Centrifugally cast double-layer tube with resistance to carbon deposition
AssigneesJgc Corporation, Taihei Kinzoku Kogyo Co., Ltd.
InventorsKeikichi Maeda, Takahiro Iijima, Eiichi Sato
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Abstract
A centrifugally cast double-layer tube with resistance to carbon deposition, comprising an inner layer of a specific metallic material containing 1-10 wt % of Al and an outer layer of a heat resisting metallic material, can be applied to apparatuses for treating a fluid, containing hydrocarbons, their derivatives, or carbon monoxide, at elevated temperatures and to piping for transferring the fluid without carbon deposition on its inside surface, because the surface of said inner layer is oxidized to form a firm Al-containing oxide film prior to and/or during the treatment of the fluid, and also a sufficient strength and ductility of the tube are preserved by the support of the outer layer of said tube.
Claims7
A centrifugally cast double-layer tube which exhibits improved resistance to carbon deposition on the inner surface thereof caused by treating a fluid containing hydrocarbons, derivatives of hydrocarbons or carbon monoxide at an elevated temperature within said tube, said tube comprising an outer annular layer of a first, heat-resistant metal and an inner annular layer bonded directly to said outer layer, said inner layer being made of a second metal containing from 1 to 10 wt. % of aluminum and the balance is selected from the group consisting of austenitic steel, ferritic steel, austenite-ferrite duplex-phase steel, low-alloy steel, Ni alloy, Ni-Cr alloy, Co alloy and Co-Cr alloy.
A centrifugally cast tube which is resistant to carbon deposition on the inner surface thereof in the presence of thermally cracked hydrocarbons or derivatives thereof or in the presence of a fluid containing carbon monoxide which has been treated at an elevated temperature, said tube consisting essentially of an outer annular layer consisting essentially of a first, heat-resistant metal selected from the group consisting of steel, Ni-Cr steel alloy and Co-Cr steel alloy, an inner annular layer made of a second metal containing 1 to 10 wt. % aluminum and the balance is selected from the group consisting of austenite-ferrite duplex-phase steel, low-alloy steel, Ni steel alloy, Ni-Cr steel alloy, Co steel alloy, and Co-Cr steel alloy, and a dense, firm, stable aluminum-containing oxide film covering the inner surface of said inner layer.
Dependencies are inferred from the claim text.