Fatigue Analysis and Risk Based Inspection Planning for Life Extension of Fixed Offshore Platforms

2005 ◽  
Author(s):  
Michael Havbro Faber ◽  
Daniel Straub ◽  
Partha Chakrabarti ◽  
Ibrahim Abu-Odeh ◽  
Juan de Dios de la O. Rami´rez
Keyword(s):  
Life Extension ◽  
Present Condition ◽  
Offshore Platforms ◽  
Inspection Planning ◽  
Standard Code ◽  
Jacket Structures ◽  
Service Life Extension ◽  
Inspection And Maintenance ◽  
Cost Efficient ◽  
Recent Project

The present paper reports on the application of Risk Based Inspection (RBI) planning as conducted on a recent project for Pemex Exploracio´n y Produccio´n. The project considers the engineering assessments required for a possible service life extension of 23 fixed steel jacket structures located in the Bay of Campeche. In the project RBI plays an important role as this quantifies the relation between the overall performances of the platforms in their present condition with their future deterioration and facilitates the identification of strategies for cost efficient condition control by means of targeted inspection and maintenance activities and if necessary repair and strengthening. For the purpose of facilitating efficient RBI for larger number of structures of more or less similar characteristics, a generic scheme for RBI is pursued. The specific aspects of the generic RBI for the considered group of structures in regard to risk acceptance criteria, modeling of inspection qualities and the probabilistic fatigue and fracture mechanical modeling are outlined. Finally also a study is reported whereby the benefit of the RBI approach is assessed as a means of risk control in comparison to standard code based requirement for inspection planning.

Residual Strength of Damaged Jacket Type Offshore Platform and the Effects of Local Repair

2009 ◽  
Author(s):  
Banafsheh Naderi ◽  
A. A. Aghakouchak ◽  
Madhi Mirzaei
Keyword(s):  
Residual Strength ◽  
Pushover Analysis ◽  
Life Extension ◽  
Design Stage ◽  
Offshore Platforms ◽  
Environmental Loads ◽  
Existing Structures ◽  
Service Life Extension ◽  
The Persian Gulf ◽  
Reserve Strength

In the design of offshore platforms, the aim is to have a characteristic capacity higher than the characteristic environmental loads with a return period of typically 100 years multiplied by some partial safety factors for loads and resistance. Simplified of the assumptions is inherent in the derivation of force components. In addition, any potential of the structure for yielding and load redistribution, giving the inherent “reserve capacity” is neglected in the design stage. Reserve strength is commonly defined as the ability of a structure to sustain loads in excess of the design value. The frame action and system redundancy are implicit sources of reserve strength which are not generally controlled or quantified in design. Reserve strength should not be solely considered as overdesigning of structures. However, there are situations where such reserve strength may be demonstrated, for example in case of reassessment of existing structures, e.g. improved exploitation methods or increased petroleum service may call for service life extension, the characteristic loads may increase due to installation of new modules. It is also important that a structure can sustain damage without collapse so that it has sufficient remaining or “residual” strength. Such damage may result from extreme overloading of structures as a whole, or from localized damage such as ship impact or dropped object. This paper is concerned with the reserve strength of a jacket evaluated by pushover analysis in intact and damaged conditions. The tested structure is a PP (Production Platform) jacket, a K-braced space frame, located in the Persian Gulf. The loading on the structure contains functional and environmental loads. The test is carried out under displacement control. The influence of damages including “Local Denting” and “Out of Straightness” on the critical members is investigated, and then reassessment and Probabilistic Collapse Analysis of the platform are considered to illustrate the mechanisms of failure caused by each damage The effects of some repair scenarios is investigated too.

Field Implementation of RBI for Jacket Structures

2003 ◽  
Author(s):  
Michael H. Faber ◽  
Daniel Straub ◽  
John D. So̸rensen ◽  
Jesper Tychsen
Keyword(s):  
Sensitivity Analysis ◽  
Data Base ◽  
Stress Ratio ◽  
Oil And Gas ◽  
Inspection Planning ◽  
The North ◽  
Large Numbers ◽  
Structural Details ◽  
Jacket Structures ◽  
The North Sea

The present paper first gives a brief outline of the simplified and generic approach to reliability and risk based inspection planning and thereafter sets focus on a recent application of the methodology for planning of in-service NDT inspections of the fixed offshore steel jacket structures in the DUC concession area in the Danish part of the North-Sea. The platforms are operated by Maersk Oil and Gas on behalf of DUC partners A.P. Mo̸ller, Shell and Texaco. The study includes a sensitivity analysis performed for the identification of relevant generic parameters such as the bending to membrane stress ratio, the design fatigue life and the material thickness. Based on the results of the sensitivity analysis a significant number of inspection plans were computed for fixed generic parameters (pre-defined generic plans) and a data-base named iPlan was developed from which inspection plans may be obtained by interpolation between the pre-defined generic plans. The iPlan data-base facilitates the straightforward production of large numbers of inspection plans for structural details subject to fatigue deterioration. In the paper the application of the generic inspection plan database iPlan is finally illustrated on an example.

