Author(s) : Brown, Lu 1992 Eindhoven
The test, called PENT, consists in measuring the resistance to slow crack growth of precisely notched specimens under constant load in air. The specimen geometry is designed and conditions are chosen so that failure is by slow crack growth as occurs under service in the field. The test conditions for producing failure...
Author(s) : Kanninen, Buczala, Kuhlman, Green, Grigory, O'Donoghue, McCarth 1992 Eindhoven
Most current procedures for the design, installation and qualification of electrofused jointsin polyethylene gas piping systems are empirical in nature. To improve this situation, the Gas Research Institute initiated an integrated experimental and analysis research program at the Southwest Research Institute. The...
Author(s) : Strebel, Moet 1992 Eindhoven
Medium density polyethylene (MDPE) pipe resins exhibit extraordinarily long time-to-failure, due to their superior brittle cracking resistance. Attempts to quantify this phenomenon using the J integral approach have been hampered by the large specimen thickness required to effect plane strain conditions and because...
Author(s) : Holloway, Naaktgeboren 1992 Eindhoven
The relatively high safety factors used in the design of PVC-U pressure pipes reflect concern about the possibility of brittle failure in service. Toughness may be improved by the addition of iinpact modifiers and plasticisers but normally strength is impaired. In this paper we show that pipes exhibiting a high...
Author(s) : Leis 1992 Eindhoven
The effect of blunting at crack-like notches on the apparent subcritical toughness measured in terms of slow crack growth is discussed with regard to mechanics and materials aspects. Notch tip blunting is shown to rationalize the apparent enhanced subcritical toughness trends, leading to so-called super tough...
Author(s) : Gedde, Smith, Ifwarson, Viebke 1992 Eindhoven
Polyolefin pipes subjected to extensive hoop stresses fail in a ductile manner (stage I). At lower stresses failure is brittle and may in certain cases be preceded by degradation of the polymer (stage 111). Reviewed in this paper are the changes in polymer structure and antioxidant concentration profiles preceding the...
Author(s) : Dib, Day, Benkreira, Wood 1992 Eindhoven
A computer program for the prediction and optimisation of process parameters for the butt fusion welding of polymer pipes is described. At the core of the program a mathematical model predicts bead size, melt layer thickness,pipe displacement and temperature : time history during each stage of the process for...
Author(s) : Harget, Skarelius, Imgram 1992 Eindhoven
Processes for the production of Crosslinked Polyethylene Pipe are discussed, with particular emphasis on peroxide crosslinking. Performance characteristics are presented in relation to key requirements of pressure pipe systems. Electrofusion is shown to provide an effective solution to pipe jointing, resulting in...
Author(s) : Ewing, Greig 1992 Eindhoven
Operation of high density polyethylene (HDPE) pipes at 7 bar has been very successful in British Gas over the last few years. Using HDPE pipes at higher pressures requires a high level and correct balance of pipe properties of strength, stress crack and rapid crack propagation resistance. Raised levels of jointing...
Author(s) : de Putter 1992 Eindhoven
The Plastics Pipes Industry (users and manufacturers) has made great progress to achieve European Standardization of their products. Much work still must to be done, including supporting at a national level what has been achieved with draft prEN or prEN ' s Insecurity exists with the harmonization of the...
Author(s) : Alferink, Wolters 1992 Eindhoven
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) : Farshad, Flueler 1992 Eindhoven
In this paper, results of short and long time internal pressure tests on a number of PVC pipe samples are pre- sented. Modes of failure of the pipe specimens consisting of ductile rupturing and brittle fracturing have been...
Author(s) : Wood, Moore 1992 Eindhoven
The erosion of pipe materials in slurry flow streams occurs through a variety of wear processes. As a result, the comparative wear resistance of materials is extremely difficult to predict from a knowledge of basic physical and engineering properties. Design and selection criteria must hence be based on empirical...
Author(s) : Overton 1992 Eindhoven
For many years the plastics pipes industry has had various voluntary certification schemes available. With the advent of the European single market and the preparation of harmonised European product standards a natural progression is the development of a single European certification system. In October 1990 a meeting...
Author(s) : Bon 1992 Eindhoven
GAZ DE FRANCE has devised a method for monitoring the length-wise development of a longitudinal crack via the wall of a pipe submitted to constant deformation. Deformation is induced by inserting a cone of graded diameter into a pipe end. This test permits an easy, rapid (test duration is roughly five days) and...
