Crack behaviour of pipes under internal pressure and simultaneous external bending moment

To investigate the strength behaviour, the influence of toughness to crack initiation and instability, the strain behaviour, the crack opening as well as the leak-before-break behaviour of artificially cracked piping, pipe bend tests were carried out. The dimensions of the pipes were 800 mm O.D. and 47 mm wall thickness, similar to the dimensions of the main cooling piping system of a 1300 MWe German PWR plant. Two types of nuclear grade materials similar to A 533 Cl 2 were used with high upper shelf impact energy of 50 and 150 J. The pipes were weakened by circumferential oriented surface notches respectively by through-wall flaws having a length of 60 degrees and various depths. The 5 m-long pipe, closed on both ends, was mounted into a newly developed 10 MNm 4-point bending device for loading. After heating up to 3000C and pressurizing up to 15 MPa, the bending moment was increased until failure occurred. (orig.)