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UNIVERSITI PUTRA MALAYSIA EXPERIMENTAL LEAKAGE ANALYSIS FOR PUSH FIT ELASTOMERIC STEEL PIPE SPIGOT AND SOCKET JOINT FAIEZA BINTI HJ. ABDUL AZIZ FK EXPERIMENTAL LEAKAGE ANALYSIS FOR PUSH FIT ELASTOMERIC STEEL PIPE SPIGOT AND SOCKET JOINT By FAIEZA BINTI HJ. ABDULAZIZ Thesis Submitted in Fulfilment of the Requirement for the Degree of Master of Science in the Faculty of Engineering Universiti Putra Malaysia January 2002 Abstract of thesis presented to the Senate ofuniversiti Putra Malaysia in fulfilment of the requirement for the degree of Master of Science. EXPERIMENTAL LEAKAGE ANALYSIS FOR PUSH FIT ELASTOMERIC STEEL PIPE SPIGOT AND SOCKET JOINT By FAIEZA BINTI HJ. ABDUL AZIZ January 2002 Chairman Faculty Barkawi Bin Sahari, Ph.D. Engineering Pipes have been used for many centuries for transporting fluids. Steel is one of the most versatile materials for pipe walls, as it is ductile yet has a high tensile strength. Steel pipes are made in lengths of up to 10m and jointed on site. Several pipes need to be joined to form a piping system. The type of joint to use on a pipeline will depend on the type of pipe materials, strength and flexibility requirement, cost, water tightness and the facilities available on site. Currently used joints for large diameter steel pipes are welded sleeve (i.e. spigot and socket), mechanical, flanged and butt welded joints 11 This research is carried out to investigate the capability of the elastomeric ring as a seal for large diameter steel pipe joint. A pair of spigot and socket pipe with a mean outer diameter of 668 mm is being used in this project. A socket pipe which has groove for elastomer location has an inner diameter of mm while spigot pipe which has tapered part having outer diameter of 654 mm at its end. An elastomeric lip seal of dual hardness which is having 702 mm outer diameter is also being used in this work. The technique of push-fit method has yet to be introduced as an alternative joining method for larger steel pipes to quicken and ease the process. An experimental test rig is designed and fabricated to test the performance of the joint as in working environment. Two type of tests are conducted - pressure test and leakage test. The findings indicated that the water pressure inside the pipe is MN/m2, lower than the contact pressure exist at the top and bottom surfaces of elastomer that are MN/m 2 and MN/m 2 respectively. The results of pressure test shows that no leaking occurs along the test including the extension of 10 minutes after full pressure test has been attained. The leakage test is also success as no water is added/pumped to maintain the pressure of 4.17 bar for a period of 24 hours. III Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk Ijazah Master Sains ANALISIS KEBOCORAN SECARA UJIKAJI SAMBUNGAN BERELASTOMER PAIP SPIGOT DAN SOKET JENIS KELULI Oleh FAIEZA BINTI BJ. ABDUL AZIZ January 2002 Pengerusi Fakulti Barkawi Bin Sahari, Ph.D. Kejuruteraan Paip telah digunakan berabad lamanya sebagai saluran air. Keluli pula merupakan salah satu bahan serba boleh yang biasa digunakan di dalam industri pembuatan paip kerana kemulurannya dan kekuatan tegangan yang tinggi. Paip keluli kebiasaannya boleh dibuat sepanjang 10m dan penyambungan dilakukan di tapak projek. Beberapa batang paip periu disambungkan untuk membentuk satu sistem perpaipan. Jenis sambungan yang digunakan untuk sistem perpaipan bergantung kepada jenis bahan, keperluan kekuatan dan tahap kelenturan, kos, kekedapan air dan kemudahan yang terdapat di tapak projek. Kebanyakan sistem penyambungan untuk paip keluli berdiameter besar yang diaplikasikan pada masa kini adalah seperti spigot dan soket (secara kimpalan sarung), mekanikal, bebibir dan kimpal temu. tv Penyelidikan yang dibuat ini mengkaji kebolehan elastomer sebagai bahan penyambungan bagi paip keluli berdiameter besar. Sepasang paip iaitu soket dan spigot yang mempunyai purata