|Purpose of issue||Rev||Date of issue||Technical author||Policy contributions||Technical editor|
|Comment||0||July 09||M Birkinshaw||A Stacey|
|Issued||1||September 09||M Birkinshaw||A Stacey|
M Birkinshaw - OSD4.2
Structural integrity management (SIM): The means of ensuring that the people, systems, processes and resources that deliver structural integrity are in place, in use and will perform when required over the whole lifecycle of the structure in accordance with the Offshore Installations and Wells (Design and Construction, etc.) Regulations 1996 (DCR).
The means of ensuring structural safety on floating structures is currently being formulated. As many floating installations have a degree of Class, the interaction between the requirements of Class and the Regulations is under study. However principles and technical requirements will probably not change.
The standard set by this policy is compatible with the International Standards Series for Offshore Structures and there should be no adverse impact on new installations, or on existing structures. A structured approach to structural integrity should bring considerable benefits, especially in relation to ageing and life extension matters.
The UKCS has been developed for oil and gas production for over 40 years, and a significant body of structural integrity management (SIM) practice has developed. This practice must now reflect the fact that many UKCS structures are in various phases of damage and/or deterioration, including those that now exceed their originally intended operating life. The introduction of the safety case regime in 1992 and DCR replaced the prescriptive certification system for SIM with risk based and goal setting activities structured around the management of safety critical elements (SCEs). SCEs are defined (in the Offshore Installations (Safety Case) Regulations 2005 (SCR) as parts of an installation and its plant whose purpose is to prevent, control or mitigate major accident hazards and the failure of which would cause or contribute substantially to a major accident. SIM activities cover these elements and are monitored by independent verification. These changes have necessitated a change in the way structural integrity is approached and the requirement for a managed approach has developed.
There are no precise methods to quantify risk of structural failure and sound engineering principles are required to keep this risk to a low level. These principles involve interactions between design, construction and life time inspection and the management of these interactions. Managing the risk by use of techniques and methods in the ISO Standards for offshore Structures is used to ensure that no sudden, catastrophic failure is encountered.
Management elements of all safety systems should be drawn together in the duty holder’s management system and elements for a structural integrity management system that follows good practice include:
With many offshore installations in the UK sector of the North Sea now reaching or exceeding their original anticipated design life, there is a particular need to evaluate approaches to structural integrity management by offshore operators to ascertain their adequacy in managing ageing structures. In addition to this, a significant proportion of the ageing structures are now operated by duty holders who are not the original duty holders and hence may have limited knowledge of the structural integrity history of the structure. A pilot study by HSE, undertaken during 1995-1996 and the results of the KP3 audit programme have highlighted the varying approaches to structural integrity management by duty holders, in terms of both the methods used and their effectiveness.
The definitive modern standards for structures are those of the International Standards Organisation (ISO) which contain world wide, harmonised practice:
Offshore Installations (Safety Case) Regulations 2005
Offshore Installations and Wells (Design and Construction, etc) Regulations1996
Offshore Installations (Prevention of Fire and Explosion, and Emergency Response) Regulations 1995 (PFEER)
Compliance with ISO Standards or equivalent which includes:
An appropriate SIM system which is achieved by identifying the gaps in current installation specific operating practice and the practice outlined in the ISO Standard, prioritise the needs, assess resource needs and costs, and managing their implementation. This may cover all or some of the following:
The implementation plan should be fully documented and provide appropriate rationale for any departures from good practice.
References that are relevant to this technical policy, as well as useful references to do with the subject matter of this policy e.g. relevant standards, and a list of background notes giving guidance on specific topics are given below.
Continual improvement: Ongoing implementation of findings of audits and reviews to improve the SIM process.
Information management: The process by which all relevant historical and operational documents, data and information are collected, communicated, stored and made available to those who need it.
Performance standards: A statement of the performance required of a system, item of equipment, person or procedure and which is used as the basis for managing the hazard through the life cycle of the installation.
