Papers
Plastic Pipes Conference Association # 2016 Berlin
Carlos Domínguez, Nuria Robledo, Rafael A. García-Muñoz
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. Strain Hardening modulus (SH) determination at 80ºC seems to be one of the best alternatives. Correlation between SH method and classic SCG tests are reported on this work. It is proved that the method guarantees a rapid and accurate evaluation.
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. Fourth generation PE resins have shown very high resistance to slow crack growth, with failure times even higher than one year at the standard temperature of 80ºC used in conventional tests like Full Notch Creep Test (FNCT), Pennsylvania Notched Tensile Test (PENT), Notch Pipe Test (NPT) and Point Loading Test (PLT). More severe conditions increasing temperature and load for PENT and FNCT tests have been proposed in recent years with significant reduction on the failure time. These stricter test conditions must be rigorously controlled due to the possibility that the SCG was not the main process that regulates the failure mechanism of the resin. For that purpose, the failure morphology inspection and the crack opening displacement (COD) curve have been evaluated to assess such failure mechanism.
On the other hand, among the different alternatives to conventional methods that are being developed to accelerate the resin evaluation, the Strain Hardening (SH) modulus determination at 80ºC is becoming as the best alternative for the evaluation of the SCG process. Thus, the SH modulus has been determined for a wide range of PE resins grades. The results show that the method guarantees a rapid and accurate evaluation. Additionally, the method unexpectedly displayed remarkable differences in resins with the same SCG resistance measured by conventional methods but with different comonomer type used in the resin synthesis. To the best of our knowledge, this is the first report where these differences are depicted.
Related papers
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) : Peter Hubbard, Linqing Luo, Andrew Yeskoo, Kenichi Soga, Krista (Moita) Araica, Gus Cicala, Marshall McLeod
Seismically active faults pose a risk to buried water pipelines that can be complicated to quantify. Fault type, slip rate, pipeline geometry, and soil conditions all factor into a complex soil-pipeline interaction. For critical pipelines that cross faults, high-density polyethylene (HDPE) has become an attractive...
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...
Author(s) : Sjoerd Jansma, René Hermkens
More than 20,000 km of rigid PVC (or PVC-U) pipes are currently in use for the distribution of natural gas in the Netherlands. In this decade, the majority of these pipes will reach their initially specified lifespan of 50 years. In the light of a possible replacement surge, it is increasingly important to...
Author(s) : Ernst van der Stok
For PE 100-RC, two tests are still under development for pipes: the point load test (PLT) and the accelerated notch pipe test (aNPT). The PLT was developed by a project group consisting of manufacturers and end users. The PLT determines the resistance to point loads as they can occur in practice. An earlier study...
Author(s) : S. Nestelberger, J. Cheng
The Point Load Test (PLT) [ 1, 2] was designed to simulate the SCG (slow crack growth) failure initiated by a rock pressing into the exterior wall of a polymer pipe. Today’s PE materials sustain long PLT testing times, due to its high SCG resistance design. Consequently, an accelerated “PLT+” with the support...
Author(s) : Mario Messiha, Britta Gerets, Jan Heimink, Andreas Frank, Florian Arbeiter, Gerald Pinter
A majority of field failure of viscoelastic plastic pipes can be attributed to slow crack growth (SCG) and has become crucial in terms of characterization of newly developed materials – particularly, if they are designed for pressurized pipe applications. In this study, investigations in terms of SCG resistances...
Author(s) : M. Eckes & Dr. B. Baudrit, Dr. M. Troughton & D. Wylie, H. van Laak & J. Fritz
Unplasticized polyamide 12 (PA-U12) is increasingly being used in pipe applications, especially in the gas sector. However, the material behavior in the usual quality tests for pipe welds has not yet been thoroughly investigated. For this reason, two research institutes, worked in cooperation with a manufacturer of...
