The Role of Engineering Critical Assessment in the Life Extension of Risers Connected to Floating Systems

2020 ◽  
Author(s):  
Basim Mekha ◽  
Robin Gordon
Keyword(s):  
Systems Approach ◽  
Production Systems ◽  
Critical Size ◽  
Fatigue Cracks ◽  
Phase 1 ◽  
Critical Assessment ◽  
Life Extension ◽  
Original Design ◽  
Acceptance Criteria ◽  
Design Life

Abstract As many offshore production systems approach the end of their original Design Life, Operators are faced with the choice of either decommissioning or demonstrating that the original Design Life can be extended (Life Extension). Life extension requires the Operator to perform detailed engineering analyses to verify that the system can be operated safely over the period of Life Extension. In many cases this requires detailed fatigue analysis and inspection programs to demonstrate that original fabrication flaws or fatigue cracks that may have existed during the welding of the riser joints or initiated over the original Design Life will not grow to a critical size resulting in failure. Engineering Critical Assessment (ECA) is now routinely applied in the design and fabrication of new offshore riser systems to develop girth weld flaw acceptance criteria. The resulting flaw acceptance criteria ensure that fabrication flaws will not extend to a critical size over the Design Life and thus the riser still meet its calculated fatigue life. Although ECA procedures for new construction are well established and standard practices have been adopted throughout the industry, ECA procedures for Life Extension have not yet evolved to the same level of acceptance. This paper will review specific issues associated with applying ECA to support Life Extension of offshore Riser Systems. The paper will provide the overall ECA philosophy and methodology for life extension to be adopted for the historical (hindcast or Phase 1) and future (forecast or Phase 2) analysis of the risers. Some thoughts will also be given to the approach implemented to take advantage of the actual weld fabrication data with the focus on the fatigue critical sections of the risers. Finally, the paper will address the requirements for riser in-situ inspection and how the results could be analyzed and applied to the life extension analysis in conjunction with the ECA analysis.

A Framework for the Management of Ageing of Safety Critical Elements Offshore

2011 ◽  
Author(s):  
John V. Sharp ◽  
Edmund G. Terry ◽  
John Wintle
Keyword(s):  
Life Extension ◽  
Original Design ◽  
Safety Critical ◽  
Critical Elements ◽  
The North ◽  
Design Life ◽  
Offshore Installations ◽  
Management Processes ◽  
The North Sea ◽  
And Performance

Many offshore installations in the North Sea have now exceeded their original design life and are in a life extension phase. A Framework of six processes has been developed for the management of ageing of Safety Critical Elements (SCEs) in offshore installations. The processes include an analysis of the effect of ageing modes on SCE performance. Examples of performance indicators for typical SCEs are proposed based on how their condition and performance as may be affected by physical deterioration and other effects of ageing. Indicators for calibrating the maturity and effectiveness of the management processes are also suggested.

An Oil Field Structural Integrity Assessment for Re-Qualification and Life Extension

2013 ◽  
Author(s):  
Abe Nezamian ◽  
Joshua Altmann
Keyword(s):  
Weight Control ◽  
Structural Integrity ◽  
Offshore Structures ◽  
Oil Field ◽  
Assessment Process ◽  
Performance Criteria ◽  
Life Extension ◽  
Original Design ◽  
Integrity Assessment ◽  
Design Life

