METHOD FOR PROTECTING FROM UNDERGROUND CORROSION IN LOCAL DAMAGED PORTIONS OF ISOLATING COATING OF METAL PIPELINES FREE OF ELECTROCHEMICAL PROTECTION Russian patent published in 2003 - IPC

FIELD: mechanical engineering. SUBSTANCE: method involves injecting into ground chemical reactant such as calcium hydroxide with concentration of 1.0-1.5 g/l, which reacts under natural conditions with carbon dioxide and carbonates contained in ground pores and ground water to result in formation of calcium carbonate on metal surface. Method allows pipeline insulation to be recovered without using repair operation and without necessity for stopping of pumping out process and opening of underground metal constructions. EFFECT: increased efficiency in protecting insulating coating from underground corrosion and improved quality of recovered metal surface. 1 tbl