METHOD OF MAKING HEAT-INSULATED TUBING Russian patent published in 2016 - IPC F16L9/133 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to metallurgy and can be used in making heat-insulated tubing used in operation of oil producing wells in permafrost zone. Method of making heat insulated lift pipe consisting of coaxially located internal and external pipe and end inserts, including installation of internal pipe and end of inserts in outer tube with formation of annular space, internal and external pipes connection by welding with terminal inserts in shielding gas, inner and outer tube and end inserts are made from steel, in chemical composition of which mass fraction of S ≤ 0.010 % , mass fraction of P ≤ 0.020 %, and connection of internal and external pipes with end inserts is carried out by welding after pre-heating zone of weld joint to temperature of 100-400 °C with installation of plug on end of external pipe, opposite welding is performed.

EFFECT: use of method simplifies process of assembly of insulated lift pipe, provides possibility of its operation at subzero temperatures.

2 cl, 1 dwg