METHOD OF REVEALING SECTION OF MAIN PIPE LINES PREDISPOSED TO CORROSION CRACKING UNDER STRESS (STRESS CORROSION) Russian patent published in 2000 - IPC

FIELD: pipe line transport; diagnosis of operating pipe lines. SUBSTANCE: method consists in analysis of design and actual positions of pipe line relative to level of protected state of subsoil water, conjunction of line of subsoil water level on surface of pipe line to clock orientation, assigning index (Pi) to each factor causing corrosion cracking and determination of destruction hazard criterion (Kp) by total index (ΣPi).. Extent of section being diagnosed is limited by sections of pipe line located between section fully immersed in non- flooded soil or fully immersed in subsoil water. Type of diagnosis depends on extent of separate sections liable to corrosion cracking and total affected area (exceeding 50 %). Diagnosis is performed by three methods: full opening of pipe with nondestructive testing of surface, acoustic emission and inter-pipe flaw detection. All three methods are used for complex diagnosis of extended sections at increased density of location of potentially dangerous sections of pipe line. Depending on the results of diagnosis, type of preventive maintenance or repair jobs are assigned to obtain required reliability of pipe line. EFFECT: enhanced reliability due to revealing of defective sections in due time. 2 cl, 7 dwg, 1 ex