Reliability Based Assessment for Fatigue Integrity Management

2008 ◽  
Author(s):  
M. Manzocchi ◽  
N. Shetty ◽  
A. Stacey
Keyword(s):  
System Reliability ◽  
Structural Reliability ◽  
Offshore Structures ◽  
Structural Failure ◽  
Component Reliability ◽  
Offshore Installations ◽  
Integrity Management ◽  
Inspection Techniques ◽  
Overall Reliability

Reliability analysis can be used to assess the risk of structural failure in ageing offshore installations and to subsequently optimise inspection plans. This paper describes the findings of a joint industry project to develop and implement a methodology for system reliability updating based on the results of in-service inspections. The effects of different combinations of inspection techniques, namely flooded member detection (FMD) and magnetic particle inspection (MPI), and inspection intervals on the component reliability were examined. Additionally, a case study was performed to demonstrate the system reliability of actual structures with inspection histories. A comprehensive methodology for updating the assessment of system reliability of offshore structures based on in-service inspection results was developed. The methodology allows several important features associated with system reliability, i.e. redundancy, stress redistribution and correlation between the random variables, to be accounted for. The structural reliability is given in terms of an overall reliability for combined fatigue and pushover. The study demonstrated that the methodology may be used to target inspections to those areas of the structure with low fatigue life and low redundancy.

Criticality Rating of Ageing Fixed Offshore Structures

2011 ◽  
Author(s):  
S. Gupta ◽  
D. Sanderson ◽  
A. Stacey
Keyword(s):  
Structural Integrity ◽  
Offshore Structures ◽  
Structural Failure ◽  
Offshore Installations ◽  
Integrity Management

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.

A Dynamic Service Pool Size Configuration Mechanism for Service-Oriented Workflow

2011 ◽  
Vol 186 ◽  
pp. 499-504 ◽  
Author(s):  
Pan He ◽  
Jie Xu ◽  
Kai Gui Wu ◽  
Jun Hao Wen
Keyword(s):  
System Reliability ◽  
Environmental Changes ◽  
Point Of View ◽  
Pool Size ◽  
Reliability Model ◽  
Optimal Method ◽  
Service Oriented ◽  
Overall Reliability

Service-oriented workflows are the fundamental structures in service-oriented applications and changes in the workflow could cause dramatic changes in system reliability. In several ways to re-heal workflows in execution, re-sizing service pools in the workflow is practical and easy to implement. In order to quickly adjust to workflow or environmental changes, this paper presents a dynamic service pool size configuration mechanism from the point of view of maintaining workflow reliability. An architecture-based reliability model is used to evaluate the overall reliability of a workflow with service pools and an optimal method is proposed to get the combination of service pool size aiming at minimizing the sum of service pool size subject to the workflow reliability requirement. A case study is used to explain this method and experiment results show how to change service pool size to meet the workflow reliability requirements.

Probability of Uncontrolled External Leakage During the Production Phase of a Subsea Well

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
André L. R. Alves ◽  
T. A. Netto
Keyword(s):  
Failure Modes ◽  
Base Case ◽  
Component Reliability ◽  
Production Phase ◽  
Distribution Parameters ◽  
Common Cause Failures ◽  
Integrity Management ◽  
Closed Position ◽  
The Impact

Abstract This work presents a methodology for evaluating the uncontrolled external leakage probability of a subsea well during the production phase. Based on a barrier diagram, an algorithm for possible leak path identification is proposed, considering different operation modes: gas lift operation, free-flowing, or well closed at the subsea Christmas tree. Considering the equivalency between these paths and the minimum cut sets from a fault tree modeling, the uncontrolled external leakage probability is calculated using the upper bound approximation. The effect of common cause failures is considered for the failure mode fail-to-close-valve. The instantaneous availability function of each component is considered. Non-repairable, repairable, and periodically tested items are used. Probability distribution parameters are estimated in order to make a case study. The failure rate functions determined are used as input for the proposed model, regarding the following failure modes: fail-to-close, external-leakage, and internal-leakage at the closed position. Finally, failure probability results and sensitivity analysis are demonstrated for a base case study. Parameters like time between tests, inspections, and component reliability are varied in order to identify the impact on the uncontrolled external leakage probability. The main objective of the proposed methodology is to support decision-making on the well integrity management system during the production phase of a subsea well. To this end, actual and reliable input data should be considered.

