Page 33 - MDI Steel Reference Guide

ROUND TUBING - TERMS
COLD DRAWN SEAMLESS (CDS)
Produced to OD and ID dimensions by a process that pierces a hot rolled bar. Normally furnished in the “as drawn” condition. CDS offers good surface quality and greater mechanical properties than hot finished seamless tubing. Made from 1026 grade steel. Conforms to ASTM A519.
DRAWN OVER MANDREL (DOM)
DOM has very little wall variation and no spiraling eccentricity. The tube is formed and welded from strip steel which has very little gauge variation. The tube is then cold drawn to size, causing the weld seam to virtually disappear. Tubing 10 ga and lighter is made from 1020 grade steel, heavier than 10 ga is made from 1026. Conforms to ASTM A513 Type 5 (mandrel drawn).
Drawn Over Mandrel Tubing: Advantages of DOM
1. More uniform wall 4. No spiral on ID thickness 5. Denser ID surface
2. Better surface finish 6. Closer tolerance 3.Lessstockremoval 7.Comparableorlowercost
ELECTRIC RESISTANCE WELDED TUBES are produced from a cold rolled or hot rolled scale-free strip which is formed by rolls at room temperature into a tubular shape. Welding takes place as an electric current heats the two edges of the strip as they are pressed together. Only a narrow band of metal is heated while the rest of the tube remains at room temperature. The weld flash is always trimmed off the outside of the tube. The flash can also be trimmed from the inside by special tooling.
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