Industrial Implementation of Risk Based Inspection Planning Lessons Learnt From Experience: Part 1 — The Case of FPSOs

2004 ◽  
Author(s):  
Jean Goyet ◽  
Antoine Rouhan ◽  
Michael Havbro Faber
Keyword(s):  
Offshore Structures ◽  
Lessons Learned ◽  
Risk Assessments ◽  
Structural Components ◽  
Inspection Planning ◽  
Industrial Implementation ◽  
Lessons Learnt ◽  
Specific Risk ◽  
Planning Methods

This paper is the first part of a report dealing with industrial implementation of Risk Based Inspection planning methods to offshore facilities. The first part deals with FPSO/FSO while the second deals with fixed steel offshore structures. The objective of the report is to convey “lessons learned” from experience using RBI methods. Theses methods aim at establishing inspection planning based on optimization procedures derived from specific risk assessments. Experience of the three authors is based on the last methodological developments in the area of RBI planning for structural components subject to fatigue degradation and on application of these methods to various types of offshore facilities. The main steps of the RBI methodology are summarized in the first paper. General conclusions related to the two types of facilities are given at the end of the second paper.

Industrial Implementation of Risk Based Inspection Planning Lessons Learned From Experience: Part 2 — The Case of Steel Offshore Structures

2004 ◽  
Author(s):  
Antoine Rouhan ◽  
Jean Goyet ◽  
Michael Havbro Faber
Keyword(s):  
Industrial Application ◽  
Offshore Structures ◽  
Lessons Learned ◽  
Offshore Platforms ◽  
Inspection Planning ◽  
Industrial Implementation ◽  
Planning Methods ◽  
Technical Issues ◽  
Risk Acceptance ◽  
Industrial Context

Risk Based Inspection (RBI) planning methods for structures have been under development for years. They have now reached a maturity allowing their use in an industrial context. The first applications of detailed RBI where devoted to single components and lately applied in a more extensive way to a set of components, using generic approaches. As being the second part of a report on industrial application of RBI, this present paper focused on RBI for fixed steel offshore structures. The challenge here is the full implementation of the method to a whole set of offshore platforms. General questions arise, such as how to use detailed RBI planning that builds inspection plans of details to establish inspection campaigns for a given platform and, in a more general way, how to go from detailed RBI planning to inspection campaigns for a set of platforms. Also, several more technical issues have been raised during the studies, such as fatigue computations, push-over analyses, risk acceptance criteria and scheduling phases. This paper presents part of the experiences gained using and applying these RBI methods to a specific field of jackets.

Greater Plutonio Riser Tower Installation: Studies and Lessons Learnt

2009 ◽  
Author(s):  
Charles-Alexandre Zimmermann ◽  
Guilhem Layrisse ◽  
Daniel de la Cruz ◽  
Jeremy Gordonnat
Keyword(s):  
Water Depth ◽  
Bending Moment ◽  
Lessons Learned ◽  
Field Development ◽  
System A ◽  
Analysis Methodology ◽  
Lessons Learnt ◽  
Future Improvement ◽  
Tower System

The BP operated Greater Plutonio field development offshore Angola comprises a spread-moored FPSO in 1,300 m water depth, serving as a hub processing the fluids produced from or injected into the subsea wells. The selected riser system is a Hybrid Riser Tower comprising 11 risers bundled around a central structural tubular (Core Pipe), tensioned by a steel Buoyancy Tank at its top and maintained by an anchor base at its bottom. The Riser Tower is fabricated onshore and then towed to the field for final installation in deepwater near the FPSO. Once the Riser Tower installation is completed the risers are connected to the FPSO by means of flexible jumpers and to the flowlines by means of rigid spools. All fabrication and installation work has been performed by Acergy. This paper presents the studies performed to cover all the steps of the installation phase: build-up of the Orcaflex model, miscellaneous studies to determine model and analyses parameters, towing analysis, upending analysis, Buoyancy Tank ballasting and deballasting analyses, and contingency analyses. This paper is mainly focused on the Riser Tower installation but also covers the installation of the Riser Tower anchor and of the flexible jumpers in order to give a complete overview of the operations related to the Riser Tower system. A comparison between computed data and data measured during operations is also presented to support the overall installation analysis methodology. Lessons learned are provided for future improvement of Riser Tower installation covering main challenges such as Riser Tower modeling, weight/buoyancy repartition along the Riser Tower, Buoyancy Tank ballasting adjustment in Lobito bay, fatigue issues during surface and subsurface tow, bending moment issues during upending, etc.

Safe Operation of Jacket Platforms in a Major Oil Field in the North Sea

2018 ◽  
Author(s):  
Ingar Scherf ◽  
Trine Hansen ◽  
Gudfinnur Sigurdsson
Keyword(s):  
Emergency Preparedness ◽  
Structural Integrity ◽  
Fatigue Cracks ◽  
Regulatory Compliance ◽  
Offshore Structures ◽  
Oil Field ◽  
Inspection Planning ◽  
Original Design ◽  
Safe Operation ◽  
Integrity Management

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.

