Wolters
System Experience & Training # 1998 Gothenburg
In the Netherlands, rigid PVC and impact-modified PVC pipes have been used in gas distribution systems for dozens of years. In general, these pipes have performed excellently. Some years ago, however. questions were raised about the resistance of these materials to certain gas constituents. An extensive research programme was then started to investigate these problems.The results of this research programme are reported in this paper and are of value to other pipe applications as well. Crazing and cracking in various gaseous environments and in natural gas condensate have been examined in many long-term studies. Long-term failure in PVC pipe systems is always preceded by crazing. Crazing and cracking are strongly affected by the various gaseous environments. However, below certain concentrations, which are representative of the commonly distributed natural gases, higher hydrocarbons have no detrimental effect on PVC pipe materials. Natural gas condensate only affects PVC under extreme conditions which hardly ever occur. It was proven once again that (impact-modified) PVC is an excellent pipe material for low-pressure gas distribution systems.
Related papers
Author(s) : Emiel Drenth, Ton Bor, Roy Visser and Mannes Wolters
Various non-destructive methods, based on different physical principles, were investigated for their ability to differentiate between uPVC pipes having various levels of gelation. It was found that the micro-hardness method was not able to differentiate between uPVC samples of different levels of gelation. A possible...
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,...
Author(s) : Wolters, Wikkerink
The use of plastic pipeline materials in gas distribution systems is still increasing. Presently PE and high impact PVC are the dominating materials in gas distribution networks up to 4 bar. Most of these networks operate at these pressures, only a limited part of the network operates at higher pressures, up to 10 to...
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...
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...
Author(s) : Wikkerink, Wolters, van den Berg, Huppes
Environmental aspects tend to be increasingly important in designing gas distribution systems and in selecting gas distribution materials. Therefore the environmental aspects of various materials options for gas distribution networks were analyzed by means of a quantitative life cycle assessment. This paper describes...
Author(s) : Scholten, Wolters
An investigation has been carried out into butt welding and electrofusion welding of PEX pipes, which had been crosslinked using the peroxide, silane and electron beam processes (PEXa, PEXb and PEXc respectively). A new hypothesis was set-up to explain the good weld quality of PEXa pipes electrowelded with regular...
Author(s) : Alferink, Wolters
Results of deformation measurements carried out on buried plastics pipes installed at six different tests sites are discussed in this paper. The results show that the deflection of buried pipes is usually rather small and the time dependence is limited to a few years after installation. Traffic loading does not result...
Author(s) : Rijpkema, Wolters
In the Netherlands about 20,000 km of uPVC (unplasticized PolyVinylChloride) gas pipes are in use. The oldest uPVC pipes have been in operation for over 30 years now. These systems were usually designed for a period of between 30 and 50 years. Probably, however, the actual service life will turn out to be much...
Author(s) : Alferink, Wolters
Knowledge about the behaviour of buried flexible pipes has become more and more important in the Netherlands. It serves several objectives, for instance, to evaluate stress corrosion, installation techniques and new materials, as well as drawing up new design codes and test procedures for pipes and components. This...
Author(s) : Alferink, Blom, Venema, Wolters
Joints in PE casings of district heating pipelines are made by extrusion welding, butt welding or sleeves in which sealing is obtained by an adhesive. To set up guidelines for making these joints a lot of research has been performed, part of which is described in this paper. Joints of a good quality are obtained if...
Author(s) : Wolters
The modified Robertson test is a test method by which ina rather simple and quick way crack arrest and (limited) crack propagation are distinguished, provided that crack speed over the crack length is measured. Rather large variations in rapid crack propagation (RCP) behaviour of different PE types have been found. At...
Author(s) : Wolters, Venema
The weld strength of some butt welds and extrusion welds in pipeline systems, made of the newer PE types, has been evaluated by means of short-term and long-term tests. Butt welding appears to be a reliable jointing method. Welding strength is almost independent of the heating plate temperature and weldinq pressure. A...
Author(s) : Scholten, Wolters
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