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) : 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...
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) : Dominique GUEUGNAUT, Pascal AUSSANT, Romuald BOUAFFRE, Myriam BECHROURI
Concerns regarding the environment and sustainable development have revived interest in the reprocessing and re-use of polymer materials from manufactured objects that have reached the end of their operating life. Within this framework, formal professional agreements have been put in place at global level under the...
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) : 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 of...
Author(s) : Greg Scoby, PE
This paper will detail the steps taken during adoption of HDPE for potable water systems improvements including material justification, creation of related specifications, investigation of available piping components, qualification of contractors and the construction/inspection of related systems. The City of...
Author(s) : Stephan Kneck, Henrik Iskov
It has become ever clearer that the resources of natural gas are an energy source, which will be less important in the future due to limitations in use of natural reserves. In order to prepare for the future the gas industry is looking at the alternative fuel gases, one such fuel gas is hydrogen. In order to prepare...
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) : Suleyman Deveci, Nisha Preschilla, Sulistiyanto Nugroho, Birkan Eryigit
Carbon black (CB) has been used as a perfect and the cheapest solution to prevent photo degradation of polyethylene against UV light exposure. The effect of carbon black on the mechanical properties of polyethylene pipes was studied extensively, but only on well dispersed and distributed carbon black...
Author(s) : Gisbert Rieß, Katrin Berger, Anna Kaltenegger-Uray, Florian Arbeiter
The effect of electron-beam and silane crosslink of polyethylene on the resulting permeation characteristics was investigated. Polyethylene sheets were processed and crosslinked by irradiation with high energy electrons and by grafting and subsequent hydrolysis of organosilanes during a reactive extrusion process. The...
Author(s) : Alex Stolarz, Klaus Grønnegaard Lauridsen
Low temperature District Heating – COOL DH – addresses the challenges of the upcoming decades in the energy sector for new housing developments. Energy efficiency is an important aspect of modern building construction. Improved building insulation and other technologies result in lower heat demand and enable new...
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) : Xinwen Yu, Aimin Xiang, Dongyu Fang, Peck Tze Kang, Jinghui Li
The Chinese PE water pipe market has developed significantly in recent years and particularly over the last 12 months. Against a background of water scarcity and growing urbanization, this evolving market has grown significantly in both size and quality awareness. On the back of past experiences, a fundamental...
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) : 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) : 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...
Author(s) : Patrick Campbell, Joanne Claronino, Shana Meeus, Joseph Sanders, David Chrystie-Lowe
Polyethylene (PE) potable water mains, with design life of 50 years (BS EN 12201), have been in widespread use in the UK water industry for more than 30 years. PE pipe is light, flexible and reliable in comparison with other pipe materials and the UK water industry has made a considerable investment in replacing...
Members of the Association
