METHOD OF MAKING HEAT INSULATED PIPE Russian patent published in 2016 - IPC E21B17/00 F16L13/00 

FIELD: production of hydrocarbons.

SUBSTANCE: invention can be used for production of columns for injecting heat carrier into oil formation. Method includes coaxial placement of the internal pipe with insulation, getters and centralizers in outer pipe. Structure assembled on tacks at one end is placed in vacuum chamber. Heating of internal and external pipes is performed in vacuum 10^-4-10^-3 mm Hg to final temperature of 400°C. Evacuation of intertubular space is carried out through annular gaps between sleeve and external pipe to pressure of 10^-4-10^-3 mm Hg. Rate of pipe heating during vacuum pumping is set so that pressure in intertubular space does not exceed 0.1 mm Hg. External and internal pipes are connected through steel bushings by welding to pipes using vacuum tight welds with the help of electron-beam welding in vacuum. Thermal treatment of welds is performed after vacuum removal for increasing ductility of welds by removing thermal stresses in welds and heat affected zone. Design of the external thread at the external pipe ends is performed after mechanical processing of vacuum-tight welds.

EFFECT: reduced heat losses at heat carrier passage through the column, higher reliability of the column and efficiency of the column section assembly.

2 cl, 1 dwg