Papers
Plastic Pipes Conference Association # 2018 Las-Vegas
E.J.W. van der Stok
The effect of eleven different test parameters on the strain hardening modulus was investigated using the Design of Experiments statistical method. The changes in strain hardening modulus due to temperature, tensile drawing speed and the cooling rate after annealing were assessed. The importance of taking account of proper preparation of the test setup was also demonstrated.
The Strain Hardening Test (SHT) is a simple tensile test carried out at 80°C (176°F) in accordance with ISO 18488. The effect of eleven different test parameters on the strain hardening modulus was investigated using Design of Experiments (DoE). This is a statistical method used to quickly determine and quantify the effect of multiple test parameters, including their interactions. It requires only a limited number of tests.
The statistical analysis demonstrated that the locations of the markers, the clamping area and the alignment of the test specimen have a statistically significant effect on the strain hardening modulus. This shows the importance of properly preparing the test setup. The test temperature and the cooling rate after annealing are also important. A change in test temperature of 10°C can result in a change of up to 19 MPa in the strain hardening modulus. This means that the 2°C temperature variation allowed by the ISO 18488 standard may lead to a variation of about 3.8 MPa in the strain hardening modulus.
The DoE statistical analysis also assessed any interactions between the test parameters. For example, it was found that the effect of temperature on the strain hardening modulus for firstgeneration PE differs to that for PE 100RC.
Finally, although the tensile speed on its own is not statistically significant, the tensile speed combined with the test temperature does have a statistically significant effect on the strain hardening modulus.
Related papers
Author(s) : Andreas Moerman, Flip van der Valk, Mirjam Blokker KWR, Tjakko Haaijer, Jan Vreeburg,
Drinking water companies with ageing networks are facing vast amounts of drinking water network reconstructions during the coming decades. This development coincides with the energy transition, which puts pressure on the available space underground. These external drivers give drinking water companies an opportunity...
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) : Joe Babcanec, P.E., Dan Currence, P.E.
The newly released Drainage Handbook provides complete guidance on corrugated polyolefin pipe. Perhaps the biggest contribution this new handbook makes to the advancement of both HDPE and PP corrugated plastic pipe is the design procedure presented. The design procedure reflects the industry’s recommended practice for...
Author(s) : James F. Mason, Akshay Ponda, Hermann van Laak, Buc Slay
The effects of liquid hydrocarbons on long term strength of pipe grade thermoplastic resins is an important consideration when designing pressure pipe for use in the oil and gas industry. There is an extensive body of work going back several decades descri bing these effects for pipe grade polyethylenes, and all...
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 identify...
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) : Gerald Pinter, Johannes Wiener, Florian Arbeiter, Abhishek Tiwari, Otmar Kolednik
For pipe applications, catastrophic failure due to crack growth has to be prevented by all means. Techniques to develop new and even tougher pipe materials are explored in this contribution. The aim is to create a multi-layer architecture, that exhibits high toughness as well as damage tolerance towards sharp notches....
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) : 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) : Dustin Langston
The design and installation of polyethylene systems can be complex, specifically due to the many applications and environmental conditions that surround those systems. Online design tools have been developed to address this complexity and the various factors that must be considered. These online tools used widely in...
Author(s) : Guido Quesada
An important breakthrough for belled PVC pipe was made around 2006, when the first versions an integral joint restraint were released, after about two years in development. This type of restraint comprises a casing, usually made of metal such as ductile iron or stainless steel, a rubber seal, and a “C” grip ring,...
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) : 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...
Author(s) : Britta Gerets, Mirko Wenzel, Kurt Engelsing
The strain hardening test (SHT, ISO 18488 [1]) becomes increasingly important for the characterization of high-density polyethylene (HDPE) grades and pipes made thereof. With regard to small pipe diameters, a smaller test specimen than the one defined in ISO 18488 has been developed. SHT results were demonstrated to...
Author(s) : Hermann van Laak, Jan Heimink, Mario Messiha, Andreas Frank, Christoph Bruckner, Thomas Kratochvilla
For high pressure pipes above maximum operation pressure of 10 bar, this paper emphasizes PA-U12 as the easy to install alternative to steel. It underlines the superb performance of PA-U12 pipes for alternative installation techniques without need for a separate mechanical protection. An unplasticized polyamide 12...
Author(s) : Jörg Wermelinger, Sunwoong Choi
In the development of an international standard on non-destructive test for polyethylene electrofusion socket (EF) joints, the inspection capability of the phased array ultrasonic test (PAUT) in assessing flaws in the joints was needed to establish procedure qualification of the test method. For this, a worldwide...
Author(s) : Thomas R. Kratochvilla, Raimund Eremiasch, Christoph Bruckner
In the last years effort has been made to develop and standardise new accelerated test methods to evaluate PE 100-RC materials in short times in form of test bars. The two most important developments, the cracked round bar test (CRB test) and the strain hardening test (SH test) were published as final ISO standards in...
Author(s) : Gerald Pinter, Florian Arbeiter, Johannes Wiener, Andreas Frank, Otmar Kolednik
In order to further increase the fracture toughness of pipes, biomimetic layer design of the pipe wall can be used. Therein, soft polymer interlayers can act as crack-arresters in a matrix of stiffer and inherently more brittle polymers. The effectiveness of the crack arresting role of soft interlayers in a...
Members of the Association
