edition Heiner Brömstrup (Editor) PE 100 Pipe...

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Heiner Brömstrup (Editor)

PE 100 Pipe Systems3rd edition

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PE 100 PIPE SYSTEMS

00_PE_100_Pipe_Systems_2759:PE_100_Umbruch 13.10.2009 15:00 Uhr Seite 1

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Bibliographic information by Die Deutsche Bibliothek

Die Deutsche Bibliothek is listing this publication in the German NationalBibliography;detailed bibliographic data are available in the Internet under

http://dnb.ddb.de

ISBN 978-3-8027-2759-7

© 2009 Vulkan-Verlag GmbHA company of the Oldenbourg groupHuyssenallee 52-56, D-45128 EssenTelephone: +49 (0) 201 8 20 02-0, Internet: http://www.oldenbourg.de

Managing Editor Nico HülsdauE-Mail: [email protected]

This book including all illustrations is protected by copyright. Any utilization out of thelimits of the copyright law without the publisher’s authorization is inadmissible andliable to prosecution. This applies in particular to duplication, translation, microfilmingand to the storage and processing in electronic systems.

Reproduction of commercial names, trade-marks and so on mentioned in this work –even if not particularly indicated – does not justify the assumption that such names canbe considered, as out of coyright, in the sense of trade-marks or brand names protec-tion and could therefore be used by anybody.

This work has been elaborated thoroughly. And yet, author and publisher do notacceptany responsability for the incorrectness of statements, indications and recom-mendations mentioned therein as well as for misprints.


Heiner Brömstrup (Editor)

PE 100PIPE SYSTEMS

3nd Edition

VERLAGVULKAN


Transform your performance.

Hostalen and Lupolen are trademarks owned or used by LyondellBasell group companies. Hostalen is a trademark registered in the U.S. Patent and Trademark Offi ce. PB-1 is not being sold in pipe applications intended for use in North America.

For more than 50 years, customers have relied on LyondellBasell’s industry-defining products andservices to address the demanding requirements of pressure and non-pressurepipe applications.

With properties that transcend the performance

of conventional materials, the company offers a vast range of products used in a variety of piping systems.

Achieve the stiffness, flexibility, light weight,easy handling and pressure and corrosion resistance you need, with innovative resins such as:

Hostalen HDPE

Lupolen PE and PEX

Hostalen PP andPolybutene-1

For more information, visit lyondellbasell.com

lyondellbasell.comDrinking water pipe produced using Hostalen CRP100 blackgrade, which can withstand amaximum operating pressure of 40 bar.


Foreword

In recent years, piping systems consisting of high-density polyethylene of the PE 100pressure class have demonstrated with their high performance, reliability and safety,their excellent suitability for applications in gas and water supplies, waste-water dis-posal, industrial piping engineering and the renewal and repair of damaged pipes. Thispipe material is corrosion-proof, largely resistant to chemicals and abrasion-proof.PE 100 pressure pipes are flexible and possess a very good creep rupture strengthcombined with high resistance to slow crack growth and rapid crack propagation.

The high capital expenditure necessary for the maintenance, renewal and expansion ofgas, drinking-water and waste-water piping systems makes the use of safe, reliableand durable piping systems essential. The strength reserves of PE 100 piping systemsare so great that a useful life of one hundred years can be postulated and, indeed,many supply and disposal enterprises already expect comparable periods of servicefrom their systems. Since not only the investment costs for the technical solution,i.e., production and installation costs, but also, increasingly frequently, operating,maintenance and repair costs are important factors in cost-efficiency analyses, a high-quality piping system with the longest possible service-life is an absolute priority for thesystem operator, in view, in particular, of the fact that period of service, alongsideinitial costs, is definitive for overall cost-efficiency.

