Structural integrity management system (SIMS) implementation within PETRONAS operations

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1 Journal of Marine Engineering & Technology ISSN: (Print) (Online) Journal homepage: Structural integrity management system (SIMS) implementation within PETRONAS operations N. W. Nichols & R. Khan To cite this article: N. W. Nichols & R. Khan (2015) Structural integrity management system (SIMS) implementation within PETRONAS operations, Journal of Marine Engineering & Technology, 14:2, 61-69, DOI: / To link to this article: Published online: 29 Oct Submit your article to this journal Article views: 645 View related articles View Crossmark data Citing articles: 1 View citing articles Full Terms & Conditions of access and use can be found at

2 Journal of Marine Engineering & Technology, 2015 Vol. 14, No. 2, 61 69, Structural integrity management system (SIMS) implementation within PETRONAS operations N. W. Nichols and R. Khan PETRONAS Carigali Snd Bhd, Suria Klcc, Petronas Twin Towers, Jalan Ampang, Wilayah Persekutuan, Kuala Lumpur, 50088, Malaysia Since 2008, PETRONAS Carigali Snd Bhd (PCSB) has embarked on developing a structural integrity management system (SIMS) within its Malaysian operations, which is compliant with the recently balloted American Petroleum Institute Recommended Practice for the Structural Integrity Management of Fixed Offshore Structures (API RP 2SIM) and International Standards Organization (ISO) 19902:2007. Increasing demand to extend the life of fixed steel offshore structures due to further oil and gas discoveries has resulted in the platform being subjected to higher loading due to modifications, upgrading and the demands of additional loading due to new drilling campaigns for which the platform may not have originally been designed. In addition, PCSB platforms are also be faced with other challenges and events such as major damage anomalies identified from the inspections performed, an increase in environmental metocean loading, the presence of shallow gas and seismic/earthquake loading for which the structure may have not originally been designed. As such, PCSB must be able to manage these additional integrity triggers and justify the ongoing integrity and fitness for purpose (FFP) of its platforms, beyond the design life of the structure. Introduction PETRONAS Carigali Snd Bhd (PCSB) currently operates approximately 190 fixed steel offshore platforms in the three regions in Malaysia (Regions A, B and C). Of these platforms, over 60% have been in operation for more than 20 years, 30% have already exceeded 30 years and several others in the very near future will reach their initial design life (20 to 25 years). The number of facilities for each of the regions by platform operation is shown in Table 1. A number of platforms have been extended beyond their original intended life as a result of additional oil/gas discoveries and thus there is a need to address the ongoing structural integrity of these ageing assets. As the platforms operating lives have been extended, there are factors which need taking into consideration, including changes in the design codes, increases in metocean loading, additional topside facilities with increased loading, the damage and loss of members and other challenges for which the platforms were not originally designed such as shallow gas and seismic loading, which makes an understanding of the operating structural risk of the platform even more important. Due to the nature of one or more of the above triggers, structural reassessments have to be conducted. Generally for structural (re)assessments, the primary objective is to ensure that component strength/foundation capacity and fatigue of the various components do not violate the minimum code requirements. Should the reassessment indicate that the above requirements are not met then there is a need to undertake more detail assessments, which normally involve more complex analysis. However, the structural assessments shown in Figure 1 require amongst other things a detailed knowledge and understanding of the non-linear behaviour of the structure and the application of risk-based inspections (RBIs) and structural reliability assessments (SRA). The structural integrity management system (SIMS) The PCSB structural integrity management system (SIMS), compliant with the recently balloted American Petroleum Institute Recommended Practice for the Structural Integrity Management of Fixed Offshore Structures (API RP 2SIM; API 2000, 2014), is an ongoing process for ensuring the continued fitness-for-purpose (FFP) of offshore structures. The four phases of the SIMS process data, evaluation, strategy and programme are shown in Figure 2 and described within the framework of API RP 2SIM and International Standards Organization (ISO) 19902:2007 for Petroleum and Natural Gas Industries Fixed Steel Offshore Structures (ISO 2007). In 2008, PCSB embarked on developing a SIMS within their Malaysian operations for understanding and managing the operational structural risk throughout the lifecycle of an offshore platform. Structural integrity management (SIM) is the application of qualified standards, by competent people, using appropriate processes and procedures throughout the structure s life cycle, from design through to decommissioning, to ensure that through a process of risk management the structure s FFP is maintained [API RP 2SIM; API (2104)]. *Corresponding author. riazk69@yahoo.com 2015 PETRONAS Carigali Sdn Bhd.