Evaluation of Residual Life of Existing Offshore Platforms in Western Offshore, India

2021 ◽  
Author(s):  
A. Renugadevi ◽  
S. Nallayarasu ◽  
S. Karunanithi
Keyword(s):  
Residual Life ◽  
Probability Of Failure ◽  
Oil Field ◽  
Life Extension ◽  
Offshore Platforms ◽  
Strength Assessment ◽  
Encounter Probability ◽  
Reliability Method ◽  
Reserve Strength ◽  
Extension Period

Abstract Western offshore oil field in India has nearly 300 offshore platforms for oil and gas exploration, of which almost 50% of platforms have outlived their life. Life extension of these platforms has become essential for further production activities. In many cases, design level analyses combined with ultimate strength assessment, life extension has been granted. However, risk-based assessment based on the probability of failure based on available reserve strength linked to additional life extension could be a logical method. The Reserve Strength Ratio (RSR) is defined as a ratio of reserve capacity of the jacket structure and the design level environmental loads (1 year or 5year or 10 year or 100-year return period). The encounter probability of these design storms for the life extension period has been established probability for the extension period has been used as a threshold to determining the required RSR using the probability of collapse. For the present study, four typical aged wellhead platforms with different water depths are selected, and RSR is evaluated by carrying out push over analysis. The Monte Carlo Simulation method is used to generate the statistical values of RSR. The probability of failure is then calculated by First Order Reliability Method (FORM) using MATLAB for different RSR values. Reassessment criteria for the existing offshore platforms have been described from the reliability analysis results based on probability failure and encounter probability.

Initial Implementation of IHI Zone Logic Technology at Philadelphia Naval Shipyard

1989 ◽  
Vol 5 (02) ◽  
pp. 79-89
Author(s):  
Koichi Baba ◽  
Takao Wada ◽  
Soichi Kondo ◽  
M. S. O'Hare ◽  
James C. Schaff
Keyword(s):  
Service Life ◽  
Life Extension ◽  
Initial Application ◽  
Initial Implementation ◽  
Late Fall ◽  
The Future ◽  
Service Life Extension ◽  
Extension Program ◽  
Technical Services

Philadelphia Naval Shipyard's application of zone logic to ship overhaul is neither small nor isolated. PNSY started its implementation of zone logic in the late fall of 1986, targeting the Service Life Extension Program (SLEP) for USS Kitty Hawk (CV-63) as the initial application. The technical services of Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI), Japan were contracted to assist in this transition. This implementation on the Kitty Hawk is not a trial effort but involves about one third of the production man-days and covers over one half of the compartments on the ship. The actual SLEP production work on Kitty Hawk began in January 1988. Even though it is early in the three-year SLEP, zone logic already is proving its worth. This paper explains the zone logic methods and methodology applied at PNSY on Kitty Hawk. It also discusses the future of zone logic at PNSY and its continued application.

scholarly journals Sensitivity of Service Life Extension and CO2 Emission due to Repairs by Silane Treatment Applied on Concrete Structures under Time-Dependent Chloride Attack

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Aruz Petcherdchoo
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Treatment Strategies ◽  
Time Dependent ◽  
Life Extension ◽  
Silane Treatment ◽  
Application Time ◽  
Free Service ◽  
Chloride Attack ◽  
Service Life Extension

This paper presents sensitivity of service life extension and CO2 emission due to silane (alkyltriethoxysilane) treatment on concrete structures under time-dependent chloride attack. The service life is predicted by the Crank–Nicolson-based finite difference approach for avoiding the complexity in solving Fick’s second law. The complexity occurs due to time-dependent chloride attack and nonconstant diffusion coefficient of concrete with silane treatment. At the application time of silane treatment, the cumulative CO2 emission is assessed. The effectiveness of silane treatment is defined as the ratio of the service life extension to the cumulative CO2 emission assessed within the corrosion-free service life. The service life extension is defined as the difference between corrosion-free service life of concrete structures without and with time-based application of silane treatment. From the study, the diffusion of chlorides in concrete with silane treatment is found to be retarded. In comparison, the strategy without deterioration of silanes during effective duration is more suitable for service life extension but less effective than that with deterioration. In the sensitivity analysis, there are up to eight parameters to be determined. The service life of concrete structures without silane treatment is most sensitive to the water-to-cement ratio and the threshold depth of concrete structures. Considering only five parameters in silane treatment strategies, the service life is most sensitive to the first application time of silane treatment. The cumulative CO2 emission is most sensitive to either the first application time of silane treatment or the amount of CO2 emission per application.

