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efforts tailored to suit engineering based on addressing specific threats to pipeline integrity. Despite all these developments, there is a duty of operators to conduct periodic inspections and perform maintenance as appropriate. A long-term performance is directly related to how well the composite materials are protected and maintained. Failure to properly maintain these repair systems will result in sub-standard performance. Thus, Structural Health Monitoring (SHM) is one of the answers to the current reliability issue of composite-repaired ageing pipelines. 2.5 Corrective and Preventive Actions Protecting pipelines from rapid crack propagation is a critical issue to avoid casualties and disaster. The mechanism of avoiding crack propagation in high pressure steel gas pipelines, so as to set up a second defence line against the rupture has to be sought. Hence, there have been many studies on this matter and one good example is a study carried out by You et al. (2003). They used a unique modified finite element (FE) code, PFRAC that was initially used to simulate the behaviour of steel rings as crack arrestors by O'Donoghue and Zhuang (1999), and with this proper FE simulation, together with experiment data (Drop Weight Tear Test), they managed to estimate the deceleration of fracture propagation in high strength and high toughness steel gas pipelines. Another study carried out by Ostsemin and Saidov (2004) shows that the evaluation of the crack resistance and mechanical properties of the pipe metal under static and dynamic loading enables to model the pipeline more closely. In addition, a research project funded by the Australian Pipeline Industry Association confirms that after a pressure cycling equivalent of approximately 8,000 years of daily and maintenance-related pressure cycling, SCC cracks can safely survive in service for many pipe lifetimes, provided the corrosion environment is removed by recoating as shown in Figure 2.11 (Linton, 2008). However, the Office of Pipeline Safety (OPS), USA still considers SCC to be a safety risk to the pipeline and includes 28
the SCC assessment in their integrity management plans. Hence, In-line Inspection technology and a hydrostatic programme are the two main and most suitable approaches to identify SCC as reported by Wang et al. (2001). Figure 2.11: Photos of (left) test set-up reinforcement sleeves applied over stress corrosion cracking, and (right) Opened stress corrosion crack (black region) which had extended with fatigue (Linton, 2008) In the process of effectively assessing crack behaviour, BMT Fleet Technology (2005) developed engineering assessment expertise, tools and techniques mainly to provide support for equipment design and to evaluate the long-term structural integrity of welded and non-welded structures and facilities. The pipeline integrity assessment software ―FlawCheck‖ offers a comprehensive assessment tool for crack-like flaws in metallic structures that incorporates stress intensity factor and net section stress solutions for various structures and flaw geometries. Dinovitzer et al. (2002) report that ASME B31.4 and B31.8 allow dents in pipelines up to 6% of their diameter. But leaks have been known to occur from dents with a depth even less than 3% of pipe diameter. They believe the depth of a dent is not the only factor affecting the operating life of the dented pipe segment. Thus, the issue of dent characterisation using a dent assessment model based on the FE method has been developed. Another practical assessment, as 29
Page 1: 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: increase in the yield limit of stee
Page 51 and 52: Manufacturers such as Walkers Techn
Page 53 and 54: Company L.P, 2005); Aquawrap ® pro
Page 55 and 56: monitoring, inspection, and damage
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
Page 105 and 106:
Figures 3.16 and 3.17 show that the
Page 107 and 108:
Figure 3.20 shows that as the relat
Page 109 and 110:
3.7.4 Concluding Remarks A biaxial
Page 111 and 112:
yarns change and lateral contact be
Page 113 and 114:
For predicting E2 and Gl2, a number
Page 115 and 116:
Where: Ar = weight of one sheet of
Page 117 and 118:
Where; The Stiffness matrix is trad
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simulations for the hoop strain at
Page 121 and 122:
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
Page 129 and 130:
Table 3.11: Predicted Elastic Const
Page 131 and 132:
Table 3.13: Axial Stress v/s L/W ra
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Hoop Stress (MPa) Figure 3.3: Hoop
Page 135 and 136:
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
Page 141 and 142:
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
Page 153 and 154:
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
Page 161 and 162:
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
Page 169 and 170:
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
Page 189 and 190:
consideration for the selection of
Page 191 and 192:
5.4 Methodology of Thermal Expansio
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Figure 5.1: Some preventive measure
Page 195 and 196:
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
Page 205 and 206:
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
Page 217 and 218:
6.3 Primary PhD Achievements The ea
Page 219 and 220:
In Chapter 5, the CTE was determine
Page 221 and 222:
ASM International (2002), "Thermal
Page 223 and 224:
Bucinell, R. B. (2001), Calculating
Page 225 and 226:
Proceedings of OMAE'01 20th Interna
Page 227 and 228:
Greenwood, R. (2002), UKOPA Pipelin
Page 229 and 230:
Kotrechko, S. A., Krasovskii, A. Y.
Page 231 and 232:
Mousavi, S. E., Xiao, H. and Sukuma
Page 233 and 234:
Raju, I. S. and Newman, J. C. (1986
Page 235 and 236:
Tennyson, R. C. and Mufti, A. A. (2
Page 237 and 238:
Xue, L., Widera, G. E. O. and Sang,
Page 239 and 240:
General Technical Specifications: T
Page 241 and 242:
Photos of the Design and Build of t
Page 243 and 244:
Composite Installation Process usin
Page 245 and 246:
APPENDIX 3 - STRAIN GAUGE INSTALLAT
Page 247 and 248:
Figure 7: Mylar tape was stuck onto
Page 249 and 250:
Figure 19: Repeating the above proc
Page 251:
2) Electrical Insulation Test Resul
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