Integrity Management System for Fixed Offshore Structures Inspection Strategy

2004 ◽  
Author(s):  
Mohamed A. El-Reedy
Keyword(s):  
Management System ◽  
Offshore Structures ◽  
Assessment Method ◽  
Offshore Platforms ◽  
Offshore Structure ◽  
Structure Comparison ◽  
Actual Structure ◽  
Existing Structures ◽  
Integrity Management

The GUPCO offshore structure management system was developed as a part of an integrated infrastructure management system. This paper presents a case study of providing an integrity management system for inspection, evaluation and repair of the fixed offshore platforms in Gulf of Suez. The management system procedure is presented focusing on the first step for defining the highly risky weight to the lower risky weight structure based on API criteria for assessment of the existing structures. The risk analysis methodology for developing design and assessment criteria for fixed offshore structure based on consequence of failure is illustrated. In our case study the assessment method is applied for a number of fixed offshore structures. The above methodology is performed after theoretical assessment and then verifying by using ROV subsea inspection for the fixed offshore structure. Comparison between the actual structure performance and the predicting risk assessment for the structure from the model will be studied. The overall management system will be illustrated in scope of predictive maintenance philosophy and reliability for all offshore structures.

Hull Structure Integrity Management in Floating Structures–FSO Puteri Dulang Case

2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Ajith Kumar Thankappan ◽  
M. Fazli B. M. Yusof
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Structural Response ◽  
Offshore Structures ◽  
Design Phase ◽  
Floating Structures ◽  
Offshore Installations ◽  
Hull Structure ◽  
Integrity Management ◽  
New Buildings

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.

Structural Integrity Management Framework for Fixed Jacket Structures

2008 ◽  
Author(s):  
A. Stacey ◽  
M. Birkinshaw ◽  
J. V. Sharp ◽  
P. May
Keyword(s):  
Structural Integrity ◽  
Good Practice ◽  
Offshore Structures ◽  
Management Framework ◽  
Offshore Installations ◽  
Jacket Structures ◽  
Integrity Management ◽  
Offshore Industry

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.

Structural Integrity Monitoring: Review and Appraisal of Current Technologies for Offshore Applications

2008 ◽  
Author(s):  
P. May ◽  
D. Sanderson ◽  
J. V. Sharp ◽  
A. Stacey
Keyword(s):  
Structural Integrity ◽  
Health And Safety ◽  
Offshore Structures ◽  
Monitoring Methods ◽  
Regulatory Requirement ◽  
Integrity Monitoring ◽  
Monitoring Techniques ◽  
Offshore Installations ◽  
Integrity Management ◽  
Further Development

The use of structural integrity monitoring techniques on offshore installations provides the potential to reduce the risk of structural failure. The Health and Safety Executive’s (HSE’s) Offshore Division has funded a review of relevant technologies in structural integrity monitoring with potential application to offshore installations as well as practical offshore experience with structural integrity monitoring. The purpose of the study was to identify current capabilities of structural integrity monitoring techniques for structural integrity management of offshore installations (i.e. offshore jackets and semi-submersible structures used for drilling and or production operations but excluding FPSOs), to identify limitations in current approaches and identify areas for further development, to identify opportunities for technology transfer from other industries and to review and assess key research and development including current initiatives. The key structural integrity monitoring methods relevant to offshore structures were reviewed. It was found that offshore experience of structural integrity monitoring is limited to date and that all current systems are for bespoke applications. Current codes and standards refer in a limited sense to the use of structural integrity monitoring and this may influence the limited take up to date of this technology. However, there is a regulatory requirement for leak detection in ageing semi-subs as a recent introduction to DNV classification rules OSS-101 [1].

