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.


Are methods for tightness testing fit for purpose?

 

Posters

Plastic Pipes Conference Association # 2012 Barcelona

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 has been carried out in order to find the cause of the problems and suggest suitable actions. The first part was an enquiry directed towards users of pipelines and firms performing tightness testing. The objective was to find out about the practical performance of testing and the experience from it. The second part of the study was a scrutiny of a number of methods used in Sweden, Norway, USA, Finland, Germany, and Great Britain. The general problem is to distinguish, by measuring pressure or volume over time, on one hand the leakage and on the other hand the time-dependent expansion of the pipeline. The principles used have weaknesses e g in terms of sensitivity, which may be pronounced when new types of material and designs are introduced. The main conclusions are (1) the risk for accumulation of several minor errors in performance, as e g calibration, means that test performers should revise and update working procedures, and if need be to introduce a quality assurance system, (2) if, for European harmonisation, it is wished to introduce the EN 805 generally, this method should be assessed more carefully and revised. An indication is that substantial national modifications have been made in at least Norway and Germany and (3) the quality assurance can be facilitated by further education of operators and that calibrated equipment with high accuracy are used. The Swedish method has several advantages. If it is to be used in the future it should, however, be modified. One simple way would be to increase the accepted leak flow for larger sizes and thinner pipe walls, in order to diminish the sensitivity of the method for these.

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

Related papers

2018 Las-Vegas : Large pressure pipe system – Fully PE100

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...

2018 Las-Vegas : New testing method for electrofusion welds

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...

2016 Berlin : Strain hardening modulus: a measure for ranking time to failure of random polypropylene pipe materials

Author(s) : Rieky Steenbakkers, Linda Havermans, Patrick Voets, Jonathan Rabiei, Rudy Deblieck

The resistance to Slow Crack Growth of HDPE is related to the strain hardening modulus as determined from a tensile test at 80 °C. Correlatio ns between traditional methods (e.g. Full Notched Creep Test, Notched Pipe Test) and other accelerated tests (e.g. fatigue testing) show that the same failure mechanism is...

2012 Barcelona : Contribution of the Plastic Pipe Industry to the PVC Voluntary Commitment

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...

2012 Barcelona : Strain Hardening Modulus: An Accurate Measure For Slow Crack Growth Behavior Of HDPE Pipe Materials

Author(s) : Havermans Linda

Resistance to slow crack growth is an important material property of polyethylene which determines the application lifetime, especially for utility pipe applications. Usually, the slow crack growth resistance of materials is accessed by time consuming testing methods such as NPT, FNCT, PENT, etc. These methods require...

2012 Barcelona : The functioning of flange joints - Findings from full scale experiments and fem analyses

Author(s) : 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...

2010 Vancouver : Durability of polypropylene pipes for nonpressure applications - Influence from surface damage and point loads

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...

2010 Vancouver : Influence of shock pressure testing on the service life of HDPE piping systems

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...

2010 Vancouver : Plastic pipe systems for petrol stations and beyond; stretching the boundaries of plastic pipe applications

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...

2010 Vancouver : Scratches in polyethylene pipes - Sensitivity to scratching and influence on lifetime

Author(s) : L.Karlsson

Over the last years, the question has been raised how scratches and indentations effects the strength and lifetime of pressurised pipes. A method for testing the pipe surface’s sensitivity to this kind of damage was devised, and the scratch sensitivity of different polyethylene grades and coating materials was...

2004 Milan : How will the Lifetime of Different Multi-Layer Pipes be Affected when Exposed to a Circulation Loop

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...

2001 Munich : Which Factors Control the Lifetime of Plastics Pipes and How the Lifetime Can be Extrapolated

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...

1998 Gothenburg : Results and Experiences from Tests on PEX, PP and PVC Pipes Exposed to Different Chemicals

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

BOREALISBOROUGEFormosa Plastics CorporationHanwha TotalEnergiesINEOS O&PIRPCKorea Petrochemical IND. Co., LTD (KPIC)LyondellBasellPetroChina Dushanzi Petrochemical CompanyPRIME POLYMERSABICSCG Chemicals & Thai PolyethyleneSinopecTASNEE
TOP