3 62 N.W. Nichols and R. Khan Table 1. PCSB platform profile age distribution. Age Distribution (years) > 30 Region A Region B Region C RSR/Member Importance Analysis/SRA Assessing Ageing Jackets in Malaysia Not meeting Code requirements Structural Integrity of Existing Ageing Jackets Optimum Inspection/RBI Maintaining Figure 1. PCSB flow diagram for structural reliability analysis. Source: Nichols et al. (2006). Data gathering and management To effectively deliver SIM, it is essential that the data be the most recent information regarding the design, construction and installation of a structure. The condition of the jacket in the operational phase is important in order to optimize future inspections: any findings of reassessment/fitness assessment, inspections and maintenance on the structure are therefore to be considered. As part of SIMS implementation, all relevant available data was collected from the three operating regions (Regions A, B and C), reviewed, put through a quality assurance (QA) process and input into a dedicated database. The availability and accuracy of the information was evaluated for each of the platforms considered. The information gathered included design basis and specifications, structural drawings, design/(re)analysis reports, inspection reports and maintenance and repair records. Structural Integrity Compliance System (SICS) To facilitate the SIM process and implementation, PCSB has developed a web-based tool called the Structural Information Computer System (SICS). SICS provides quick, worldwide access to key platform information and documentation in addition to several inspection and evaluation tools. It is a secure system for the archive and retrieval of offshore platforms with an intuitive graphical interface for ease of accessing the data. SICS provides a quick screening of structural damage with the following benefits and functionality: A cost-effective risk-based approach to integrity management, reducing the risk of business loss as well as the risk to life safety and the environment. The screening of offshore structures for the determination of assessment requirements. Intervention planning and data management for strengthening, modification and repair. Continuously updated risk-ranking of assets to allow the focus of resources on higher-risk assets and to determine the effect of repairs or remediation on the overall risk picture. A suite of online interactive assessment tools to assist in the evaluation of anomalies or in-service damage, corrosion and other forms of degradation. A system for the management of anomalies and defects detected during inspections, including priority ratings, monitoring and remediation tracking. Evaluation Evaluation is continuous throughout the life of a platform. As additional data are collected, an engineering evaluation is performed by a structural integrity engineer who should consider all the relevant SIM data for the platform and similar platforms where appropriate. Evaluation does not automatically imply a structural analysis; it can include an engineering judgement based on specialist knowledge or operational experience, simplified (screening) analysis or reference to research data, a detailed analysis of similar platforms, etc. During the operation of Figure 2. The SIM process. Source: O Connor et al. (2005), Puskar et al. (2010) andapi(2014).

