Determination of the slow crack growth resistance of PA12 pipe grades

 

Papers # 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 show an excellent resistance against relevant pipe failure mechanisms such as slow crack growth (SCG) as well as any third-party attack or external surface damages. Within the current paper, four different PA12 materials with varying macromolecular structure were investigated. On the one hand, a major focus was put on the general applicability of the Cyclic Cracked Round Bar (CRB) Test as fracture mechanical test method. On the other hand, the influence of the molecular weight, expressed by the relative viscosity number VNrel, on the fracture mechanical failure behavior was examined. The results demonstrate that the Cyclic CRB Test is a suitable method to provoke real SCG, and that the viscosity number has a considerable influence on the SCG resistance of PA12.

Related keywords : polyamide 12, gas piping systems, slow crack growth, cyclic cracked round bar test.
Please note that the whole article content is available on PPCA website only


Related papers

2018 Las-Vegas : Accelerated pipe test methods to evaluate PE 100-RC materials - Possibilities for iso standardisation

Author(s) : Thomas R. Kratochvilla, Raimund Eremiasch, Christoph Bruckner

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...

2018 Las-Vegas : 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

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...

2018 Las-Vegas : Development of cyclic pressure fatigue (CPF) test method

Author(s) : Ernest Lever

Six different polyethylene materials were tested using Cyclic Pressure Fatigue (CPF) as the accelerating process to correlate the results to conventional long-term hydrostatic test results that were previously developed as part of the material qualification process. The designation of the materials was unknown to the...

2018 Las-Vegas : Development of polyethylene ball valve to pursue robustness

Author(s) : Ryosuke Nagahisa, Shinichi Katoh

We investigated the possibility of using a greaseless polyethylene (PE) ball valve by applying a coating on it to improve the valve’s robustness. In order to verify the valve’s operability, we performed initial-operating-torque, abrasion, and dust tests on both grease-applied and coatingapplied ball valves. These...

2018 Las-Vegas : Discover: plastics

Author(s) : Davidovski Zoran

To get a deeper insight in why plastic pipes systems in some cases are deselected by designers, installers and users, European Plastics Pipes and Fittings Association (TEPPFA) initiated a research including interviews in four pilot countries: Poland, France, Germany and the UK. The first phase was concentrating on...

2018 Las-Vegas : 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

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...

2018 Las-Vegas : Effect of eccentricity on the measurement of hydrostatic pressure resistance of plastic pipes

Author(s) : Suleyman Deveci, Birkan Eryigit, Senthil K. Kaliappan

The effect of eccentricity on the failure time of pipes under hydrostatic pressure test has a significant magnitude that it can easily mislead the evaluation of pipes according to requirement of ISO 4427-2. Therefore, authors propose a maximum relative eccentricity limit of 0.015, even lower, for pipes being tested...

2018 Las-Vegas : 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

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...

2018 Las-Vegas : 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

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...

2018 Las-Vegas : High density polyethylene (HDPE): an overview of the first ever asme bPVC section iii, class 3 nuclear piping installation

Author(s) : Ali Al Hammadi, Shane R. Schuessler, Mohamed Ali Awadh Jaber

This paper presents the advancements of HDPE piping materials, design and installation for use in ASME Class 3 piping systems at nuclear power plants. The paper will specifically introduce details of the first ever ASME Class III nuclear new build use of Class 3 HDPE pipe and fittings at the Emirates Nuclear Energy...

2018 Las-Vegas : Investigation of the creep failure behavior of polyamide pipes

Author(s) : Hiroto Taguchi, Kaori Numata

We elucidated the creep failure behavior of polyamide pipes. We conducted the hydrostatic test and Notched Pipe Test (NPT) at 80 and 90 °C for up to 10000 h for PA pipes whose creep failure behavior has not been fully elucidated yet. In the tests, the change in the failure mode from ductile failure to brittle...

2018 Las-Vegas : Investigation of the failure behavior of polyethylene electrofusion sockets

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...

2018 Las-Vegas : 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

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...

2018 Las-Vegas : New en standard for infiltration units

Author(s) : Peter Verlaan

Ten years ago, The European Plastic Pipes and Fittings Association (TEPPFA) has taken the initiative to prepare a draft 'Standard for Infiltration units' based on existing national specifications, at that time (in particular) available in France, Germany, United Kingdom and the Netherlands. This draft 'Standard for...

2018 Las-Vegas : New testing method for electrofusion welds

Author(s) : Dr. Love Pallon, Dr. Karin Jacobsson, Daniel Ejdeholm, Marie Allvar, Rikard Kärrbrant

This work presents the development of the Full Length Tensile Test (FLTT), a method that enables an objective judgement of welding quality of electrofusion welds by measuring the energy to break (J/mm2 ). In this way a brittle, ductile and transitional mode failure can be differentiated without subjective visual...

2018 Las-Vegas : Polyehthylene/aluminum/polyehthylene composite pipe for fuel gas application

Author(s) : Baiqian Li, Jun Wang, Lixian Zheng, Xiaoyi Peng, Lei Wang, Yu Cui, Guozhi Xu

Polyethylene/Aluminum/Polyethylene (PAP) composite pipe has the advantages of corrosion resistance, limited joints and convenient installation. Nowadays PAP pipes are widely used in indoor gas conveyance. But a number of companies encounter difficulties in installing gas meter in users’ house as well as billing....

2018 Las-Vegas : Product environmental footprint (PEF) method compared with environmental product declarations (EPDS)

Author(s) : Ludo Debever, Peter Sejersen, Carolin Spirinckx

Until today there are various ways of demonstrating the Environmental Performance of products, such as Life Cycle Assessments (LCA), Life Cycle Impact Assessments (LCIA), Environmental Performance Declarations (EPDs). The methods to obtain the result, however, can vary from country to country and can be interpreted...

2018 Las-Vegas : Rehabilitation of abandoned dn1000mm steel pipe with PE100 in malaysia

Author(s) : KianLin Ng, WengKeong Tan, KumHoong Lou

Heavy and constant trucked container traffic combined with an accelerated ground settlement in a coastal reclaimed land caused a DN1000mm cement-lined mild steel water pipeline that crossed under it to sink by more than 6m from its original buried depth. This then caused the internal & external cement lining to...

2018 Las-Vegas : Sensitivity of strain hardening modulus to molecular structure of polyethylene

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

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...

2018 Las-Vegas : 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

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...

Members of the Association

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