Energy of the Extended Pipeline Failure under Pressure

The results of systematic field pneumatic tests of gas pipes of strength class K65(X80) are analyzed. The geometric and energy parameters of the extended failure of pipes 1420 mm in diameter are determined. The relations between the plastic band elongation at the fracture, the band width, and the fracture energy (per linear meter) are confirmed. On a break path, energy A is shown to decrease severalfold along with a decrease in the break velocity and the gas pressure. This adaptive failure is caused by a change in the ratio of the fractions of slopes and flat sections in the fish-scale fracture. The maximum energy at the start of a crack is the energy consumed for pipe failure. It is determined by a material constant, namely, the hardening factor determined by the ratio of the ultimate strength to the yield strength (σu/σ0.2). In the existing gas pipelines made of pipes of strength class X80, the energy capacity is higher than that to be provided by experimental pipe steels of strength classes X100 and X120.