PSI - Issue 17

V. Chmelko et al. / Procedia Structural Integrity 17 (2019) 520–525 Chmelko, V., Bíro, D./ Structural Integrity Procedia 00 (2019) 000 – 000

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Destruction pressures have reached values:

• Specimen 1 - 32.1 MPa (nominal wall thickness 4 mm, corrosion depth 24%) • Specimen 2 - 30.0 MPa (nominal wall thickness 4 mm, corrosion depth 35%) • Specimen 3 - 18.5 MPa (nominal wall thickness 4 mm, corrosion depth 75%)

Fig. 3. The specimens of pipes after destruction.

The pipeline specimens in Fig. 3 were modelled for using in numerical analysis (FEM). Tensile test of pipe material ST52 was carried out for obtaining tensile diagram, which was recalculated into true stress by equation (5). This recalculated diagram was used as the material model in numerical analysis (Fig. 4). = = (1 + ) (5) The material properties in tangential and radial directions were different caused by manufacturing technology, which was confirmed by measurement on material specimens. Material strength in tangential direction was about 10% higher than in axial one caused by rolling process.

Fig. 4. The material model used in numerical simulation.