METHOD OF WELDING PIPELINES WITH INTERNAL ANTICORROSION COATING Russian patent published in 2020 - IPC F16L13/02 

FIELD: transportation.

SUBSTANCE: invention relates to pipeline transport and can be used in construction and repair of pipelines with internal anticorrosive coating in industries and in municipal services. Method of welding pipelines with internal anticorrosive coating comprises preparation for welding of edges and inner surfaces of connected ends of pipes by cleaning from dust and contaminants and degreasing with acetone of internal cavities of pipes in the zone of ends at depth of 100–200 mm, thereafter, an internal protection sleeve of the welded joint of pipelines with an inner anticorrosive coating is placed inside one of the connected pipes, comprising a cylindrical housing with flared ends and an internal anticorrosion coating, with radial stops made in the form of annular projections made near the ends of the housing, which outer diameter is equal to inner diameter of connected pipes. On outer surface of said housing there is heat-insulating material, in the middle there are external stops, and between radial stops above heat-insulating material there is a layer of thermoactive material, which is evenly distributed throughout the radius with the height of the radial stops, between the said stops and flared ends of the bushing there are elastic collars the outer diameter of which exceeds the internal diameter of the pipeline. Thermoactive material used is a composition consisting of an epoxy-polyester mixture which, when heated, is polymerised, and a gas-forming agent which enables to color the inner surface of the pipes by thermal action, after which the pipes are brought to rest against the stop of the pipe ends into external stops and leveled, after which the attached pipes are clasped and external stops are removed, then the root seam is welded, avoiding at the same time metal burns and the electrode or welding wire pumping into the pipe cavity, section of welded seam at 10–15 mm above semicircle is left to release thermoactive material during its thermal expansion and released gases, filling of the seam is performed immediately after the passage of the root seam until the thermoactive material leaves the non-welded section, when the thermoactive material is released, the welding process is stopped, waiting for termination of output of thermoactive material and gases, released material is removed from non-welded section and welding filler is continued, after termination of released gases, root is welded and filler seam is finished, and in case of non-availability of thermoactive material from non-welded part of pipe seam, pipes are uniformly heated in area of installed bush by 200–240 mm with gas burner along entire surface from bottom to top up to moment of thermoactive material output from unprocessed section of welded seam, after that it is cleaned and brewed.

EFFECT: method is characterized by simplicity and speed of pipe butt welding.

1 cl, 2 dwg