The further development of the PE 100 pipe material provides an excellent example ofsuccessful Research & Development work. Process-engineering optimisation of theproduction of bimodal and multimodal polyethylene pipe materials has enabled thematerials producers to develop PE 100 pipe materials possessing excellent resistanceto stress cracking and extremely high resistance to slow crack growth. This group ofPE 100 pipe materials is referred to as "PE 100-RC" and is described in PubliclyAvailable Specification (PAS) 1075, "Polyethylene pipes for alternative installationmethods". Publication of PAS 1075 is overseen by the Technology Department of the"DIN Deutsches Institut für Normung e.V." (German Institute for Standardisation).

This new third revised edition, like the first and second editions published in 1998 and2004, deals exclusively with pressure-pipe systems from production of the necessaryPE 100 and PE 100-RC high performance pipe materials and the pipes and shapesthemselves, up to pipe laying and installation. New case studies from Germany,Portugal, Romania, Scotland and Switzerland then follow. The book is addressedprimarily to decision-makers, engineers, technicians and practitioners in the fields ofgas and water supplies, waste-water disposal, and industry in general.

I take this opportunity of expressing my sincere thanks to all the authors for their ded-ication and their productive endeavours in the compilation of this work. We all trust andbelieve that it will be of interest, use and assistance to all its readers.

Wiesbaden, Okt. 2009 Heiner Brömstrup

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At home in your world

Polyethylenefor pipe systems

For us, a major player in the pipe and fi ttings market, with a long lasting commitment, innovation and partnership are key :

> 1997, first to offer hexene based PE100. > 2001, first PE100 Super Slow Crack Growth resistant pipe compounds. > 2006, best-of-class low sag PE100, specifi cally developed for very large

diameter pipes.

: [email protected]

: www.totalpetrochemicals.com

Hexene inside

R&D and Technical Support

Expertise based on a long-standing presence and continuous investments in people andresearch


7

List of authors

Dipl.-Ing. Jürgen AllmannSIMONA AktiengesellschaftTeichweg 16D-55606 [email protected] 7

Pierre BelloirTotal Petrochemicals Research FeluyZone Industrielle CB-7181 Feluy / [email protected] 15

Trygve BlomsterPipelife NorgeP.O.Box 6078 EtterstadN-0601 Oslo / [email protected] 15

Dipl.-Ing. Thomas BöhmLyondellBasell IndustriesIndustriepark Höchst, C 657D-65926 Frankfurt am [email protected] 11

Dipl.-Ing. Heiner BrömstrupInternationale Ingenieurberatung GmbHKaiser-Friedrich-Ring 58D-65185 [email protected] and Chapter 3

Dipl.-Ing. Robert EckertFRIATEC AktiengesellschaftSteinzeugstraße 50D-68229 [email protected] 6 and 16

Dipl.-Ing. Thomas FrankFRANK GmbHStarkenburgstraße 1D-64546 Mö[email protected] 4, 5, 6 and 12

Dipl.-Ing. Axel FrerichsOOWV Oldenburgisch-OstfriesischerWasserverbandGeorgstraße 4D-26919 [email protected] 10

Dr. Boris GibbeschSTEULER IndustriellerKorrosionsschutz GmbHGeorg-Steuler-StraßeD-56203 Hö[email protected] 7

Dipl.-Ing. Ralf GlanertWAVIN GmbHKunststoff-RohrsystemeIndustriestraße 20D-49767 [email protected] 18

Dipl.-Ing. Karl-Heinz GollGolükes Ingenieure GmbH & Co. KGZur Eisernen Hand 27D-64367 Mü[email protected] 17


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Dr.-Ing. Joachim HesselHESSEL Ingenieurtechnik GmbHAm Vennstein 1aD-52159 [email protected] 6

Ing. Wolfgang HuszarINEOS PolyolefinsSchönbrunnerstraße 59-61/6A-1050 Vienna / [email protected] 1 and 2

Dipl.-Ing. Jan-Herbert JohanninkSTRABAG AktiengesellschaftDirektion Düsseldorf - Bereich NordhornAlte PiccardieD-49828 [email protected] 17

