Papers
Plastic Pipes Conference Association # 2016 Berlin
Carl F. Baker
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 are reported as hours to failure. Failure time has increased from a few hundred hours to over 50,000 hours in some cases. Crosslinked polyethylene (PEX) is known to have very high slow crack growth resistance as a result of crosslinking. Unfortunately the methods used to measure the slow crack growth resistance of PEX are different than those used for standard polyethylene (PE) pipe grades. This study reports PENT data for PEX pipe resins, which allows a more direct comparison of the slow crack growth properties of crosslinked PE pipe grades with standard PE pipe grades.
Crosslinked Polyethylene (PEX) pipe and tube are being used globally for potable water plumbing systems, industrial piping systems, radiant heating systems, etc., successfully. PEX materials are generally believed to have very good slow crack growth properties and some would argue that they are immune to slow crack growth. In general, the three common methods of crosslinking, peroxide, silane grafted, and radiation, are treated equally in the standards with regard to physical and mechanical properties. Most PEX standards include some sort of notched pipe test to demonstrate adequate resistance to crack propagation when a defect (notch) is present. However, there is little slow crack growth data available for PEX materials in a form that can be directly related to other materials. This paper will present PENT data for PEX pipe resins. The methodology used to prepare the samples is critical to successful PENT testing of PEX materials and this will be discussed. The data presented will include multiple temperatures and stresses along with failure mode analysis for each resin.
Related papers
Author(s) : Ajay Taraiya, Peter Degenhart, Mark Boerakker
In PPXX, a technology was presented for the first time that could bi-axially orient polyolefin pipes. With this technology, it is possible to prepare pipes that have a performance far beyond the standard ones. One approach to achieving this performance is via a continuous in-line process. To optimize the in-line...
Author(s) : Federico Muñoz
Following the recent approval of European Standards series EN 1555 for Polyethylene piping systems for the supply of gaseous fuels which introduces the PE100RC, a new material with enhanced resistance to Slow Crack Growth (SCG) and anticipating the imminent revision of European Standard series EN 12201 for...
Author(s) : Kevin Copher, Patrick Vibien
High Density Polyethylene (HDPE) conduit is a durable product designed to protect cables for multiple generations buried underground or encased in concrete. Conduit is subject to coiling stresses, installation stresses and in-service stresses, such as those generated from installed curvature, soil loading, or rock...
Author(s) : Robin Bresser, Ilari Aho, Shima Holder, Tijana Duric, Kaisa Suvilampi
Through innovation and experience, PEX pipe solutions have been enabling comfortable heating and safe plumbing with a successful 50-year track record. They are an important facilitator of the green energy transition and the ambitious climate targets of, for example, the European Union (EU) Green Deal by enabling...
Author(s) : Dr. Michael Pluimer, Sara Stone
The Notched Constant Ligament Stress test (NCLS test, ASTM F2136)[1] is a test method that measures the slow crack growth in High Density Polyethylene. The NCLS test requires a notch on all test specimens to act as a stress concentration at that point so crack propagation can be easily predicted and studied. In...
Author(s) : Jacob John, Suresh Shenoy, Patrik Roseen
Cross-linked polyethylene (PEX) pipes continue to gain popularity in plumbing and indoor climate applications around the globe. This study focuses on increasing the sustainability of PEX pipes by utilizing recycled PEX and production waste streams into PEX production. Different methods available for recycling and the...
Author(s) : Aisha Khaleel, Suleyman Deveci, Sulistiyanto Nugroho, Fatima AlHameli
The use of polyethylene pipes in transportation networks of pressurized water and gas have shown superb performance over the history. High density, high-molecular-weight, and bi-modal polyethylene materials, known as PE80, PE100 and PE100RC, have successfully served the market for many years in standard applications....
Author(s) : Jessica Hinczica, Mario Messiha, Florian Arbeiter, Gerald Pinter
In Europe, only 1.8 million tons of recycled material is processed in new products within the building and construction sector [1]. Recyclates and blends of recyclates with virgin materials are already used for different products in the plastic pipe industry, such as cable trays, or storm water management...
