Strain hardening tests on PE pipe materials

Author(s) : Stefanus Johannes van Vuuren

Biofilm establishes itself over a short period of time in all pipelines conveying raw and treated water. Depending on the type of biofouling, it is documented that it will inevitability lead to a reduction in the hydraulic capacity. Since none of the current design relationships used to calculate the friction loss in...

Author(s) : M. Boerakker, S. van Mierloo, D. v. Beek, R. Schipper, P. Voets, M. Soliman, K. Jacobson, D. Lukes, B. Rabaud, F. Zraick

HDPE pipes are used for standard pressurized water pipes, offering an excellent solution for safe transport of (drinking) water. The HDPE pipe market is growing globally. Especially in countries that suffer from water scarcity, surface water and water from rivers have to be used for drinking water supply. To guarantee...

Author(s) : Mario Messiha, Andreas Frank, Isabelle J. Berger, Jan Heimink, Hermann van Laak, Florian Arbeiter, Gerald Pinter

Since the last decade polyamide 12 (PA12) has been successfully introduced as material for SDR 11 gas piping systems up to 18 bar, representing itself as an attractive alternative to steel pipes for high-pressure applications. Practical experience has confirmed that beside the higher strength, PA12 pipe grades also...

Author(s) : Marc van Loo (Dr.), Constant Van Aerschot, KumHoong Lou

In many parts of rural developing Asia and even some parts of Africa, sewerage from households is often discharged directly to the surrounding. This unfortunate fact means that many waterborne diseases such as cholera, dysentery and typhoid continue to afflict these communities. Numerous efforts from governments,...

Author(s) : E.J.W. van der Stok, K. Jacobson, S.O. Jansma, D. Lukes

The lack of a fast, universally-accepted test method for chlorine-dioxide-disinfected water is hindering the development of improved plastic piping materials. A literature survey was performed to define the degradation process in which chlorine dioxide affects the ageing of polypropylene, and to describe and reflect...

Author(s) : 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...

Author(s) : René Hermkens, Ernst van der Stok, Johannes de Bruin, Jeroen Weller

The replacement of fossil fuels like natural gas by sustainable gases such as biogas and hydrogen can mitigate global warming. There has been some debate about the impact of sustainable gases on the materials used in the gas grid. An extensive study of the behaviour of PE, PVC, POM and rubber materials was therefore...

Author(s) : Ernst van der Stok, Frans Scholten

Samples machined directly from pipe show that orientation has a large influence on the strain hardening modulus. No effects arising as a result of residual stresses were found. Samples machined in the axial direction from a hydrostatic pressurised pipe showed no effect as a result of this mechanical degradation. For...

Author(s) : Johannes de Bruin, Dr. Bert Dalmolen, Albo van Hateren

Normal High Density Polyethylene (HDPE) is commonly used as the fluid contacting element, or the “inner-liner”, in Reinforced Thermoplastic Pipes (RTP) and steel pipes up to 65 ºC. Through a modification of the HDPE polymer matrix, by adding nanoparticles, the E-modulus can be increased. Research shows that...

Author(s) : Frans Scholten, Ernst van der Stok

The residual quality of first generation PE50 gas pipes, installed in Netherland between 1961 and 1979, is still remarkably good. The only premature failures of a few PE50 pipes were exclusively caused by point loads. When under point loading, they started failing in practice after 8 to 26 years, in a brittle manner....

Author(s) : Frans Scholten, Ernst van der Stok, Britta Gerets, Mirko Wenzel, Mike Boege

The current condition of 35-50 years old uPVC main (110 mm) and service (32 mm) pipes for gas and water distribution was assessed. From 27 excavation sites in total about 400 segments of 1.2 meters length each were tested using many techniques. The K-value (average molecular weight) of the PVC, the degree of gelation...

Author(s) : Ernst van der Stok, Jeroen Weller, Frans Scholten

This paper describes falling-weight tests as a first step towards determining the effect of residual stresses on the fracture behaviour of old PVC-U gas pipes at impact. Results showed that the level of surrounding pipe support, the quality of the material and the diameter of the striker had a major effect on the...

Author(s) : Tony Calton, Roel van’t Veer, Henk Meerman

The European plastic pipes and fittings industry has made a commitment through TEPPFA to use a quarter of a million tonnes of recycled material a year by 2020. This presentation provides background to the growth in the use of recycled material for pipe applications and outlines some of the achievements to date and the...

Author(s) : J. Weller, R.J.M. Hermkens, E.J.W. van der Stok

To prevent an enormous surge in the replacement costs of the Dutch PVC gas distribution grid a so-called Exit Assessment programme was started in 2004. This programme determines the actual quality of old excavated PVC-U and PVC-Hi pipes using a tensile-impact test at temperatures varying from -25°C to +47,5°C, whereby...

Author(s) : Paul van Doesburg, Berend Stel, Rob Spekreijse

PVC-O is the accepted pipe solution for the future. Worldwide, more and more countries go in the direction of PVC-O. The main applications for PVC-O at this moment are potable water, wastewater, irrigation and gas. PVC-O is produced for many years from the 80’s until 2007 the sizes were in majority small (mainly...

Author(s) : Frans Scholten, Ernst van der Stok, Jan Breen

Very occasionally PVC-U water pipes suddenly fail due to a long brittle crack with a length of many meters which propagates with the speed of sound along the pipe and causes extensive water loss. This phenomenon has been recognized as Rapid Crack Propagation (RCP). The conditions under which RCP can occur are an...

Author(s) : Frans Scholten

When electro fused joints in newly installed PE100 pipelines are tested using the Peel test (ISO 13954 [1]) they too often fail in a brittle manner. Contamination in the interface between the surfaces to be fused is usually the cause. About 77 % of the contaminants in 39 cases of brittle test bars could be identified...

Author(s) : Ernst van der Stok, Frans Scholten

The Strain Hardening (SH) test and the Point Load Test (PLT) are two complementary tests designed to determine the quality of PE 100-RC. The SH test is a resin test, whereas the PLT is a pipe test. The SH test is a tensile test performed at 80 °C. Extensive research on the SH test has been conducted and published in...

Author(s) : E.J.W. van der Stok, F.L. Scholten, L.G.P. Dalmolen

A mathematical model was set up to assess the equilibrium gas pressure in the annulus of the reinforcement layer of an RTP pipe. This is done by using the theory of gas permeation, ruled by Fick's Law and the theory for a temperature gradient over the pipe wall, ruled by Fourier's law. The model allows calculating the...

Author(s) : Frans Scholten and Mannes Wolters

PA11, PA12 and plasticized PA6.12 pipes are interesting candidates for gas transport and distribution pipelines at 16 bars pressure, which is beyond the maximum pressure for PE100 pipeline systems (10 bars). However, PA pipelines are not meant as an alternative to PE pipelines, but to steel pipelines. Therefore,...