diameter luar 668 mm digunakan untuk projek ini. Paip soket yang mempunyai lurah untuk meletakkan elastomer mempunyai diameter dalam iaitu mm manakala paip spigot yang mempunyai pengecilan saiz dihujungnya mempunyru diameter luar sebanyak 654 mm. Elastomer yang berbentuk bibir berdiameter luar 702 mm dan mempunyai dua kekerasan yang berbeza juga digunakan untuk projek ini. Teknik penyambungan berelastomer ini perlu diperkenalkan sebagai altematif kepada kaedah sedia ada untuk paip keluli berdiameter besar bagi memudahkan dan mempercepatkan proses penyambungan. Oleh yang demikian sebuah radas ujikaji direkabentuk dan dihasilkan untuk menguji kemampuan sambungan ini seperti di persekitaran Kerja. Dua jenis ujian perlu dijalankan - ujian tekanan dan ujian kebocoran. Keputusan yang diperolehi menunjukkan tekanan air di dalam paip iaitu MN/m2, lebih rendah berbanding dengan permukaan tekanan yang wujud di bahagian atas dan bawah elastomer iaitu MN/m 2 dan MN/m 2 masing-masing. Keputusan ujian tekanan menunjukkan tiada kebocoran berlaku sepanjang ujian dijalankan termasuk waktu tambahan 10 minit selepas mencapai ujian tekanan maksima. Ujian kebocoran juga berjaya memandangkan tiada air yang ditambahldipam untuk mengekalkan tekanan pada 4.17 bar untuk selama 24 jam. v ACKNOWLEDGEMENTS In the name of Allah, the Most Gracious, the Most Merciful, I would like to express my appreciation to my supervisor, Associate Professor Ir. Dr. Barkawi Bin Sahari for his invaluable guidance, advice, comments and suggestion throughout the period of my study. Thanks are also due to the members of supervisory committee, Associate Professor Dr Y ousiff A. Khaliq and Associate Professor Dr. Azni Bin Idris for their guidance and comments. I would also like to make a special mention of help from all the technical staff from Mechanical Engineering Department, UPM, especially Mr. Shaarani, Mr. Shaifuddin, Mr. Azmi, Mr. Zulkifli and Mrs. Mahayon for their assistance during the lab work. My appreciation goes to Mr. Fahmi Affandy from Universiti Malaya, Mrs. lahariah Wahid from Universiti Kebangsaan Malaysia, Mr. Chin from Dewetron Malaysia Sdn. Bhd., Mr. Alfred Yong and Mr. Kelvin Kek from Kistler Singapore for discussion and comments of DasyLab application. Special recognition is also extended to Mrs. Nooml and Mrs. Sharifah from the library of labatan Bekalan Air, labatan Kerja Raya for their information and assistance. Last but not least, I would like to express my utmost appreciation to my husband Fadzri Md. laafar and son Emiml Adzfar for their loving support, cooperation and understanding, and my parents for their encouragements, cares and supports. Vi I certify that an Examination Committee met on 2nd January 2002 to conduct the final examination of Faieza Binti Haji Abdul Aziz on her Master of Science thesis entitled Experimental Leakage Analysis for Push Fit Elastomeric Steel Pipe Spigot and Socket Joint in accordance Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulations The committee recommends that candidate be awarded the relevant degree. Members of the Examination Committee are as follows: SHAMSUDDIN SULAIMAN, Ph.D. Associate Professor Faculty of Engineering, University Putra Malaysia (Chairman) BARKA WI BIN SAHARI, Ph.D. Associate Professor Faculty of Engineering, University Putra Malaysia (Member) YOUSIF A. KHALID, Ph.D. Associate Professor Faculty of Engineering, University Putra Malaysia (Member) AZNI BIN IDRIS, Ph.D. Associate Professor Faculty of Engineering, University Putra Malaysia (Member) AINI IDERIS, Ph.D. Professor Dean of Graduate School Universiti Putra Malaysia Date: 2 2 FEB 2002 VII This thesis submitted to the Senate of Universiti Putra Malaysia has been accepted as fulfilment of the requirements for the degree of Master of Science. AINI IDERIS, Ph. D. Professor Dean of Graduate School Universiti Putra Malaysia Date: LJl APR 2u . Vlll DECLARATION I hereby declare that the thesis is based on