Dipl.-Ing. Guido KaniaREHAU AG + Co.Ytterbium 4D-91058 [email protected] 14

Dipl.-Ing. Jürgen KernAGRU-FRANK GmbHIndustriestraßeD-61200 Wö[email protected] 7 and 19

Dipl.-Ing. Frank KrauseREHAU AG + Co.Ytterbium 4D-91058 [email protected] 14

Dipl.-Ing. Heiner KrietenbrinkGELSENWASSER AGWilly-Brand-Allee 26D-45891 [email protected] 9

Dipl.-Ing. Andreas KrugStadtentwässerung Frankfurt am MainGoldsteinstraße 160D-60528 Frankfurt am [email protected] 17

Dipl.-Ing. Georg LarischSABIC EuropeEuropaboulevard 1, P.O. Box 5151NL- 6130 PD Sittard / [email protected] 13

Daniel LibertTotal Petrochemicals Research FeluyZone Industrielle CB-7181 Feluy / [email protected] 15

George MerryKWH Pipe (UK) LtdBrunleys, Kiln FarmMilton KeynesMK11 3EW / [email protected] 11

Dipl.-Ing. Thomas MeyerPfeiffer GmbHAltfrankener Straße 2D-01159 [email protected] 12


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James McGoldrick BScBorealis Polyolefine GmbHSt.-Peter-Strasse 25A-4021 Linz / [email protected] 1 and 2

Dr. Mary McCarthySABIC EuropeUrmonderbaan 22, P.O. Box 319NL-6160 AH Geleen / [email protected] 1 and 2

Dipl.-Ing. Werner RothhöftLyondellBasell IndustriesIndustriepark Höchst, C 657D-65926 Frankfurt am [email protected] 1, 2 and 3

Christophe SallesBorealis France SAS9/11 Rue Benoit Malon92156 Suresnes Cedex / [email protected] 8

Dipl.-Ing. Axel SchönrockGolükes Ingenieure GmbH & Co. KGZur Eisernen Hand 27D-64367 Mü[email protected] 17

Dipl.-Ing. Ulrich SchulteLyondellBasell IndustriesIndustriepark Höchst, C 657D-65926 Frankfurt am [email protected] 5

Dr.-Ing. Thorsten Späthegeplast W. Strumann GmbH & Co. KGRobert-Bosch-Straße 7D-48268 [email protected] 4

Dr. David WaltonBorouge Pte LtdHeat office Maketing1 George Street 18-01Singapore [email protected] 8


The weak spots of any pipeline are the joints

Together with you in service for the civilisation !

As provider for complete solutions of top quality, we manufacture pipes made of PE 100, PE 100 RC and PE-Xa and supply the complete program of fi ttings for gas and water applications, sewage and for in-dustrial applications. We set quality standards with premium welding devices, machines and tools for construction sites and workshops to contribute to

the security of pipeline networks. High degree in engineering and excellent raw materials guarantee long-lasting and economical solutions for our clients. We are partner and supplier for complete plastic pipe systems. Pipes are the arteries of civilisation – that’s what the FRANK Group has specialised in for over 40 years.

FRANK GmbH Tel.: +49 6105 4085-0 [email protected] www.frank-gmbh.de


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Contents

Foreword ............................................................................................................ 5

List of authors .................................................................................................. 7

1. Introduction to Polyethylene .............................................................. 19

Wolfgang Huszar, Dr. Mary McCarthy, James McGoldrick and Werner Rothhöft

1.1 Chemical Structure of PE-HD .............................................................. 191.2 Relation structure and properties ........................................................ 201.2.1 Crystallinity and Density ...................................................................... 231.2.2 Flowability (MW, MWD, MFR) .............................................................. 261.2.3 Creep behaviour .................................................................................. 261.2.4 Process of Slow Crack Growth (SCG) .................................................. 281.3 Polymerisation Processes of PE 100 .................................................... 291.4 Benefits of PE 100 ................................................................................ 301.5 Ongoing development .......................................................................... 31