4 Journal of Marine Engineering & Technology 63 the assets, continuous engineering evaluation of new and changing data is an essential element of the SIM process. The structural integrity engineer will be familiar with the overall SIM process and have experience with the relevant issues for the structures to which the data pertains. The engineering evaluation must determine whether the new data change the operating risk (either consequence or likelihood) of the failure of the platform. Platform risk assessment It has been determined within PCSB that the three major accidents and hazards (MAHs) that affect the offshore structures in Malaysia are abnormal structural loads due to extreme storm, seismic and vessel impact. The probability of failure of each of these MAHs can be determined through non-linear methods and used with their consequences of failure to determine the platform risk. Determining the platform risk (for each MAH) is accomplished Figure 3. Risk matrix. by using the 5 5PCSBRiskMatrix(seeFigure3). Risk is commonly defined as the product of the likelihood of an event occurring and the consequence of its occurrence. In order to reduce risk, therefore, it is necessary either to reduce the likelihood of an event or reduce its consequences or both [API RP 2SIM; API (2014)]. System redundancy Each structure has an inherent reserve and/or residual strength which is directly related to the ability of the structure to provide alternative load paths after the failure of a member. The redundancy in the structural system in the jacket structure of the platform is primarily associated with the arrangements of the braces within the system. A reduction in component capacity does not necessarily imply that the system strength is compromised. Redundancy analysis simulates the loss of the connected member by removing it from the model and performing a non-linear analysis. The redundancy analysis is carried out to evaluate the probability of failure due to any overloading on the structure. The redundancy of the structure is generally reported in terms of a reserve strength ratio (RSR; Mitaheri et al. 2009). The RSR is evaluated using non-linear finite element analysis of the structural model, often termed pushover analysis or ultimate strength analysis. Typically the analysis is undertaken by applying the gravity loading as an initial load step. The environmental design load for the chosen direction is then applied to the model, and the environmental loading is factored incrementally until the ultimate strength of the structure is reached, typically characterized by a plateau in the global load-deflection behaviour of the structural model. The minimum ultimate strength reporting requirements are shown in Figure 4. Figure 4. Ultimate strength reporting requirements. Source: Westlake et al. (2006).

5 64 N.W. Nichols and R. Khan Operating risk PCSB is required to perform structural assessments on all their operating structures for each one of the MAHs (extreme storm, seismic and vessel impact). In the case of extreme storm conditions, one of the platforms assessed had a probability of failure of e10 4 being of consequence of failure (Category D). This is mapped to the Medium Risk Category (on the Risk Matrix) for this platform at this time of its operating life (Figure 5). The operating risk for the structure must be continuously evaluated over its operating life using non-linear methods to determine the probability of failure (which includes all inspection data in the structural model). If the platform is in the High Risk Category, the structural integrity engineers need to demonstrate areas of continuous improvement to lower the operating risk. Such areas of improvement may include developing a strengthening and repair scheme for structural critical members to improve platform robustness. Similarly, if the platform is classed as low or medium risk, the prescribed inspection plan must be adhered to in order to avoid further risk escalation. Assessment engineering A platform FFP assessment is a detailed evaluation or structural analysis that compares the estimated strength of the structure against acceptance criteria (API 2000, 2014; Westlake et al. 2006). For operating fixed structures, regional acceptance criteria have been developed for Malaysian waters by PCSB, expressed as an RSR. PCSB and their consultants perform detailed platform ultimate strength analyses (Figure 6) for their fleet throughout the life cycle of the platform, including a baseline RSR value at the design stage, which serves as a benchmark value for the intact undamaged condition. As the platform undergoes loading changes due to damage, corrosion, degradation, modifications, extreme loadings, etc., it is reassessed against the acceptance criteria to determine Figure 5. Operating risk for a PCSB platform (extreme storm). Note: VH = very high; H = high; M = medium; L = low; VL = very low. Figure 6. Platform ultimate strength analysis and reporting (extreme storm).

