Patent ID: 7653999

Claim:
A method for successfully rolling co-extruded tubing into drums of a boiler bank in a corrosion and erosion boiler environment comprising the steps of: providing a co-extruded tubing containing a carbon steel base tubing, an outer layer of high alloy tubing, an area that is to be rolled into the drum by machining, and an area that is to be exposed to the boiler environment; removing the outer layer of high alloy tubing in the area that is to be rolled into the drum by machining; swaging the co-extruded tubing using multiple swaging steps and annealing treatments to swage the co-extruded tubing to a required diameter and wall thickness; inserting the co-extruded tubing into the drums; rolling the co-extruded tubing; and sealing the co-extruded tubing into the drums.