Propagating Shear Fracture Test of Large Diameter Gas Transmission Line Pipes for Arctic Grade

Abstract

So called separations are often observed on the surface of propagating shear fracture of line pipes for arctic grade, which are made of severely controlled-rolled steel plates. In order to investigate the effects of these separations on the propagating shear fracture bahavior, two series of tests were conducted. One is the series of full scale burst tests of large diameter pipe lines (200 m in length) highly pressurrized by natural gas (Athens Type Test). The other is the short length burst tests of large diameter pipes pressurized by a mixture of N₂ gas and water (West Jefferson Type Test). The latter series of tests was planned to examine the effect of temperature on the propagating shear fracture behavior and to determine whether the toughness parameter for the propagating shear fracture is temperature-dependent or not. The results show that the separations have no influence on the propagating shear fracture speed and that the propagating shear fracture behavior is strongly dependent on the test temperature. The fracture speed increased and the absorbed energy decreased with lowering test temperatures. It is concluded that the toughness parameter for the propagating shear fracture should be temperature dependent and the intercept energy which is independent of temperature cannot be an appropriate criterion for the toughness required to arrest propagating shear fracture.