Forming insulated conductors using a final reduction step after heat treating

Abstract

A method for forming an insulated conductor heater with a final cross-sectional area includes reducing a cross-sectional area of an insulated conductor assembly to form an insulated conductor heater with a final cross-sectional area. The insulated conductor assembly may have been previously treated with at least one combination of a cold working step and a heat treating step. Reducing the cross-sectional area of the insulated conductor assembly to form the insulated conductor heater with the final cross-sectional area may include cold working the insulated conductor assembly to further reduce the cross-sectional area of the insulated conductor assembly by at most about 20% of the cross-sectional area of the insulated conductor assembly after the at least one combination of the cold working step and the heat treating step has been completed.

1 . A method for forming an insulated conductor heater, comprising:
 placing an insulation layer over at least part of an elongated, cylindrical inner electrical conductor, wherein the insulation layer comprises one or more blocks of insulation;   placing an elongated, cylindrical outer electrical conductor over at least part of the insulation layer to form the insulated conductor heater;   performing one or more cold working/heat treating steps on the insulated conductor heater, wherein the cold working/heat treating steps comprise:
 cold working the insulated conductor heater to reduce a cross-sectional area of the insulated conductor heater; and 
 heat treating the insulated conductor heater at a temperature of at least about 870° C.; and 
   reducing the cross-sectional area of the insulated conductor heater by at most about 20% to a final cross-sectional area.   
     
     
         2 . The method of  claim 1 , wherein cold-working the insulated conductor heater reduces the cross-sectional area of the insulated conductor heat by at least 30%. 
     
     
         3 . The method of  claim 1 , wherein an amount of reduction to the final cross-sectional area of the insulated conductor heater ranges between about 5% and about 20%. 
     
     
         4 . The method of  claim 1 , wherein an amount of reduction to the final cross-sectional area of the insulated conductor heater ranges between about 10% and about 20%. 
     
     
         5 . The method of  claim 1 , wherein the insulated conductor heater is not heat treated after reducing the cross-sectional area of the insulated conductor heater by at most about 20%. 
     
     
         6 . The method of  claim 1 , wherein reducing the cross-sectional area of the insulated conductor heater by at most about 20% increases the dielectric strength of the insulation layer to within about 5% of the dielectric strength of the pre-heat treated insulation layer. 
     
     
         7 . The method of  claim 1 , wherein reducing the cross-sectional area of the insulated conductor heater by at most about 20% provides a breakdown voltage of between about 12 kV and about 20 kV for the insulated conductor heater. 
     
     
         8 . The method of  claim 1 , wherein the cold working/heat treating steps are repeated more than once prior to reducing the cross-sectional area of the insulated conductor heater to the final cross-sectional area. 
     
     
         9 . A method for forming an insulated conductor heater, comprising:
 placing an insulation layer over at least part of an elongated, cylindrical inner electrical conductor, wherein the insulation layer comprises one or more blocks of insulation;   placing an elongated, cylindrical outer electrical conductor over at least part of the insulation layer to form the insulated conductor heater; and   performing one or more alternating cold working/heat treating steps on the insulated conductor heater with a final step being a cold working step that reduces the cross-sectional area of the insulated conductor heater to a desired final cross-sectional area of the insulated conductor heater.   
     
     
         10 . The method of  claim 9 , wherein cold working/heat treating steps comprise:
 cold working the insulated conductor heater to reduce a cross-sectional area of the insulated conductor heater; and   heat treating the insulated conductor heater at a temperature of at least about 760° C.   
     
     
         11 . The method of  claim 9 , wherein the final step comprises reducing the cross-sectional area of the insulated conductor heater by at most 20% to the desired final cross-sectional area. 
     
     
         12 . The method of  claim 9 , wherein the cold working/heat treating steps are performed at least twice. 
     
     
         13 . The method of  claim 9 , wherein reducing the cross-sectional area of the insulated conductor heater to the desired final cross-sectional area increases the dielectric strength of the insulation layer to within about 5% of the dielectric strength of the pre-heat treated insulation layer. 
     
     
         14 . The method of  claim 9 , wherein performing the cold working/heat treating steps on the insulated conductor heater reduces a gap between at least two of the blocks. 
     
     
         15 . The method of  claim 9 , wherein reducing the cross-sectional area of the insulated conductor heater to the desired final cross-sectional area provides a breakdown voltage of between about 12 kV and about 20 kV for the insulated conductor heater. 
     
     
         16 - 61 . (canceled)