Pipelines constructed on unstable terrain (e.g., permafrost), submarine lines, etc. may shift, producing stresses which can lead ultimately to rupture. The authors have used magnetometer surveys to detect bending stresses in buried pipelines and to monitor new construction. The perturbations to the earth's field are large and complex; typically fluctuations of 5-10 kilogramma are found 2 m above 1 m diameter buried line. These signals record initial magnetization joints, construction history, etc. and include the results of stress induced magnetization changes. The magnetostrictive effect in steel depends on field, stress, and cyclic history. There is little basic data on the inverse effect, stress induced changes in magnetization. In a pipeline the bending stress distribution is complex so that fringing field changes due to stress magnetization changes are not calculable. However, experience now enable them to interpret some of the features of their magnetometer surveys. Since stress effects are large they are optimistic that they can eventually develop the technique for surveying pipelines for unusual stress concentrations.
Detection of anomalous stresses in gas pipelines by magnetometer survey
Nachweis anomaler Spannungen in Gas-Pipelines durch magnetometrische Vermessung
Journal of Applied Physics ; 53 , 11, PT.2 ; 8130-8135
1982
6 Seiten, 4 Quellen
Aufsatz (Zeitschrift)
Englisch
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