L51516 Preventing Pipeline Failure in Areas of Soil Movement – Part 1

Ordinarily, buried pipelines undergo little or no movement in service. In a stable soil environment the longitudinal stress in a pipeline seldom approaches the limiting design value set by applicable codes and regulations. Pipeline serviceability under such conditions is seldom, if ever, threatened by the degree of longitudinal stress. In contrast, localized areas may exist along a pipeline where soils and/or slopes are unstable or where subsidence or differential settlement can occur. In these areas, longitudinal stresses may become severe enough to cause a failure. Over the years various techniques have been developed to monitor the status of pipelines in unstable areas, and various remedial techniques have been attempted. In more recent times, with the advent of Arctic and offshore pipelining, such potential movements of pipelines are being taken into account in the initial designs. In any case, there is a continuing need to develop better monitoring and remedial techniques to prevent pipeline failures in unstable soil areas. The objectives of this project are to develop a versatile and reliable prototype strain monitoring system, to demonstrate its applicability on an actual pipeline, and to establish allowable limits on strains due to soil movement or subsidence. The scope of the project includes:(1) Review of previous or on-going monitoring efforts by others.(2) Analysis of strains and development of models to predict strain behavior(3) Calculations to establish limits on strains(4) The design and construction of a microprocessor-controlled automatic monitoring system(5) The implementation of the system on an actual pipeline(6) The collection, analysis and interpretation of strain data from the system.