Originally Posted by Rocky
Huh? D.O.M. is Drawn over a mandrel hence the DOM and why it's seamless. Sure your not thinking of HREW tube?
No, its seam has been flattened, but it still starts life as welded seam.
So, 'HREW' and DOM, such as ASTM A513, tube start as flat bar, which is rolled and welded.
Seamless tube, like ASTM A519 starts as round bar, and is pierced to make truly seamless tube. Very common for gas line applications.
People like to call DOM seamless, becase it doesn't have a big bump at the seam, but the seam is there. Its just been worked.