2018 Las-Vegas : Design of large diameter buried pipes
Author(s) : Anders Andtbacka, Frans Alferink, Peter Sejersen
The behavior of buried plastic pipes is already well described in standards and technical specifications and as well as proven in real life conditions. Plastics pipes in diameters up to around 400 mm are already in use for more than 60 years and pipes with larger diameters for more than 20 years now. All with good...
2016 Berlin : Determining the residual quality of PE pipes using the strain hardening test
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...
2016 Berlin : Predicting the lifetime of PE50 gas pipes under point loading
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....
2016 Berlin : Residual quality of excavated UPVC gas and water distribution pipelines
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...
2016 Berlin : The experience with the use of UPVC pipes in various buried applications
Author(s) : Frans Alferink
PVC pipes for buried applications for water, sewer and gas, has developed an excellent track record. PVC is very inert, has a high resistance against permeation of soil contaminations and gas components and meanwhile has a long proven lifetime. Next to that, the lifecycle costs of buried PVC pipe systems are amongst...
2014 Chicago : Designing Against Rapid Crack Propagation in PVC Water Pipes
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...
2014 Chicago : PVC-O: Expanding in Technology and Application
Author(s) : André Nijland, Frans Alferink
PVC-U is used around the globe for potable water supply and sewer applications. This is due to its strength and stiffness as well as to its excellent flow properties. PVC-U shows an excellent performance in protecting the potable water quality. And it is registered that failure rates of PVCU pipelines are very low....
2014 Chicago : Two Complementary Tests to Determine the Quality of PE 100RC
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...
2012 Barcelona : Strain hardening tests on PE pipe materials
Author(s) : Van der Stok, Scholten
The Strain Hardening (SH) test developed by Kurelec et al. has been applied to a variety of PE pipe and resin materials. The clear trend in the strain hardening modulus, of first, second and third generation PE pipe resins and PE100 RC pipe resins, illustrates the large progress in resin quality during the past four...
2010 Vancouver : Cover blow-off resistance of reinforced thermoplastic pipes for gas service
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...
2010 Vancouver : Residual quality of first generation PE gas and water pipes
Author(s) : F.Scholten
Segments from 32 mm gas service pipes installed in 1975-1976 and from 40 mm water
service pipes installed in 1967-1968 in Germany have been excavated and tested for
residual quality. Two different HDPE resin populations discovered among the German
gas pipes were also found among excavated Dutch gas pipes. Internal...
2004 Milan : Combined Loading of Buried Thermoplastics Pressure Pipes
Author(s) : Janson, Alferink, Wolters
This paper presents the results of work that was performed at the request of TEPPFA , The
European Plastics Pipes and Fittings Association, on the issue of “Combined loading”
(external and internal loading) of buried thermoplastics pressure pipes.
The work is of great importance for users and designers of...
2004 Milan : The Durability of a Low-Pressure Gas Distribution System of Ductile PVC
Author(s) : Meijering, Wolters, Hermkens
One of the options for a low-pressure gas distribution system is the use of ductile PVC pipes
and joints. The long-term performance of ductile PVC pipes has been reported in a number of
previous studies. In this paper the long-term performance of the socket joints, in which
elastomeric (NBR) sealing rings are used, is...