Author(s) : McPherson 1992 Eindhoven
Polyethylene (PE) pipeline systems are quickly becoming one of the preferred material choices for the large utilities such as Water and Gas. The material is now enjoying a rapid growth and acceptance as the NORM within the industry, as newer materials are introduced which increase the scope and pressure rating of PE...
Author(s) : Channell, Cawood, Capaccio 1992 Eindhoven
A critical appraisal has been carried out of the creep fracture of the fibrils in the pre-crack damage zone (craze) of polyethylene homo and copolymers. It has been shown that by assuming that the fibrils are drawn to the natural draw ratio of the material, a clear correlation can be established between the creep rate...
Author(s) : Scholten, Rijpkema 1992 Eindhoven
Eight excavated HDPE pipes of the 1st generation along with 3 modern PE types have been investigated. Comonomer content as a function of molecular weight of the old HDPE pipes appeared to be nonoptimal with respect to the modern PE types. Further unwanted effects in the old pipes were : particles, oxydation,...
Author(s) : Kuhlmann, Kanninen, Tweedy 1992 Eindhoven
Accelerated slow crack growth testing procedures that are coupled with newly developed bi-directional time-temperature shifting functions can provide reliable fracture mechanics based forecasts of long-term service performance of polyethylene gas distribution pipes. This methodology is first reviewed, then used in...
Author(s) : Lawrence 1992 Eindhoven
The limited demand for very large bore plastic pipes systems has resulted in a dearth of associated test data or strategy, but the need to now transport large quantities of water demand closer attention to this problem. The 'type testing' and routine (Q.C. ) testing of plastic pipe systems is already a difficult area,...
Author(s) : Morris, Gill 1992 Eindhoven
The introduction of a new grade of polyethylene for pressure pipes has presented a challenge to the UK Water Industry. Some aspects of the performance of the pipe itself are claimed to be significantly better than those of existing MDPE grades which would offer significant economic and operational benefits. However,...
Author(s) : Dewitt 1992 Eindhoven
In the design and the realization of distribution or transportation networks of fluids under moderate pressure, the PE/MRS 80 option (2nd generation) is generally favourable for small to medium diameter, up to 200 mm. For larger diameter (200-500 mm), more often is the PE/MRS 100 option competitive. High performance...
Author(s) : Ward, Atkinson, Greig, Hansard 1992 Eindhoven
A novel die-drawing process has been developed at Leeds University. By incorporating a mandrel, pipes may be expanded hoopwise whilst being drawn axially. Such biaxially-oriented pipes have properties better suited to the transmission of gases and liquids than either isotropic or longitudinally-drawn pipes. In this...
Author(s) : Burn 1992 Eindhoven
When plastics pipes are installed in water reticulation or pumped sewer systems they are normally subjected to installation damage, the level of which can vary enormously depending on the care taken during installation. Cyclic pressure testing of uPVC pipes with various levels of simulated installation...
Author(s) : Janson 1992 Eindhoven
New research and development particularly concerning the long-term strain of modern PE resins have created a basis for a simple and adequate method for tightness testing of plastics pressure pipelines. Thus, it is shown that for plastics pipes subjected to constant internal hydraulic pressure, it is quite possible to...
Author(s) : Mamoun, Grigory, Mallow, Bucza 1992 Eindhoven
In current practice. even relatively benign damage to plastic ipes can require the complete replacement of the damaged section. T is costly process can be performed more efficiently with a n in situ patch repair procedure that uses a newly synthesized repair material. This material has mechanical properties comparable...
Author(s) : Vanspeybroeck 1992 Eindhoven
This paper describes the test methods to study rapid crack propagation (RCP) behaviour of polyethylene (PE) pipes, including the evaluation of the correlations between different test methods. The test methods concerned are the Full Scale test, the Small Scale Steady State (S4) test, the Small Scale Steady State Scum...
Author(s) : Meijers, van Beurden 1992 Eindhoven
The reconnecting of drains after lining sewer pipes is a major stumbling block in the acceptance of the no-dig renovation techniques. A fitting and robotics have been developed to solve this problem without digging up the existing connection. The solution is based on the expansion of a thermoplastic connector by means...
Author(s) : Berndtson 1992 Eindhoven
Polyethylene has found increasing usage in industrial pipes, especially in large diameter submarine pipes. This paper outlines the benefits of polyethylene in this application, comparing it to competitive materials. Examples are given on projects were polyethylene has been chosen, and the reasons behind this choice.
