Method for producing a clad steel pipe
AssigneeKuroki Kogyosho Co., Ltd.
InventorsTakanori Kuroki, Toshio Yoshida
Life of this patent
Estimating the term…
Abstract
A method for producing a clad steel pipe having resistance to corrosion and wear at the inner and/or the outer faces includes plural base pipes which are mechanically fixed and metallurgically joined by diffusion welding before the plural base pipes are elongated to produce an elongated clad steel pipe.
Claims27
A method of producing a clad pipe comprising coaxially assembling a plurality of cylindrical tubular blanks of different metals, seal welding the longitudinal ends of said tubular blanks about the entire circumferential interface of said tubular blanks, maintaining vacuum conditions about said tubular blanks to a temperature of at least 750.degree. C. and a pressure of at least 200 kg/cm.sup.2 to effect metallurgical bonding over the whole interface of said tubular blanks, and elongating said metallurgically bonded tubular blanks such that the cross-section area thereof is reduced to one-third or less of its pre-elongated cross-section area to thereby produce an elongated clad pipe.
A method of producing corrosion and wear resistant clad pipes for use in the oil industry to transport oil and the like comprising assembling a plurality of cylindrical tubular blanks of dissimilar metals having different ductibility and different deforming resistance, seal welding the longitudinal ends of said blanks, placing the entire assembled blanks within a hot isostatic press enclosure, simultaneously heating for about one hour the entire assembled blanks to a temperature of at least 750.degree. C. in said enclosure, simultaneously with said heating, pressurizing for about one hour the entire assembled blanks including the inside and outside of the assembled blank to a pressure of at least 200 kg/cm.sup.2 in said enclosure, providing a one hundred percent metallurgical bond between said blanks and a thick diffusion layer of coarse grains at the matrix of said assembled blanks during said steps of simultaneously heating and pressurizing said assembled blanks in said enclosure, removing said metallurgically bonded blanks form said enclosure, elongating said metallurgically bonded blanks such that the cross-section area of the metallurgically bonded blanks is reduced to one-third or less of its pre-elongated cross-section area, said step of elongating said metallurgically bonded blanks comprising simultaneously elongating said diffusion layer, reducing the thickness of said diffusion layer, and refining said coarse grain in said diffusion layer, thereby producing a strong, corrosion resistant and wear resistant clad pipe suitable for use in the oil industry.
A method of producing a clad pipe comprising coaxially assembling inner and outer cylindrical tubular blanks, forming a radial projection on at least one longitudinal end of said inner tubular blank such that said projection abut one longitudinal end of said outer tubular blank, simultaneously subjecting said tubular blanks to a temperature of at least 750.degree. C. and a pressure of at least 200 kg/cm.sup.2, and elongating said metallurgically bonded inner and outer tubular blanks such that the cross-section area thereof is reduced one-third or less of its pre-elongated cross-section area to thereby produce an elongated clad pipe.
Dependencies are inferred from the claim text.