Patent ID: 6231690
Filing Date: 2001-05-15
Classification: C23C

Abstract:
A method of oxidation treatment of the inner surface of a ferritic stainless steel pipe, comprising, feeding an oxidizing gas into steel pipe from one end thereof while moving the steel pipe in a pipe length direction; heating the pipe in a heating furnace having a non-oxidizing atmosphere at a specific temperature of T.degree. C. which falls within the range of 700 to 1000.degree. C. to form a Cr oxide film on the inner surface of the steel pipe; wherein the oxidizing gas refers to a mixed gas containing 10 to 99.9999 volume % hydrogen gas, 1 to 300 volume ppm steam, and the balance being an inert gas, and the non-oxidizing atmosphere refers to an atmosphere comprising 3 volume ppm or less oxygen and 30 volume ppm or less steam, or a vacuum atmosphere in which the pressure of residual gas is 5 Pa or less.