INVESTIGATION OF THE FAILURE BEHAVIOR OF POLYETHYLENE ELECTROFUSION SOCKETS

Papers # 2018 Las-Vegas

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 paper presents a scientific approach for a fracture mechanics lifetime prediction based on quasi-brittle failure behavior of EF sockets made of polyethylene. Therefore, various internal pressure tests on EF sockets were conducted under elevated test conditions with focus on generating quasi-brittle failure curves and investigating characteristics of crack initiation and SCG. In combination with internal pressure tests, a numerical simulation (FEM) model for the stress intensity factor characteristics in EF sockets was created to predict the time to brittle failure. The results demonstrate that with the fracture mechanics approach a reliable prediction of minimum lifetimes of EF sockets for internal pressure loading situations and application oriented installation situations is possible.

Related keywords : Joining, E-sockets, slow crack growth, lifetime prediction.
Please note that the whole article content is available on PPCA website onlySource : 2018 Las-Vegas


Related papers

A new flexible jointing method of plastic (PE) pipes

Author(s) : Yilaing He, Tianjun Zhang 2018 Las-Vegas

A new electrofusion PE belt is developed by reinforcing it with various layers of steel mesh. It’s of sandwich structure, consisting of steel mesh reinforcement, heating wire and polyethylene. One or more layers of steel mesh is encapsulated in the middle, and heating wire is embedded onto “inner side” of the...

ACCELERATED PIPE TEST METHODS TO EVALUATE PE 100-RC MATERIALS – POSSIBILITIES FOR ISO STANDARDISATION

Author(s) : Thomas R. Kratochvilla, Raimund Eremiasch, Christoph Bruckner 2018 Las-Vegas

In the last years effort has been made to develop and standardise new accelerated test methods to evaluate PE 100-RC materials in short times in form of test bars. The two most important developments, the cracked round bar test (CRB test) and the strain hardening test (SH test) were published as final ISO standards in...

CHARACTERIZATION OF POST-USE POLYETHYLENE AND POLYPROPYLENE RECYCLATE BLENDS FOR PIPE APPLICATIONS

Author(s) : Markus Gall, Reinhold W. Lang, Joerg Fischer, Ansgar Niehoff, Steven Schmidt 2018 Las-Vegas

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...

DETERMINATION OF THE SLOW CRACK GROWTH RESISTANCE OF PA12 PIPE GRADES

Author(s) : Mario Messiha, Andreas Frank, Isabelle J. Berger, Jan Heimink, Hermann van Laak, Florian Arbeiter, Gerald Pinter 2018 Las-Vegas

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...

EFFECT OF BETA-NUCLEATION ON AGING AND CRACK GROWTH RESISTANCE OF POLYPROPYLENE EXPOSED TO CHLORINATED WATER

Author(s) : Joerg Fischer, Paul J. Freudenthaler, Patrick R. Bradler, Reinhold W. Lang, Susan C. Mantell 2018 Las-Vegas

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...

EVALUATION AND COMPARISON OF STANDARD AND ACCELERATED SLOW CRACK GROWTH DETERMINATION METHODOLOGIES: EFFECT OF THE COMONOMER TYPE INFLUENCE

Author(s) : Carlos Domínguez, Álvaro Pérez, Nuria Robledo, Cristina González, Beatriz Paredes, Rafael A. García-Muñoz 2018 Las-Vegas

Last methodologies for fast evaluation of the SCG resistance on polyethylene pipe materials are analyzed in this work and compared with traditional PENT and FNCT tests. Strain Hardening (SH), Crack Round Bar (CRB) and Accelerated Creep Test (ACT) will be good alternatives for evaluating PE100RC resins. Moreover, SH...

FATIGUE CRACK GROWTH TESTING IN CHLORINATED WATER AT ELEVATED TEMPERATURES - TEST EQUIPMENT AND TEST PROCEDURE

Author(s) : Joerg Fischer, Patrick R. Bradler, Reinhold W. Lang 2018 Las-Vegas

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...

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...

PRESERVING MARINE ENVIRONMENT FROM HYDROCARBONS CONTAMINATION WITH LEAK-FREE PE100 PIPES USED IN OFF-SHORE OIL WELLS

Author(s) : Farraj Tashman, Mohamed Ali Jaber, Sultan Al Kendi 2018 Las-Vegas

Analysis of subsea PE100 pipeline conveying oil produced water effluent with traces of hydrocarbons was done after 5 years of leak-tight continuous operation at boundary conditions showed that properties of PE100 pipes are intact when benchmarked with test results conducted on reference pipe sample kept for this...