A Novel Approach to Improving the Structural Reliability of a Fixed Offshore Platform Subject to Wave-in-Deck Loading Using a Holistic Structural Integrity Management (SIM) TRIAD Approach

2020 ◽  
Author(s):  
Mehrdad Kimiaei ◽  
Jalal Mirzadeh ◽  
Partha Dev ◽  
Mike Efthymiou ◽  
Riaz Khan
Keyword(s):  
Structural Reliability ◽  
Structural Model ◽  
Structural Integrity ◽  
Reliability Assessment ◽  
Offshore Structures ◽  
Offshore Platform ◽  
Offshore Platforms ◽  
Effective Manner ◽  
Integrity Management ◽  
Fixed Offshore Platform

Abstract Fixed offshore platforms subject to wave-in-deck loading have historically encountered challenges in meeting target reliability levels. This has often resulted in costly subsea remediation, impacted platform occupancy levels or premature decommissioning of critical structural assets due to safety concerns. This paper addresses the long-standing industry challenge by presenting a novel structural reliability approach that involves converging the analytical behavior of a structure to its measured dynamic response for assessment. In this approach, called the Structural Integrity Management (SIM) TRIAD method, the platform model is calibrated based on the measured in-field platform natural frequencies using a structural health monitoring (SHM) system, so that the reliability assessment can be performed on a structural model whose stiffness is simulated as close to reality as possible. The methodology demonstrates the potential of unlocking structural capacity of offshore structures by removing conservatism normally associated with traditional reliability assessment methods, thus significantly improving the ability to achieve target structural reliability levels in a cost effective manner. The SIM TRIAD method has been implemented while assessing an existing fixed offshore platform subject to wave-in-deck loads, which is located in East Malaysian waters. It has enabled the facility operator to achieve acceptable target structural reliability and has assisted in developing an optimized risk-based inspection (RBI) plan for ensuring safe operations to end of asset field life. The methodology and findings of the assessment are presented in this paper to illustrate the benefits of the SIM TRIAD method.

Computational Structural Reliability Analysis of a Turbine Blade

1993 ◽  
Author(s):  
H. R. Millwater ◽  
Y.-T. Wu
Keyword(s):  
Reliability Analysis ◽  
Turbine Blade ◽  
System Reliability ◽  
Structural Reliability ◽  
Failure Modes ◽  
Component Reliability ◽  
Importance Sampling Method ◽  
Creep Stress ◽  
Analysis Methodology ◽  
Computational Implementation

A system reliability methodology has recently been developed to determine accurately and efficiently the reliability of structures with multiple failure modes. This paper explores the computational implementation and application of the methodology through the structural system reliability calculation of a turbine blade subject to randomness in material properties. Failure due to creep, stress overload, and vibration is considered. The methodology consists of a probabilistic system reliability analysis methodology integrated with finite element methods. The failure paths and failure modes are organized using a fault tree. An efficient method for assessing the reliability of a single failure mode, i.e., component reliability, is implemented as well as an efficient adaptive importance sampling method to assess the system reliability. A probabilistic structural analysis program, NESSUS, is used for the calculations.

scholarly journals Estimation of Damage Induced by Single-Hole Rock Blasting: A Review on Analytical, Numerical, and Experimental Solutions

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 29
Author(s):  
Mahdi Shadabfar ◽  
Cagri Gokdemir ◽  
Mingliang Zhou ◽  
Hadi Kordestani ◽  
Edmond V. Muho
Keyword(s):  
Structural Reliability ◽  
Numerical Models ◽  
Experimental Models ◽  
Rock Blasting ◽  
Discussion Section ◽  
Reliability Models ◽  
Fine Grain ◽  
Experimental Approaches ◽  
Engineering Projects

This paper presents a review of the existing models for the estimation of explosion-induced crushed and cracked zones. The control of these zones is of utmost importance in the rock explosion design, since it aims at optimizing the fragmentation and, as a result, minimizing the fine grain production and recovery cycle. Moreover, this optimization can reduce the damage beyond the set border and align the excavation plan with the geometric design. The models are categorized into three groups based on the approach, i.e., analytical, numerical, and experimental approaches, and for each group, the relevant studies are classified and presented in a comprehensive manner. More specifically, in the analytical methods, the assumptions and results are described and discussed in order to provide a useful reference to judge the applicability of each model. Considering the numerical models, all commonly-used algorithms along with the simulation details and the influential parameters are reported and discussed. Finally, considering the experimental models, the emphasis is given here on presenting the most practical and widely employed laboratory models. The empirical equations derived from the models and their applications are examined in detail. In the Discussion section, the most common methods are selected and used to estimate the damage size of 13 case study problems. The results are then utilized to compare the accuracy and applicability of each selected method. Furthermore, the probabilistic analysis of the explosion-induced failure is reviewed using several structural reliability models. The selection, classification, and discussion of the models presented in this paper can be used as a reference in real engineering projects.

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