Patent ID: 8464568

Claim:
A production method of a seamless pipe or tube comprising the steps of: heating a billet in a heating furnace, subjecting the heated billet to piercing and rolling by a piercer to produce the hollow shell, applying a lubricant containing carbon to a mandrel bar, subjecting the hollow shell to drawing and rolling in a mandrel mill using the mandrel bar to which the lubricant is applied, to produce a material pipe or tube, and reheating the material pipe or tube in a reheating furnace, wherein when a temperature of the material pipe or tube is 550° C. or higher and 1000° C. or lower in the reheating step, an oxidizing gas is fed into the material pipe or tube, a flow rate of the oxidizing gas being determined so as to satisfy the condition of the following equation (1): Q ≥ 7.7394 × 10 12 · exp ⁡ ( - 22748 ( T ∞ + T p ) × 0.5 + 273 ) · C in T in + 273 · 1 ρ c ⁢ D c · A b · π ⁢ ⁢ D p ⁢ L p , ( 1 ) wherein Q represents a flow rate of the oxidizing gas [Nl/sec], T ∞ represents a temperature of atmosphere in the reheating furnace [° C.], T p represents a temperature of the material pipe or tube at the time when the material pipe or tube is introduced into the reheating furnace [° C.], C in represents an oxygen content of the oxidizing gas [vol. %], T in represents a temperature of the oxidizing gas [° C.], ρ c represents a particle density of carbon which the lubricant applied to the mandrel bar contains [kg/m 3 ], D c represents a particle diameter of carbon which the lubricant applied to the mandrel bar contains [μm], A b represents an adhesion density of carbon which the lubricant applied to the mandrel bar contains [g/m 2 ], π represents Ludolphian number, Dp represents an inner diameter of the material pipe or tube [m] and L p represents a length of the material pipe or tube [m].