Papers
Plastic Pipes Conference Association # 2012 Barcelona
Lars Jacobsson, Hans Andersson, Daniel Vennetti and Sven-Erik Sällberg
Leakages are reported in flange joints of large pipelines for water supply although mounted according to recommended practise. FEM analyses and full scale experiments have been performed in order to better understand the functioning of the joints. The objectives were to find out about the sensitivity to mounting and service conditions and, if possible, to suggest improvements in today’s practise. A FEM script was developed, where arbitrary joint geometries can be simulated with a time hardening visco-elastic behaviour. In-house relaxation tests on a PE 100 material were used to assess the parameters of the material model. Simulations were performed for 400 and 630 mm flange joints with various geometries, gaskets and loading conditions. Principally, bolts were given forces corresponding to recommended torques and then a pressure of 10 bars was applied, leaving the system to relax for up to 10,000 hours. The main results are that the pressure in the joint surfaces is concentrated to the outer parts, that it decreases significantly and that most of the decrease, relaxation, occurs for short times. It is also possible to study the influence of gaskets, flexible backing rings and re-tightening. Experiments were performed with 630 mm joints, which were tightened with different torque levels and then pressurized until leakage occurred. Since strain gauges were applied on some bolts the real bolt force resulting from the nominal torque could be registered with time. Configurations which remained tight up to 13 bars were tightness tested for up to seven days. Among the important findings were that the bolt forces are much lower than foreseen from the formula usually used to convert torque to force. Further, the forces are very unevenly distributed, partly since much of the relaxation occurs already during the tightening rounds. Soft rubber gaskets and re-tightening significantly improve the performance of the flange joints.
Related papers
Author(s) : Daniel Currence, Michael Plumier
Over a ten-year period, the North American corrugated plastic pipe industry successfully demonstrated that post-consumer and post-industrial recycled materials could be responsibly incorporated into corrugated pipes used for drainage applications. Prior to this work, the material standards were established for ...
Author(s) : Sverre Tragethon, Martin Andersson
Global mega trends push for investments in sewage treatment capacity & efficiency. A trend is to go for central regional treatment sites, typically remotely located from dense populated cities. This calls for high capacity pressure sewage transmission pipelines. Reliable operation is of course of paramount importance...
Author(s) : Dr. Love Pallon, Dr. Karin Jacobsson, Daniel Ejdeholm, Marie Allvar, Rikard Kärrbrant
This work presents the development of the Full Length Tensile Test (FLTT), a method that enables an objective judgement of welding quality of electrofusion welds by measuring the energy to break (J/mm2 ). In this way a brittle, ductile and transitional mode failure can be differentiated without subjective visual...
Author(s) : Jan H. Sällström, Johan Sandström, Sven E. Sällberg
Flange joints connecting plastic pipes to valves are studied. The pipes have a reduced flange adaptor or a HP-flange adaptor. In the full scale experiments all flanges have a bolt circle diameter Ø725 mm. Four types of gaskets are used: an O-ring, a standard and a profiled gasket of EPDM with a steel core without and...
Author(s) : Karin Jacobson, Daniel Ejdeholm, Rikard Kärrbrant, Kenth Olsson
IT IS WELL KNOWN THAT IT IS NECESSARY TO SCRAPE OFF A 0.2 MM OUTER LAYER OF A POLYETHYLENE (PE) PIPE SURFACE AT THE LOCATION FOR THE ELECTROFUSION WELD PRIOR TO WELDING. THE REASON FOR THIS PROCEDURE IS SAID TO BE REMOVAL OF AN OXIDIZED LAYER WHICH CAN RESTRICT MOLECULAR DIFFUSION ACROSS THE WELDING INTERFACE LEADING...
Author(s) : Daniel Libert, Pierre Belloir
PE-RT is now well established in the Hot & Cold market with various pipe designs and associated standards. For many years, PE-RT has found a good place in Under Floor Heating applications in many places around the world. The comprehensive testing performed on raw materials led to a better knowledge of high temperature...
Author(s) : Daniel Ejdeholm, Karin Jacobson
Since decades, non-metallics have been the preferred choice of material to be used in the process equipment of pickling plants to cope with the metal-corrosive environments. The present experience regarding the corrosion performance of different plastic materials in various pickling applications and elsewhere has...
Author(s) : Sergio Kempenich, Markus Hartmann, Carsten Schuett, Ralf Tuellmann, Daniel Crucello, Vitor Lavini
Unplasticized Polyamide 12 (PA-U 12) has been investigated as an alternative to steel for high pressure gas installations with operation pressures up to 18 bar (261 psi). Several tests developed and conducted in Germany, USA and Brazil have reached positive results in terms of performance and costs. However, Brazilian...
Author(s) : Lars Jacobsson, Hans Andersson and Linda Karlsson
Problems sometimes occur in tightness testing of plastic pipelines using pressurized water and accounting for the diametrical expansion, particularly so for larger sizes and higher pressure rating. Pipelines that are in fact tight enough for acceptance are rejected when first tested. A study consisting of two parts...
Author(s) : Telgen Hans
Abstract : In 2000 the PVC chain embarked in a ten year program to improve the environmental footprint of the PVC industry : Vinyl 2010. Challenging targets have been fixed and all of them have been achieved : recycling, substitution of heavy metals, energy saving etc. The pipe industry and specially the members of...
Author(s) : Libert Daniel
Heating and/or air conditioning systems based on ground heat pumps are increasingly popular in European countries, their growth fuelled by both private and public investments in sustainable energy sources. These systems typically circulate water inside boreholes, effectively using the ground as a constant temperature...
Author(s) : Sven-Erik Sällberg, Kristian Thörnblom, Hans Sandberg
As trenchless installation techniques and coarse-grained backfill materials are gaining in interest for plastics pipelines, the influence from surface damage on the technical lifetime is becoming more and more important. For non-pressure applications, such as gravity sewers, this aspect is relevant, e.g., when...
Author(s) : Ulrich Schulte, Heinz Vogt, Hans-Friedrich Enderle, Dieter Lilge
The completion of a pressure test is mandatory for all new pipe systems. Its purpose is to demonstrate the overall leak-proof condition of the system. In the course of this test, HDPE pipes of SDR 17 class are exposed to high stress loads. In an extensive test programme, all failure mechanisms observed in long-term...
Author(s) : Lars Selling and Ingrid Andersson, Christophe Salles and Lars Höjer
Kungsors Plast AB, in co-operation with Borealis, has pioneered the underground plastic piping for petrol filling stations with the first polyethylene piping used by Shell Sweden in 1981. The retail sector with petrol filling stations has used PE-based underground piping since the early 1980s. With increased awareness...
Author(s) : Andersson
The lifetime of plastic pipes has been studied at Bodycote Polymer AB for more than 30 years. This paper will compare two test methodologies for evaluating multi-layer pipes. An attempt will be made to investigate antioxidant consumption as a function of exposure time for three different PE based multi-layer pipes...
Author(s) : Andersson
The lifetime of plastic pipes has been studied at Bodycote Polymer AB (formerly Studsvik Polymer AB) for more than 27 years. This paper presents some of the factors found to control the lifetime of plastic pipes. How to extrapolate the lifetime of plastic pipes will be presented and discussed. A question will also be...
Author(s) : Ifwarson, Andersson
This paper presents experimental data for PEX, PEM, PP and PVC pipes exposed to different chemicals. More than 150 plastic pipes of PEX, PEM, PP and PVC have been pressure tested with different chemicals. The chemicals used are; 97% Sulfuric acid, 100% Acetic acid, 30% Sodium hydroxide and a solution of 50%...
Members of the Association