6 Journal of Marine Engineering & Technology 65 its continuing FFP. Other types of assessment performed include spectral fatigue analysis, local joint flexibility, pile ageing assessments, seismic assessments and the effects of shallow gas. For risk assessment of the offshore structures, PCSB has developed specific methodologies for evaluating the likelihood of failure of each offshore structure through their risk-based underwater inspection (RBUI). Nichols et al. (2014) outlined this RBUI methodology, which also employs a semi-quantitative approach and utilizes the benefits of the RSR value derived from detailed ultimate strength assessments to recategorize the risk levels. For a qualitative assessment where the evaluation is based on experience, the failure probability is expressed as a ranking category. The likelihood of structural failure is determined using a rule-based system that determines a likelihood score based upon key platform information, including: Installed Likelihood of Failure Rules: Platform Vintage; Number of Legs & Bracing Systems; Grouted Piles; Shallow Gas. Platform Present Condition Rules: Last Inspection; Mechanical Damage; Corrosion; Marine Growth; Scour; Flooded Member; Unprotected Appurtenances. Platform Loading Susceptibility Rules: Deck Loading; Wave in Deck; Additional Appurtenances; Fatigue. PCSB has in recent years conducted ultimate strength assessments for the majority of its fleet and this has proven to be a very useful tool to quantitatively establish a measure of the platform s likelihood of structural failure. However, there are a number of likelihood factors that are overridden by the RSR value itself and included in the ultimate strength assessments (see Table 2). For the semi-quantitative approach to risk evaluation, the use of the RSR can be used to re-evaluate the risk levels, and thus the inspection intervals may be extended to longer durations. This has the added advantage of developing a more robust long-term planning approach to resource management, budgetary constraints and life safety implications by reducing underwater activity over the life cycle of the asset. Table 3 provides some details on the risk classification for three structures where the RSR override approach was employed. For Platform A its risk levels have been reclassified to 1E from 2E, thus extending its underwater inspection interval from 5 years to 7 years. Similarly, Table 2. Likelihood Factor Likelihood factors with RSR override. Platform Vintage Number of Legs and Bracing System Grouted Piles Shallow Gas Last Inspection Mechanical Damage Corrosion (Anode Depletion) Flooded Members Marine Growth Thickness Scour Depth Unprotected Appurtenances Deck Load Deck Elevation (Wave in Deck) Appurtenance Load Fatigue RSR Override? No No No No Table 3. Risk levels and inspection intervals with and without the RSR override. Qualitative Approach Semi-Quantitative (using RSR Override) Risk Inspection Risk Inspection Platform Level Interval (years) Level Interval (years) A 2E 5 1E 7 B 3C 7 2C 10 C 4C 5 3C 7 for Platform B, the risk level is now 2C compared to 3C, with inspection intervals at a 10-year frequency compared to 7 years, while Platform C now has a risk level of 3C from 4C and inspection intervals have extended from 5 years to 7 years. Fatigue assessments Offshore steel jacket structures consist primarily of tubular joints, which are formed by the intersection of brace and chord members. The complex geometry at joint intersections results in stress concentrations of varying intensity. Wave loading causes fluctuations in stresses around the intersections, potentially leading to fatigue-induced crack growth and ultimately failure. Fatigue failure is defined as the number of stress cycles, a function of time, needed to reach a predefined failure criterion. Fatigue failure analysis is not a rigorous science and the idealizations and approximations inherent in it prevent the calculation of a value for absolute fatigue. Nevertheless, the prediction of the point of absolute fatigue is essential for the life-cycle management of an offshore installation. Local joint flexibility The flexibility of a tubular joint is considered to be the difference between the displacements at the member

