1、 GUIDE FOR SURVEYS USING RISK-BASED INSPECTION FOR THE OFFSHORE INDUSTRY DECEMBER 2003 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 Copyright 2003 American Bureau of Shipping ABS Plaza 16855 Northchase Drive Houston, TX 77060 USA This Page Intentionall
2、y Left Blank ABSGUIDE FOR SURVEYS USING RISK-BASED INSPECTION FOR THE OFFSHORE INDUSTRY .2003 3 Foreword This Guide contains the technical requirements and criteria employed by ABS to consider alternate Survey arrangements using Risk-Based Inspection (RBI) approaches for offshore installations. It i
3、s applicable to static pressure retaining equipment, and structures for offshore floating and fixed-base platforms. ABS supports the implementation and use of RBI technologies as a means for optimizing inspection resources, while maintaining or perhaps lowering levels of risk. ABS recognizes the ben
4、efits that RBI can bring to an asset and makes provision within its rules for classification of assets, accordingly, thus allowing RBI to be utilized as an alternative for the Owner to maintain ABS classification for the asset. This Guide has been written for worldwide application and, as such, inst
5、allation specific data, analyses and plans are generally required to demonstrate the adequacy of the RBI plan. It is not the intention of this Guide to impose requirements or practices in addition to those that have previously proven satisfactory in similar situations. This ABS Guide does not inhibi
6、t the use of any technological approach that can be shown to produce an acceptable service performance during the life of the structure with the risks understood and appropriately controlled. The application of this Guide does not cover any statutory survey requirements that may apply to the install
7、ation being considered (e.g., MODU code, SOLAS, MARPOL, coastal state regulations, etc.). Although ABS is authorized to perform statutory surveys on behalf of some authorities, ABS is not in a position to alter or waive them. The cognizant administration or regulatory body is the final determining b
8、ody for statutory or regulatory requirements under their jurisdiction. The Owner shall ensure that in developing the RBI plan, due consideration is given to Coastal and Flag State requirements. This Page Intentionally Left Blank ABSGUIDE FOR SURVEYS USING RISK-BASED INSPECTION FOR THE OFFSHORE INDUS
9、TRY .2003 v GUIDE FOR SURVEY BASED ON RISK-BASED INSPECTION FOR THE OFFSHORE INDUSTRY CONTENTS SECTION 1 Introduction 1 1 General 1 3 Purpose2 5 Scope.2 7 Definitions 3 SECTION 2 Fundamentals of RBI .5 1 Definition of RBI.5 3 Risk Assessment and Inspection.5 5 The RBI Process7 7 RBI Benefits .7 9 RB
10、I Limitations.8 FIGURE 1 Risk Matrix .6 SECTION 3 RBI Program Development9 1 Main Steps in the Development of an RBI Program9 3 RBI Team Setup 11 5 Component Grouping and Baselining12 5.1 Asset Hierarchy.12 5.3 Breakdown into Inspectable Units.12 5.5 Baselining and Fitness for Service (FFS) Assessme
11、nt .13 7 Risk-Based Prioritization14 7.1 The Risk Assessment Methodology16 7.3 Assessment of Likelihood of Failure18 7.5 Assessment of Consequence of Failure18 7.7 Potential for Escalation .20 9 Inspection Plan Development 20 9.1 Degradation Mechanisms and Inspection Methods.21 9.3 Scope of Inspecti
12、on (Sample Population Size, Location and Extent of Inspection) 24 9.5 Frequency of Inspection26 9.7 Compiling the Inspection Plan.26 vi ABSGUIDE FOR SURVEYS USING RISK-BASED INSPECTION FOR THE OFFSHORE INDUSTRY .2003 11 Inspection Execution27 11.1 Controlling the Inspection Execution .27 13 Analysis
13、 of Inspection Results .28 13.1 Anomalies28 13.3 Trending of Results .29 15 RBI Program Updating.29 15.1 Operational Events30 15.3 Improved Inspection and Integrity Knowledge.30 15.5 Unanticipated failures31 TABLE 1 Basic Elements for an RBI Risk Prioritization15 TABLE 2 Advantages and Disadvantages
14、 of Qualitative and Quantitative Risk Analysis Approaches .18 TABLE 3 Degradation Mechanisms, Causes and Inspection Methods .23 TABLE 4 Inspection Types, Techniques and Factors Affecting Confidence.24 FIGURE 1 Main Steps in the RBI Program Development.10 FIGURE 2 Levels of RBI Analysis .17 SECTION 4
15、 RBI Program Approval and Classification Activities 33 1 General 33 3 Program Requirements33 3.1 Approach.33 3.3 Implementation for Existing Units 33 3.5 Site Specific Information34 3.7 Survey Status 34 3.9 Inspection Scope and Frequency34 3.11 Computerized System .34 3.13 Implementation Survey34 3.