2. Pipe Properties .................................................................................... 32


2.1 Hydrostatic Pressure Resistance .......................................................... 322.1.1 100 Years Service Life .......................................................................... 342.2 Resistance to Slow Crack Growth ...................................................... 352.2.1 Behaviour of Notched Pipes - Notched Pipe Test (NPT) .................... 352.2.2 Full Notch Creep Test – FNCT .............................................................. 362.2.3 Other tests methods describing the Resistance to Slow Crack

Growth .................................................................................................. 372.2.3.1 Pennsylvania Notch Tensile Test – PENT ............................................ 372.2.3.2 Notched Ring Test (NRT) ...................................................................... 382.2.3.3 Point Loading Test – PLT ...................................................................... 392.2.3.4 Fatigue crack growth testing ................................................................ 392.2.3.5 Strain hardening modulus .................................................................... 392.3 Resistance to Rapid Crack Propagation .............................................. 402.3.1 Full Scale Test ...................................................................................... 422.3.2 Small Scale Steady State Test - S4 Test .............................................. 422.4 Installation and operational aspects .................................................... 432.4.1 Behaviour of buried pipes .................................................................... 432.4.2 Chemical Resistance ............................................................................ 442.4.3 Abrasion Resistance ............................................................................ 47

3. Pipe dimensioning .............................................................................. 48Heiner Brömstrup and Werner Rothhöft

3.1 Pipe classification ................................................................................ 483.2 Internal pressure loads ........................................................................ 48


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3.2.1 Calculation of pipe wall thickness ........................................................ 523.2.2 Calculation of internal pipe pressure .................................................... 523.2.3 Calculation of effective service-life ...................................................... 533.2.4 Calculation of safety factor .................................................................. 533.2.5 Hydrostatic strength diagrams for PE 100 and PE 80 pressure

pipes .................................................................................................... 543.2.6 Pipe series in accordance with the SDR (Standard Dimension Ratio) .. 543.2.7 Intermittent exposure to internal pressure .......................................... 563.2.8 Pressure-surge loads ............................................................................ 583.3 External pressure loads ........................................................................ 603.4 Hydraulic calculation ............................................................................ 603.4.1 Fundamental equation of pipe flow ...................................................... 603.4.1.1 Mean velocity of flow ............................................................................ 613.4.1.2 Reynolds number .................................................................................. 613.4.1.3 Laws of resistance ................................................................................ 613.4.1.4 Moody diagram .................................................................................... 623.4.2 Calculation applying the individual concept ........................................ 623.4.3 Calculation applying the global concept .............................................. 633.4.4 Codes, rules and standards ................................................................ 64

4. Production of pipes and shapes ...................................................... 65Thomas Frank and Dr. Thorsten Späth

4.1 Pipe production .................................................................................... 654.2 Production of fittings ............................................................................ 674.2.1 Injection moulding ................................................................................ 674.2.2 Fittings produced from pipe ................................................................ 70

5. Quality Asssurance ............................................................................ 74Ulrich Schulte and Thomas Frank

5.1 Quality assurance requirements for producers of pipe extrusioncompounds .......................................................................................... 74

5.1.1 Quality Management ............................................................................ 745.1.2 Quality Control ...................................................................................... 745.1.3 The PE 100+ Association quality tests ................................................ 755.1.3.1 Test schedule ........................................................................................ 755.1.3.2 Test requirements ................................................................................ 765.1.3.3 Tests ...................................................................................................... 775.1.3.4 The PE 100+ Association “List of Quality Materials” .......................... 775.2 Quality assurance requirements for the pipe and fittings producer .... 785.2.1 Incoming goods inspection .................................................................. 785.2.2 Quality criteria ...................................................................................... 785.2.3 Tests on the product ............................................................................ 795.2.4 Inspection certificates .......................................................................... 805.2.5 Marking and traceability ...................................................................... 82


BorSafe™ solutions

Refreshingideas

The drive to conserve water resources has found a focus on the reliability of water distribution systems and the elimination of losses through pipe failures.

