Slow Crack Growth-Notches-Pressurized Polyethylene Pipes
نویسنده
چکیده
A general method for predicting the life time of a polyethylene structure that fails by slow crack growth was applied to the case of externally notched pressurized pipes. An analysis of experimental data indicated that the residual stress must be taken into account. The critical notch depths associated with a given life time were calculated as a function of pipe size, PENT value of the resin and temperature. The results were tabulated to serve as practical guide lines for deciding whether a pipe should be discarded if the notch is too deep. The current 10% of the thickness rule now used by industry was found to be invalid.
منابع مشابه
Intrinsic Lifetime of Polyethylene Pipelines
An equation was developed for calculating the time to failure by slow crack growth (SCG) failure in any polyethylene structure. The equation requires the following experimental inputs: (1) the resistance to SCG as measured by the PENT test (ASTM F1473), (2) the stress intensity of the defect from which failure originates, and (3) the temperature. A simple experiment for determining the stress i...
متن کاملNumerical Analysis of the Effect of External Circumferential Elliptical Cracks in Transition Thickness Zone of Pressurized Pipes Using XFEM
The present work investigates the effect of the elliptical three-dimensional (3D) cracks on a pipe with thickness transition, considering internal pressure. Level sets were defined using the extended finite element method (XFEM), the stress intensity factors (SIFs) of 3D cracks were investigated and compared between straight pipes and pipes with thickness transition. The results show that the X...
متن کاملAN INVESTIGATION INTO THE PHYSICAL PROPERTIES OF POLYETHYLENE GAS PIPES BY THE INCORPORATION OF ANTI-RODENT MASTERBATCHES
The incorporation of several anti-rodent masterbatches into polyethylene (PE) granules used for gas pipes and the effects of the masterbatches on the physical properties of the pipes were studied. Four commercial anti-rodent masterbatches from different international companies including, Clariant, Alchemix, PolyOne, and Newgen were used in this research. Each of the masterbatch was primarily dr...
متن کاملNumerical Analysis of the Effect of External Circumferential Cracks in Transition Thickness Zone of Pressurized Pipes Using XFEM – Elastic-Plastic Behavior
The elastic-plastic behavior of the material is considered to analyze the effect of an external circumferential crack on a pipe with thickness transition and double slopes. Using the extended finite element method (XFEM), the J-integral of 3D cracks were investigated and compared between straight pipes and pipes with thickness transition and different slopes. Considering internal press...
متن کاملNumerical modeling and comparison study of elliptical cracks effect on the pipes straight and with thickness transition exposed to internal pressure, using XFEM in elastic behavior.
The present work deals with the effect of an external circumferential elliptical crack located at thickness transition on a varied stepped diameter pipe . The purpose is the application of the extended finite element method (XFEM) for the calculation of SIF at the thickness transition region of pipe considering internal pressure and compare the effect of the crack between pipes straight and wi...
متن کامل