Author(s) : Thoresson 1992 Eindhoven
The Great Artesian Basin is one of the world's greatest natural resources. Underlaying a large part of the Australian continent, the basin and its water is a necessity to survive in this part of the world. The basin was discovered more than one hundred years ago. The intensive use of the water has over time caused...
Author(s) : Bjorklund 1992 Eindhoven
Investigations of failure frequencies in municipal water distribution networks have been performed on several occasions over the past 15 years in Sweden. In a follow-up study, reasons for failure in PVC and PE water pipes during the period 1986-1990 have been studied. It was found that PVC pipes manufactured after...
Author(s) : Schepers 1992 Eindhoven
Where are we The plastic pipe industry in Europe has realised dominant positions against traditional materials in the markets for gas and water transport and in the building industry. . Considerable scope for growth is available in larger sizes where predominantly traditional materials still hold a strong...
Author(s) : Bowman,Medhurst, Portas 1992 Eindhoven
For two sample shapes different procedures have been examined as methods to quickly and quantitatively assess the strength of electrofusion joints. It is shown that the peel test, specified in BS7336, can be added to in order to obtain a quantitative measure of joint strength either using the % ductility on the...
Author(s) : Kanninen, Leung, O'Donoghue 1992 Eindhoven
This paper outlines a theoretical approach developed to quantify the conditions for a long-running crack in PE gas distribution pipes. Comparisons with a full-scale experiment on a 250 mm diameter SDR 17.6 MDPE pipe are made to demonstrate the validity of the model. The present status of a user-oriented procedure to...
Author(s) : Lund 1992 Eindhoven
The design requirements of an axially flexible and cross-sectionally stiff pipe for use in pipe renovation are discussed. This application also puts stringent demands on the joint configuration. Ways to solve these problems are proposed. One renovation system, marketed as Fiexoren, based on such a pipe is described...
Author(s) : Mayrhofer 1992 Eindhoven
The advantages of PVC, whicn have led to its predominant position amongst polymeric materials used for pipe applications ranging from sewer pipes and water pressure pipes to drainage pipes, rain water goods and cable ducting are well known. Besides being light in weight and energy efficient in their production, PVC...
Author(s) : Leevers, Venizelos, Ivankovic 1992 Eindhoven
The small-scale 'S4' test for rapid crack propagation seems set to acquire the status of a specifying standard for polyethylene gas distribution pipe. This paper describes parallel research projects on pressureinstrumented S 4 t e s t s a n d on Finite-Volume numerical analysis of S4 and full-scale tests....
Author(s) : Ziebell 1992 Eindhoven
It is unavoidable that rejects and scrap of a significant value occur during the extruding process of plastic pipes and profiles. This has been recognized by the manufacturers, and these days there is hardly an extruding company that does not see its production scrap, an amount between two and five percent, as a...
Author(s) : Elzink 1992 Eindhoven
The problems associated with our pipeline infrastructure are addressed in a broad sense. Optional solutions of rehabilitating existing systems with plastics pipelines are described and illustrated.
Author(s) : Rijpkema, Wolters 1992 Eindhoven
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) : Farshad, Flueler 1992 Eindhoven
In this paper, results of an investigation on behavior of HDPE pipes under internal shock pressure are presented. A number of HDPE pipe segments have been subjected to travelling shock wave of internal water pressure produced by an axial impacting mechanism. Three types of failure, consisting of ductile rupture,...
Author(s) : Tight 1992 Eindhoven
In 1989, a project was launched by the Gas Research Institute to develop a method of pipe joining and repair that utilized a new constant-temperature heating technology. In the project, prototype fittings with molded-in wire heater structures were inductively heated to achieve a pipe fusion joint that passed all of...
Author(s) : Boeen 1992 Eindhoven
The production of thermoplastics pipe is firmly tied to the extrusion technique. The principle is simple and the effectiveness of working and homogenizing the material is the best obtainable. What has not been possible, is by extrusion alone to give the pipe wall a profile other than in the longitudinal direction. To...
Author(s) : Boot, Guan 1992 Eindhoven
The case for development of rational design criteria for thinwalled polyethylene pipe linings is argued. Progress to date on a programme of research formulated to meet this objective is discussed. Short and long term behaviour under stress is modelled using elasto-plastic and elasto-viscoplastic constitutive models...
Author(s) : Maine, Ross 1992 Eindhoven
Renovation of an old main, by insertion of a medium density polyethylene (MDPE) pipe, reduces costs in excavation and reinstatement. Traditionally the inserted pipe is smaller than the existing main resulting in a reduction in flow capacity. This paper reviews the development and evaluation of a lining technique,...