Borealis and Borouge have addressed this issue with the introduction of BorSafe™, a unique family of PE80 and PE100 grades developed specifically for pressure pipes and pressure fittings.

From simple everyday products that make life easier to step changing technological developments, Borealis and Borouge are leading the way.

www.borouge.comwww.borealisgroup.com


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5.2.6 Quality Management ............................................................................ 845.2.7 External supervision ............................................................................ 84

6. Joining of pipes .................................................................................. 85Dr. Joachim Hessel, Robert Eckert and Thomas Frank

6.1 Welded joints ........................................................................................ 856.1.1 Equipment and welder requirements .................................................... 856.1.2 Heating element butt welding .............................................................. 856.1.3 Electrofusion welding ............................................................................ 886.1.4 Long-term weld quality ........................................................................ 906.1.4.1 Heating element butt welds .................................................................. 906.1.4.2 Elektro fusion welds .............................................................................. 936.1.4.3 Conclusion ............................................................................................ 946.2 Flanged joints ...................................................................................... 95

7. Pipe installation .................................................................................. 97Jürgen Allmann, Dr. Boris Gibbesch and Jürgen Kern

7.1 Open-trench installation ...................................................................... 977.2 Trenchless installation .......................................................................... 1007.2.1 Pipe ploughing ...................................................................................... 1017.2.2 Impact moling ...................................................................................... 1037.2.3 Flush-drilling ........................................................................................ 1037.3 Culvert installation ................................................................................ 1037.4 Rehabilitation of pipelines .................................................................... 1047.4.1 Relining ................................................................................................ 1057.4.2 Burst-lining ............................................................................................ 1067.4.3 Ovoid pipe repair .................................................................................. 1067.5 Pressure testing of gas pipelines ........................................................ 1077.6 Pressure testing of water pipelines ...................................................... 1087.6.1 European Standard DIN EN 805 .......................................................... 1097.6.2 DVGW Code W 400, Part 2: Construction and testing ........................ 1107.6.2.1 Pressure-loss (“head-loss”) method .................................................... 1107.6.2.2 Water-loss method ................................................................................ 1137.6.2.3 Visual inspection at operating pressure .............................................. 1147.6.3 DVS Code 2210, Part 1, Supplement 2 ................................................ 115

8. Development of a whole-life costing model for large diameterwater mains ........................................................................................ 116Dr. David Walton and Christophe Salles

8.1 Introduction .......................................................................................... 1168.2 Design criteria ...................................................................................... 1168.3 The whole-life costing model .............................................................. 1178.4 Summary and conclusions .................................................................. 119


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9. Introduction of a PE 100 piping system at a major water utility –background, cost analysis and operating experience .................... 121Heiner Krietenbrink

9.1 General .................................................................................................. 1219.2 Background .......................................................................................... 1229.3 Operational experience ........................................................................ 1239.3.1 Retrospective ........................................................................................ 1239.3.2 The system adopted ............................................................................ 1249.3.3 Repair methods .................................................................................... 1259.3.4 Detection methods .............................................................................. 1259.3.5 Quality assurance ................................................................................ 1259.3.6 Pipe pulling for renewal of pipelines .................................................... 1269.4 Cost analysis ........................................................................................ 1289.5 Conclusion ............................................................................................ 129

10. Experience gained with PE pipes for conveyance of water, usingthe example of a 710 mm PE 100 drinking-water main .................. 130Axel Frerichs

