Applicability and Limitations of Current Life-Time Prediction Models for Thermoplastics Pipes Under Internal Pressure [PE]

Author(s) : Paul J. Freudenthaler, Joerg Fischer, Mathias Eder, Reinhold W. Lang

For controlled water disinfection, typically chlorine is used and preliminary studies demonstrate its aging and crack growth acceleration effects on polyolefin pipe materials [1, 2]. Although the use of recycled plastics is not prohibited in some ISO standards for polyolefin piping systems [3–5], only small amounts...

Author(s) : Gerald Pinter, Johannes Wiener, Florian Arbeiter, Abhishek Tiwari, Otmar Kolednik

For pipe applications, catastrophic failure due to crack growth has to be prevented by all means. Techniques to develop new and even tougher pipe materials are explored in this contribution. The aim is to create a multi-layer architecture, that exhibits high toughness as well as damage tolerance towards sharp notches....

Author(s) : Mario Messiha, Britta Gerets, Jan Heimink, Andreas Frank, Florian Arbeiter, Gerald Pinter

A majority of field failure of viscoelastic plastic pipes can be attributed to slow crack growth (SCG) and has become crucial in terms of characterization of newly developed materials – particularly, if they are designed for pressurized pipe applications. In this study, investigations in terms of SCG resistances...

Author(s) : Lukas Travnicek, Pavel Hutar, Jan Poduska, Andreas Frank, Florian Arbeiter, Jaroslav Kucera, Jiri Sadilek, Gerald Pinter, Lubos Nahlik

The application of recycled material in pressure piping systems has been considered lately – it was suggested, that the recycled polyethylene could be used as a part of a multilayer pipe together with virgin material. This type of pressure pipes is not availableon the market yet, so their properties can be only...

Author(s) : Andreas Frank, Mario Messiha, Günter Dreiling, Norbert Schuler, Jens-Martin Storheil, Erwin Mayrbäurl, Stuart Ramella, Frank Krause, Rudi Berning, Philippe Gabriëls, Alpay Aydemir, Thomas Koch, Florian Arbeiter, Gerald Pinter

The Cyclic Cracked Round Bar (CRB) Test has been applied to study the slow crack growth (SCG) resistance of virgin, recycled, and reprocessed PVC-U. This fracture mechanical test allows a quick ranking of the SCG resistance of PVC-U. A clear correlation between the K-value and the SCG resistance has been elaborated....

Author(s) : Márton Bredács, Andreas Frank, Amaia Bastero, Alex Stolarz, Gerald Pinter

Accelerated aging experiments by the immersion of a commercial polyethylene (PE) pipe grade in 10 ppm of chlorine dioxide (ClO2) and in 100 ppm of hypochlorite (HOCl) solution at 60 °C were performed. An additional immersion test was conducted in 1 ppm of ClO2 at 40 °C. The exposure parameters were continuously...

Author(s) : Gerald Pinter, Florian Arbeiter, Johannes Wiener, Andreas Frank, Otmar Kolednik

In order to further increase the fracture toughness of pipes, biomimetic layer design of the pipe wall can be used. Therein, soft polymer interlayers can act as crack-arresters in a matrix of stiffer and inherently more brittle polymers. The effectiveness of the crack arresting role of soft interlayers in a...

Author(s) : Markus Gall, Reinhold W. Lang, Joerg Fischer, Ansgar Niehoff, Steven Schmidt

Despite recent efforts in promoting the utilization of recycled polymeric materials for more diverse and more advanced applications, there are still significant knowledge gaps with regards to the applicability of certain recyclate types for specific “re-use” purposes. When it comes to pipe applications, for instance,...

Author(s) : Mario Messiha, Andreas Frank, Isabelle J. Berger, Jan Heimink, Hermann van Laak, Florian Arbeiter, Gerald Pinter

Since the last decade polyamide 12 (PA12) has been successfully introduced as material for SDR 11 gas piping systems up to 18 bar, representing itself as an attractive alternative to steel pipes for high-pressure applications. Practical experience has confirmed that beside the higher strength, PA12 pipe grades also...

Author(s) : Joerg Fischer, Paul J. Freudenthaler, Patrick R. Bradler, Reinhold W. Lang, Susan C. Mantell

This research addresses the effect of nucleation on the global aging behavior and the fatigue crack growth (FCG) resistance of commercial alpha- and beta-nucleated polypropylene random copolymer pipe grades (PP-R) when exposed to chlorinated water (5 mg/l free chlorine) at an elevated temperature of 60°C. Comparing...

