Patent ID: 11927495
Assignee: nan
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 11:
12. A method for contactless determination of mechanical stresses in a pipeline, comprising:
performing a contactless measurement of a magnetic flux density using arrays of sensors through a sequential contactless measurement of characteristic parameters along an axis of the pipeline, the characteristic parameters being represented by magnetic field induction gradients dB that characterize a change in the magnetic flux density passing through the arrays of sensors when the arrays of sensors move along the axis of the pipeline at a distance from the pipeline, wherein said performing the measurement of the magnetic flux density comprises:
i) performing the contactless measurement of the magnetic flux density in an YZ plane, the YZ plane defining an action area of transverse hoop stresses of the pipeline,
ii) performing the contactless measurement of the magnetic flux density in an XY plane, the XY plane defining an action area of longitudinal horizontal stresses of the pipeline and bending moments,
iii) performing the contactless measurement of the magnetic flux density in two XZ planes spaced apart from each other, the XZ planes defining an action area of longitudinal vertical stresses and bending moments;
wherein the contactless measurements are performed simultaneously in the YZ, XY planes and the two XZ planes;, receiving, by a computing device for determining the mechanical stresses, the characteristic parameters as the magnetic field induction gradients dB that characterize the change in the magnetic flux density;, calibrating, by the computing device, the characteristic parameters based on the received data, said calibrating comprising determining calibration coefficients according to a known data, the calibration coefficients characterizing a magnetomechanical state of a homogeneous pipeline throughout the pipeline as a dependence of the change in the magnetic flux density on a change in a mechanical moment, the calibration coefficients being determined as ratios of magnetic and mechanical moments, said calibrating being based on conditions of previously known differences in magnetic moments in two different cross-sections of the pipeline or known differences in mechanical moments under conditions of a difference in an internal pressure or temperature;, calculating, by the computing device, distributions of mechanical stresses at each measure point throughout the pipeline by means of matrix transformations, wherein increments of a main stress vector at each measure point are determined based on the matrix transformations, wherein the transverse hoop, longitudinal horizontal and longitudinal vertical stresses are calculated separately as projections of the main stress vector on the corresponding planes lying in the action area of the stresses;, determining, by the computing device, the mechanical stresses in the pipeline based on the calculated distribution of mechanical stresses at each measure point throughout the pipeline, wherein anomalies are determined at given criteria for limit values of the stresses, wherein a maximum deviation from permissible values of the mechanical stresses is used to determine a concentration value of the mechanical stresses, and a shape of the distribution of mechanical stresses is used to determine a type of an anomaly source; and storing storing, in a database of mechanical stresses, the characteristic parameters as the magnetic field induction gradients dB, the determined calibration coefficients and the calculated distributions of mechanical stresses at each measure point throughout the pipeline.