M.Lamborn
# 2010 Vancouver
Good resistance to Rapid Crack Propagation (RCP) is considered to be important to the field performance of polyethylene (PE) pipe. Even though RCP occurrences in PE pipe are very rare, it remains important to understand the RCP phenomenon to ensure that pipes are designed to avoid RCP events. The characterization of RCP performance depends on a variety of factors, such as the test conditions (temperature and pressure), pipe geometry (diameter and wall thickness), and choice of RCP test. Presented here are an accumulation of results from various experimental programs undertaken by us to develop a basic understanding of RCP in PE pipes and the test methods used to characterize RCP performance. Data are presented showing critical pressure critical temperature failure surfaces for MDPE, HDPE, and bimodal HDPE pipe, and their use in the selection of RCP resistant pipe based on specific service conditions is discussed. Data are presented to demonstrate the phenomenon of false arrest and to show how this can lead to misleading and incorrect interpretations of RCP performance from single-point S4 tests at excessively high pressures. The results of experimental work to assess the influence of pipe size on S4 test results are also presented. Analysis of these data, combined with consideration of the effects of shear lips and residual stress effects, indicates that an Irwin-Corten relationship can be employed to provide conservative estimates RCP performance for different size pipe, subject to specific restrictions on the relative geometries between pipes.
Related papers
Author(s) : Vivek Rohatg, Gregor Hiesgen, Mark J. Lamborn, Ashish M. Sukhadia, Douglas E. Simpson, David W. Borrego, Pamela L. Maeger
Maintaining dimensions within specifications is problematic for the extrusion of large diameter thick-wall polyethylene (PE) pipe (> 75 mm wall) due to sag caused by insufficient resin melt strength. However, sag can be controlled through careful resin selection and optimization of the pipe cooling process. This paper...
Author(s) : Ashish M. Sukhadia, Mark J. Lamborn, Pam L. Maeger
Over the past several years, we have conducted extensive investigations of the Rapid Crack Propagation (RCP) behavior of Polyethylene (PE) pipes. While the typical data of interest is the Critical Pressure (Pc) and/or Critical Temperature (Tc), we chose to take our investigations further by exploring and generating...
Author(s) : Mark J. Lamborn, Pam L. Maeger, Rick E. Kunc, Vivek Rohatgi, Paul J. DesLauriers, Ashish M. Sukhadia
Dual cooling is a post-extrusion cool down process employed for polyethylene (PE) pipe, whereby either water or ambient air is forced through the pipe bore following extrusion, in order to accelerate cooling. The primary benefits offered by the dual cooling process are increased production rates and reduced resin...
Author(s) : Krishnaswamy, Leevers, Lamborn, Sukhadia, Register, Maeger
The influence of molecular architecture on the rapid crack propagation (RCP) resistance of a wide variety of high-density polyethylene (HDPE) pipes was investigated. It was concluded that high molecular weight, high crystallinity and a relatively narrow molecular weight distribution are important architectural...
Author(s) : Maeger, Vanspeybroeck, Lamborn, Mamoun, Leevers, Oliphant
As polyethylene pressure pipes enter the global marketplace under an ever-wider range of operating conditions, there is increasing emphasis on their rapid crack propagation performance. It is important that both producers and end-users are able to rely on the robustness of the rapid crack propagation test results and...
Author(s) : Bradley, Slay, Self, Register, Lamborn
The crack growth rate in HMN 5202 and HXM 50100 polyethylcne has bcen studied as a function of stress intensity using deeply notched three-point bend specimens. l'he load-line displacen~entin response to a static applied load has been measured, with tlie material compliance as a function of time determined from the...
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