Papers
Plastic Pipes Conference Association # 2018 Las-Vegas
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 according to ISO 1167.
Polyolefin pipes are increasingly used as the preferred product to transport water from the source to the service. Potable water networks are pressurized to create the required flow inside the pipe, which creates a circumferential or hoop stress on pipe wall. Therefore the pipeline has to be designed accordingly to withstand these hoop stresses. This is achieved by the correct selection of material and pipe dimensions.
The standard test method for measuring a material’s resistance to hoop stress is the hydrostatic pressure test (HPT) performed according to ISO 1167; this is applied at 20°C and elevated temperatures and used in conjunction with the ISO 9080 testing scheme to fully characterize the material’s performance. An important aspect of this method is the accurate measurement of pipe dimensions including (critically) the minimum wall thickness, which is used to calculate the required internal pressure to give a pre-defined hoop stress. The thinnest point in the pipe wall is the location of the highest hoop stress and is the point where the test specimen fails.
Plastic pipes are produced according to given standard dimensions as specified in international standards, e.g. ISO 4427-2, where limits on the outer diameter, wall thickness variation and out-of-roundness are prescribed. Wall thickness of the pipe defines the inner diameter of the pipe and the inner and outer circumferences of the pipe are expected to be concentric or at minimum eccentricity, although there is no specific mention of this in the standards. Therefore, one can produce pipe at a certain eccentricity but still comply with the product standards.
In this study, we have evaluated the effect of eccentricity of 32 and 110 mm diameter SDR11 pipes made from PE100 material on the HPT performance at 20°C and 80°C with the support of heat transfer and thermal analyses. It has been observed that pipe eccentricity has a significant effect in internal pressure testing. The effect of eccentricity is of technical significance even within the limited range of eccentricity allowed by wall thickness variation specified in current pipe standards. Therefore, we suggest a maximum eccentricity level of pipe specimens be introduced in ISO 1167 in order to prevent the misjudgment of material properties from pressure testing.
Related papers
Author(s) : Dr. Henning Stieglitz
Urbanization and the increasing effects of climate change have meant the supply of fresh water and the disposal of wastewater, have become increasingly important in recent years. It is foreseeable that this demand will continue and intensify. In this context, plastic pipe plays a major role due to its unique...
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) : Anders Andtbacka, Peter Sejersen
In March 1999, a project report on the performance of buried Thermoplastics pipes was published by TEPPFA /1/. In the report, deflection and strain data on buried pipes were analyzed and compared with calculation results from several well-known static calculation models in use in Europe. Pipes were installed to...
Author(s) : James F. Mason, Akshay Ponda, Hermann van Laak, Tobias Bauer
The long-term strength of unplasticized polyamide 12 (PA-U12) has been characterized using standard methods for plastic pressure pipe during the qualification process for use in buried piping systems for natural gas delivery operating at low ambient temperatures, usually less than 20 to 30°C at pressures...
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) : Ernst van der Stok, Mirko Wenzel, Thomas Kratochvilla, Kurt Engelsing, Werner Weßing, Britta Gerets
It has not been possible to derive an accelerated procedure for the Point Load Test (PLT) as a pipe test before now. Further research and testing were therefore needed to establish appropriate requirements for standards including EN 1555-1 to rule out uncertainty in the market. The PLT is a central product test for...
Author(s) : Sunwoong Choi, Robert Stakenborghs , Pyeongan Lee, Byoungho Choi
This work developed a hydro-axial tension (HAT) test as a whole pipe axial tensile test and applied to evaluate the polyethylene (PE) pipe and fusion joints containing various flaws. HAT test was designed to utilize hydrostatic pressure to cause axial tension in pipes. The experimental and numerical analysis was...
Author(s) : Norbert Jansen
A practical requirement of temperature resistance of minimum 50 years at 70°C was established for the extra high voltage (EHV) corridor projects in Germany. Experts have debated what tests are best suited to prove the suitability of a pipe resin for cable protection pipes which may be installed hastily and under...
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) : Carine Lacroix, Philippe Louvel, Danielle Mark, Dominique Gueugnaut
A test program was carried out on two Polyamide resins, Polyamide 11 (PA11) and Polyamide 12 (PA12), both certified for gas networks. Polyamide’s advantage lies in its implementation, similar to that of polyethylene, and its properties allowing it to operate at up to 18 bar for gas, all other conditions being equal....
Author(s) : Cindy Bray
For over two decades, the plastics pipe industry in Australia has aimed to recycle the maximum amount of usable plastic pipe and other suitable materials into new plastic pipes through programs such as take-back schemes and providing collection facilities on manufacturing sites. In Australia long-term sustainability...
Author(s) : Tobias Johnsen, Ole Grøndahl Hansen
With a growing global population that will primarily settle in urban areas, more and more agricultural land will be converted into dwellings, roads etc. As the demand for food in 2050 will be 60% greater than today, a conflict between Sustainable Development Goals 2 (Zero Hunger) and 11 (Sustainable Cities and...
Author(s) : Zhanjie Wang, Jing Guo, Lin Wang
In the past two years, the Chinese plastic pipe industry has faced a complex and changeable development situation. The domestic economy has faced the pressure of demand shrinkage, supply impact, and expected weakness, and the market has changed greatly. The impact of the Covid-19 and the influence of many unfavorable...
Author(s) : Márton Bredács, Jutta Geier, Mario Messiha, Gernot Oreski, Gerald Koinig, Raphael Horvath, Szilveszter Gergely, Gerald Pinter
In 2020, the global plastics production was 367 million tons. In Europe 20 % was used in the building and construction sector to manufacture in significant proportion polyethylene (PE) and polypropylene (PP) pipes [1]. To increase the current 30 % recycling rate, it is crucial to improve the quality of recyclates and...
Author(s) : A. Marangoni
The competitiveness of plastic pipes vs. non plastic pipes for water and sewer networks relies on both a superior performance to cost ratio and environmental benefits that can be offered to the utility industry, across the whole lifecycle of these networks. In order to help the European pipe network owners in...
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) : Tobias Johnsen
To ensure the highest possible quality of plastic pipes for the Nordic market, the Nordic Poly Mark currently only allows virgin material or own reprocessed material. In order to accelerate the circular plastic pipe economy in the Nordics, a partnership between a PVC pipe waste collection system, a PVC pipe producer...
Author(s) : Chris Greggs
Much has been done to improve the quality and efficiency of HDPE pipe installations over the years. Now, a totally new concept for fusion where the machine meets the pipe where it lays to improve worksite safety, boost jobsite efficiency, and minimize the amount of time spent between fusions has been developed. This...
Author(s) : Jay Parvez, Richard Nichols
All thermoplastic and thermoset pipes must consider the impacts of cyclic loading on overall performance. Since its first use, PVC pipes have been tested for its resilience to such loading. As testing evolved over time, the method to determine cyclic capacity for gasketed PVC pipes has improved. Previously, the...
Members of the Association
