In order to make pipe from plate, the big, rectangular sheets are first crimped upward along the longitudinal edges. The first hydraulic press forms the sheets into a U shape. Then another press, capable of exerting 28,000 tons of pressure, bends the U into an O.
Next, separate machines weld the seams, first from the inside and then from the outside using the submerged arc welding process.
Until they are welded to become pipe, the shaped steel sheets are known as "cans."
One of the final jobs involves forcing an expander through the pipe from one end to the other, making it a uniform size and relieving stress. The pipes are typically 40 feet long.
Each pipe undergoes through a host of testing and inspections including flouroscoping, physical inspection, End X-Ray, Ultrasonic testing etc. to ensure quality product.