Appendix: Workshop proposal for the assessment of aging processes and management of the life extension phase. The content of the life extension consent application and the processes that may be involved are presented in the form of a process flow diagram. Finally, the report discusses how an application for life extension consent can be evaluated and verified, and the need for greater vigilance by duty holders and regulators during the life extension period.
An evaluation of the impact of KP3 on the Norwegian approach to life extension is recommended. Currently, there is a lack of relevant guidelines and standards on the processes and criteria required for consent to life extension. Life extension planning is a good time to review integrity management systems and the human resource required to manage an aging installation.
What are the principles for managing safety systems during the life extension period. Obstacles to consent to life extension and the conditions necessary for the implementation of life extension are discussed.
Hazards and ageing
- Major hazards on offshore installations
- Age related threats and damage mechanisms
- Barrier function
- Equipment for barrier systems
- Prioritisation of active and passive systems
- Organisational, management and human aspects of barrier systems
The composition of well fluids changes with life, and older fields tend to be more acidic, leading to an increased rate of corrosion. The functional performance of the barriers may vary from optimal over time due to factors such as aging processes and aging of the original (i.e. factors affecting performance). Historical barriers: these were put in place in the early stages of the platform's life (eg secure design, redundancy, diversity, optimized layout).
Due to improvements in knowledge and technology, or as a result of poor initial design, its functionality can no longer be optimized to the current state of the art. More details on barrier function and the effects of aging are given in Table 2 below. The key barriers, shown in Figure 3, that minimize the risk of structural collapse are good steelwork design, selection of appropriate materials and good weld design against fatigue failure, together with inspection, repair and maintenance and effective layout of the factory and weight management.
The main barriers, shown in Figure 2, are of the 'historic' type as they depend on the original design and layout, together with inspection and maintenance. Depending on the effectiveness of the 'historic barriers', an increased level of inspection and maintenance may be required to compensate for deficiencies in barriers introduced at the design stage. Reduction of the risk of corrosion occurring during the life of the installation by a good design of a corrosion protection system.
Reduced capacity of the emergency shutdown system due to aging processes, e.g. corrosion of valves. It is useful to provide a list of the broad categories of barrier systems against which a more detailed equipment list can be judged. At a more detailed level, examples of the types of equipment associated with these systems are shown in Table 3.
Assurance would be needed that active component asset management was proactive and up-to-date. A separate campaign to reduce test and maintenance backlogs and a review of monitoring and asset management arrangements for active components would be a minimum requirement before resources could be focused on passive components. An assessment of the extent and accuracy of available knowledge and the adequacy of that knowledge to make sound judgments is an essential part of the life extension process.
It is known that most of the current workforce is approaching retirement, and succession must be part of life extension planning. Demonstrating the competence of the workforce to manage aging systems is a significant challenge facing the offshore industry.
2 Integrity Indicators
- Design and operating lives .1 Original design life
- Anticipated extended operating life
- Compliance with standards .1 Issues to be addressed
- Compliance with original specification and design and construction standards
- Comparison with modern standards
- Standards of fabrication
- Functionality requirements and fitness-for-purpose
- Inspection, monitoring testing and data trend analysis .1 Overview
- Initial condition of an installation
- Inspection and maintenance data
- Monitoring and test data
- Failure and incident data
- Assessment of quality and trend of data in relation to life extension
- Risk factors, assessments and guidance .1 Factors influencing risk and rate of ageing
- Fitness-for-service and remnant life assessment
- Current guidance on the management of ageing and life extension
- Stages of ageing
- Classification of equipment
- Assessment of transitions in the stage of ageing
- Integrity indicators according to stage of ageing
In addressing this issue, it is recommended that duty holders determine whether the equipment continues to meet the safety limits and functional requirements of the original specification and design and construction standard, and assess whether it is functioning within prescribed limits. The magnitude of the response depends on what is reasonably practicable and proportionate to the intended life beyond the original design life. Protection against falling loads then depends on the integrity of the gears and shafts in the gearbox.
The design standards of the original manufacture are an important consideration for life extension, especially if a significant life extension is anticipated. An assessment of the standards of manufacture should be made, recognizing features that indicate good or bad practice. A systematic review and review of plant performance will reveal many of these aspects.
