IN-SITU METHOD FOR DIAGNOSING ROUTES OF UNDERGROUND STRUCTURES Russian patent published in 1999 - IPC

FIELD: inspection of metal pipelines. SUBSTANCE: method relates to biotechnology, ecological safety of buried oil pipelines and gas pipelines without their exposing to surface. According to method, gas phase of ground is taken from ground surface. Carried out is summed determining of gases which characterize danger of local corrosion (hydrogen sulfide, phosphorous hydride, volatile organic combinations, ammonia). Effected is indication of methane which characterizes danger of stress corrosion. Also made is statistical discriminant analysis for finding dependence of danger of local corrosion or stress corrosion depending on concentration of corrosive gases. Calculated is value of discriminant function F and its value is compared with preliminarily determined criteria values which characterize danger of local corrosion and stress corrosion. Conclusion about danger of local corrosion or stress corrosion is made according to results of determining place of location of calculated discriminant function F on scales with earlier determined criteria values such as centroid of local corrosion, centroid of stress corrosion which relate to sections with risk of local corrosion and risk of stress corrosion. Application of aforesaid method allows for defining dangerous and non-dangerous sections of underground pipeline routes without disturbing route ground that is without exposing of pipeline. EFFECT: higher efficiency. 1 cl, 3 tbl, 5 dwg