2018 Las-Vegas : Extrusion of thick wall pipes using a new bimodal PE 4710/PE 100 resin
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...
2014 Chicago : An Evaluation of Aged MDPE Gas Pipes
Author(s) : Karen S. Lively, Pamela L. Maeger
Medium Density Polyethylene (PE80/PE2708 type) pipelines have been used globally in natural gas service applications for over 50 years. The condition of existing pipelines is critical to assessing existing infrastructures for utility operators and various regulatory bodies. This paper includes a review of the...
2014 Chicago : Critical Flaw Size in Butt-Fusion Joints for Service Life Prediction of HDPE Pipes
Author(s) : P. Krishnaswamy, S. Kalyanam, Y. Hioe, D.J. Shim, E. Focht
There is a significant interest in the US nuclear industry to use HDPE piping in essential service water applications at commercial power plants. The unique challenges posed by the use of HDPE in safety-related applications have led to the recent activities in the plastics pipe industry, ASME Code Committees, and US...
2014 Chicago : The Effects of Dual Cooling on the Rapid Crack Propagation Performance of Polyethylene Pipes
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...
2006 Washington DC : Rapid Crack Propagation in Loosely Fitted PE Liner Pipe
Author(s) : Leevers, Henderson, Pereira
Laboratory-scale S4 tests have been used to determine whether it would be possible, at any
realistic working pressure, for a loosely-fitted PE liner within a rigid host pipe to fail by
Rapid Crack Propagation (RCP). The standard ISO 13477 S4 method was modified by
replacement of the containment ring cage by a rigid,...
2006 Washington DC : S4 Critical Pressure and Critical Temperature
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...
2004 Milan : S4 critical temperature tests: procedure and interpretation
Author(s) : Patrick Leevers
International Standard ISO 13477 defines the ‘S4’ RCP test itself, and specifies two
procedures which use it. The first procedure, already well embedded in referring standards,
evaluates a critical pressure at constant temperature (usually 0°C) below which RCP arrests.
The second procedure evaluates, at constant...
2001 Munich : Fully Predictive Model of RCP in Plastics Pipes
Author(s) : Ivankovic, Tropsa, Jasak, Leevers
This work presents a 3D coupled solid-fluid model for predicting fast failures in pressurised
plastic pipes. It is developed within a unified computational procedure where both solid
pipe and pressurising media are discretised using the Finite Volume method. The coupling
is achieved across the pipe-fluid interface...
2001 Munich : The Ductile-Brittle Transition in Pipe-Grade PE
Author(s) : Leevers, Moreno, Paizis
The resistance of PE pipes to rapid crack propagation depends strongly on temperature.
The critical pressure measured using ISO 13477 ‘S4’ tests increases abruptly above a
transition temperature Tc. For PE100 grades Tc has become a primary index of quality : it
must remain below 0°C despite a tendency to increase...
1998 Gothenburg : Ductile deformation in Pipe Grade PE
Author(s) : Hillmansen, Davis, Leevers
Rapid Crack Propagation in PE-100 gas pipes is governed primarily by a brittle-tough transition temperature
TBT,above which ductile deformation will absorb energy and promptly arrest a fast-running brittle crack. Even at
low temperatures, a layer of plastically deformed material is formed at the pipe bore during...
1998 Gothenburg : Impact Rate and Geometry Effects in Pipe Grade Materials
Author(s) : Douglas, Leevers
A model for dynamic and impact fracture has been recently proposed whereby the fracture event is controlled by adiabatic heating and subsequent melting of the cohesive crack tip craze. The crack initiation resistance is shown to be an inherent function of specimen geometry and impact speed. This theoretical framework...