10.1 Introduction .......................................................................................... 13010.2 Project conception ................................................................................ 13010.3 Project planning .................................................................................... 13210.3.1 Route selection .................................................................................... 13310.3.2 Soil and groundwater conditions .......................................................... 13410.3.3 Pipe materials ...................................................................................... 13510.4 Organization of site operations ............................................................ 13610.5 Pressure testing and disinfection ........................................................ 13810.6 Conclusion and prospects .................................................................... 138

11. Large-diameter PE 100 pipes for drinking-water supply to theScottish metropolis of Glasgow ........................................................ 140Thomas Böhm and George Merry

11.1 Introduction .......................................................................................... 14011.2 Brief portrait of Scottish Water ............................................................ 14011.3 Loch Katrine: Drinking-water reservoir for Glasgow ............................ 14111.4 Katrine Water Project: Investment in Glasgow’s drinking water

supply .................................................................................................. 14111.5 Mugdock: Water treatment plant with a long history .......................... 14111.6 Scope of the construction project ........................................................ 14211.6.1 Planning obstacles: Engineering and conservation interests finally

harmonized .......................................................................................... 14311.6.2 Project requirements ............................................................................ 14311.7 Selection of pipe material .................................................................... 14411.8 Manufacture of pipes and fittings ........................................................ 14511.9 Project implementation ........................................................................ 14511.10 Perspectives ........................................................................................ 148


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12. Repair of a DN 1500 drinking-water pipeline operated byLandeswasserversorgung Baden-Württemberg via subliningwith a PE 100 liner pipe ...................................................................... 149Thomas Meyer and Thomas Frank

12.1 Introduction .......................................................................................... 14912.2 Selection of the subline method .......................................................... 15112.3 Assembly of the pipe string .................................................................. 15212.4 Preparation of the inliner ...................................................................... 15312.5 Pulling and restoration of inliner section .............................................. 15412.6 Connection of the inliner ...................................................................... 15612.7 Conclusion and prospects .................................................................... 156

13. PE 100 pipe material first choice in Eastern Europe – Ongoingreplacement of steel with PE 100: Case of a 630 mm gas pipe .... 158Georg Larisch

13.1 Introduction .......................................................................................... 15813.2 Romania’s gas industry ........................................................................ 15913.3 Gas supplies in Bucharest, choice of material .................................... 15913.4 Basic project data ................................................................................ 15913.5 Pipe production and Quality Assurance .............................................. 15913.6 Pipe material ........................................................................................ 16013.7 Quality Assurance ................................................................................ 16013.8 Installation ............................................................................................ 16113.9 Prospects .............................................................................................. 162

14. Expansion of rural infrastructure by means of a 7.2 km longPE 100-RC pressure pipe feeding to a treatment plant .................. 163Guido Kania and Frank Krause

14.1 Introduction .......................................................................................... 16314.2 General requirements for cost-efficient pipeline construction ............ 16314.3 Implications for sewage disposal ........................................................ 16414.4 Planning, installation and challenges .................................................. 16514.5 Conclusion ............................................................................................ 167

15. New application for PE 100 pipes: 2,000 mm SDR26 pipelineto bring seawater to world’s largest fish farm ................................ 168Pierre Belloir, Daniel Libert and Trygve Blomster

15.1 Introduction .......................................................................................... 16815.2 The project ............................................................................................ 16915.2.1 The material .......................................................................................... 16915.2.2 Pipe extrusion ...................................................................................... 16915.2.3 Towing .................................................................................................. 17115.2.4 Ballasting and installation .................................................................... 171


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15.2.5 Fish farm facts and figures .................................................................. 17315.3 Conclusions .......................................................................................... 174

16. RobSwitzerland: New natural gas pipeline from Thun toInterlaken ............................................................................................ 175Robert Eckert

16.1 Project data .......................................................................................... 17516.2 Installation under water ... .................................................................... 17816.3 ... and ashore ........................................................................................ 17916.4 Focus on safety and quality ................................................................ 180

17. Relining-based rehabilitation of a 2 x 10 km long pressure sludgeline operated by Stadtentwässerung Frankfurt am Main .............. 181Andreas Krug, Axel Schönrock, Karl-Heinz Goll and Jan-Herbert Johannink

