The present paper reports on a NDT-technology, which was introduced in the Ukraine, in order to characterize strain ageing of welds, when estimating the critical age of gas- and oil-pipeline structures. The integrated tests during monitoring were carried out using a magnetic method, i.e., the measurement of the coercivity, and also performing an ultrasonic testing method (UT), hardness measurement, and X-ray radiography (RT). To determine threshold values of the coercivity in the weld and the heat-affected zone (HAZ), calculations were made on the basis of the developed procedure and data obtained in the tensile tests. Based on the measurement results obtained by monitoring and the preliminary calculation of the coercivity threshold values for the different zones of circumferential joints, statistical analysis were carried out and the safety condition of the welded joints was estimated. The results shows that NDT of the circumferential welded joints of a pipeline section using the technique to measure the magnetic coercivity together with UT, RT, and hardness measurement provides information of high value about the technical condition of the microstructure of the pipeline welded joints after long-term service.
Influence of service life of gas pipelines on magnetic properties of welded joints
Einfluss der Nutzungsdauer von Gaspipelines auf magnetische Eigenschaften von Schweißverbindungen
2007
5 Seiten, 3 Bilder, 5 Tabellen, 5 Quellen
Conference paper
English
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