The ageing of offshore infrastructure presents a constant and growing challenge for operators. Ageing is characterised by deterioration, change in operational conditions or accidental damages which, in the severe operational environment offshore, can be significant with serious consequences for installation integrity if not managed adequately and efficiently. An oil field consisting of twelve well head platforms, a living quarter platform (XQ), a flare platform (XFP) and a processing platform (XPA) are the focus of this paper, providing an overview of the integrity assessment process. In order to ensure technical and operational integrity of these ageing facilities, the fitness for service of these offshore structures needs to be maintained. Assessments of the structural integrity of thirteen identified platforms under existing conditions were undertaken as these platforms are either nearing the end of their design life or have exceeded more than 50% of their design life. Information on history, characteristic data, condition data and inspection results were collected to assess the current state and to predict the future state of the facility for possible life extension. The information included but was not limited to as built data, brown fields modifications, additional risers and clamp-on conductors and incorporation of subsea and topside inspection findings. In-service integrity assessments, pushover analyses, corrosion control and cathodic protection assessments and weight control reports were completed to evaluate the integrity of these facilities for requalification to 2019 and life extension to 2030. The analytical models and calculations were updated based on the most recent inspection results and weight control reports. A requalification and life extension report was prepared for each platform to outline the performance criteria acceptance to achieve requalification until 2019 and life extension until 2030. This paper documents the methodology to assess the platform structural integrity in order to evaluate platform integrity for the remaining and extended design life. An overview of various aspects of ageing related to these offshore facilities, representing risk to the integrity, the required procedures and re assessment criteria for deciding on life extension of these facilities is presented. This paper also provides an overall view of the structural requirements, justifications and calibrations of the original design for the life extension to maintain the safety level by means of maintenance and inspection programs balancing the ageing mechanisms and improving the reliability of assessment results.

A Life Extension Perspective for a CANDU-6 NPP: Gentilly-2 Plant Condition Assessments

2003 ◽  
Author(s):  
Marc Aubray
Keyword(s):  
Plant Production ◽  
Life Extension ◽  
Original Design ◽  
Design Life ◽  
Plant Life ◽  
Detailed Assessment ◽  
The Government ◽  
Condition Assessments ◽  
Detailed Work ◽  
Economical Feasibility

To extend the life of a CANDU-6 reactor beyond its original design life requires a major investment for the replacement of reactor components (380 pressure and calandria tubes). After a preliminary technical and economical feasibility study [ref 1], Hydro-Quebec, owner of the Gentilly-2 NPP, has decided to perform a more detailed assessment to: • Get assurance that it is technically and economically viable to extend Gentilly-2 for another 20 years beyond the original design life; • Identify the detailed work to be done; • Define the overall cost and the general schedule; • Ensure an adequate licensing strategy to restart after refurbishment; • Complete all the Environmental Impact Studies required to obtain the government authorizations. Two processes have been used to assess the “health” of the station Systems, Structures and Components (SSCs): • The Plant Life Management Studies (PLIM) for approximately 10 critical SSC or families of SSC (PLIM Studies); • The Condition Assessment Studies for other SSC with a lower impact on the Plant production or safety. These two processes are briefly presented in the paper, as they were realized and applied at Gentilly-2 NPP.

Lifetime Assessment of Flexible Pipes

2014 ◽  
Author(s):  
Jorgen Thomas Wold Eide ◽  
Jan Muren
Keyword(s):  
Systematic Approach ◽  
Assessment Process ◽  
Life Extension ◽  
Risk Level ◽  
Flexible Riser ◽  
Original Design ◽  
Design Life ◽  
Flexible Pipes ◽  
Guidelines And Standards

This paper presents a methodology for performing a lifetime assessment of flexible pipes applicable to re-qualification during the original design life and at life extension. A systematic approach is developed, providing flexible riser and flowline engineers a standardized methodology for determining the current integrity- and risk level. The objective is to provide methodology that is easy to implement, thus enabling consistent assessments of all flexible pipes in the operator’s portfolio. The methods described are taken from work performed in a recent JIP run jointly by MARINTEK/NTNU and 4Subsea, and is based on substantial experiences with lifetime assessment combined with a review of relevant guidelines and standards. Key areas are suggested for industry improvement and recommendations to further developments, to increase both efficiency and quality of the lifetime assessment process.

Unbonded flexible pipe integrity management, reuse and life extension

2008 ◽  
Vol 48 (1) ◽  
pp. 319
Author(s):  
Adriana Botto ◽  
Céline Banti ◽  
Enda O'Sullivan
Keyword(s):  
Asset Management ◽  
Production Systems ◽  
Cost Effective ◽  
Later Life ◽  
Life Extension ◽  
Original Design ◽  
Flexible Pipe ◽  
Effective Manner ◽  
Manufacturing Testing ◽  
Integrity Management

