Our site uses cookies necessary for its proper functioning. To improve your experience, other cookies may be used: you can choose to disable them. This can be changed at any time via the Cookies link at the bottom of the page.


PVC Pressure Pipes The Importance of Gelation to Ensure

 

Materials and their Characteristics # 1982 York

The field performance of PVC pressure pipes is generally acceptable. Yet a substantial international research effort is being devoted to spontaneous brittle failures.

A model describing the nature of such failures will be presented. In this model a pipe is considered to be a matrix with defects. To obtain satisfactory pipe durability, the matrix strength must be sufficient to withstand "common defects under service conditions. It is hypothesised that the relevant matrix toughness is dominated by gelation.

The way in which this hypothesis was checked experimentally will be presented.

The field performance of PVC pressure pipe 1s generally acceptable and the failure rate low (ref. 1.). Sporadic brittle failures do occur but are not sufficient to justify the substantial international research effort being devoted to PVC pressure pipe reliability. This effort has probably been stimulated by the lack of predictability of spontaneous brittle failures.
A vast amount of literature is devoted to the nature of brittle failures.
Although significant progress has been made in that area, the answers to many questions still have to be found. It is not the intention of this paper to review the present state of the art. Instead, a model has been formulated which, if confirmed, could further reduce the incidence of brittle failures in PVC pressure pipes. It assumes that the relevant pipe property to control brittle failure is matrix toughness. Because this property is difficult to measure directly, it is hypothesised that gelation is the main characteristic which controls matrix toughness.

The hypothesis was checked in the following way. Three pressure test techniques were selected in accordance with the model. These tests, in combination, are assumed to simulate the effects of typical field conditions on pipe durability. The pressure tests were applied to commercially available pipes in a wide range of pipe sizes (diameters and wall thicknesses) obtained from different sources. The results of the pressure tests were then related to those of a new gelation test.

Please note that the whole article content is available on PPCA website only


Related papers

2018 Las-Vegas : Biofilm growth and the impact it has on the hydraulic capacity of pipelines

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...

2018 Las-Vegas : Chlorine dioxide resistant HDPE mechanism, analytical tools and solutions

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...

2018 Las-Vegas : Determination of the slow crack growth resistance of PA12 pipe grades

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...

2018 Las-Vegas : High modulus PP tanks delivers practical & cost effective sewage treatment to rural indonesia

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,...

2018 Las-Vegas : Literature review: effect of clo 2 on ageing of polymer materials and related test methods

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...

2018 Las-Vegas : Testing parameters influencing the strain hardening modulus

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...

2016 Berlin : Can PE and PVC gas distribution pipes withstand the impact of sustainable gases?

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...

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 : Expanding the application range of high density polyethylene for use as an inner-liner material in reinforced thermoplastic pipe and steel pipe

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...

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 effect of residual stresses and external effects on the fracture behaviour of PVC pipes

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...

2016 Berlin : The european plastic pipes industry - Recycling commitment

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...

2016 Berlin : The remaining quality of the PVC gas grid - Results of 10 years of on-going research

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...

2016 Berlin : Total overview of developments in PVC-O in size and couplers.

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...

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 : 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...

2004 Milan : Polybutene-1 - Entering the Next Generation

Author(s) : Schemm, Van de Vliet, Koennecke, Grasmeder

Polybutene-1 (PB-1) is a relatively unexplored polyolefin which shares many features in common with conventional polyolefins like polypropylene and polyethylene, while at the same time offering versatility, value and opportunity through a range of properties not usually associated with this type of resin. Pipes made...

Members of the Association

BOREALISBOROUGEFormosa Plastics CorporationINEOS O&PIRPCKazanorgsintez PJSCKorea Petrochemical IND. Co., LTD (KPIC)LyondellBasellPetroChina Dushanzi Petrochemical CompanyPRIME POLYMERSABICSCG Chemicals & Thai PolyethyleneSinopecTASNEE
TOP