Service Life Extension and CO2 Emission due to Silane Treatment on Chloride-Exposed Concrete Structures

2017 ◽  
Vol 728 ◽  
pp. 384-389
Author(s):  
Aruz Petcherdchoo ◽  
Chotima Ongsopapong
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Treatment Strategies ◽  
Life Extension ◽  
Chloride Diffusion ◽  
Silane Treatment ◽  
Free Service ◽  
Before And After ◽  
Chloride Attack ◽  
Service Life Extension

This study presents assessment of the environmental impact in terms of the CO2 due to silane treatment for extending corrosion-free service life of concrete structures under chloride attack. To achieve this, there are two issues to be addressed; prediction of corrosion-free service life extension, and assessment of the amount of CO2 emission. In predicting the corrosion-free service life extension, the behaviors of chloride diffusion before and after time-based silane treatment are considered. Then, the cumulative CO2 due to silane treatment is accordingly calculated. The ratio of the corrosion-free service life extension to the cumulative CO2 is defined as the effectiveness of silane treatment, and used to compare different silane treatment strategies.

RISK-BASED MANAGEMENT OF STRUCTURAL INTEGRITY FOR BASS STRAIT PLATFORMS

2001 ◽  
Vol 41 (1) ◽  
pp. 727
Author(s):  
A.D. Barton
Keyword(s):  
Structural Integrity ◽  
Risk Model ◽  
Offshore Platforms ◽  
Integrity Assessment ◽  
Inspection And Maintenance ◽  
Tubular Joint ◽  
Maintenance Activities ◽  
Consistent Basis ◽  
Inspection Data ◽  
Inspection Techniques

Esso Australia Pty Ltd (Esso) has embraced the framework of risk management to improve the focus and priorities of its inspection and maintenance activities. Structural integrity is one of the disciplines that has adopted a risk-based approach to inspection and integrity assessment and this has been applied to Esso/BHP’s 18 offshore platforms located in Bass Strait.The paper provides a discussion of the issues faced in the management of structural integrity of offshore platforms which lead to the development of a risk-based inspection (RBI) strategy. RBI is applied to improve the prediction of the structures’ condition and provides a consistent basis for continued improvement in the future. The RBI model generates targeted inspection workscopes for each platform that, coupled with the implementation of appropriate inspection techniques, ensure that the integrity of the platforms can be managed with greater confidence and at lower cost.The RBI approach has resulted in reduced focus on traditional areas of uncertainty such as fatigue of tubular joints, and increased focus on secondary structures, for example service caissons. This shift in focus is made possible by building into the risk model a calibration process that considers previous inspection data. A key component of this calibration is a new method developed to calibrate tubular joint fatigue lives.

Development of a New Methodology for Riser Deformed Shape Prediction/Monitoring

2018 ◽  
Author(s):  
Junho Choi ◽  
Joseph Moo-Hyun Kim
Keyword(s):  
Oil And Gas ◽  
Cost Effective ◽  
Evaluation Methods ◽  
Gas Production ◽  
Life Extension ◽  
Monitoring Method ◽  
Oil And Gas Production ◽  
Shape Prediction ◽  
Structural Evaluation ◽  
Service Life Extension

Ocean environmental conditions, such as waves, winds, and currents, are getting harsher due to climate change. This means that oil and gas production platforms in the ocean may experience unexpectedly large environmental loads bigger than previous design loads. Also, many platforms are reaching the end of their design lives. Ensuring riser integrity is one of the most important issues for platform safety and service-life extension. Currently, monitoring sensors are deployed on risers, and structural evaluation methods are utilized to examine riser integrity. However, there are some limitations to the structural evaluation methods. Furthermore, platform operators continue to seek for more direct and cost-effective riser monitoring method due to the low price of oil. In this study, the MultiSensor Fusion (MSF) system is proposed to surmount technical and economic obstacles in real-time riser-monitoring technology. The MSF system is validated for TLP (tension-leg platform) risers by using numerical sensors and numerical-simulation tools.

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