Author(s) : Joerg Fischer, Patrick R. Bradler, Reinhold W. Lang

In the present paper, a novel test system for conducting fatigue crack growth (FCG) experiments under superimposed mechanical-environmental conditions is presented. FCG experiments were performed on a polypropylene (PP) grade and a short-glass fiber reinforced polyamide 66 (PA-GF) grade as model materials. The...

Author(s) : Isabelle J. Berger, Andreas Frank, Gerald Pinter, David Nitsche, Dirk Petry

Electrofusion (EF) sockets constitute a well-established and practically proven technology for the joining of polyethylene (PE) pressure pipes. As for the pipes, the potential lifetime of such welding connections is beside other properties also depending on the resistance against slow crack growth (SCG). The current...

Author(s) : Pavel Hutar, Jan Poduska, Pavol Dlhy, Andreas Frank, Jaroslav Kucera, Jiri Sadilek, Gerald Pinter, Lubos Nahlik

This paper investigates possible use of recycled material as a part of a multilayer polyethylene pressure pipe system. Crack propagation in different configurations is simulated. Lifetimes of pipes containing recycled material are calculated. Results are compared with lifetimes of pipes made of virgin...

Author(s) : Andreas Frank, Isabelle J. Berger, Mario Messiha, Carl-Gustaf Ek, Norbert Schuler, Jens-Martin Storheil, Erwin Mayrbäurl, Steve Heeley, Frank Krause, Lodewijk Niemöller, Philippe Gabriëls, Yogesh S. Deshmukh, Florian Arbeiter, Thomas Koch, Gerald Pinter

In order to improve the circular economy of polymers in terms of sustainability and reduced carbon footprint, the increased use of recyclates has become a topic of major importance. Due to their long design lifetimes, pipe applications represent an excellent opportunity to create added value to non-virgin polymers. In...

Author(s) : Joerg Fischer, Paul J. Freudenthaler, Patrick R. Bradler, Reinhold W. Lang

Cyclic tests with cracked round bar (CRB) specimens have been used for some time to characterize the slow crack growth behavior of polyolefin pipe grade materials. In fact, most recently a standardized test procedure for cyclic CRB testing has been released in ISO 18489. To obtain kinetic data for cyclic crack growth...

Author(s) : G. Pinter, F. Arbeiter, A. Frank

The cyclic cracked round bar test has recently been added as a full-fledged ISO standard (ISO 18489) for comparison of polyethylene pipe grade materials’ slow crack growth resistance. However, possibilities of this test are yet far from being exhausted. Seeing, that polyethylene is only used in approximately 30% of...

Author(s) : Joerg Fischer, Patrick R. Bradler, Reinhold W. Lang, Gernot M. Wallner

The present paper aims to study the crack growth resistance of a black-pigmented polypropylene pipe grade when exposed to elevated temperatures and various environmental media (air, deionized water, ionized water with a specific chloride content, and chlorinated water) under the simultaneous application of cyclic...

Author(s) : Márton Bredács, Anita Redhead, Andreas Frank, Amaia Bastero, Gerald Pinter

To maintain the high quality of potable water chlorine based disinfectants are frequently dosed into the drinking water network. Considering the oxidative nature of these species their long-term impact on the aging of polyolefin pipes is a matter of interest. In this study four polyolefin pipe grades were objected to...

Author(s) : Andreas Frank, Isabelle J. Berger, Florian Arbeiter, Pavel Hutař, Gerald Pinter

Due to the high slow crack growth resistance of modern polyethylene pipe grades a reliable lifetime assessment of pipes with focus on stage II failure has become challenging. The current paper presents a scientific approach for a fracture mechanics lifetime prediction based on Cyclic Cracked Round Bar (CRB) Tests....

Author(s) : Univ.-Prof. DI Dr. mont. Gerald PINTER, DI Florian ARBEITER

Applying scientifically well established and investigated linear fracture mechanic methods (LEFM) the kinetics of the slow crack growth (SCG) on polypropylene layers and coextruded interfaces on multi-layer-pipes could be investigated. Taking effects of ageing and stress relaxation during the service lifetime into...