HEAT-INSULATED PIPE STRING Russian patent published in 2003 - IPC

FIELD: oil and gas producing industry, particularly, oil production with use of heat carrier injection into oil formation for prevention of permafrost thaw and deposition of paraffin in tubings in oil recovery from wells in regions with permafrost grounds and also in other branches of national economy for heat insulation of pipelines. SUBSTANCE: essence of the invention consists in that heat-insulated pipe string including concentric sections of external pipes with joint unit and sections of internal pipes contains, between sections in annular space, heat-insulating and screening materials, expansion joints, elastic rings installed between adjacent sections of pipes in their joint unit. Expansion joints are made in the form of loop-shaped clamp with cylindrical shells, and they are located on joints of string sections at level of joint units. Expansion joints are located at one end of internal pipe and rigidly connected by one cylindrical end of shell to external surface of internal pipe, and by the other cylindrical end of shell, they are installed with sliding on internal pipe and rigidly connected with internal surface of external pipe. EFFECT: higher operating reliability of heat-insulated pipe strings. 2 cl, 2 dwg