TUBING.
Tubes of lead and brass are cast in short and thick pieces, and then drawn through holes in a draw-plate, similarly to wire, but having a rod or “mandril” passed through the length of the tube to keep the hollow of the right calibre.
TUBE DRAWING.
Iron tubing for gas and water pipes, if more than about two inches in diameter, is cast; but smaller, or “service-pipes,” are made of wrought iron plate rolled on a mandril, and welded at the edges by being drawn at a white heat through a draw-plate.