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Article 4.1: Non-metallic composite repair systems for pipelines and pipeworks for High Risk Applications, which provides details on how composite materials are to be used to repair pipes (Ochoa and Alexander, 2007). According to Malcolm (2009), all aspects of composite repairs that include the prequalification of materials and repair system, the design of the repair, training and validation of applicators, are now governed not only by the above PCC-2 standard but also ISO/TS 24817 (composite repairs for pipework; qualification and design, installation, testing and inspection). He reports a repair is only compliant if the materials used have been tested in accordance with the above standards. In order to ensure that the manufacturer or supplier complies with the above standards, ACORES (Association of Composite Repair Suppliers) which is a trade association has been established. All the accredited members of ACORES are independently audited at regular intervals and the audit process covers issues with regard to qualification, design, installer training and installation process (Frost, 2008). 2.6 Structural Health Monitoring (SHM) 2.6.1 Definitions In ensuring the reliability of the composite repair in solving pipeline damage, the above maintenance strategy and adherence to the related standards are still inadequate to have a completely successful lifetime extension programme without a contribution from the Structural Health Monitoring (SHM) system. Before discussing the techniques and contributions of SHM in the pipeline repair, it is useful to really understand what SHM is all about in terms of its definition. In this literature review, there have been several authors who define and explain SHM. Rao et al. (2006) for example, define SHM as the process of establishing some knowledge of the current physical condition of a structure. The essence of SHM technology is to develop autonomous built-in systems for the continuous real-time 34
monitoring, inspection, and damage detection of structures with minimum labour involvement with a high level of confidence and reliability. According to Chung (2001), SHM refers to the monitoring of the integrity of a structure for the purpose of hazard mitigation, whether the hazard is due to live load, earthquake, ocean, waves, fatigue, heat, ageing and other factors. This process involves the observation of a system over time using periodically sampled dynamic response measurements from an array of sensors, the extraction of damage-sensitive features from these measurements, and the statistical analysis of these features to determine the current state of the system‘s health (Fixter and Williamson, 2006). In addition, Sohn (2007) emphasises that SHM has the ability to perform its intended function in the light of the inevitable ageing and degradation resulting from operational environments and Inaudi and Glisic (2006) describe it as one of the most powerful management tools that has become important in the civil engineering community. A typical health monitoring system is composed of a network of sensors that measure the parameters relevant to the state of the structure and its environment. Herszberg et al. (2007) define SHM as the system that has the potential to continually monitor the health of a structure through strategically located sensors coupled with monitoring technology enabling remote interrogation of the sensors. This is endorsed by Wang et al. (2001a) but they remind us that a major challenge for the development of robust SHM system is all about the accurate interpretation of sensor measurement in terms of physical changes in structure. The summary of the concept of SHM is clearly presented by Herszberg et al. (2007) and is shown in Figure 2.14. 35
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CRANFIELD UNIVERSITY MAHADI ABD MUR
Page 4 and 5: ABSTRACT One of the most common pro
Page 7 and 8: TABLE OF CONTENTS ABSTRACT ........
Page 9 and 10: 3.7.1 Introduction ................
Page 11: 5.6 Summary and Conclusions .......
Page 14 and 15: Figure 3.1: Schematic diagram of th
Page 16 and 17: Figure 5.4: The average temperature
Page 18 and 19: NOMENCLATURES ACFM Alternating Curr
Page 21 and 22: 1 INTRODUCTION One of the most comm
Page 23 and 24: 1.1 Objectives Knowing this backgro
Page 25 and 26: The methodology of this integrated
Page 27 and 28: Chapter 6 contains the summary and
Page 29 and 30: period of the major part of the exi
Page 31 and 32: Figure 2.2: Reported interest in de
Page 33 and 34: Figure 2.4: Dent damage caused by v
Page 35 and 36: presented current practices, recent
Page 37 and 38: Energy Workforce Sdn Bhd (2011) cla
Page 39 and 40: available provides real time detect
Page 41 and 42: 2.3.3 Reliability Analysis of Infor
Page 43 and 44: Figure 2.9: Pipeline failure probab
Page 45 and 46: 2.3.3.1 NDT Reliability and POD cur
Page 47 and 48: increase in the yield limit of stee
Page 49 and 50: the SCC assessment in their integri
Page 51 and 52: Manufacturers such as Walkers Techn
Page 53: Company L.P, 2005); Aquawrap ® pro
Page 57 and 58: 2.6.2 Aims of Structural Health Mon
Page 59 and 60: Figure 2.16: Application fields and
Page 61 and 62: egistered by the piezoelectric sens
Page 63 and 64: discretization error. Round-off err
Page 65 and 66: notches and Neuber‘s is better fo
Page 67 and 68: maximum local stress at discontinui
Page 69 and 70: De Carvalho (2005) concludes that t
Page 71 and 72: accurate simulation of loading espe
Page 73 and 74: Based on the above facts, the opera
Page 75 and 76: 3 FINITE ELEMENT ANALYSIS (FEA) IN
Page 77 and 78: Figure 3.2: Schematic diagram of th
Page 79 and 80: In this modelling work (i.e. compos
Page 81 and 82: This partition toolset also helps u
Page 83 and 84: Figure 3.6: Mesh control using Swee
Page 85 and 86: Figure 3.7: Schematic representatio
Page 87 and 88: discretization. Therefore, in this
Page 89 and 90: According to Staten et al. (2010b),
Page 91 and 92: 3.5 The influence of pressure on th
Page 93 and 94: each pressure value remains constan
Page 95 and 96: Axial Stress, σa (S22) was referre
Page 97 and 98: Figure 3.14 shows a graph of analyt
Page 99 and 100: the notch defect is found to be in
Page 101 and 102: One of the contributions of this st
Page 103 and 104: Table 3.4: Convergence tests on var
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Figures 3.16 and 3.17 show that the