my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UPM or other institutions. FAIEZA BINTI HJ. ABDUL AZIZ Date :).'2. fes~u R~?oo~ lx TABLE OF CONTENTS Page ABSTRACT 11 ABSTRAK tv ACKNOWLEDGEMENTS V1 APPROVAL SHEETS DECLARATION FORM IX TABLE OF CONTENTS X LIST OF ABBREVIATIONS GLOSSARY OF TERMS CHAPTER 1 IN1RODUCTION Problem Statement Objectives Thesis Outline 4 2 LITERATURE REVIEW 2.1 Pipes Pipe Materials Pipe Joints Joints Performance Pipe Stress Analysis Elastomer Behaviour of Elastomer Styrene-Butadiene Rubber (SBR) Sealing Rings Pressure and Leakage Analysis The Effect of Pressure Leakage Criteria Discussions and Conclusions 52 3 METHODOLOGY 3.1 Spigot and Socket Pipe Elastomeric Ring Test Procedures Pipes Assembly Pressure Test Leakage Test Discussions 74 V11 XlI Xlll 4 RIG DESIGN AND EQUlPMENTS 4.1 Test Rig Design and Fabrication Parts Design Supporting Rods Base Frame 87 x 4.2.3 End Closing Plate Weld Design of End Closing Plate Elastomer Stopper 4.3 Rig Fabrication 4.4 Experimental Equipmant Layout 4.5 Force Transducer Principle of Operation Force Transducer Preloading 4.6 Unigraphic Software 4.7 DASYLAB Software 4.8 Discussions 5 RESULTS AND DISCUSSION 5.1 Theoretical Work Contact Force Installation Pushing Force Pushing Force 5.2 Test Speciment Measurement 5.3 Experimental Results Pipe Assembly Filling the Pipe Pressure Test Leakage Test 5.4 Discussion CONCLUSIONS AND RECOMMENDATION 132 REFERENCES APPENDICES VITA Xl UST OF ABBREVIATIONS A b d dsp else Fx L p P w P esp P esc Ri Ro Smax t T J.l area contact width diameter external diameter of pipe at spigot ends internal diameter of pipe at socket ends pushing force length average contact pressure pressure due to water in pipe elastomer contact pressure at spigot elastomer contact pressure at socket inner radius of pipe outer radius of pipe maximum permissible working stress thickness time coefficient of friction (j stress 1: shear stress Xll GLOSSARY OF TERMS AC BS CAD CI CMM DASYLab DI GRP HOPE IRHD MDPE MS SBR UPVC Asbestos Cement British Standard Computer Aided Design Cast Iron Coordinate Measuring Machine Data Acquisition System Labaratory Ductile Iron Glassfibre Reinforced Plastics High Density Polyethylene International Rubber Hardness Degrees Medium Density Polyethylene Malaysian Standard Styrene Butadine Rubber unplasticised polyvinyl chloride Xlll CHAPTERl INTRODUCTION A pipe can be defined as a tube made from either homogeneous or composite materials. Pipes are used to transport liquids, gases, slurries and/or fine particles. Pipes joined to form networks have been in use since prehistoric times, originally for water distribution purposes. Pipes are usually available with different lengths, diameters, wall thickness and materials. A piping system is generally considered to include the complete interconnection of pipes, including in-line components such as pipe fittings and flanges. Pumps, heat exchangers, valves and tanks are also considered part of the piping system. The contributions of piping system are essential in an industrialized society - they provide efficient transport of clean drinking water to cities, irrigation water to farms and cooling water to building and machinery. In terms of construction, several pipes need to be joined. There are several types of pipe materials available such as Cast Iron, Ductile Iron, Asbestos Cement, Steel, High Density Polyethelene, Unplasticized Polyvinyl Chloride, Glassfibre Reinforced Plastic etc. The major factors to be considered when selecting the type of pipe are: - (a) working and test pressure, including surge pressure (b) strength of pipe to withstand designed internal and external load 1 (c) durability of the pipe (d) suitability and workability for laying and operating requirements ( e) capital, operation and maintenance costs (f) extent of possible leakage A particular type of the pipe can be joined with one or more types of joints to suit the circumstances in which the pipeline