... by the hot-rolled, cold-rolled or cold Seamless steel ingot is made of perforated or solid ... , cold-rolled or cold call is made. Seamless steel pipe with a hollow cross section, a large number ... of channels for transporting fluids, such as steel pipe and solid steel bar, compared with the same ... oil and gas industries, such as drill pipe, petroleum oil pipe, oil and natural gas and so on. Seamless Pipe