Implementation of Structured Benefit-Risk Assessments in Marketing Authorization Applications: Lessons Learned

2016 ◽  
Vol 50 (6) ◽  
pp. 718-723 ◽  
Author(s):  
JuAn Wang ◽  
Anne Wolka ◽  
Kristin Bullok ◽  
Greg Anglin ◽  
Christine Radawski ◽  
...  
Keyword(s):  
Lessons Learned ◽  
Risk Assessments ◽  
Marketing Authorization

Development of Risk-Based Maintenance Software for Gas Turbines

2007 ◽  
Author(s):  
Tomoharu Fujii ◽  
Terutaka Fujioka ◽  
Chris Ablitt ◽  
Julian Speck ◽  
Brian Cane
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Damage Mechanism ◽  
Risk Assessments ◽  
Inspection Planning ◽  
Risk Matrix ◽  
Hot Gas ◽  
Path Component ◽  
Software Risk ◽  
Maintenance And Inspection

Risk-based maintenance software has been developed to perform risk-based maintenance and inspection planning on gas turbine hot gas path components. The software allows the user to easily prepare a risk matrix, plotting every active damage mechanism for each hot gas path component. Based on the result of the risk assessments the components can be ranked, allowing inspection plans to be focused and prioritized and aiding the user to identify the most appropriate and effective risk mitigating activity within the software. Risk assessments are performed on a component-by-component basis, with the software’s scope including all combustor and turbine hot gas path components. The software also contains comprehensive help documents to aid the user in identifying and assessing peculiar damage mechanisms and prescribing the most effective inspection methods for gas turbines.

Fatigue reliability assessment of tubular joints of existing offshore structures

2001 ◽  
Vol 28 (4) ◽  
pp. 691-698 ◽  
Author(s):  
A A Aghakouchak ◽  
S F Stiemer
Keyword(s):  
Decision Making ◽  
Reliability Assessment ◽  
Offshore Structures ◽  
Fatigue Reliability ◽  
Inspection Planning ◽  
Additional Information ◽  
Linear Elastic ◽  
Tubular Joints ◽  
Elastic Fracture ◽  
Tubular Joint

Tubular joints of offshore structures are prone to fatigue damage. Because of uncertainties involved in quantifying the fatigue process in this type of structure, a reliability approach may be adopted to assess the risks of failure. In-service inspections of structures produce additional information, which may be taken into consideration in order to update the reliability. The paper reviews the methods for carrying out such reliability analyses based on principles of linear elastic fracture mechanics and applies them to a sample tubular joint. The results of this type of analyses may be used for inspection, planning, and (or) decision making regarding repairs or modification of the service life of a structure.Key words: fatigue, reliability, tubular joints, offshore structures, condition assessment.

Wellhead Fatigue Analysis Method: Benefits of a Structural Reliability Analysis Approach

2012 ◽  
Author(s):  
Torfinn Hørte ◽  
Lorents Reinås ◽  
Jan Mathisen
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Offshore Structures ◽  
Probability Of Failure ◽  
Fatigue Analysis ◽  
Life Extension ◽  
Inspection Planning ◽  
Structural Reliability Analysis ◽  
Extreme Load ◽  
Input Parameters

Structural Reliability Analysis (SRA) methods have been applied to marine and offshore structures for decades. SRA has proven useful in life extension exercises and inspection planning of existing offshore structures. It is also a useful tool in code development, where the reliability level provided by the code is calibrated to a target failure probability obtained by SRA. This applies both to extreme load situations and also to a structural system under the influence of a time dependent degradation process such as fatigue. The current analysis methods suggested for service life estimation of subsea wells are deterministic, and these analyses are associated with high sensitivity to variations in input parameters. Thus sensitivity screening is often recommended for certain input parameters, and the worst case is then typically used as a basis for the analysis. The associated level of conservatism embedded in results from a deterministic analysis is not quantified, and it is therefore difficult to know and to justify if unnecessary conservatism can be removed from the calculations. By applying SRA to a wellhead fatigue analysis, the input parameters are accounted for with their associated uncertainty given by probability distributions. Analysis results can be generated by use of Monte-Carlo simulations or FORM/SORM (first/second order reliability methods), accounting for the full scatter of system relations and input variations. The level of conservatism can then be quantified and evaluated versus an acceptable probability of failure. This article presents results from a SRA of a fictitious but still realistic well model, including the main assumptions that were made, and discusses how SRA can be applied to a wellhead fatigue analysis. Global load analyses and local stress calculations were carried out prior to the SRA, and a response surface technique was used to interpolate on these results. This analysis has been limited to two hotspots located in each of the two main load bearing members of the wellhead system. The SRA provides a probability of failure estimate that may be used to give better decision support in the event of life extension of existing subsea wells. In addition, a relative uncertainty ranking of input variables provides insight into the problem and knowledge about where risk reducing efforts should be made to reduce the uncertainty. It should be noted that most attention has been given to the method development, and that more comprehensive analysis work and assessment of specific input is needed in a real case.

scholarly journals STABILITY CONSIDERATIONS AND CASE STUDIES OF SUBMERGED STRUCTURES CONSTRUCTED FROM LARGE, SAND FILLED, GEOTEXTILE CONTAINERS

2011 ◽  
Vol 1 (32) ◽  
pp. 60
Author(s):  
Jose Carlos Borrero ◽  
Shaw T Mead ◽  
Andrew Moores
Keyword(s):  
Case Studies ◽  
Wave Attenuation ◽  
Numerical Models ◽  
Cost Effective ◽  
Offshore Structures ◽  
Lessons Learned ◽  
Shore Protection ◽  
Submerged Breakwater ◽  
Cost Effective Method ◽  
Design Guidance

The use of large, sand filled geotextile containers for the construction of offshore structures is gaining acceptance as a cost effective method of submerged breakwater or reef construction. This method of construction is partuicularly well suited for multipurpose structures where the intent is to provide breakwater-like wave attenuation and shore protection while at the same time providing recreational amenities such as ecological enhancment or surfing. Because the materials and methods used in these structures is relatively new, design guidance is lacking. This paper discusses the general stability considerations for submerged structures constructed from sand filled geotextile containers (SFC’s) and describes a method of assessing container stability through the use of numerical models and empirically derived stability formulae. The paper also describes lessons learned from case studies of four very differnt examples of this type of construction.

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