is laid and has to operate. Some types of joints commonly used are flanged, welded (fillet and butt), gibault, flexible mechanical coupling, sleeve coupling, push-on spigot and socket, single gland - mechanical and stepped coupling. In the Malaysian water industry, butt welded joint, fillet welded, bolted flanged joint, flange adaptor joint and mechanical coupling joint are currently used for joining large diameter steel pipe. 1.1 Problem Statement This project is carried out to study the push-fit techniques as a means of joining steel pipes. The use of push-fit method, which is fast and could be economical, has yet to be introduced as an alternative joining method for larger steel pipes. A pair of spigot and socket steel pipes with a diameter of 668 mm is being used for this experiment investigation. Currently this joining method is very common and widely used but only for small diameter pipes (maximum of 160 mm diameter only) and the materials are ductile iron, PVC and vitrified clay pipes. They also have been used for hydraulic and pneumatic purposes and only limited to where the working environment is not very severe. 2 Boon & Cheah Steel Pipes Sdn. Bhd supplies the specimen pipe and elastomeric seal used in this project. A test rig is to be designed and fabricated in the Mechanical Engineering, Universiti Putra Malaysia laboratory for the purpose of testing the performance of the joint as in working environment. There are two types of test to be conducted. They include the pressure test and the leakage test. The pressure test is to be carried out by increasing the water pressure in the incremental of one bar and one minute pause until the pressure achieve 6.25 bars. The test shall be considered pass if no reduction occurs during the specify one minute pause between each increment and including the extension of 10 minutes after full pressure test has been attained. The leakage test will then be followed by reducing the pressure from 6.25 bars to 4.17 bars and it has been noticed that the pressure of bars is maintained for 24 hours, thus satisfy the criteria. 1.2 Objectives The objectives of the project are as follows: - 1. To determine the sealing mechanisms of integral spigot and socket joints when subjected to internal pressure. 2. To determine the force to assemble the pipes. 3. To determine the capability of the pipe on the pressure capacity. 3 1.3 Thesis Outline This thesis has been organized to seven chapters. It starts with the introduction and followed by second chapter, which review the literature related to this project. Among the subjects discussed in chapter two are pipes, pipe joints, sealing properties and the software used in this study. Chapter 3 consists of materials and methods used in the experiment as well as the tests to be conducted to determine the capability of the joint. Chapter 4 concentrates on the design and fabricating the test rig. Chapter 5 presents the output and discussion on the tests conducted. The conclusion in Chapter 6 compare the results obtained by finite element analysis with the results in this investigation. Finally Chapter 7 recommends a few items to be done in getting better results in the experiment. 4 CHAPTER 2 LITERATURE REVIEW In this chapter, literature related to pipe, its materials and joints, rubber, elastomer and sealing properties will be reviewed. At the beginning of the chapter, the review will be focused on pipes, pipe materials and joints currently in use. It will be then followed by the study of elastomer, the behaviour and its sealing component. An example of the existing elastomeric ring types and its failure causes were also covered. The effect of pressure on elastomer and leaking criteria would also be discussed. 