison is drawn versus as-welded processing, not seamless versus welded.
On this page
The short answer
The comparison is mislabeled from the start: DOM is ERW tubing. Every DOM tube began on an ERW mill; the difference is the cold-drawing operation afterward. So the real question is whether your part needs what the draw adds — tighter OD/ID/wall relationships, refined surfaces, a worked weld zone, and increased strength from cold work — enough to pay for it.
As-welded ERW is the right answer more often than catalogs suggest: welded frames, brackets, rollers, sleeves with generous fits, and painted or powder-coated products rarely benefit from drawn product.
Tradeoffs
Drawing can improve dimensional relationships and surface while adding conversion cost and potentially changing mechanical response. As-welded tubing may be the efficient choice when its capability meets the part drawing.
| Aspect | As-welded ERW (Types 1–2) | DOM (Type 5) |
|---|---|---|
| Dimensional relationships | Standard limits by type/size | Tightest in the A513 family |
| Surface finish | Follows strip and mill practice | Refined by drawing |
| Weld zone | As welded (flash options vary) | Cold worked and typically blended |
| Strength | As-welded condition | Raised by cold work (condition-dependent) |
| Relative cost | Lower | Higher |
| Typical fit | Frames, fabrications, coated parts | Machined, sliding, sealing parts |
A practical decision test
Ask three questions. Does a machined feature, sliding fit, or seal depend on the tube's OD/ID relationship? Does machining stock or setup scrap on as-welded tube exceed the DOM price premium? Does the weld bead interfere with anything inside the tube? If all three answers are no, as-welded ERW deserves the quote.
Sources and limitations
- ASTM A513/A513M — Standard Specification for Electric-Resistance-Welded Carbon and Alloy Steel Mechanical Tubing — ASTM International. Controlling specification for types, tolerances, and ordering requirements. Purchase the current edition for all normative values.
These sources inform the qualitative guidance on this page. This publication does not reproduce their text, tables, numerical settings, or acceptance criteria. Normative requirements come only from the purchased current edition of the governing standard and your supplier agreement.