ASTM A513 Type 5 DOM tubing

Type 5 — drawn-over-mandrel (DOM) — is ERW tubing that is subsequently cold drawn through a die over an internal mandrel. The draw simultaneously works the outside and inside surfaces, which is why DOM offers the tightest OD/ID/wall relationships in the A513 family and a refined surface finish.

DOM is not seamless. It begins life as welded tube; the drawing operation cold-works and typically blends the weld zone, but the weld is still there. If a design genuinely requires seamless product, the conversation belongs in ASTM A519, not A513.

Drawing reduces and sizes the tube through tooling. The operation can improve outside- and inside-diameter relationship, wall consistency, and surface compared with as-welded product. The exact result depends on reduction, tooling, condition, and producer practice.

Cold drawing also work-hardens the material, raising strength and reducing ductility relative to the as-welded condition unless a subsequent thermal treatment is specified. Condition (as-drawn versus stress-relieved or annealed) is therefore part of the specification, not an afterthought.

Type 5 is frequently evaluated for shafts, bushings, sleeves, hydraulic or mechanical components, and parts with machining or fit requirements. Specify the dimensions and characteristics that matter instead of assuming the word DOM guarantees every outcome.

DOM commonly reduces machining stock requirements and setup scrap for turned parts, which is where its higher per-foot price is recovered. If the part is welded into a frame and painted, that recovery rarely happens — use an as-welded route instead.

Calling DOM seamless on a drawing; ordering “DOM” without stating condition; assuming every OD/wall combination is stocked; and specifying DOM for parts whose requirements an as-welded route would satisfy at lower cost.