Author(s) : Elzink, Molin 1992 Eindhoven
Today, in some parts of Europe plastics pipes and fittings are considered as mature products which have obtained an established position in underground applications. However, in others due to their flexible nature, their use is still sometimes questioned. This paper describes the actual performance of plastics pipes...
Author(s) : Jones 1992 Eindhoven
The challenge for water pipe systems in the 2lst Century is addressed. Factors influencing the change process in meeting the challenge are identified and explored. It is noted that, whilst construction of new water pipe systems will continue to be important major effort will need to be expanded in relation to the...
Author(s) : Pittman, Whitman, Gwynn, Beech 1992 Eindhoven
Comprehensive operating data from a large-scale pipe cooling lime are reported, including in-situ measurements of temperatures within the pipe wall. A finite element simulation of cooling, coupled with gravity induced flow, or slump, in the pipe wall is described. Computed temperatures within the wall are compared...
Author(s) : Beech, Allwood 1992 Eindhoven
The basis for the evaluation of polyethylene materials for pressure pipe applications is hydrostatic stress rupture testing for the prediction of long term hoop strength. However it is crucially important that the fracture properties of the materials are understood and indeed may result in limitations of their use....
Author(s) : Girardi 1992 Eindhoven
Various test geometries with known defects, such as might occur in practice. were evaluated and compared to the British Gas standard for butt fusion welds. Novel testing techniques are described. A suitable test geometry was established and used to assess the influence of defect size on properties. Small defects were...
Author(s) : De Craene, Schwenke 1992 Eindhoven
Because pipes are submitted to cyclic stresses in the UEWS test, this method offers some advantages over the standard long term burst pressure test. Clear transition points between elastic and inelastic regions of the stress-strain curve can be identified. These transition points are a sound basis for the...
Author(s) : Marhsall, Harry, Ward, Pearson 1992 Eindhoven
Existing test methods used for the characterisation of long term strength properties of plastic materials for use in pressure pipe duties have been reviewed. A notched "C" ring type test has been developed to define the long term crack resistance and strength properties of a CPE modified PVC. Since materials of this...
Author(s) : Mamoun 1992 Eindhoven
A brief overview is presented on some important research programs on plastic pipes conducted within the last ten years. Several signif icant research results and their impact on manufacturers and users of plastic pipes are high1 ighted. Results of research and development (R&D) on material characterization,...
Author(s) : Bowman 1992 Eindhoven
The influence of time and temperature on the long term strength of a multilayer pressure pipe has been investigated. The pipe consists of five layers, one of which is an aluminium foil while the other four layers are polyethylene based and form the significant ( > 8 5 % ) part of the pipe wall. In respect of strength...
Author(s) : Lamond 1992 Eindhoven
The use of polyethylene in pipe systems for the distribution of gas, water and other industrial applications has grown rapidly over recent years. The development of polyethylene compounds with ever improving combinations of toughness and flexibility has contributed to this success but the key factor has been the...
Author(s) : Bevis 1992 Eindhoven
Europe has accepted that resources should be recycled to avoid waste and is incorporated in European Community stragegy for waste management : - The prevention and reduction of waste arisings at source. - The increased use of recycling and re-use of materials wherever possible. - The safe disposal of unavoidable...
Author(s) : Clutton, Dear, Channell 1992 Eindhoven
Two novel techniques have been applied to the problem of determining the fracture toughness of polyethylene appropriate to the situation of rapid crack propagation in pipe systems. Agreement is found between the data from the two methods used for evaluating four grades of polyethylene of widely different toughness....
Author(s) : Del Gaudio 1992 Eindhoven
The use of polyethylene for gas distribution networks was authorized in Italy only in 1984. Genoa's AMGA was the first in Italy to use medium-density polyethylene for an extension of its gas network of over 150 kilometres. A trench - machine supplied by British Gas was used for the excavations. Significant...
Author(s) : Ifwarson, Leijstroem 1992 Eindhoven
The lifetime of plastic pipes has been studied at Studsvik for nearly 20 years. This paper presents results obtained from hydrostatic pressure testing of pipes made from polyethylene, crosslinked polyethylene and polypropylene. Examples of how different factors influence the lifetime of plastic pipes are explained in...
Author(s) : Allan, Bevis, Chuah, Ma 1992 Eindhoven
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