17.1 Introduction .......................................................................................... 18117.2 Inspection and damage analysis .......................................................... 18217.3 Rehabilitation-planning requirements .................................................. 18317.4 Selection of the rehabilitation method .................................................. 18317.5 Appraisal of variants ............................................................................ 18417.6 Project planning and tendering ............................................................ 18517.7 Project execution .................................................................................. 18817.8 Operating experience up to the time of writing .................................... 19017.9 Summary .............................................................................................. 190

18. Trenchless installation of PE pipes in Klingenberg am Main ........ 192Ralf Glanertd

18.1 Site description .................................................................................... 19218.2 Pipe materials ...................................................................................... 19318.3 Installation ............................................................................................ 19418.4 Pipe joints ............................................................................................ 19518.5 Result .................................................................................................... 196

19. Surwey of standards and guidelines ................................................ 197Jürgen Kern

19.1 International standards (ISO) ................................................................ 19719.2 European standards (EN) ...................................................................... 19919.3 German standards (DIN) and work sheets (DVS, DVGW, DWA) .......... 201

Advertisers’ index .............................................................................................. 207


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1. Introduction to Polyethylene


Polyethylene is one of the most popular plastics used for a wider range of applicationslike bags, bottles and everyday-use articles. It is the material of choice for use in pres-sure pipes for gas and drinking water applications.

Polyethylene can be produced using different processes. Low-Density Polyethylene(PE-LD) can be produced using a high-pressure process, such as autoclave or tubereactor. High-Density Polyethylene (PE-HD) and Linear-Low-Density Polyethylene(PE-LLD) are manufactured using a low-pressure process, such as slurry, gas-phase ora solution process. Ethylene, the monomer, is converted to polyethylene by one of theabove mentioned processes using a catalyst. This conversion process is known aspolymerisation, in which individual molecules of ethylene form chains of polyethylenemacromolecules. The process parameters as well as the type of catalyst employedhave a direct influence on the structure and therefore also on the properties of the poly-ethylene.

1.1 Chemical Structure of PE-HDThe polymerisation is carried out with the aid of a catalyst at a relatively low tempera-ture (80 to 100°C) and a low pressure (40 to 100 bars). This process results in theformation of pure and linear chains of polyethylene also known as polyethylenehomopolymer (Fig. 1.1).

The incorporation of other monomers (e.g. butene, hexene, octene, called comonomer)during the polymerisation process leads to the formation of short-chain side branches.(Fig. 1.2 and Fig. 1.3).

A typical polyethylene material contains a wide range of molecular chain lengths(= molecular weights MW). This so called molecular weight distribution (MWD) is shownin Fig. 1.4.

The MW and the MWD are controlled by the choice of catalyst as well as the poly-merisation process parameters.

A very practical method of getting an indication of the molecular weight (MW) is tomeasure the Melt Flow Rate (MFR).

As shown in Fig. 1.5 the solid polyethylene is placed in a metal barrel and heated upto the test temperature. When the polyethylene is molten a defined weight is loaded to

Fig. 1.1:Polymerisation of ethyleneto linear polyethylene


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the piston and the polyethylene is forced to pass through a defined capillary. Depend-ing on the viscosity of the material, as a consequence of molecular chain length as wellas long and short chain branching, a certain quantity of material can pass through thecapillary in a given time. The MFR value is expressed as grams per 10 minutes undera defined load (2.16 kg, 5 kg or 21.6 kg) and generally speaking at 190°C for polyeth-ylene.

1.2 Relation structure and propertiesThe range of properties of PE is influenced by its structure which is a result of: the cat-alyst type, process type, polymerisation conditions, MW, MWD, comonomer type, -content and -distribution.

Fig. 1.2: Copolymerisation using butene

Fig. 1.3: Copolymerisation using hexene


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