ULTRASONIC METHOD FOR DETERMINATION OF RESIDUAL STRESSES IN WELDED JOINTS OF PIPELINES Russian patent published in 2016 - IPC G01N29/04 

FIELD: measurement technology.

SUBSTANCE: invention can be used for determination of residual mechanical stresses in welded joints of various pipelines. Present invention comprises using an echo method to measure propagation time of longitudinal and transverse elastic waves, wherein estimation of stress carried using Poisson coefficients ν₃₁ and ν₃₂ of material, determined through propagation time of longitudinal and transverse elastic waves. In zones of pipeline, where there is no residual stress, linear relationship applies between Poisson coefficients ν₃₁ and ν₃₂. Presence of residual welding stress results in deviation of points {ν₃₁; ν₃₂} from initial linear relationship. Based on value of deviation difference of circular and axial stresses is estimated σ₂-σ₁.

EFFECT: determination of difference in axial and circular main stresses on investigated pipeline section in mode that does not require unloading structure; enabling determination of distribution of difference in axial and circular main stresses on investigated pipeline section in mode that does not require unloading of structure.

1 cl, 3 dwg