Author(s) : Jiyong Park, JaeHyuck Han, YoungGu Kim, Eunjin Park
This study investigates the influence of various parameters on polymer design to determine the slow crack growth. HDPE(High Density Polyethylene) materials with different molecular weight distribution and comonomer content for PE100-RC pipe were investigated with cracked round bar test. The cracked round bar test...
Author(s) : Michael Pluimer, Christian Herrild, Patrick Vibien
With enhanced interest in a circular economy and the potential use of recycled HDPE within HDPE conduit, a research project was undertaken to investigate the necessary technical requirements when using recycled HDPE. High Density Polyethylene (HDPE) conduit is a durable product designed to protect cables...
Author(s) : Rafael A. García-Muñoz, Rafael Juan, Mónica de la Cruz, Beatriz Paredes, Carlos Domínguez
Plastics are widely used in various industries, resulting in the generation of significant amounts of plastic waste, which causes environmental and economic problems. Although mechanical recycling is the most commonly employed technology, the resulting recyclates often suffer from degradation and contamination. This...
Author(s) : Gerald Pinter, Lukas Travnicek, Johannes Wiener, Jan Poduska, Florian Arbeiter, Pavel Hutar
Crack initiation and subsequent crack growth are known to be the key factors which determine the final lifetime of a polymeric pipe. Subsequently, exact knowledge regarding the crack growth behavior is a key issue to guarantee safe operation. Furthermore, novel concepts are needed to satisfy increasing demands, for...
Author(s) : Yanlei Hu, Jin Sun
Slow crack growth is the main reason for brittle failure of polyethylene pipes. At present, the traditional slow crack growth test generally has many problems, such as too long test time, using chemical reagents that pollute the environment, poor reproducibility, etc., which limit the accurate evaluation of the slow...
Author(s) : Carlos Domínguez, Predrag Micic, Rafael Juan, Nuria Robledo, Rafael A. García-Muñoz
Slow Crack Growth (SCG) resistance is the main property that must be controlled for assessing the long-term performance on polyethylene resins used for pipe application. The latest generation of bimodal and multimodal ethylene-α-olefin copolymers with exceptional balance of mechanical properties and processability...
Author(s) : Roland Valk
To gain an insight into the residual quality of first-generation polyethylene (PE) pipes used in the Dutch gas distribution grid, pipe segments from all over the Netherlands were excavated by the Dutch Distribution System Operators (DSOs) and tested by Kiwa Technology. The residual quality was determined by...
Author(s) : Mario Messiha, Jessica Hinczica, Márton Bredàcs, Alwin Huisjes, Florian Arbeiter, Gerald Pinter
BSTRACT Engineering structures, such as operating plastic pipes, are often submitted to unexpected influences that may shorten their lifetime. An increasing understanding about the processes that govern these sudden failures has been attained in the last decades. This has led to a remarkable improvement of pipe...
Author(s) : A. Taraiya, P. Degenhart, M. Soliman, M. Boerakker, R. Handstanger, R. Kleppinger
Since the introduction of polyolefins for pressure pipes, continuous improvements have been made to meet ever-higher demands on their performance and to expand their application window beyond their original scope, mostly based on new resin formulations. Today, we also continue to push the limit to provide better...
Author(s) : Chris Ampfer, Gene Palermo, Ernest & Oren Lever
This paper looks at the origin of the 10% allowable scratch depth rule for polyethylene (PE) pressure pipe developed in 1971 and research that has been performed over the years since its inception to determine the validity of this rule. The 10% rule has been used by natural gas pipeline operators since the 1970’s to...
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) : Shuhei Nishida, Shintaro Iwasaki, Hidefumi Yamanaka, Takahiro Kasatani
Polyethylene pipelines have been used for natural gas service applications for over 40 years in Japan. It is thought that they will continue to be used widely for many years. Therefore, it is important to confirm the conditions of the existing pipelines being used for the long term. In this study, polyethylene pipes...