7 66 N.W. Nichols and R. Khan ends of a joint modelled with beam elements and a joint modelled with shell elements, at unit load. It is conventionally assumed in structural analysis that tubular joints can effectively be represented as a discrete point to which members are rigidly attached. Therefore, in the traditional design (using computer-based analyses) of fixed offshore structures, the effect of joint flexibility is generally not considered. However, in the limited studies undertaken, the inclusion of joint flexibility in the analysis of offshore structures has identified an effect on both the global static and dynamic responses of the structure. The inclusion of local joint flexibility in the global structural analysis of offshore structures can lead to a significant redistribution of calculated member-end forces and moments, which in turn may result in lesser structural demands on the tubular joints. In particular, joints to which relatively short members are attached, as in the case of horizontal conductor bracing, tend to benefit the most. In the reanalysis of existing structures, accounting for local joint flexibility may obviate the need of costly, underwater strengthening schemes (Buitrago et al. 1993; MSL Engineering 2001; Dier & Hellan 2002). A conventional, rigid-joint,spectral fatigue analysis has been carried out for a typical PCSB platform approaching the end of its operating life (Figure 7). The fatigue analysis was repeated, with local joint flexibility explicitly modelled in the analysis (Nichols et al. 2006). The resulting fatigue life predictions were then compared with the rigid-joint analysis results and the inspection results. The results of the spectral fatigue analysis with local joint flexibility implemented show that, in all cases, the fatigue-life predictions increased. Figure 8 shows the number of joints that would be considered in an underwater inspection campaign. The categories identified below have been generated to group the inspected joints in order of predicted fatigue life. The categories have been created solely for the purposes of assessing the impact of local joint flexibility on what might be considered a rational inspection prioritization: Figure 7. Illustration showing importance of local joint flexibility. Figure 8. A comparison of rigid and flexible joint fatigue inspection categorizations. Source: Nichols et al. (2006). Category 1: Highest Priority, predicted fatigue life of less than 10 years. Category 2: High Priority, predicted fatigue life of between 10 and 30 years. Category 3: Medium Priority, predicted fatigue life of 30 to 60 years. Category 4: Inspection not justified on the basis of fatigue assessment. The example platform has been installed and operational for 30 years; assuming a reasonable level of reliability in the fatigue life predictions, some of the Category 1 joints should have developed crack indications. A smaller proportion of the Category 2 joints may also have some visible indications. Assuming that Category 1 and Category 2 joints are included in the periodic inspections, the implementation of local joint flexibility in the fatigue analysis reduces the requirement for underwater inspection by approximately 70% (see Figure 8). Data PCSB has also developed data trending exercises and site-specific studies such as a marine-growth sensitivity study. The principal objective of the study was to determine if trends in marine growth can be established that may support a change in the present design and/or assessment philosophy for PCSB domestic operations. To achieve this goal, the project has collated and reviewed the wealth of marine-growth survey data that has been collected by underwater inspection contractors. The data was retrieved from PCSB databases and actual inspection reports, which span over 20 years of platform inspections. In 2006, as a result of the tsunami event, PCSB engaged D Appolonia Consultants to perform site-specific seismic studies in order to determine the nature of seismic activity for platforms in the Sarawak Operations (SKO), Sabah Operations (SBO) and Western Malaysia regions. Seismic

8 Journal of Marine Engineering & Technology 67 zoning maps were developed for the region, which is now being considered as an integral part of seismic assessments for extreme level earthquakes (ELEs) and abnormal level earthquakes (ALEs) occurring within the region. As with the marine-growth study, PCSB has adopted this study within their technical practices to ensure that both designers and integrity engineers adopt the findings in the structural assessment of new and ageing offshore platforms. New technologies Strengthening, modification and repair (SMR) relates to improving a platform s ultimate strength. For ageing structures, PCSB has exploited and engaged new technologies within the offshore industry. In the early 2000s, MSL Consultants managed two joint industry projects (JIPs) on behalf of various global operators: Assessment of Repair for Ageing and Damaged Structures (Mineral Management Service 2004) and Guidelines for the Definition and Reporting of Significant Damage of Fixed Steel Structures (Mineral Management Service 2003). These JIPs had a fundamental impact on how assessments and SMR techniques are viewed in the offshore structures industry, with key findings being adopted in the recently published API RP 2SIM (API 2014). PCSB has developed an SMR toolkit which allows the user (integrity engineer/manager) to quickly and efficiently determine all available SMR options for both jacket and topsides structures. The SMR toolkit is fully integrated into PCSB