The management of aging systems requires a good knowledge of the current and previous structural states of the device and its peaks. For several older devices, the quality of the DFI summary is known to be limited by significant data gaps from the design, installation, and manufacturing phases. As part of the case for life extension, it is important to assess the quality of available data from inspection, monitoring, maintenance and failure analysis, including that for the DFI CV.
When reviewing equipment for life extension, Duty Holders should be aware of any factors during the history of the equipment that may increase the risk and rate of obsolescence, and thus advance the time when its effects become significant. The results of fitness-for-service assessment and the available margins are key indicators of the integrity of obsolete equipment. The report presents a framework for managing corrosion based on the concept of the six stages of a safety management system.
The guide is intended to ensure consistent judgment of the extent of external corrosion associated with hydrocarbon and other systems. In order to assist the management of the process of life extension, Duty Holders may find it useful to classify safety critical equipment forming barrier systems in a phased scale of aging according to the integrity indicators. Classification in this way makes it possible to take a more holistic view of the condition and viability of the equipment for life extension.
Lack of information or maintenance and inspection backlogs have reached a level where confidence in the continued reliable performance of the equipment has been eroded. When aging damage is isolated (step 1), integrity indicators are necessary to confirm that the condition of the equipment is as expected from design considerations.
Life
Damage rate
3 Generic Framework for Life Extension
- Application for consent to life extension
- Organisation and management
- Application assessment, acceptability and checks
- Obstacles and conditions to life extension
- Increased vigilance during life extension
The processes for preparing and implementing a life extension application are a matter for each Duty Holder to decide. Monitor the implementation of life-extending actions. Manage the integrity of .. barriers according to plan during life. Life extension is inevitably a period of greater uncertainty and increased vigilance is required from both the Duty Holder and the regulator.
Fitness-for-service cannot be guaranteed over the life extension period based on current knowledge. Where improvements are not available at reasonable cost, obligee asks to review the period of life extension that is acceptable. Criterion Sample checks Possible issues .. outstanding Mitigation actions recommended Monitoring, . maintenance and testing of barrier systems during life extension.
Determine the trend in the level of maintenance and inspections that the carrier plans during the life extension. The following can be considered as obstacles and conditions for consent to life extension. a) Failure to state original life or expected extended life. The end of the extended life expectancy is another point where requests for further life extension should be revisited.
Failure to demonstrate fitness for service of barrier systems without an acceptable plan for further assessment or remedial action can be a barrier to life extension. A history of hydrocarbon leaks and safety warnings resulting from aging equipment may be a barrier to consent to life extension. Such a history marks the duty holder's inability to manage aging effectively and does not provide confidence in safe operation during the life extension phase where aging effects are likely to increase.
If this is not done without good reason, it would indicate an attitude within the Duty Holder organization that is inconsistent with the attitude expected towards the continuation of the life extension. A history of maintenance delays and the inability to address this before the start of the life extension phase may be an obstacle to agreeing to life extension. The life extension phase poses a greater risk of aging mechanisms affecting integrity, performance and safety.
4 Conclusions and Areas for Further Work
Increased awareness of aging effects and vigilance for change in condition or performance should be required of both the Duty Holder and regulator. In practice, this means greater and more frequent dialogue on aging issues, both within the company (offshore and onshore) and between the Duty Holder and the regulator. The form this vigilance and dialogue will take will vary by installation and company.
For example, it can be expected that inspection and maintenance schedules will be reviewed more frequently, and that there will be a program to upgrade or replace aging facilities on an ongoing basis. The stock of spare parts for safety related equipment will be maintained at an adequate level where spare parts are no longer readily available. The analysis of inspection, monitoring and test data, and of failure and incident reports will become more rigorous.
Access to technical expertise and experience in aging mechanisms and fitness for service assessment would be strengthened. For the regulator, increased vigilance may mean more frequent meetings with the Duty Holder to ensure that the right management is in place to manage the aging population, possibly accompanied by inspection visits to the offshore locations. For companies that fail to maintain the safety of outdated installations, the regulator must take appropriate action.
The regulator also has a role in encouraging awareness and research on aging issues, and in assisting the transfer of information and good practice across the industry.
5 References
Appendix
Proposed workshop for assessment of ageing processes and management of the life extension phase
