PROCESS OF FORMATION OF ANTICORROSIVE COAT OF PIPE-LINE Russian patent published in 1999 - IPC

FIELD: protection of irrigation systems of steel pipe-lines against corrosion. SUBSTANCE: process provides for isolation of section of pipe-line from irrigation network by insertion of elastic chambers into its space through hydrants and risers located on boundaries of section, cleansing of internal surface of isolated section by filling of it with 0.01% pickling solution of hydrochloric acid in the course of three days, subsequent pumping of pickling products from this space and rinsing of pipe- line. Corrosion-resisting coat is formed on cleansed surface of pipe-line by way of filling of space starting from upper part with 0.01-% solution of superphosphate for surface passivation in the course of 5-7 days simultaneously with pumping away of rinsing products. As result insoluble film of hydro- and iron phosphates is formed and spent phosphate solution is later pumped away and distributed in the field as fertilizer. Air is circulated to diminish condensation of moisture on passivated surface in internal space of pipe-line with the use of plenum-exhaust ventilation manufactured in the form of risers of different length installed in hydrants of pipe-line. Auxiliary operations executed before main technological process include preparation of solution, supply of water, their feed, pumping away of spent solutions from pipe-line, their distribution on the fields with the help of plant fitted with tank, pump and sprinkler nozzles. EFFECT: increased functional reliability of pipe-line of irrigation system. 4 cl, 3 dwg