Rapid Crack Propagation Failures in HDPE Pipes; Structure-Property Investigations [PE]

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...

Author(s) : Ashish M. Sukhadia, Wes Long

Polyethylene (PE) pipe is a frequent choice for transporting slurry solutions. It has proven to have superior wear resistance than other pipe materials. For example, when carrying fine grain slurries, polyethylene pipe has been shown in laboratory tests to be three to five times more wear resistant than steel pipes....

Author(s) : Vivek Rohatgi, Pamela L. Maeger, Ashish M. Sukhadia

This study is related to two common approaches used for pipe fabrication, viz. in-line compounding and extrusion of a pre-compound. Pipes were extruded using both approaches and properties were evaluated per the relevant ASTM and ISO standards for water and gas pressure pipe applications to compare the performance of...

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...

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...

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 Prabhat

The ASME Boiler and Pressure Vessel Codes Committee (BPVC) has recently published Revision 1 of Code Case N-755 that describes the requirements for the use of High Density Polyethylene (HDPE) pipe for the construction of Section III, Division 1 Class 3 buried piping systems for service water applications in nuclear...

Author(s) : P.Krishnaswamy

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Codes Committee (BPVC) has published Code Case N-755 that describes the requirements for the use of Polyethylene (PE) pipe for the construction of Section III, Division 1 Class 3 buried piping systems for service water applications in...

Author(s) : M.Lamborn

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...

Author(s) : Patrick Leevers, Christos Argyrakis

There is renewed interest in the correlation between critical pressures from lab-scale (S4) and full-scale RCP tests. The standard, supposedly material-independent correlation factor does provide a lower bound for data from many PE grades, but for some grades it is overconservative and for PA12 its applicability has...

Author(s) : P.Leevers

This paper outlines a PE100 design methodology which gives central importance to the separate modelling and measurement of plane-strain and plane-stress dynamic fracture resistance. The former is difficult to measure but can be estimated from weight-average molecular weight; the latter is related to high-rate...

Author(s) : Krishnaswamy

A comprehensive analysis of ductile and brittle failures from creep rupture testing of a wide spectrum of HDPE pipes (PE-80 and PE-100 pressure rating) was conducted; the HDPE resins studied included those polymerized using chrome-oxide, Ziegler-Natta and metallocene catalyst technology. The analysis indicates that...

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,...

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) : 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...

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...

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...

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...

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...