s current version of SICS. PCSB developed a five-step process for both jacket (Figure 9) and topside structures which aids in the selection of suitable SMR technologies for a range of applications based on several key pieces of user-input information. The toolkit not only provides a single recommended option for the given requirements; rather it provides a number of recommended options for strengthening and repair schemes. The toolkit also provides cost estimations for the chosen schemes, which is ideal for facilitating the long-term planning of resource allocation and scheduling. For offshore structures that are ageing, exhibit dynamically sensitive behaviour or are subjected to the effects of shallow gas or subsidence, online monitoring (OLM) systems have been installed to better understand the performance of these structures through the changes in the natural frequency of the platform. As of 2013, a total of 19 structures have OLM systems installed, that is, 9, 8 and 2 structures in Regions A, B and C respectively. Of these 19, 4 are guyed wire caissons, 3 of which guyed wire caissons are in Region A, with 1 in Region C. This technology has proven quite useful for PCSB when assessing particular structures. Platforms D and E are located within an area of shallow gas while Platform F is a guyed wire caisson with little redundancy if the loss of one cable occurs. Measured results from the OLM shows that Figure 9. Five-step workflow for SMR jacket module in PCSB SMR toolkit. Table 4. FEA results vs OLM measured results. Natural Period (s) Triggering Platform Criteria FEA OLM % difference D Shallow Gas E Shallow Gas F Guyed Wire Caisson Source: Nichols and Harif (2014). for the shallow gas phenomenon, the finite element analysis (FEA) results over-predict jacket behaviour, while for guyed wire caissons FEA results under-predict the behaviour of this structure (Table 4).

9 68 N.W. Nichols and R. Khan With this understanding of structural behaviour, OLM results can be used to develop more robust mitigation and maintenance plans, as well as benchmarking FEA work appropriately to ensure that analytical and assessment work is carried out in a way that represents real structural behaviour as closely as possible. Strategy The SIM strategy defines the overall inspection philosophy and mitigation philosophy for the platform or fleet of platforms. It may also define any facility expansion opportunities and/or limits. Strategies are also developed for any mitigation and controlling measures that should be put in place to assure integrity (API 2000, 2014; ISO2007). The strategies should include general descriptions of the systems, records of any known anomalies, the roles and responsibilities of the personnel concerned, full inspection requirements and the corresponding inspection programmes. As such PCSB has adopted an RBUI approach. The principal purpose for carrying out RBUI planning on a platform structure is to control the risk level over the intended service life of the structure and initiate costeffective remedial actions when they are found to be necessary. The RBUI strategy allows a better focus of inspection resources on platforms that will benefit from more frequent inspections, and has been developed to satisfy regulatory requirements. Knowledge from the evaluation of previous below-water inspection data for the PCSB fleet is the single-most important contributor to the development of the inspection strategy. Other essential considerations in the development of the strategy include risk-ranking the platform, its present condition, frequency of previous inspections, trend analysis and the knowledge gained from performing ultimate strength assessments. Evaluation results may suggest a strategy of monitoring or intervention for SMR. Depending on the circumstances, these changes in strategy may or may not affect future inspection frequency. Programme Throughout the life of the facility, new data is collected through periodic inspections as a result of accidental events, planned modifications and additions to the platform. Data may also emanate from technology development projects or in-service experience of similar structures or components within industry (API 2000, 2014; ISO 2007). These data are subject to qualified engineering evaluations which assess the impact they have on the existing SIM strategy for the platform. If necessary, the programme is adjusted in accordance with the change in strategy, which might mean, for example, that the inspection becomes more detailed, perhaps moving from visual to non-destructive testing survey techniques or vice versa. Performance-based design (PBD) approach Through extensive data collection, specialist studies, trending exercises, assessment engineering techniques and employing new technologies, PCSB has collected and catalogued a substantial database of structural performance of their offshore fleet. With this dataset it is possible