Patent ID: 8906511

Claim:
A bimetallic tube for fired heater tubes and/or transfer line exchangers for transport of hydrocarbon feedstocks in petrochemical process and/or refinery process units, comprising: i) an outer tube layer of a HP45Nb alloy or HP16Nb alloy comprising 22.5 to 27.0 wt. % Cr, 33.0 to 38.0 wt. % Ni, 1.2 to 1.8 wt. % Si, 1.2 to 1.7 wt. % Mn, 0.2 max. wt. % Mo, 0.14 to 0.5 wt. % C, 0.6 to 1.6 wt. % Nb, 0.02 max wt. % P and 0.02 max wt. % S with balance being Fe; ii) an inner tube layer being formed from an alumina forming bulk alloy comprising 6.19 to 6.33 wt. % of Al, 20.97 to 21.00 wt. % Cr, 0.41 to 0.43 wt. % Si, 38.7 to 38.9 wt. % Fe and 0.1 wt. % to 30.0 wt. % of at least one intermetallic precipitate chosen from Ni3Al, NiAl, sigma-phase, and combinations thereof with balance being Ni, wherein the inner tube layer is formed by plasma powder welding the alumina forming bulk alloy on an inner surface of the outer tube layer; and iii) an oxide layer formed on a surface of the inner tube layer, wherein the oxide layer comprises alumina.