Method for detecting temporally varying thermomechanical stresses and/or stress gradients over the wall thickness of metal bodies

Patent metadata

Field	Value
Publication number	US-9903840-B2
Application number	US-201414771162-A
Country	US
Kind code	B2
Filing date	Feb 20, 2014
Priority date	Feb 28, 2013
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

The present invention relates to a method for detecting temporally varying thermomechanical stresses and/or stress gradients over the wall thickness of metal bodies, in particular pipelines. In the method, the temperature on the outer surface of the body is measured in order to determine a temperature progression and stress progression therefrom. In addition, electromagnetic ultrasonic transducers are used at at least one measuring point on the outer surface in order to determine the progression of the stresses and/or stress gradients over time over the wall thickness of the body in conjunction with the result of the temperature measurement. The method allows the fatigue monitoring of pipelines even in the event of rapid stress changes.

First claim

The invention claimed is:

1. A method for detecting temporally varying thermomechanical stresses and stress gradients over a wall thickness of metal bodies, in particular pipelines, in which a temperature is measured at at least one measurement point on an outer surface of a body and additional measurements are carried out using electromagnetic ultrasound transducers in a region of the measurement point to determine the one or more of stresses or stress gradients over the wall thickness of the body via the measured temperature from the additional measurements,
wherein a temperature curve between an inner surface and the outer surface is ascertained from the measured temperature and is used for the determination of the one or more of stresses or stress gradients over the wall thickness of the body from the additional measurements;
characterized in that one or more of ultrasound runtime, amplitude, or eddy current impedance measurements are carried out using the electromagnetic ultrasound transducers, wherein the one or more of stresses or stress gradients are determined by analyzing the one or more of ultrasound runtime, amplitude, or eddy current impedance measurements in conjunction with the measured temperature or the ascertained temperature curve; and
characterized in that the determination of the one or more stresses or stress gradients is performed on the basis of a layer model of a wall of the body, which uses the ascertained temperature curve and a stress curve derived therefrom as well as measured and temperature-corrected ultrasound runtimes, amplitudes, and eddy current impedances as input variables and supplies layer-related ultrasound runtimes, amplitudes, eddy current impedances, and stress curves as output variables, wherein the layer-related stress curves are determined by iterative optimization of the layer model from the layer-related ultrasound runtimes, amplitudes, and eddy current impedances.

2. The method as claimed in claim 1 ,
characterized in that two linearly polarized transverse waves, which are perpendicular to one another, are emitted perpendicularly into a wall of the body in each case using the electromagnetic ultrasound transducers, to measure ultrasound runtimes and amplitudes in pulse echo operation.

3. The method as claimed in claim 2 ,
characterized in that, during the measurement on a pipe as the body, one of the transverse waves is linearly polarized in an axial direction of the pipe and the other is linearly polarized in a circumferential direction of the pipe.

4. The method as claimed in claim 2 ,
characterized in that two pairs of electromagnetic ultrasound transducers in separate transmission-reception arrangement are additionally used, which generate Rayleigh waves or horizontally polarized transverse waves, wherein the two pairs are arranged at an angle of 90° in relation to one another at the measurement point.

5. The method as claimed in claim 1 ,
characterized in that the electromagnetic ultrasound transducers are used at multiple measurement points distributed over an external surface.

Assignees

• Areva Gmbh

Inventors

• Altpeter Iris
• Tschuncky Ralf
• Herrmann Hans Georg
• Kurz Jochen
• Dobmann Gerd
• Huebschen Gerhard
• Bergholz Steffen
• Rudolph Juergen

Classifications

• G01N29/2412 Primary

  using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; (investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18) · CPC title

• G01N29/07 Primary

  by measuring propagation velocity or propagation time of acoustic waves · CPC title

• G01N2203/0069

  Fatigue, creep, strain-stress relations or elastic constants · CPC title

• G01N2291/02827

  Elastic parameters, strength or force · CPC title

• G01M5/0025

  of elongated objects, e.g. pipes, masts, towers or railways (G01M5/0058 takes precedence) · CPC title