PIPE

Lifetime management of underground pipelines is mandatory for safe hydrocarbon transmission and distribution systems. The use of high-density polyethylene tubes subjected to internal pressure, external loading and environmental variations requires a reliability study in order to define the service limits and the optimal operating conditions. In service, the time-dependent phenomena, especially creep, take place during the pipe lifetime, leading to significant strength reduction. In this work, the reliability-based assessment of pipe lifetime models is carried out, in order to propose a probabilistic methodology for lifetime model selection and to determine the pipe safety levels as well as the most important parameters for pipeline reliability. This study is enhanced by parametric analysis on pipe configuration, gas pressure and operating temperature.

Time for Development of Internal Erosion and Piping in Embankment Dams. [Journal of Geotechnical and Geoenvironmental Engineering 129, 307 (2003)]. Robin Fell, Chi Fai Wan, John Cyganiewicz, Mark Foster. Abstract. ... Internal Erosion and Piping Process. ...

The equations of motion for straight fluid filled pipes are greatly simplified. It is found, for frequencies below a third of the ring frequency, that the radial-axial waves in cylinders are as if the circumferential motion were inextensional. This is the fundamental assumption for the analysis. The derivation is also based on the assumption of long axial wavelengths, resulting in the axial inertia of the fluid and the axial flexural stiffness of the pipe wall being negligible. The formulation is restricted to frequencies well below the cut-on of higher order fluid modes. For such frequencies, the compressibility of the fluid is neglected and the internal fluid loading, on the pipe, is approximated as an increase in the radial inertia. Upon this basis, the equations of motion, for each circumferential mode, are similar to those for a Timoshenko beam on a Winkler foundation. Numerical experiments are made, comparing the approximate theory with results from calculations from the Helmholtz equation for the fluid and accurate thin-walled cylinder theory. Criteria of the application of the simplified theory are formulated.

Small-scale providers of water services are no longer seen as merely temporary substitutes for formal utilities. In many developing countries governments and donors increasingly view them as long-term partners in the work to extend and improve water services, particularly as governments accelerate efforts to meet water targets associated with the Millennium Development Goals. But a host of problems complicate efforts to make small-scale providers productive partners, including their lack of access to finance. In Kenya, a collaborative program is bringing together community-based organizations and micro-lenders to provide better water services to poor people -- and generating lessons for similar initiatives.

The purpose of this study was to simplify and improve the mechanistic model developed by Taitel and Dukler (1976) for estimating the liquid holdup in horizontal two-phase flow. An experimental study was first conducted to develop a data bank used for evaluation and ...