Risk Informed Structural Systems Integrity Management: A Decision Analytical Perspective

Author(s):  
Michael Havbro Faber

The present paper is predominantly a conceptual contribution with an appraisal of major developments in risk informed structural integrity management for offshore installations together with a discussion of their merits and the challenges which still lie ahead. Starting point is taken in a selected overview of research and development contributions which have formed the basis for Risk Based Inspection Planning (RBI) as we know it today. Thereafter an outline of the methodical basis for risk informed structural systems integrity management, i.e. the Bayesian decision analysis is provided in summary. The main focus is here directed on RBI for offshore facilities subject to fatigue damages. New ideas and methodical frameworks in the area of robustness and resilience modeling of structural systems are then introduced, and it is outlined how these may adequately be utilized to enhance Structural Integrity Management (SIM). Finally, the concept of Value of Information analysis (VoI) from the Bayesian pre-posterior decision analysis is proposed, as an overarching methodical platform for the planning and optimization of structural Health Monitoring (SHM) activities in the context of SIM at both operational and strategic levels.

Author(s):  
Wei-Heng Zhang ◽  
Da-Gang Lu ◽  
Jianjun Qin ◽  
Sebastian Thöns ◽  
Michael Havbro Faber

AbstractThe concept of Value of Information (VoI) has attracted significant attentions within the civil engineering community over especially the last decade. Triggered by the increasing focus on structural health monitoring, availability of data and emerging techniques of Big Data analysis and Artificial Intelligence, important insights on how to take benefit from VoI in structural integrity management have been gained. This literature review starts out with a summary of the historical developments and contains (1) a summary of two different VoI analysis origins, (2) a compilation of existing VoI analyses research and (3) current engineering interpretations and applications of VoI in the field of civil and infrastructure engineering. VoI analysis has roots in communication theory and Bayesian decision analysis in conjunction with utility theory. Starting point is thus taken in brief introduction of these theoretical foundations, followed by a discussion on the relevant modelling aspects such as information, probability and utility modelling. A detailed review of relevant existing research is presented, divided into the following main areas: computational methods, optimal sensor placement and engineering risk management. Finally, by way of conclusion and outlook, challenges and some promising directions for VoI analysis in the field of civil and infrastructure engineering are identified.


2010 ◽  
Vol 26 (02) ◽  
pp. 106-110
Author(s):  
Ge Wang ◽  
Michael Lee ◽  
Chris Serratella ◽  
Stanley Botten ◽  
Sam Ternowchek ◽  
...  

Real-time monitoring and detection of structural degradation helps in capturing the structural conditions of ships. The latest nondestructive testing (NDT) and sensor technologies will potentially be integrated into future generations of the structural integrity management program. This paper reports on a joint development project between Alaska Tanker Company, American Bureau of Shipping (ABS), and MISTRAS. The pilot project examined the viability of acoustic emission technology as a screening tool for surveys and inspection planning. Specifically, testing took place on a 32-year-old double-hull Trans Alaska Pipeline System (TAPS) trade tanker. The test demonstrated the possibility of adapting this technology in the identification of critical spots on a tanker in order to target inspections. This targeting will focus surveys and inspections on suspected areas, thus increasing efficiency of detecting structural degradation. The test has the potential to introduce new inspection procedures as the project undertakes the first commercial testing of the latest acoustic emission technology during a tanker's voyage.


Author(s):  
A. Stacey ◽  
J. V. Sharp

This paper presents a primary integrity management (PIM) framework for mobile installations (semi-submersibles and self elevating installations) and permanently moored floating installations (FPSOs, FSUs, etc.). The primary integrity of self-elevating and floating installations depends on both the primary structure and additional systems. The framework is based upon the UK regulatory requirements for offshore installations, including the need for a thorough review of the safety case accounting for any changes in condition and future plans and verification of the primary integrity management (PIM) process. Requirements and guidance are provided for all aspects of the integrity management process covering: • primary integrity hazard identification and risk control; • resources, organisation and management, including competency assurance; • information management and documentation; • primary integrity management policy, objectives and strategy; • inspection, examination and testing; • evaluation of structure and other primary systems; • maintenance, repair and upkeep; • audit, review and continual improvement. The framework also contains guidance based on the application of existing standards and industry published documents. Finally, guidance is given on the implementation of the framework.


Author(s):  
Ingar Scherf ◽  
Trine Hansen ◽  
Gudfinnur Sigurdsson

Offshore Structures operate for decades in extremely hostile environments. It is important during this period that the structural integrity is efficiently managed to ensure continuous and safe operation. Increased use of enhanced oil and gas recovery means it is likely that many existing installations will remain operational for a significant period beyond the original design life. The operator needs to capture, evaluate and, if necessary, mitigate design premise changes which inevitably occur during the life of a structure. Further, advances in knowledge and technology may imply changes in codes and standards as well as in analysis methodologies. Changes in corporate structures, transfer of operator responsibility and retirement of experienced engineers call for reliable means to transfer historical data and experience to new stakeholders. Effective emergency preparedness capabilities, structural integrity assessments and inspection planning presuppose that as-is analysis models and corresponding information are easily accessible. This paper presents an implementation of the in-service integrity management process described in the new revision of NORSOK standard N-005 [1] for a large fleet of jackets at the Norwegian Continental Shelf. The process, comprising management of design premise changes as well as state-of-the-art technical solutions over a range of disciplines, has enabled the operator to prolong the service life with decades at minimum investments. A structure integrity management system (SIMS) has been developed and digitized over years and streamlined to meet the needs and challenges in the operation and management of the jacket platforms. SIMS enables a rather lean organization to control the structural integrity status of all load-bearing structures at any time. Platform reinforcements and modifications along with other operational risk reducing measures like unman the platforms in severe storms enable continued use with the same level of safety as for new manned platforms. Advanced analyses are used to document regulatory compliance. Modern fatigue and reliability based inspection planning analyses have reduced the costs needed for inspection of fatigue cracks significantly. The benefits from the SIMS system are substantial and the resulting safety and productivity gains are apparent. The continuity of knowledge and experience is maintained, reducing risk to safety and regularity. The digital transformation related to management of structural integrity status as described in NORSOK standard N-005 is realized through SIMS.