2.1 Pipes This section provides information on various types of pipe materials, their range of pipe sizes and the joints usually associated with these pipes. It also discusses the general specifications and performance of these pipes materials [1] Pipe Materials The selection of pipe materials for water distribution is discussed. It is very important to identify the most cost effective material option to suits the application. The following section also provides information and guidance which can be used to formulate an optimum pipe materials selection rules. 5 Asbestos Cement (AC) Pipes AC pipes are commonly available in sizes of 80- to 600 mm nominal diameter and are manufactured in standard lengths of 4 metres. AC pipes commonly used are of Class 20 and Class 25 and can be used for maximum working pressure of 10 and 12.5 bar respectively (see Table 2.1). The principles advantages of AC pipe are its strength, rigidity and relatively good corrosion resistance [2] Ductile Iron (DI) Pipes DI pipes are available in a wide range of sizes, from 80 to 1600 mm diameter, and are available in length of 4 to 6 metres [1]. DI pipe is made from a ductile material more like steel than iron but with good resistance to external corrosion. The thickness and diameter of Class K9 [2] ductile iron pipes are as given in Table 2.2. The mechanical strength and toughness of ductile iron pipe make it suitable for high stress application (e.g. very high pressure mains, pumping mains, under heavily trafficked roads, where there may be a high risk of interference and in areas subject to ground movement and subsidence), where other materials may be less satisfactory [2]. 6 Unplasticised Polyvinyl Chloride (upvc) Pipes Unplasticised Polyvinyl Chloride (upvc) pipes are semi rigid pipes. The standard length for upvc is 6 metres [3]. Nominal diameter can range from 80 rom to 575 mm (Table 2.3). The main advantages of upvc pipes are their relatively light weight, ease of handling and laying, simple jointing technique and corrosion resistance [2] Glass Fibre Reinforced Plastic (GRP) Pipes GRP Pipe is available in diameters ranging from 300 mm to 2500 mm, smaller sizes down to 200 mm nominal diameter can also be obtained. In addition, GRP pressure pipe provides for sizes up to 4000 mm nominal diameter (and down to 25 mm). All sizes manufactured, are supplied in standard for 6m lengths, although for convenience 2500 mm diameter pipes are usually produced in 3 m length for ease of site handling. In Malaysia GRP pipes are relatively new and have not been widely used. The GRP pipe manufacturer shall design the pipe wall thickness based on various parameters in accordance with the British Standard, BS 5480 [3]. The principles advantages of GRP pipes are their corrosion resistance, and their relatively light weight. GRP pipes normally require no internal and external protection for water supply application. 7 Prestressed Concrete Pipes Prestressed concrete pipes normally consists of an inner core pipe which is precompressed by means of a high tensile wire wound spirally around the core under a controlled tension. Two basic types of prestressed concrete pipes are cylinder (or steel cylinder ) and non-cylinder pipes. Prestressed concrete pipe is used at high pressure. Conceptually, it is similar to a ductile iron system, which is its natural competitor [4]. Prestressed concrete cylinder pipes are presently manufactured in sizes ranging from 600 mm to 1400 mm nominal internal diameter in 100 mm increments. These are normally supplied in lengths of 4 and 5 metres. The advantageous of prestressed concrete pipes are their generally acceptable resistance to corrosion, high beam strength and, as rigid pipes, the lack of high compaction requirements during installation. One of the most disadvantageous is their weight, the lightest (600 mm nominal diameter) being 1.6 tonne. Heavy transportation and lifting equipment are required Polyethylene (PE) Pipes -MDPE / HDPE All polyethylene (PE) pipes made from polymer having a density greater than 0.93 glml. The following density classification is applicable. MDPE (Medi
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