Plastic Pipes Conference Association # 2021 Amsterdam
Mike Troughton, Amir Khamsehnezhad, Changyi Yu
When butt fusion welding polyethylene (PE) pipes in the field, it is often specified that the pipes must undergo fusibility testing in all combinations of suppliers, diameters and thicknesses before being fused in production. This is a very onerous and expensive task, but must be carried out to ensure that the PE pipes are of sufficient quality to produce acceptable butt fusion joints. One of the reasons why PE pipes might not be of sufficient quality is insufficient homogenization of the resin, which during the extrusion of black pigmented PE pipes, may result in features called “windows”. These are local areas where there is a lack of carbon black pigmentation and normally occur in thicker- walled pipes, towards the mid-wall thickness. They can be seen, for example, in the shavings from the end of the pipes produced during the trimming stage of the butt fusion process. Two potential reasons why insufficient homogenization of pigmented PE resin might cause a reduction in the performance of butt fusion joints are: 1) if there are areas in thepipe where the carbon black content is zero, there are likely to be areas where the carbon black concentration is significantly higher than the average. These areas may act as either stress concentrations or cause lack of fusion in the butt fusion joints; 2) after the PE melt passes through the mandrel support plate in the pipe extruder, which contains hundreds of holes, the molten strands need to fuse back together to form a homogeneous melt stream. However, if there are areas in the melt that contain higher viscosity material, these melt strands may not fuse together perfectly and may subsequently result in areas of reduced fusion in the butt fusion joint. This paper describes an investigation into the effect of insufficient homogenization of pigmented resin in PE pipes on the integrity of the subsequent butt fusion joints and the development of a test to quantify the amount of windows in the pipe. It will describe the analysis carried out on a number of PE pipes, made using both pre-compounded and in- line compounded resin on the same pipe extruder but using different extrusion conditions in order to obtain different degrees of homogenization. The results of mechanical tests carried out on the butt fusion joints from these pipes were used to determine a critical value of windows below which the joint integrity is not affected.
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) : Joe Babcanec, P.E., Issam Khoury, Ph.D, P.E., Shad Sargand,
The use of corrugated HDPE and PP pipe for gravity flow storm sewers is a growing trend throughout the United States. Many of these drainage pipes are buried in shallow cover conditions under roads with heavy traffic. It is well established that thermoplastic pipe installations under shallow cover respond differently...
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) : 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) : Jie Wu, Yushan Hu, Todd Hogan
Recycling of plastic materials is key to demonstrating that these high value materials are much more than a waste stream and a key component of a sustainable future. The plastic pipe market effectively utilizes in-plant recycle systems where standards and codes allow processors to recapture the value of these...
Author(s) : Kevin White, Shad Sargand
The current standard of practice for the installation of agricultural mains is in accordance with ASTM F449, Standard Practice for Subsurface Installation of Corrugated Polyethylene Pipe for Agricultural Drainage or Water Table Control. ASTM F449 has several limitations. Currently, the allowable maximum height of...
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) : 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) : 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) : Rachel Anderson, Rujul Mehta, Alex Stolarz, Todd Hogan, Stephanie Whited, Joel Wieliczko
Growing worldwide demand for sustainably made irrigation systems has driven the creation of new resins for longer-lasting, more durable, recycle friendly, and cost-effective pipe that can better tolerate extreme conditions year after year. Microirrigation systems deliver vital water and nutrients where they’re needed...
Author(s) : Nayib Joussef, Chris Zenthoefer, Sergio Vaccaro
Butt fusion of HDPE pipe has long been shown to be an extremely beneficial process in producing leak-free, monolithic piping systems. Continued growth of the Chilean mining sector has necessitated a substantial increase in polyethylene pipe sizes and wall thicknesses, with diameters well beyond 630 mm up to 2m...
Author(s) : Ernst van der Stok, Nadia Luijsterburg-Vleugels
The latest generation of polyethylene grades (PE 100-RC and PE 4710 PLUS) have an increased resistance to slow crack growth. Such cracks can be initiated by either a scratch during installation or a rock indentation during use. The Accelerated Notch Pipe Test (ANPT) was standardized in ISO 13479 in 2022 to allow the...
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) : Karin Jacobson, Daniel Ejdeholm
Plastic pipes often have much better corrosion resistance than metallic pipes and have, in addition, the benefits of low weight and flexibility. Thanks to this, they are often used to convey chemicals. There is, however, still a large potential for a much more extensive use of plastic pipes for this application. The...
Author(s) : Norbert Jansen, Andrew Wedgner, Rainer Kloth
PE100+ Association(client) has sponsored a technical investigation to define the permeation rate of hydrogen through polyethylene pipes at an external expert laboratory. Four different types of PE pipe materials in the same pipe size and SDR17 have been evaluated at 3 different target temperatures 8°C, 14°C and 20°C,...
Author(s) : Ali M Alghamdi, Recep Yaldiz, Faisal Almana, Yousof Ghazzawi, Abdul Rahim Arafath, Ratnesh Khandelwal, Azzedine Kioul, Turki Al-Shahrani, Salem Al-Anazi, Sarfraz Abbasi, Mohammed Aljasser, Parthipan B, Kavya A, Harm Caelers
Reinforced thermoplastic pipes (RTPs) are multilayer structured pipes reinforced with high-strength materials such as fibers (glass, aramid, or carbon fibers). RTPs are used to transport highly corrosive mediums at elevated pressures and temperatures. An example of that is the use of RTP in the Oil & Gas industry to...
Author(s) : Jennifer Ravereau, Catherine GIORNI, Benjamin RABAUD, Frederic Mohier, Mehdi Ahmadi
Pipe installation and renewal are critical for network management and extension both in terms of cost and of logistics for installation. Plastic materials, as polyethylene, are constantly evolving to offer additional benefits (chemical resistance improvement, mechanical resistance, innovative functionalities)....
Author(s) : Paul O’Regan, Nigel Cassidy, Neil Wallace
The United Nations Environment Programme (UNEP) has estimated that the building sector accounts for 38% of world-wide energy-related CO2 emissions and that the construction industry is responsible for nearly 30% of this figure. Modern-day pipes, sewers and water drainage systems are predominantly made of materials...
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) : Derek Muckle
A technical program has been undertaken to provide evidence on the suitability of polyethylene pipe and fitting systems for the distribution of hydrogen fuel gas. The underlying principle has been to evaluate material in the form of a pipe and to consider the performance of the pipe and of the welded jointing systems...
Members of the Association
