Effect of the residual stresses on the slow crack growth

Author(s) : Sverre Tragethon, Martin Andersson

Global mega trends push for investments in sewage treatment capacity & efficiency. A trend is to go for central regional treatment sites, typically remotely located from dense populated cities. This calls for high capacity pressure sewage transmission pipelines. Reliable operation is of course of paramount importance...

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) : 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) : Pavel Hutař, Jan Poduška, Jaroslav Kučera, Eva Nezbedová, Andreas Frank, Jiří Sadílek, Gerald Pinter

Residual stresses can significantly influence the lifetime of polymer pipes. Therefore, realistic estimation of residual hoop stress can contribute to accurate lifetime estimations. The previously used “accurate method” is quite time consuming and needs a lot of specimens to be prepared and treated. A simplified...

Author(s) : Florian Arbeiter, Martin Ševčík, Gerald Pinter, Frank Andreas, Pavel Hutař

Multi-layer pipes made from polypropylene have been widely used in sewerage applications for several years. Due to good material properties and generally low mechanical loads not many critical failures occur. Aim of this work is to determine, whether slow crack growth, consisting of crack initiation and crack growth,...

Author(s) : Martin Lackner and Carl-Gustaf Ek

Key words : Polypropylene, Sewage, Sustainability, Durability, High-modulus Polypropylene has an excellent track record after more than 30 years of service for nonpressure sewage and drainage applications. The inherent material properties and their development, energy and cost efficiency, pipe design and ease of...

Author(s) : Zhanjie Wang, Robin Bresser & Cindy Wang

The performance of utility pipelines for gas and water during natural disasters such as earthquakes has always been a matter of great concern. In 2008, two unexpected and serious natural disasters occurred in China. The first was the unprecedented cold weather in January, covering 6 provinces in southern China which...

Author(s) : Benjamin Baudrit, Dietmar Kraft, Martin Bastian and Peter Heidemeyer

In 2008, the Sueddeutsche Kunststoff-Zentrum (SKZ), a testing and R&D plastics institute based in Wuerzburg (Germany), began in cooperation with the company WIDOS, a welding machine manufacturer based in Ditzingen (Germany), to develop a testing device for establishing the mechanical properties of joints executed by...

Author(s) : Eva Nezbedová, Pavel Šindelář and Petr Bohatý

Changing the catalyst composition, it allowed us to alter placement of comonomer from lower to higher polymer molecular weight fractions together with a certain reduction of molecular weight distribution (MWD). Using this catalyst several polymer samples differing in level of branching, in comonomer unit placement and...

Author(s) : Nezbedova, Salajka, Kucera

Structural and morphological parameters together with processing conditions determine the type of fracture behaviour of polyethylenes. Long time brittle failure which occurs under low stresses and at room temperature limits the lifetime of polyethylens used as pipes for water and gas distribution. In order to optimise...

Author(s) : Martin Deters