Rehabilitation of Pipelines in Seismic Regions

Abstract

The susceptibility of oil and gas pipelines to seismic damage has been demonstrated in earthquakes everywhere around the world. The latest examples of the dangerous failures are the ruptures of gas pipelines caused by Los-Angeles earthquake 1994 and oil pipelines caused by Sakhalin earthquake 1995. A significant part of oil and gas pipelines were designed some decades ago. Earthquake design specifications acting today are more restrictive than before. That is why pipelines built more than ten years ago are of major concern to managers and engineers. Basic approaches to the aseismic design of new pipelines and retrofitting of buried pipes and above-ground transmission pipelines and piping systems located in high risk seismic regions represent the main topic of the paper. A realistic assessment of earthquake damage potentials is needed to develop construction and retrofitting procedures. Supporting this type of constructing and rehabilitation activity for pipelines requires a better definition of key input parameters like area seismicity, the identification and characterization of ground moving hazards. The nonlinear approach for predicting spatial bending, torsion, and upheaval buckling of curved pipeline is applied for stress and stability analysis of buried pipelines under operational and seismic loading. The example of calculations useful for retrofit design of pipelines is given. An experience of damping devices application to mitigate seismic movement of above-ground pipelines has demonstrated an excellent ability to prevent damages during earthquake and operational dynamic loading. These devices are useful for above-ground pipeline retrofitting. To reduce uncertainty regarding the ability of a pipe to continue to hold pressure after seismic damages and retrofitting measures, it is important to develop the test programs, which should include investigations of buried and above-ground pipeline samples.