2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Ajith Kumar Thankappan ◽  
M. Fazli B. M. Yusof

This paper highlights the key differences in practices employed in managing hull structure integrity of permanently moored floating offshore structures as against sailing vessels which are subject to periodic dry docking. During the design phase, the structural integrity management over the life of a sailing vessel is primarily taken into account by means of Class prescribed Nominal Design Corrosion Values which are added to minimum scantling requirements calculated based on strength and fatigue criteria. In contrast, for permanently moored offshore installations like FPSOs, FSOs etc. the hull structure integrity over the entire design life of the asset is a key design consideration both for new buildings and conversions. Analytic methods and tools (primarily those developed by Class Societies) are available to evaluate the strength requirements (based on yielding, buckling and ultimate strength criteria) and fatigue life of the hull structure. Typically three levels of analysis with increasing degree of complexity and analysis time are used to predict the structural response and fatigue life of the Hull during design phase. The degree of detailed analysis required needs to be determined in light of the expected optimization in terms of savings in scantlings for new building or for steel renewal requirements in case of conversions.


2021 ◽  
Vol 2 ◽  
Author(s):  
Domenic Di Francesco ◽  
Marios Chryssanthopoulos ◽  
Michael Havbro Faber ◽  
Ujjwal Bharadwaj

Abstract Attempts to formalize inspection and monitoring strategies in industry have struggled to combine evidence from multiple sources (including subject matter expertise) in a mathematically coherent way. The perceived requirement for large amounts of data are often cited as the reason that quantitative risk-based inspection is incompatible with the sparse and imperfect information that is typically available to structural integrity engineers. Current industrial guidance is also limited in its methods of distinguishing quality of inspections, as this is typically based on simplified (qualitative) heuristics. In this paper, Bayesian multi-level (partial pooling) models are proposed as a flexible and transparent method of combining imperfect and incomplete information, to support decision-making regarding the integrity management of in-service structures. This work builds on the established theoretical framework for computing the expected value of information, by allowing for partial pooling between inspection measurements (or groups of measurements). This method is demonstrated for a simulated example of a structure with active corrosion in multiple locations, which acknowledges that the data will be associated with some precision, bias, and reliability. Quantifying the extent to which an inspection of one location can reduce uncertainty in damage models at remote locations has been shown to influence many aspects of the expected value of an inspection. These results are considered in the context of the current challenges in risk based structural integrity management.


Author(s):  
S. Gupta ◽  
D. Sanderson ◽  
A. Stacey

The effective structural integrity management of the ever-increasing population of ageing offshore installations on the UKCS requires the identification of key parameters which provide a measure of the criticality of installations to structural failure, thus enabling priorities to be set. This paper describes a model for the evaluation of the criticality rating of fixed offshore installations.


Author(s):  
Arifian Agusta ◽  
Sebastian Thöns ◽  
Bernt J. Leira

Asset integrity and management is an important part of the oil and gas industry especially for existing offshore structures. With declining oil price, the production rate is an important factor to be maintained that makes integrity of the structures one of the main concerns. Reliability based and risk-based inspection (RRBI) constitutes an efficient method to optimize inspection planning. Basing the inspection planning on pre-posterior Bayesian decision analysis and especially a Value of Information analysis allows to explicitly quantify the expected benefits, costs and risks associated with each inspection strategy. A simplified and generic risk-based inspection planning utilizing pre-posterior Bayesian decision analysis had been proposed by Faber et al. [1] and Straub [2]. This paper provides considerations on the theoretical background and a Value of Information analysis-based inspection planning. The paper will start out with a review of the state-of-art RBI planning procedure based on Bayesian decision theory and its application in offshore structure integrity management. An example of the Value of Information approach is illustrated and it is pointed to further research challenges.


Author(s):  
J. V. Sharp ◽  
G. Ersdal ◽  
D. Galbraith

An increasing number of offshore installations are in the life extension stage of life, with ageing processes needing to be taken into account. This is particularly important for structural integrity. Capability Maturity Modelling enables the levels of maturity in processes associated with the management of ageing to be identified and improved if required. The paper describes the model and how it has been used for assessing the management of structural integrity for installations on the Norwegian Continental Shelf.


Author(s):  
A. Stacey ◽  
M. Birkinshaw ◽  
J. V. Sharp ◽  
P. May

In recent years, a significant amount of effort has been expended by HSE and the offshore industry on the development of good practice for structural integrity management in the new code for offshore structures, ISO 19902. However, a review of the structural integrity management of fixed offshore installations operated on the UKCS has indicated that duty holders adopt varying approaches, in terms of both the methods used and effectiveness. The elements of a framework for the management of the structural integrity of fixed jacket structures are presented.


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