Patent ID: 8091399

Claim:
A process for manufacturing a steel seamless tube comprising subjecting a steel billet having a diameter which has been soaked in a heating furnace at a temperature of 1150-1280° C. for a predetermined length of time to piercing and elongation rolling to form a mother tube having a wall thickness, and after soaking the mother tube in a reheating furnace at a temperature of 850-1110° C. for a predetermined length of time, subjecting the mother tube to sizing to produce a steel seamless tube having a wall thickness of at most 4 mm, characterized in that the soaking time in the heating furnace is at least [billet diameter (mm)×0.14] minutes and at most [billet diameter (mm) ×0.35] minutes, and the soaking time in the reheating furnace is at least [mother tube wall thickness (mm)×3.0] minutes and at most [mother tube wall thickness (mm)×10.0] minutes.