Patent ID: 8307688

Claim:
A process for producing seamless stainless steel pipes in which the process includes the steps of: piercing rolling; elongating rolling using a mandrel bar; and sizing rolling, followed by a product heat treatment, wherein when the carbon-equivalent weight, which is the sum of the weight of graphite in and the weight of the carbon content of organic binder in a lubricant used for the mandrel bar, per unit area of the lubricant adhering to the mandrel bar surface in the above-mentioned step of elongating rolling, is C (g/m 2 ), and a heating temperature for the pipe to be heat-treated in the above-mentioned heat treatment is T (° C.), then a decarburizing gas is blown into the inside of the pipe to be heat-treated during the above-mentioned heat treatment for a period of time longer than the estimated gas blowing time t 1 (seconds) satisfying the relation defined by the equation (1) given below: 2.5 ×C={ 1.326×10 8 ×t 1 ×EXP(−37460/1.987/( T+ 273))} 1/2 (1).