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Provide the means to estimate failure rates for risk assessment for pipelines Provide a more realistic and rigorous approach to the design of pipelines Determine the effect of engineering changes (e.g. wall thickness of pipe) In an effort to develop the damage database, as addressed by Greenwood (2002) above, Brennan et al. (2009) recommend reliability-based analysis procedures and uncertainty models should be further developed and refined, adopting a systematic approach. The reliability has to be estimated in a reliability-based decision format. More organisations are strongly encouraged to cooperate in obtaining reliable failure data and a proper format of data recording is also needed. Forsyth (1998) also has a similar opinion to Brennan et al. (2009) in terms of reliability of information. Without the cooperation of many organisations, the best reliability data that require a significant number of flawed or flaw-free components will be always expensive. Because of these limitations, NDE reliability is often estimated by using artificially generated flaws or even computer models. Francis (2011) presents an evaluation of the likelihood of failure occurring rather than the evaluation of consequences. For this purpose, he uses structural reliability analysis (SRA) that comprises six elements: establishment of limit states, identification of failure modes, formation of limit state functions, uncertainties analysis, evaluation of failure probability and assessment of result. He demonstrates how this probabilistic reliability analysis approach can be used specifically for the purpose of inspection and maintenance scheduling. According to Simola et al. (2009), the intention of developing the probabilistic approach is to capture the main random behaviour and uncertainties based as much as possible on data that is obtained from service records and damage statistics. Brennan et al. (2009) also agree with the above researchers that it is preferable to use a probabilistic model for presenting the degradation processes and that such a model should reflect various uncertainties and can be updated based on the latest information on structural conditions which becomes available during inspections. 24
2.3.3.1 NDT Reliability and POD curves Georgiou (2006) defines NDT reliability as the probability of detecting a crack in a given size group under the inspection conditions and procedures specified. In the NDT reliability methods, there are two related probabilistic methods for analysing reliability data and producing POD curves as functions of the flaw size a. According to him, repeat inspections of the same flaw size or the same flaw type will not necessarily result in consistent hit or miss indications. Therefore, there is a spread of detection results for each flaw size and flaw type and this is precisely why detection capability is expressed in statistical terms as POD. The POD curves provide reference to results that have been obtained for particular flaws using specific NDT procedures. There have been many researchers who put great effort into improving this reliability approach that involves POD and POS experimentally and numerically. Smith et al. (2004) present a new model-assisted POD which has more advantages over the empirical POD. With their development, a more accurate method can be provided to set the threshold since it is better able to sample noise and understand false calls and their influence on flaw detectability. They have validated their model by comparing the calculated empirical POD curve with the calculated model based POD using validated signal (i.e. transducer) and noise models (i.e. material and electronic noise), see Figure 2.10. Figure 2.10: POD Modular Methodology (Smith et al., 2004) 25
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: Figure 2.9: Pipeline failure probab
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 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
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Axial Stress, σa (S22) was referre
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Figure 3.14 shows a graph of analyt
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the notch defect is found to be in
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One of the contributions of this st
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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
Page 117 and 118:
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
Page 217 and 218:
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
Page 243 and 244:
Composite Installation Process usin
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APPENDIX 3 - STRAIN GAUGE INSTALLAT
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Figure 7: Mylar tape was stuck onto
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Figure 19: Repeating the above proc
Page 251:
2) Electrical Insulation Test Resul
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