Author(s) : Thomas R. Kratochvilla, Patrick Grünbeck, Christoph Bruckner, Raimund Eremiasch, Harald Wilhelm, Mario Vukelja
In the last decades pipe dimensions of extruded PE pipes have reached new orders of size. Today, PE pipes with outer diameters of up to DN/OD 3500 mm are produced and used for pressure pipe applications like seawater intake/discharge, outfall, sewage and industrial process piping systems. To test the long-term...
Author(s) : Kensei INOUE, Mitsuaki TOKIYOSHI, Joji HINOBAYASHI, Takeshi KARINO, Toshinori KAWABATA, Takashi KURIYAMA
As the worldwide problems are over-population, unusual weather like as localized heavy rain and climate change. Against those problem, it has to need new projects to make a new agricultural field, drainage pipeline system and to spread the new underground irrigation system at peat land whereas spots of about 2 million...
Author(s) : Florian Arbeiter, Tobias Schachinger, Stefanie Eichinger, Gisbert Rieß, Michael Stur, Michael Steiner, Florian Saliger
Plastic pipes are of outstanding importance for the distribution of potable and process waters, oil and gas, as well as for sewer and waste water disposal. However, plastic pipes are also used in many other technical areas. Especially in European countries with mountainous regions, such as Austria, Switzerland, Italy...
Author(s) : Ulrich Schulte, Dr. -Ing. Joachim Hessel
In order to protect the Austrian lakes effectively against the discharge of effluent, a 13 km long pressure pipeline made of high density polyethylene was laid on the bottom of Lake Ossiach back in 1971. The DN355 to DN200 pipes were produced from a first generation HDPE-compound. The classification would have been...
Author(s) : Justin Brandt, Mike Griffin, Tony Cuvo
As plastic pipe gains share in new markets and applications, additional joining methods add further value, enabling continued growth for plastic pipes. To date, definitions of a “fit-for-purpose” mechanical joint for High Density Polyethylene (HDPE) pressure piping systems can vary significantly. As such, mechanical...
Author(s) : Alireza Sahaf Amin, Dr. Gholamreza Pircheraghi
PE-Xa pipes used in the hot water supply are required for high mechanical strength and high creep resistance at high temperature. Because of the higher cross-link degree of PE-Xa pipes as compared with other crosslinked pipes methods , these pipes which are made by peroxide crosslinking have better performance in the...
Author(s) : Mark Boerakker, Rudy Deblieck, a Harm Caelers, Arno Wilbers, Tine Boonen a DSM, Britta Gerets, Mirko Wenzel
Components made of plastic are facing ever-increasing demands with respect to their production, use and durability. This also holds for gas and drinking water pressure pipes made of high-density polyethylene (PE-HD), where service lifetimes of up to 50 years and in some cases even 100 years are required. One of the...
Author(s) : Andreas Frank, Mario Messiha, Günter Dreiling, Norbert Schuler, Jens-Martin Storheil, Erwin Mayrbäurl, Stuart Ramella, Frank Krause, Rudi Berning, Philippe Gabriëls, Alpay Aydemir, Thomas Koch, Florian Arbeiter, Gerald Pinter
The Cyclic Cracked Round Bar (CRB) Test has been applied to study the slow crack growth (SCG) resistance of virgin, recycled, and reprocessed PVC-U. This fracture mechanical test allows a quick ranking of the SCG resistance of PVC-U. A clear correlation between the K-value and the SCG resistance has been elaborated....
Author(s) : Amster Howard
Deeper pipe burial, less expensive and environmentally friendly backfill, uniform language for contractors and inspectors, simplified installations for smaller pipe, and allowable construction in poor soil conditions are highlights in the latest edition of AWWA M55 and all benefit the users of HDPE pressure pipe. This...
Author(s) : Hua Ye, Sun Jin, Wei Ruoqi
As a safe, clean, low-carbon and reliable energy source, nuclear power, together with hydropower and coal power, constitutes the three pillars of the world's energy supply and play an important role in the world's energy structure.With the strong support of national policies, China's nuclear energy has entered a new...
Members of the Association
