Effect of the residual stresses on the slow crack growth

Posters # 2012 Barcelona

Using linear elastic fracture mechanics a new methodology for a lifetime assessment of internally pressurized polymer pipes was developed. The concept is based on the numerical calculation of stress intensity factors for pipes under different loading conditions in combination with experimentally determined creep crack growth kinetics. The main aim of the work is to estimate the effect of residual stresses on the creep crack kinetics. Based on FEM calculations, the evolution of a creep crack in the case of internal pressure loading taking into account residual stresses, is obtained. An approximate equation for the stress intensity factor in the pipe with residual stresses is presented and good agreement with the numerically obtained data is found. The results and methodology presented can be a powerful tool for estimation of a plastic pipe’s lifetime.

Please note that the whole article content is available on PPCA website onlySource : 2012 Barcelona

Related papers

Large pressure pipe system – Fully PE100

Author(s) : Sverre Tragethon, Martin Andersson 2018 Las-Vegas

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...

Multilayer polymer pipes - Possible utilization of recycled material

Author(s) : Pavel Hutar, Jan Poduska, Pavol Dlhy, Andreas Frank, Jaroslav Kucera, Jiri Sadilek, Gerald Pinter, Lubos Nahlik 2018 Las-Vegas

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...

Slow crack growth resistance of non-virgin polymers

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 2018 Las-Vegas

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...

Lifetime prediction of PE100 and PE100-rc pipes based on slow crack growth resistance

Author(s) : Andreas Frank, Isabelle J. Berger, Florian Arbeiter, Pavel Hutař, Gerald Pinter 2016 Berlin

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....

Residual stress distribution in the extruded polyolefin pipes

Author(s) : Pavel Hutař, Jan Poduška, Jaroslav Kučera, Eva Nezbedová, Andreas Frank, Jiří Sadílek, Gerald Pinter 2016 Berlin

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...

Polypropylene Multi Layer Pipe Lifetime Assessment Under Realistic Loading Conditions

Author(s) : Florian Arbeiter, Martin Ševčík, Gerald Pinter, Frank Andreas, Pavel Hutař 2014 Chicago

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,...

Stiff, stiffer, PP3000 mpa - An impressive journey through 30 years of PP development for underground sewerage applications

Author(s) : Martin Lackner and Carl-Gustaf Ek 2012 Barcelona

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...

Analysis of the pipe failures in the 2008 frozen-rain & snow, earthquake in China

Author(s) : Zhanjie Wang, Robin Bresser & Cindy Wang 2010 Vancouver

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...

Development of an Automatic Test Procedure for Determining the Mechanical Properties of HM and HD Welds with Mechanized Torsional and Linear Shear Tests

Author(s) : Benjamin Baudrit, Dietmar Kraft, Martin Bastian and Peter Heidemeyer 2010 Vancouver

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...

Effect of structural parameters on RCP in polyethylene

Author(s) : Eva Nezbedová, Pavel Šindelář and Petr Bohatý 2004 Milan

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...

Relationship between Toughness and Structural Parameter of PE-Copolymers

Author(s) : Nezbedova, Salajka, Kucera 1998 Gothenburg

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...

A New Complete PEX-A Pipe Production Concept with Infrared Crosslinking

Author(s) : Martin Deters 2008 Budapest

Members of the Association

BOREALISBOROUGEFormosa Plastics CorporationINEOS O&PIRPCKazanorgsintez PJSCKorea Petrochemical IND. Co., LTD (KPIC)LyondellBasellPetroChina Dushanzi Petrochemical CompanyPRIME POLYMERSABICSCG Chemicals & Thai PolyethyleneSinopecTASNEE