16、15 Cancellation of Program35 3.17 Coastal and Flag States Requirements.35 3.19 Damage, Failures and Repairs35 5 Submission Requirements.35 5.1 Program Description Submittal35 5.3 Program Results Submittal36 7 In Service Maintenance and Updating of RBI Plan .36 7.1 Annual Confirmation Survey of RBI P
17、rogram 36 7.3 Review of Plan Updates 37 9 Special Conditions .37 9.1 ABS Surveyor Attendance.37 9.3 Usage of Eddy Current and ACFM techniques37 ABSGUIDE FOR SURVEYS USING RISK-BASED INSPECTION FOR THE OFFSHORE INDUSTRY .2003 vii APPENDIX 1 References39 1 Risk Assessment Techniques39 2 Risk-Based Ins
18、pection .39 APPENDIX 2 Risk Assessment for Process Systems.41 1 Assessing Process Accident Scenarios.41 3 Consequence Assessment for Process Systems42 5 Likelihood Assessment for Process Systems45 FIGURE 1 Example Event Tree for a Small Gas Release 41 FIGURE 2 Example Event Tree for a Large Gas Rele
19、ase42 FIGURE 3 Results of a Process Leak of Flammable or Toxic Fluid .43 FIGURE 4 Modeling of Explosion Overpressure Area on an FPSO .44 APPENDIX 3 Reliability Analysis Approach for Marine Structures .47 1 General 47 3 Documentation.47 5 Main Components of a Structural Reliability Analysis .47 7 Typ
20、ical Failure Modes48 9 Limit states.48 11 Limit State Functions .49 13 Uncertainties and Probabilistic Models49 15 Degradation Mechanisms 50 17 Reliability analysis50 19 Acceptance Criteria (Target Reliability) .51 21 Influence of Inspection.51 APPENDIX 4 Contribution of Inspection Plan Elements.53
21、TABLE 1 Summary of Contribution of Inspection Plan Elements in an RBI Program .54 This Page Intentionally Left Blank ABSGUIDE FOR SURVEYS USING RISK-BASED INSPECTION FOR THE OFFSHORE INDUSTRY .2003 1 SECTION 1 Introduction 1 General The inspection of process equipment and offshore structural compone
22、nts play a significant role in preventing failures. Inspection and testing programs are established to detect and evaluate deterioration due to in-service operation. The methods, frequency and acceptance criteria used in inspections can affect the likelihood of component failure. The inspection freq
23、uencies for pressure equipment and structures in the marine and offshore industry have traditionally been driven by prescriptive industry practices, usually at time-based or calendar-based intervals. This inspection practice, founded mainly on general industry experience for each type of component,
24、has thus far provided an adequate level of reliability. However such a practice does not explicitly consider the likelihood of failure of a component under its operation and loading conditions, nor the consequences of a failure. Current inspection practices make it difficult to recognize if the same
25、 or improved service reliability can be achieved by varying inspection methods, locations or frequencies. Also, current practices do not easily identify if an inspection activity is excessive and provides no measure of increased assurance for the integrity of the component. Certain sectors of indust
26、ry have recognized that significant benefits may be gained from more informed inspection methods and have begun evolving into inspection program philosophies that combines factors such as satisfactory operating experience, low deterioration rates, minimal consequences of failure and condition-based
27、inspection interval setting. Most operators have reached their current practice by an evolutionary process based upon experience, regulatory and classification society compliance. However, very few operators have developed their existing programs on the basis of a systematic process that seeks to ac
28、hieve a balance between risk and the level of inspection effort. In a facility with substantial production revenues, the cost of downtime can be significant. An effective inspection program is centered on knowing when, where and how to inspect. This enables the operator to not only control the integ
29、rity of the assets, but to control it with a focus on the economic value, while maintaining an acceptable service performance. Further, having a documentation trail for the inspection process allows for a focused and confident inspection plan updating should the operator undergo changes in operation
30、s, equipment, structures, personnel, contractors, company organization, etc. Risk-Based Inspection (RBI), which focuses on the optimization of inspection programs for pressure retaining equipment and structures, is the subject of this Guide. RBI begins with the recognition that the essential goal of
31、 inspection is to prevent incidents that impair the safety and reliability of operating facilities. As a risk-based approach, RBI provides an excellent means to evaluate the consequences and likelihood of component failure from specific degradation mechanisms and develop inspection approaches that w
32、ill effectively reduce the associated risk of failure. RBI is a process that assures inspection resources are focused on the areas of greater concern, and provides a methodology for determining the optimum combination of inspection methods and frequencies. As a result of this there is a continuous i
33、mprovement aspect to the RBI process that allows for recalculation of risk and subsequent refocusing of the inspections activities. Section 1 Introduction 2 ABSGUIDE FOR SURVEYS USING RISK-BASED INSPECTION FOR THE OFFSHORE INDUSTRY .2003 The recent trend towards RBI practices is being driven by fact
