FIELD: oil and gas industry.SUBSTANCE: invention relates to oil and gas refining, chemical and other industries using heat-insulated capacitive equipment, for example separators, reactor columns and pipelines, which undergo regular technical diagnostics. Method includes arrangement of stationary window hatches in heat insulation for surface access, treatment of points of control points to required purity, performing primary and secondary measurements of wall thickness at control points with portable ultrasonic inspection sensors (transducers), determination of residual corrosion resource of equipment and pipelines based on measurement results of walls thickness. According to the first version of the method, a process template is prepared, consisting of a strong wear-resistant sheet material, the size and shape of which corresponds to the window-hatch arranged in the heat insulation. Performing single or group of holes in process template corresponding to size, shape and arrangement of working surfaces of port