SIM policy: The SIM policy sets out the overall intention and direction of the duty holder with respect to SIM and the framework for control of the SIM related processes and activities. These should be aligned with the duty holder’s strategic plan and other corporate policies.
SIM strategy: The SIM strategy sets out the duty holder’s process for delivering the integrity management of its assets, and which is consistent with the SIM Policy.
A number of key processes that constitute good practice in SIM, together with an appropriate management and documentation structure are outlined in eight processes as follows:
SIM Policy: The SIM policy sets out the overall intention and direction of the duty holder with respect to SIM and the framework for control of the SIM related processes and activities. These should be aligned with the duty holder’s strategic plan and other corporate policies.
SIM Strategy: The SIM strategy sets out the duty holder’s process for delivering the integrity management of its assets in line with the SIM Policy and sets acceptance criteria.
Inspection Strategy: A systematic approach to the development of a plan for the in-service inspection of a structure.
Inspection Programme: The inspection programme is the detailed scope of work for the offshore execution of the inspection activities to determine the current condition of the structure. It is developed from the inspection strategy.
Structural Evaluation: Review of current condition of the structure compared to that when it was last assessed and other parameters that affect the integrity and risk levels to confirm or otherwise that the acceptance criteria for structural integrity are met. This process identifies any repair or maintenance requirements to meet the acceptance criteria for structural integrity.
Maintenance: The upkeep of the required condition of the structure by proactive intervention based on output from the structural evaluation.
Information Management: The process by which all relevant historical and operational documents, data and information are collected, communicated and stored.
Audit and Review: Audit is the process to confirm that SIM is carried out in conformity with the procedures set out in the SIM policy and strategy, and legislation. The Review Process assesses how the SIM processes can be improved on the basis of in house and external experience and industry best practice.
SIM requires the duty holder to put in place an appropriate organisational structure and have defined management processes. The objective of these is to define responsibilities of individuals and to clearly set out their activities, interactions, lines of communication and interfaces. Typically, these would be recorded in the duty holder’s SIM strategy. The following aspects should be considered:
The duty holder should have in place a transparent and effective management structure.
The management systems should:
Best practice has resulted in the role of the integrity manager (IM), a role appointed by the duty holder who is responsible for ensuring performance standards in platform safety cases relating to structural integrity are met. This is typically achieved by:
Best practice has resulted in the role of structural technical authority (STA). The STA is responsible for developing the SIM strategy to define the processes by which the SIM objectives set-out in the SIM policy are achieved. The role of STA is sometimes given to an appropriately qualified third party. Responsibilities of the STA typically include:
The IC supplies personnel and resources to carry out routine survey and inspection of the structure. The IC is typically a specialist contractor, with its own inspection and quality procedures, which will need to be reviewed for consistency with SIM documentation e.g. the contractor’s response to a reported flooded jacket member will normally be recorded in the inspection procedures. It is important to ensure this response is adequate. Responsibilities of the IC typically include:
With the introduction of the safety case regime and DCR, the certification system for SIM was replaced by risk based and goal setting activities with independent verification. The IVB reports to the duty holder to provide assurance that the SIM system is adequate. The role of the IVB is specified below and forms part of the whole lifecycle of the platform SIM process. The responsibility of the IVB is to verify that the performance standards for structural SCEs have been met in accordance with the Written Scheme of Verification, which is normally produced by the IVB in agreement with the duty holder. Aspects that would typically be covered by the IVB include:
The IVB should be involved with general SIM related activities such as analysis reviews and modification reviews, and have free access to any relevant information and the remit and resources to carry out their duties as required by DCR. The IVB should be informed of any significant structural issues and should be given the opportunity to provide comments.
As the person responsible for safe operation of the offshore platform, the OIM will have a strong interest in SIM and will work closely with the IM and others to facilitate the delivery of SIM.
All personnel working on SIM have a duty to report to the OIM any issues that pose an immediate risk to the integrity of the platform.