34、ors such as: The increasing awareness and use of risk analysis in all aspects of the assets operations The location of facilities in remote locations requiring highly effective inspection programs with limited resources Asset service life longer than designed and increased reuse of equipment in diff
35、erent services Increased emphasis on the justification of inspection frequency and practices required of the asset operators by financial venture partners. The development and implementation of an RBI program requires the participation and coordination of groups within the operating organization, in
36、cluding process and hardware engineering, maintenance and operations personnel. The whole organization should commit and contribute to the RBI program. Inspections in themselves do not affect the actual failure likelihood of the components being inspected. The inspection process provides a means of
37、gaining confidence in the service reliability of the component being inspected. When an inspection reveals an excessive deterioration, actions are initiated, such as the repair or replacement of the affected component or a change to the operating conditions. By identifying potential problems in a ti
38、mely manner, RBI increases the chances that mitigating actions will be taken, thereby reducing the frequency of failures. Risk cannot be reduced to zero. There is always a “residual risk” associated with inspection. This is caused by factors such as operational errors, extreme weather, external even
39、ts, process upsets, limitations of inspection methods and unrevealed deterioration mechanisms. 3 Purpose The purpose of this document is to provide guidance to ABS Clients on the application of RBI programs to maintain class for an offshore installation. This Guide describes the fundamentals of RBI,
40、 the essential steps in the development of an RBI program and the management systems necessary for maintaining documentation, data requirements and analysis updates. It also describes the interaction between executing the RBI programs and how ABS will audit the plan and execute surveys for maintenan
41、ce of class within the context of such a program. Specifically, it identifies the minimum elements that ABS requires to be considered in the development and implementation of an RBI program so that it can be considered in lieu of the conventional maintenance of class surveys. This Guide is intended
42、to clarify the elements involved in the development and implementation of an RBI program, but it does not intend to be a detailed technical reference of RBI methodologies, nor does it intend to single out or endorse any one specific RBI methodology. Appendix 1 lists some of the most commonly used RB
43、I methodologies. 5 Scope This Guide is specifically targeted for structures and production equipment for the offshore oil and gas industry. This Guide specifically covers: i) Static pressure retaining equipment, and ii) Structures for offshore floating and fixed-base platforms Items specifically exc
44、luded from the scope of this Guide are Instrumentation and Control (I mathematically, it is the product of frequency with which an event is anticipated to occur and the consequence of the events outcome. Risk Analysis is the process of understanding (1) what undesirable things can happen, (2) how li
45、kely they are to happen and (3) how severe the effects may be. More precisely, it is an integrated array of analytical techniques, e.g., reliability, availability and maintainability engineering, statistics, decision theory, systems engineering and human behavior that can successfully integrate dive
46、rse aspects of design and operation in order to assess risk. Risk-Based Inspection is a risk assessment and management process that is focused on failure modes initiated by material deterioration, and controlled primarily through equipment and structure inspection. Section 1 Introduction 4 ABSGUIDE
47、FOR SURVEYS USING RISK-BASED INSPECTION FOR THE OFFSHORE INDUSTRY .2003 Risk Controls are the measures taken to prevent hazards from causing consequences. Controls can be physical (safety shutdowns, redundant controls, conservative designs, etc.), procedural (written operating, maintenance, or inspe
48、ction procedures) or can address human factors (employee selection, training, supervision). Risk Evaluation is the process used to compare the estimated risk against given risk evaluation criteria to determine the significance of the risk. Risk evaluation may be used to assist in acceptance decision
49、s. Risk Management is a set of coordinated activities directed to control risks within an organization. These activities usually include risk analysis, risk assessment, risk control, risk acceptance and risk communication. Scenario is a series of events that result in the occurrence of a potential consequence(s). ABSGUIDE FOR SURVEYS USING RISK-BASED INSPECTION FOR THE OFFSHORE INDUSTRY .2003 5 SECTION 2 Fundamentals of RBI 1 Definition of RBI RBI is a risk assessment and management process that is focused on failure modes initiated by material deterioration, and controlled primari
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