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Figure 3.20 shows that as the relat
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3.7.4 Concluding Remarks A biaxial
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yarns change and lateral contact be
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For predicting E2 and Gl2, a number
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Where: Ar = weight of one sheet of
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Where; The Stiffness matrix is trad
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simulations for the hoop strain at
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Figure 3.24: Finding the hoop stres
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Table 3.8: The effect of repair len
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four up to 18 layers. In this study
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hoop and axial stress concentration
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Table 3.11: Predicted Elastic Const
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Table 3.13: Axial Stress v/s L/W ra
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Hoop Stress (MPa) Figure 3.3: Hoop
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However, Frost (2008) and Alexander
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Table 3.17: Ratio of Axial Stress N
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axial load (e.g. buried pipelines t
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3.10 Numerical Strain Analysis of C
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Figure 3.36 shows the contours befo
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Stress Concentration Factor 2 1.8 1
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In fact, for Notch 40 with 18 plies
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this second approach (i.e. the expe
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4.2.2 Strain Gauge Selection and Cr
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Finally, a method used to calculate
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Where, and are the maximum and mini
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should be between 20 and 28 bar and
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welded weld neck flange at both end
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Figure 4.7: Sensor and heating elem
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Figure 4.9: A summary of data acqui
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One of the objectives of doing this
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Figure 4.14: A schematic diagram of
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Table 4.1: Strain gauge readings at
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microstrain 3.00E-04 2.50E-04 2.00E
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However, the axial load transfer is
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Mircostrain 500 450 400 350 300 250
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Since the defect is not a flat notc
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Again, the epoxy resin plays a sign
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Table 4.4: Study at the defect area
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Mircostrain 300 250 200 150 100 50
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Mircostrain 600 500 400 300 200 100
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14.25% in hoop strain and 23.5% in
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consideration for the selection of
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5.4 Methodology of Thermal Expansio
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Figure 5.1: Some preventive measure
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5.4.1 The Fundamentals of the Therm
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5.5 Analysis of Results 5.5.1 The t
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Thermal Output (strain ) 0.0002 0.0
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(Strain ,ε) Figure 5.12: Coefficie
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(Strain ,ε) 0.0002 0.00018 0.00016
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Table 5.1: The strain readings afte
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maximum shear strain increase as th
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The above results show that shear s
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shear strains becomes more stable a
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for future safe design and operatio
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has been fully cured. Poor surface
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6.3 Primary PhD Achievements The ea
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In Chapter 5, the CTE was determine
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ASM International (2002), "Thermal
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Bucinell, R. B. (2001), Calculating
Page 225 and 226:
Proceedings of OMAE'01 20th Interna
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Greenwood, R. (2002), UKOPA Pipelin
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Kotrechko, S. A., Krasovskii, A. Y.
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Mousavi, S. E., Xiao, H. and Sukuma
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Raju, I. S. and Newman, J. C. (1986
Page 235 and 236:
Tennyson, R. C. and Mufti, A. A. (2
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Xue, L., Widera, G. E. O. and Sang,
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General Technical Specifications: T
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Photos of the Design and Build of t
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Composite Installation Process usin
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APPENDIX 3 - STRAIN GAUGE INSTALLAT
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Figure 7: Mylar tape was stuck onto
Page 249 and 250:
Figure 19: Repeating the above proc
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2) Electrical Insulation Test Resul
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