Australia has a long tradition of innovation in the use of floating production systems in the past 20 years. The classical solution adopts unbonded flexible pipe, a key technology, to enable floating facilities to produce in relatively shallow waters. While unbonded flexible pipe is a reliable technology that has been in use for approximately 30 years, damage, and ultimately failure can occur during its early (i.e. during manufacturing/testing, installation and early operation) and later life. Accurate assessments of the historical records of flexible pipe usage have led to an increased understanding of the potential failure mechanisms. This enables mitigation of incidents by developing operating strategies and procedures to manage the flexible pipe in a knowledgeable and cost effective manner. This paper discusses the available techniques for the inspecting and monitoring requirements of flexible pipe, including consideration of the value offered by conventional general visual inspection (GVI) techniques. Examples of developed alternative technologies are discussed, as well as how these alternatives can reduce the requirement for GVI when supplemented with an integrated integrity management strategy. Furthermore, given the advances in understanding of complex flexible pipe inter-layer behaviour, this paper demonstrates that through proper asset management, flexible pipe technology service life can be extended beyond the original design value. Similarly, flexible pipe that had previously been considered damaged and requiring early replacement can be justified for extension to beyond the original design life. Consideration has also been given to the potential for the re-use of flexible pipes and the hazards which can arise from this activity including recovery, storage, testing and installation. The key stages required to safely manage this process have been outlined.

Risk-based corrosion assessment and refurbishment of marine structures

2018 ◽  
Vol 58 (1) ◽  
pp. 60
Author(s):  
Stephan Dickinson ◽  
Kerryn Wilson ◽  
Ali Sarandily ◽  
René van der Werf ◽  
Steve Sheen ◽  
...  
Keyword(s):  
Service Life ◽  
Phase 1 ◽  
Phase 2 ◽  
Remaining Life ◽  
Liquefied Petroleum Gas ◽  
Original Design ◽  
Marine Structures ◽  
Corrosion Rates ◽  
Design Life ◽  
Inspection Techniques

This paper outlines a holistic, risk-based approach to managing the service life of existing liquefied natural gas (LNG) and liquefied petroleum gas (LPG) marine structures in Western Australia. The structures have been in service since 1989 (LNG) and 1995 (LPG) and are nearing the end of their original design life. The objective of this approach is to extend the design life for an additional 20 years to 2040. The risk-based assessment (RBA) process is composed of three main steps undertaken in sequence to identify and quantify refurbishment requirements for the timeframe. A two-campaign approach was considered, the first being in 2019 (Phase 1) and the second in 2030 (Phase 2). The RBA process combines innovative and conventional inspection techniques with a detailed desktop structural assessment of the remaining life of the structures’ individual components to enable an informed decision to be made on the refurbishment requirements for each campaign. The results of the stepped RBA process demonstrate the effectiveness of the approach to define and manage a refurbishment program that achieves the required extended service life of the structures to 2040. The RBA process enabled the first campaign’s scope to be minimised through detailed analysis and calculation of residual design life of each critical member, deferring most of the refurbishment scope to the second campaign in 2030. The study has recommended implementation of a corrosion rate trial to verify the assumed corrosion rates for the jetty structures. Environmental monitoring stations and test coupons installed on the jetty for a five-year period will confirm the actual deterioration rates specific to the jetty structures. Confirmation of actual deterioration rates may reduce uncertainty in the values over those currently assumed in the study and positively affect the identified Phase 2 refurbishment scope.

Life Extension Issues for Ageing Offshore Installations

2008 ◽  
Author(s):  
A. Stacey ◽  
M. Birkinshaw ◽  
J. V. Sharp
Keyword(s):  
Structural Integrity ◽  
Life Extension ◽  
Original Design ◽  
The North ◽  
Design Life ◽  
Offshore Installations ◽  
Need To Evaluate ◽  
Integrity Management ◽  
The North Sea ◽  
The Uk

With many offshore installations in the UK sector of the North Sea now reaching or being in excess of their original anticipated design life, there is a particular need to evaluate approaches to structural integrity management by offshore operators. Ageing processes can affect the structural integrity of the installation and demonstration of adequate performance beyond its original design life is thus a necessary requirement. This paper addresses the issues relevant to the life extension of ageing installations.