to understand how structures will behave over time in the local Malaysian environment. Using this dataset, PCSB proposes adopting a performance-based design (PBD) approach to the concept and design of their new offshore structures. Existing industry design standards for offshore facilities (with some exceptions relating to designs for accidental loading) are component-based; therefore, the strength of the structure is defined by the strength of the weakest component. No benefit is taken from load redistribution, a feature that is largely responsible for the inherent robustness and damage tolerance of offshore platforms (Westlake et al. 2006). A PBD approach allows engineers to implement proven technologies and take advantage of the additional capacity that exists, where doing so can be demonstrated to achieve platform performance consistent with the selected performance objectives. The many lessons arising from previous designs and operational experience can be applied to future PBD. By making the design process open to the adoption of past service experience, resulting in new analytical tools and technological advancements, engineers will be able to better optimize facilities to deliver increased life cycles and enhanced performance goals more closely aligned with PCSB financial targets and Health and Safety Executive (HSE) expectations. Conclusions This paper has presented the PCSB SIMS implementation, which is compliant with industry codes and standards such as the API RP for the Planning, Designing and Constructing of Fixed Offshore Platforms (API RP 2A; API 2000), the API RP 2SIM (API 2014) and ISO 19902:2007 (ISO 2007). The SIMS implementation is a continuous process and requires a complete understanding of the processes of data, evaluation, strategy and programme as they relate to the continuous improvement and risk-reduction measures required for an ageing fleet of offshore platforms. For the design of offshore platforms in the future, it is recommended that a PBD approach be adopted at the concept stage in order to incorporate the lessons learnt, trending data, inspection findings and new technologies gathered over the years of operating in Malaysian waters, in order to ensure FFP for the platform life expectancy and life extension. Acknowledgements The authors would like to thank the management of PETRONAS Carigali Snd Bhd for their kind permission to present this paper.

10 Journal of Marine Engineering & Technology 69 Disclosure statement No potential conflict of interest was reported by the authors. References [API] American Petroleum Institute Recommended Practice for the Planning, designing and constructing fixed offshore platforms. 21st Edition. [API] American Petroleum Institute API RP2 SIM Recommended practice for the structural integrity management of fixed offshore structures. 1st Edition. Buitrago J, Healy BE, Chang TY Local joint flexibility of tubular joints, Offshore Mechanics and Arctic Engineering Conference, OMAE, Glasgow. Dier AF, Hellan O A non-linear tubular joint response for pushover analysis. Proceedings of OMAE st International Conference on Offshore Mechanics and Arctic Engineering. [ISO] International Standards Organization ISO 19902: 2007: Petroleum and natural gas industries Fixed steel offshore structures. 1st Edition. Mineral Management Service. Jan JIP on the Definition and reporting of significant damage for offshore platforms. MSL Engineering Ltd. DOC REF CH161R001 Rev 1. Mineral Management Service. Nov JIP on the Assessment of repair techniques for ageing or damage structures. MSL Engineering Ltd. DOC REF C357R001 Rev 1. Mitaheri M, et al Effect of joint flexibility on overall behavior of jacket type offshore platforms. American Journal of Engineering and Applied Sciences. 2(1): MSL Engineering Effects of local joint flexibility on the reliability of fatigue life estimates and inspection planning Health and Safety Executive. Offshore Technological Report 2001/056. Nichols NW, et al Managing structural integrity for aging platform. Adelaide Australia: Proceedings for the Society of Petroleum Engineers (SPE). Nichols NW, Harif HM Use of platform response measurements from On-Line Monitoring (OLM) system to verify the effectiveness of structural repairs & managing on-going structural integrity. OTC Asia Paper MS. Nichols NW, Khan R, et al Risk based underwater inspection within PETRONAS operations. Proceedings to the Conference of Marine, Shipping and Offshore Structures. Glasgow Aug O Connor PE, et al Structural Integrity Management (SIM) of offshore facilities. Paper OTC Offshore Technological Conference. Puskar F, DeFranco S, O Connor P, Bucknell J, Digre K API RP 2SIM: Recommended practice for structural integrity management. Proceedings of the Offshore Technological Conference (OTC) Westlake H, Puskar F, et al The role of ultimate strength assessments in the Structural Integrity Management (SIM) of Offshore Structures, OTC