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.


Towards a methodology for designing RCP-resistant polyethylenes using batch scale test methods [PE]

 

Plastic Pipes Conference Association # 2010 Vancouver

P.Leevers

This paper outlines a PE100 design methodology which gives central importance to the separate modelling and measurement of plane-strain and plane-stress dynamic fracture resistance. The former is difficult to measure but can be estimated from weight-average molecular weight; the latter is related to high-rate adiabatic tensile deformation which can be estimated from low-rate tensile test data. An overall dynamic crack resistance is then predicted as a function of temperature and pipe wall thickness. Meanwhile, employing a semi-analytical RCP model, the crack driving force is calculated as a function of temperature, pressure and pipe size. The outcome is an estimate of critical pressure as a function of temperature and, hence, of the critical temperature. The entire scheme is demonstrated using a group of experimental resins in the −20 to +10◦ C transition temperature range. Early results indicate the potential of the scheme for guiding PE100 resin design, while highlighting areas in which better modelling is needed.

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

Related papers

2010 Vancouver : S4 to full-scale test correlation: new insights from an ‘open source’ RCP model

Author(s) : Patrick Leevers, Christos Argyrakis

There is renewed interest in the correlation between critical pressures from lab-scale (S4) and full-scale RCP tests. The standard, supposedly material-independent correlation factor does provide a lower bound for data from many PE grades, but for some grades it is overconservative and for PA12 its applicability has...

2006 Washington DC : Rapid Crack Propagation Failures in HDPE Pipes; Structure-Property Investigations

Author(s) : Krishnaswamy, Leevers, Lamborn, Sukhadia, Register, Maeger

The influence of molecular architecture on the rapid crack propagation (RCP) resistance of a wide variety of high-density polyethylene (HDPE) pipes was investigated. It was concluded that high molecular weight, high crystallinity and a relatively narrow molecular weight distribution are important architectural...

2006 Washington DC : Rapid Crack Propagation in Loosely Fitted PE Liner Pipe

Author(s) : Leevers, Henderson, Pereira

Laboratory-scale S4 tests have been used to determine whether it would be possible, at any realistic working pressure, for a loosely-fitted PE liner within a rigid host pipe to fail by Rapid Crack Propagation (RCP). The standard ISO 13477 S4 method was modified by replacement of the containment ring cage by a rigid,...

2006 Washington DC : S4 Critical Pressure and Critical Temperature

Author(s) : Maeger, Vanspeybroeck, Lamborn, Mamoun, Leevers, Oliphant

As polyethylene pressure pipes enter the global marketplace under an ever-wider range of operating conditions, there is increasing emphasis on their rapid crack propagation performance. It is important that both producers and end-users are able to rely on the robustness of the rapid crack propagation test results and...

2004 Milan : S4 critical temperature tests: procedure and interpretation

Author(s) : Patrick Leevers

International Standard ISO 13477 defines the ‘S4’ RCP test itself, and specifies two procedures which use it. The first procedure, already well embedded in referring standards, evaluates a critical pressure at constant temperature (usually 0°C) below which RCP arrests. The second procedure evaluates, at constant...

2001 Munich : Fully Predictive Model of RCP in Plastics Pipes

Author(s) : Ivankovic, Tropsa, Jasak, Leevers

This work presents a 3D coupled solid-fluid model for predicting fast failures in pressurised plastic pipes. It is developed within a unified computational procedure where both solid pipe and pressurising media are discretised using the Finite Volume method. The coupling is achieved across the pipe-fluid interface...

2001 Munich : The Ductile-Brittle Transition in Pipe-Grade PE

Author(s) : Leevers, Moreno, Paizis

The resistance of PE pipes to rapid crack propagation depends strongly on temperature. The critical pressure measured using ISO 13477 ‘S4’ tests increases abruptly above a transition temperature Tc. For PE100 grades Tc has become a primary index of quality : it must remain below 0°C despite a tendency to increase...

1998 Gothenburg : Ductile deformation in Pipe Grade PE

Author(s) : Hillmansen, Davis, Leevers

Rapid Crack Propagation in PE-100 gas pipes is governed primarily by a brittle-tough transition temperature TBT,above which ductile deformation will absorb energy and promptly arrest a fast-running brittle crack. Even at low temperatures, a layer of plastically deformed material is formed at the pipe bore during...

1998 Gothenburg : Impact Rate and Geometry Effects in Pipe Grade Materials

Author(s) : Douglas, Leevers

A model for dynamic and impact fracture has been recently proposed whereby the fracture event is controlled by adiabatic heating and subsequent melting of the cohesive crack tip craze. The crack initiation resistance is shown to be an inherent function of specimen geometry and impact speed. This theoretical framework...

1998 Gothenburg : Process and Property Interactions in PE Pipelines

Author(s) : Davis, Greenshields, Dabas, Leevers

The study of Rapid Crack Propagation (RCP) in pressurised pipelines is of particular importancr to th? g a industry, where the possibility of such a failure must he minimised. Polyethylene (PE) currently dominates the market for plastic gas pipelines, and as the demands for larger diameters .and higher operating...

1998 Gothenburg : Rapid Crack Propagation

Author(s) : Leevers

The international standardisation of tests for Rapid Crack Propagation (RCP) is approaching completion, and requirements for product and systems standards x e well established. Yet some basic issues about RCP remain contentious. In contrast to slow crack growth, there is a near-absence of service failure data, and in...

1998 Gothenburg : Rapid Extension and Failure of PE Craze Material

Author(s) : Hazra, Leevers

In previous work on the impact behaviour of pipe grade polyethylene (PE), the 'thermal decohesion model' was proposed by Leevers [ l ] to explain the embrittlement of PE under impact and at low temperatures. One of the initial assumptions of the model was that the crack tip craze could be represented by a Dugdale...

1995 Edinburgh : An analytical model of the gas discharge process in the S4

Author(s) : Venizelov, Greenshields, Leevers

An analytical I-D model of the gas discharge process in the small scale steady State ( ~ 4 ) test for rapid g a c k propagation (RCP) in thermoplastic pipe has been developed. Because the gas can exert a powerful crack driving force, such a model is essential to an understanding of the test. This model yields a...

1995 Edinburgh : Fast fracture of plastic water pipes and the measurement of dynamic

Author(s) : Greenshields, Leevers

Previous research has concluded that rapid crack propagation (RCP) cannot be sustained in 100% water pressurised pipe. However, this paper shows that by reducing the decompression wave speed in water to below the crack speed, it is possible t o sustain fast cracks in thermoplastic pressure pipe. T h e prediction of R...

1995 Edinburgh : Material, structural and pressurising fluid models for RCP tests on

Author(s) : Leevers, Greenshields, Venizelos, Ivankovic

The development of pipe-grade materials to resist slow crack growth and ductile rupture has been spectacularly successful. It is a measure of this success that concern with Rapid Crack Propagation (RCP) has increased to the level evident at this conference. Stronger materials encourage the use of higher...

1995 Edinburgh : The effect of pressurizing fluid on fast fracture in plastic pipes

Author(s) : Greenshiels, Leevers

The failure of a pipe by rapid crack propagation (RCP) can, by its nature, be highly desmctive and must be avoided. Research over the past ten years has concentrated on gas pressurised pipelines and has resulted in a greater awareness and understanding of the problem. Recent attention has focused on RCP in...

1992 Eindhoven : Rapid Crack Propagation along Pressurized PE Pipe - Small Scale Testing and Numerical Modelling

Author(s) : Leevers, Venizelos, Ivankovic

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....

Members of the Association

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