Issues for Consideration in Life Extension and Managing Ageing Facilities

2011 ◽  
Author(s):  
Solfrid Ha˚brekke ◽  
Lars Bodsberg ◽  
Per Hokstad ◽  
Gerhard Ersdal
Keyword(s):  
Oil And Gas ◽  
Point Of View ◽  
Life Extension ◽  
Original Design ◽  
Material Degradation ◽  
Safety Level ◽  
Design Life ◽  
Extended Operation ◽  
Norwegian Continental Shelf ◽  
Extension Process

A large number of facilities and parts of the infrastructure on the Norwegian Continental Shelf are approaching or have exceeded their original design life. Many fields, however, have remaining recoverable oil and gas reserves which may be profitable if the field’s life is extended. From a safety point of view, the condition of systems, structures and components may not be acceptable for extended operation. Ageing and life extension have been a top priority for the Petroleum Safety Authority Norway (PSA) and PSA has asked SINTEF to conduct a study of various aspects of ageing and life extension. The paper presents main results from the study, including how to document the safety of an ageing facility and how to uphold the safety level by means of a maintenance programme balancing three aspects of ageing: 1) Material degradation, 2) Obsolescence, i.e. operations and technology being “out of date” and 3) Organisational issues. The paper presents six main steps of the life extension process and discusses important issues to consider for operators in a life extension process.

Life Extension and Management of Ageing FPSOs

2016 ◽  
Author(s):  
Hilman Salleh
Keyword(s):  
End Of Life ◽  
Deep Water ◽  
Oil And Gas ◽  
Production Systems ◽  
Gas Production ◽  
Life Extension ◽  
Oil And Gas Production ◽  
Design Life

FPSOs have been a popular choice for deep water oil and gas production with many installations worldwide. Many of these floating production systems were tanker conversions and they are now approaching their mid-life or end of life hence, facing ageing issues relating to asset integrity. Concurrently, there are also requirements for these floating production systems to operate to operate beyond the design life. As most of this maintenance and refurbishment work is to be done while on station, there needs to be a structured process to ensure that all key areas of concerns are reviewed. This paper outlines the strategy available and addresses the issues and possible solutions to manage the life extension and ageing of FPSOs.

Remaining Life Assessment and Life Extension of Offshore Pipelines

2018 ◽  
Author(s):  
Jens P. Tronskar
Keyword(s):  
Life Assessment ◽  
Life Extension ◽  
Remaining Life ◽  
Original Design ◽  
Offshore Pipelines ◽  
Field Development ◽  
Design Life ◽  
The Future ◽  
Cost Efficient ◽  
Remaining Life Assessment

Cost efficient offshore field development often involves tiebacks to existing field infrastructure. Efficient field development requires life extension of existing production facilities and pipelines to accommodate the new field resources over their life expectation. For fields near the tail end of their production the pipelines may be close to the end of their design life, and it must be shown that they have potential for extended life beyond the original design life until the end of the period of operation of the new field. Offshore pipelines are designed and constructed to recognized standards, such as the widely applied DNV OS-F101 2013 Submarine Pipelines Systems and earlier versions. The latest edition of the code was recently issued as a standard with some major updates and a modified code number i.e. DNVGL ST-F101 [1]. As pipelines age, they will inevitably be exposed to various types of degradation and an Operator must be able to both assess the significance of this damage and the pipeline remaining life to ensure that the pipelines do not fail as they age before the end of their design lives. Currently, many pipelines are operated far beyond the original design life and as mentioned above for cost efficient field development the pipeline operator often needs to demonstrate that the pipeline’s useful life can be extended another 10 or in some cases up to 30 years. For some pipelines, new operating conditions will be introduced by tie-in of new fields and this will impact the future rate of degradation. Hence, it cannot be assumed that the future degradation will be similar or less severe than experienced since commissioning of the pipeline. Extension of the life of the pipeline can be demonstrated by adopting methods of analysis that show the line is safe for an extended life under the future expected operating condition. This paper describes the risk based approach applied for pipeline remaining life and life extension analyses based on DNV GL codes and other relevant recommended practices. For illustration of the methodology a typical case of remaining life assessment of and life extension of a gas export pipeline is presented in the Case Study.

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