The duty holder is responsible for SIM, which includes competency of their own personnel, and a duty of care with respect to the competency of external contractors. It is therefore required that the duty holder acts as an intelligent customer when purchasing services from external contractors. Competence of personnel relates to the relevance of their education, training and experience to carry out their role within the SIM process. The level and area of competence differs between roles. Guidance is provided in ISO 19902, Section 24.8 and API RP 2SIM, on the topic of competence management for SIM. The engineer or group of engineers involved with SIM should be:
Details on specific requirements for evaluation and inspection, data collection and update and inspection programme are given in ISO 19902. Competency management can be aided by putting in place a suitable policy for recruitment, retention and succession planning of duty holder staff and any contractor staff to provide continuity of personnel. This provides some clear technical benefits, but also encourages development of a safety focused culture. In many instances, competency management extends to external suppliers who may have a direct effect on SIM.
Any SIM process should consider preparedness for emergencies and this should be documented as part of the SIM strategy. The process should closely interface with operator’s primary evacuation, escape and rescue (EER) plan. The emergency response process should set out the means in which relevant parties are alerted in the case of an emergency situation. This should include out-of-office hours contacts. Typically, the following personnel should be included as a minimum:
The emergency response process should demonstrate that rapid access to all integrity information, assessment software, resources is available to the named personnel.
Information Management: The process by which all relevant historical and operational documents, data and information are collected, communicated, stored and made available to those who need it.
Structural integrity management has the potential to produce large amounts of information, which needs to be collected, communicated and stored in an efficient and accessible manner. Ease of information access, clarity in presentation, information interrogation, trending and others are aspects of data management that have a pronounced effect on the overall effectiveness and efficiency of SIM. To this effect duty holders typically have computerised systems in place. As with any database system, the reliability and accuracy of the data stored is largely dependent on the quality and format of the data input in the system.
Structural Evaluation: Review of current condition of the structure compared to that when it was last assessed and other parameters that affect the integrity and risk levels to confirm or otherwise that the existing structural assessments still apply.
Structural Analysis: Calculation to predict the behaviour of the structure usually relative to specified code requirements.
Structural Assessment: Interpretation of available information including any available analysis results to confirm or otherwise the integrity of the structure.
Structural evaluation is the ongoing process to confirm that the basis for demonstrating the structural integrity and associated risk levels are still valid. Any significant changes need to be captured and the evaluation should determine whether the structure is required to be (re-)assessed.
Maintenance: The upkeep of the condition of a structure or component by proactive intervention.
Sub-sea intervention: Reactive reinstatement of the condition of a structure or component following an inspection.
Sub-sea intervention is typically reactive only, in response to a particular inspection finding but may also include strengthening of the platform. Regular planned maintenance is not normally required due to low corrosion rates or practicable due to difficulty of access. Therefore, maintenance of sub-sea structure is usually limited.
Accelerated corrosion rates and exposure to impact damage dictate that structures in the splash zone require planned inspection and maintenance activities. Maintenance activities that one would expect to be included are:
Audit: Process to confirm that SIM is carried out in conformity with the procedures set out in the SIM policy and strategy, and complies with applicable legislation.
Review: Process to review how the SIM processes can be improved on the basis of in house and external experience and industry best practice.
Continual improvement: Ongoing implementation of findings of audits and reviews to improve the SIM process.
Audit and review are an integral part of the SIM loop. These are the processes whereby the duty holder interrogates their SIM process to ensure that operations are taking place as intended, and that these continue to be effective and appropriate. These processes consist largely of interviewing personnel and review of records.
It is good practice for a number of documents to be produced and maintained, as these may be subject to periodic review by the regulator. These include:
Further good practice in documentation includes:
In the context of this policy, life extension is the demonstration of safe operation of the structure to the end of the extended anticipated operating life (EAOL).
With many platforms in the UK continental shelf now approaching or exceeding their intended design life, life extension has become a prominent part of maintaining good practice in SIM activities.