SENSITIVITY OF STRAIN HARDENING MODULUS TO MOLECULAR STRUCTURE OF POLYETHYLENE

Author(s) : Suleyman Deveci, Senthil K. Kaliappan, Joel Fawaz, Umesh Gadgoli 2018 Las-Vegas

A series of non-commercial bimodal high density ethylene-α-olefin copolymers with systematically controlled molecular parameters over a wide range that would result in extremely low and high strain hardening modulus were prepared and tested Strain hardening modulus has been published as a standard test method (ISO...

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...

THE INFLUENCE OF MOLECULAR DESIGN VARIABLES OF BIMODAL HDPE ON THE SLOW CRACK GROWTH RESISTANCE MEASURED BY ACCELERATED METHODS

Author(s) : Cliff Mure, Siddharth Athreya, Dane Chang, Rujul Mehta 2018 Las-Vegas

New generations of PE100 and PE4710 pressure pipe materials exhibit a superior balance of mechanical properties. The slow crack growth performance of these materials measured by traditional tests such as PENT and FNCT can exceed one year. Accelerated test methods, including strain hardening modulus, accelerated FNCT,...

CORRUGATED POLYETHYLENE PIPE USED IN MINING APPLICATIONS, THEIR COMPLIANCE WITH SPECIFICATIONS AND ANTICIPATED DESIGN LIFE

Author(s) : Jim Goddard, Mario Paredes 2016 Berlin

Samples of polyethylene pipe supplied to mining projects throughout the Americas were selected and tested for compliance with existing ASTM specifications. Estimated service life of these pipe products in mining applications are made based on the laboratory tests required in the ASTM specifications. Anticipated...

DETERMINING THE RESIDUAL QUALITY OF PE PIPES USING THE STRAIN HARDENING TEST

Author(s) : Ernst van der Stok, Frans Scholten 2016 Berlin

Samples machined directly from pipe show that orientation has a large influence on the strain hardening modulus. No effects arising as a result of residual stresses were found. Samples machined in the axial direction from a hydrostatic pressurised pipe showed no effect as a result of this mechanical degradation. For...

FATIGUE CRACK GROWTH RESISTANCE OF POLYPROPYLENE IN CHLORINATED WATER AT DIFFERENT TEMPERATURES

Author(s) : Joerg Fischer, Patrick R. Bradler, Reinhold W. Lang, Gernot M. Wallner 2016 Berlin

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...

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....

LIMITS ON THE SLOW CRACK GROWTH RESISTANCE EVALUATION FOR THE PE100 AND PE100RC POLYETHYLENE RESINS

Author(s) : Carlos Domínguez, Nuria Robledo, Rafael A. García-Muñoz 2016 Berlin

With the last advances and improvements in the polyethylene resins used for pipe application, new methods for evaluating long-term mechanical properties need to be introduced. Standard PENT and FNCT tests needs more than one year for characterizing the new PE100RC grades with the consequent thermal ageing problems....

LONG-TERM BEHAVIOR OF GLASS FIBER REINFORCED POLYETHYLENE

Author(s) : Mitsuaki Tokiyoshi, Philippe Vanspeybroeck, Kensei Inoue, Stephan Fullgrabe, Takashi Kuriyama, Toshinori Kawabata, Joji Hinobayashi 2016 Berlin

Big diameter polyethylene pipes used an important role due to superior performance (Flexibility, light weight, long lifetime and tighten joint) for water and industrial supply to several countries. However according to standard concerned Polyethylene pipes as like ISO4427 we are being used solid wall pipe with too...

PENT STUDY OF CROSS-LINKED POLYETHYLENE PIPE RESINS

Author(s) : Carl F. Baker 2016 Berlin

The performance of HDPE resins with regards to slow crack growth has increased dramatically over the past two decades. The most common test method for pipe products is ASTM F1473, Standard test Method for Notch Tensile Test to measure the resistance to Slow Crack Growth of Polyethylene Pipes and Resins (PENT). Results...

POLYPROPYLENE MULTI-LAYER-PIPES - 100 YEAR LIFETIME ASSESSMENT USING LINEAR ELASTIC FRACTURE MECHANICS

Author(s) : Univ.-Prof. DI Dr. mont. Gerald PINTER, DI Florian ARBEITER 2016 Berlin

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...

Members of the Association

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