INTEGRITY OF BURIED GAS PIPELINE SUBJECTED TO AN ADJACENT PIPE RUPTURE EVENT

This paper discusses the integrity of 30" OD pipeline subjected to burst of 24" pipeline located 24' away. Study discusses the detailed finite element analyses (FEA) of pipeline subjected to the stress waves emanating from the rupture event. Dynamic response of a 30" gas pipe buried approximately 6.5' deep was studied using ABAQUS, to determine how it may have been affected by the rupture of an adjacent 24" gas pipe. The pressure at the 24" OD pipe was dropped from flow pressure to zero psi in a very short interval to simulate a rupture. Sensitivity analyses were conducted by varying the soil modulus and rupture time duration using 2-D and 3-D approaches to arrive at a consensus. In-addition, nonlinear Mohr-Coulomb based advanced soil constitutive models were also used to establish the effect of the soil behavior with the rupture event. Integrity of the pipeline was established based on the stresses/strains and strain based damage factors. Based on the FEA analyses compared with analytical results, the integrity of the 30" OD pipeline can be established and also qualified as either fit or unfit for the operations. The weight equivalent of TNT required to produce this shock loading was obtained by converting internal energy from finite element model using analytical approaches. Analytical solutions and the results from earlier conducted PRCI work were used to verify the simulation approaches. Amplification of stresses on the buried pipeline by using TNT explosives on the surface was obtained through FEA and correlated using experiments conducted and listed in PRCI work. Coupled Eulerian-Lagrangian analyses were further carried out to simulate the crater formation related to the burst event of the buried pipeline.