FIELD: protection of metals against corrosion; protection of extended underground gas lines against corrosion.
SUBSTANCE: proposed method includes restoration of defective sections of gas lines by application of insulating protective coats and connection with cathode protection system; defective section of gas line is preliminarily disconnected from gas main and is freed from natural gas; gas released from this section is compressed and is charged in reservoirs under pressure; gas line surface is cleaned from soil and defective coat by forming temperature gradient and stresses between defective coat and gas line; then finish cleaning of outer surface of gas line is performed at simultaneous suction of dust and gas line is heated to temperature of 70 to 175°C, after which layers of adhesive composition and dielectric insulating coat are applied at succession at overlapping joints between steel pipes of gas line and layer of spiral-shaped coat made from metal at potential more negative as compared with potential of gas line being protected; metal coat is applied in form of tape or foil whose ends are brought out at distance of (0.01-1)d, where d is diameter of pipe. Then, insulating plastic coat is applied on metal coat and after erection of gas line, ends of tape or foil are electrically connected at points of joints of steel pipe over entire length of gas line through switching units and parameter measuring units.
EFFECT: enhanced reliability of corrosion protection; considerable reduction of energy expenses; increased service life of metal coat.
3 cl, 10 dwg
