A METHOD OF PREPARING A STEEL PIPE, AN APPARATUS THEREOF AND A STEEL PIPE

摘要

A process for reducing a raw steel pipe obtained by a solid phase bonding pi pe manufacturing method or a welding pipe manufacturing method is carried out b y heating the steel pipe to a temperature in excess of 100 C and lower than 8 00 C before it is reduced, restricting the temperature of the steel pipe durin g a rolling operation to a level in a specific range, controlling the temperature difference of the steel pipe in the circumferential direction thereof at the inlet side of a reducing mill to be in a specific range, and also controlling the temperature of the steel pipe between the stands of the reducing mill. This enables the steel pipe to be reduced with a low load wit h the work hardening effect minimized without deteriorating the properties of the surface thereof, and the dimensional precision of the product pipe to be maintained at a high level.