Structural Integrity Assessment of Aging Fixed Steel Offshore Jacket Platforms: A Persian Gulf Case Study

2013 ◽  
Author(s):  
Hamid Golpour ◽  
Mostafa Zeinoddini ◽  
Hadi Khalili ◽  
Ali Golbaz ◽  
Yashar Yaghubi ◽  
...  
Keyword(s):  
Persian Gulf ◽  
Structural Model ◽  
Structural Integrity ◽  
Global Analysis ◽  
Life Extension ◽  
Offshore Platforms ◽  
Perspective View ◽  
Integrity Assessment ◽  
Fit For Purpose

The existing knowledge on the structural integrity assessment of offshore platforms may benefit from case studies on the life extension evaluations of aging structures. This paper presents a case study for the structural integrity assessment of an existing 8 legged aging drilling platform located in the Persian Gulf. The platform is now 42 years old and the objective of the study is to check its fit for purpose for a life extension of 25 years beyond 2012. The structural model is based on the best estimates of the existing conditions of the platform. A number of analysis approach such as i) assessment based on the previous exposures, ii) linear (elastic), iii) equivalent linear (or the linear global analysis with local overload considerations), and iv) non-linear analysis methods have been used to estimate the structural integrity of the platform. The paper provides further background, clarifications and proposed updates to API-RP 2A-Section 17. The paper is divided into three parts. Section 1 is a discussion on the background of the previous assessment study and perspective view on why the case study platform needs to be assessed. Section 2 and Section 3 include the finding of the code-noncompliance points of the platform based on the recommendations of API RP 2A-2007. Section 4 presents the remedy actions recommended for the fit for purpose of the platform.

scholarly journals Residual Life Assessment of Electricity Pylons – A Case Study

2009 ◽  
Vol 413-414 ◽  
pp. 219-228 ◽  
Author(s):  
John R. Maguire
Keyword(s):  
Structural Integrity ◽  
Residual Life ◽  
Life Assessment ◽  
Original Design ◽  
Integrity Assessment ◽  
Specific Safety ◽  
Residual Life Assessment ◽  
Independent Assessment ◽  
Overhead Power Line

This case study describes a structural integrity assessment of a 220 kV overhead power line. The line comprises 70 pylons over a distance of approximately 30 km, predominantly in a valley location. The pylons are spaced at intervals of approximately 400 m and each pylon is approximately 32 m in height. The line was originally constructed in the 1950’s, approximately 50 years prior to the requested structural integrity assessment. This paper describes the independent assessment that was carried out. The review established site-specific safety factors at the time of original design and construction; at the time of the review (2007), accounting for the possible presence of the “Thomasstahl” steel; and in the future, at the anticipated end of pylon life (in 2012).

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.

AE Damage Assessment in the Bell Tower of the Turin Cathedral

2019 ◽  
Vol 817 ◽  
pp. 579-585
Author(s):  
Amedeo Manuello ◽  
Davide Masera ◽  
Alberto Carpinteri
Keyword(s):  
Damage Assessment ◽  
Structural Integrity ◽  
Cumulative Number ◽  
Height Ratio ◽  
Value Analysis ◽  
Integrity Assessment ◽  
Bell Tower ◽  
The Stability ◽  
Good Agreement

Historical churches, masonry towers and bell towers are structures subjected to high risk, due to their age, elevation and low base area on height ratio. In this work, an innovative monitoring technique for structural integrity assessment of historical buildings is reported. At the same time, the emblematic case study of the Turin Cathedral Bell tower is presented. The damage evolution in the tall masonry structure is described by the evaluation of the cumulative number of AE and by different parameters able to predict the time dependence of damage. In particular, since environmental disturbances have been minimized, and instrumental noises have been filtered out. The b-value analysis shows a downward trend to values compatible with the growth of localized macro-cracks at the base of the tower. These results seem to be in good agreement with the numerical analysis. Extension to longer monitoring periods and, later, investigation of different segments are strongly recommended to assess the stability of the monument.

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.

Procedures on Fracture Toughness Estimation Safety Assessment and Life Extension for In-Service High Pressure Vessels

2004 ◽  
Author(s):  
Guohua Chen ◽  
Bonuan Chen
Keyword(s):  
Fracture Toughness ◽  
High Pressure ◽  
Safety Assessment ◽  
Structural Integrity ◽  
Pressure Vessels ◽  
Life Extension ◽  
Temper Brittleness ◽  
Integrity Assessment ◽  
Treatment Processes ◽  
Material Fracture

Based on the typical in-service high pressure vessels made of PCrNi3MoVA for producing synthetic crystal, a systematic technology of material fracture toughness estimation, structural integrity assessment, and life extension is carried out for the in-service equipment with the following aspects: macroscopically and microscopically analyzing, the tests including KIC, AKV, FATT (50%), the predicting method of fracture, system safety assessment, and the life extension technology. Some practical conclusions can be obtained from the test and analysis as follows: The main failure factors for this kind of high pressure vessels include heat treatment processes, temper brittleness, and stress corrosion; It is found that the value of FATT (50%) increased very significantly; The comparison between the test results and the predicted results of the value of KIC is also performed, and it is shown that the value of KIC of in-service equipment can be estimated by the formula presented by Barsom-Rolfe or in API 579 with the value of AKV, The test temperature is recommended at least to reach 25 C (or room temperature) for the repaired vessels; The life extension technologies are put forward for this kind of in-service super-high pressure vessels.

Optimized Inspection and Integrity Assessment of Well Conductors for Life Extension Strategic Planning

2021 ◽  
Author(s):  
Manish Srivastava ◽  
Abeer Al Ali ◽  
Govindavilas Sudhesh ◽  
Majed Ahmed Alkarbi ◽  
Mohamed Saleh Ali ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Measurement Technique ◽  
Structural Integrity ◽  
Risk Mitigation ◽  
Thickness Measurement ◽  
Life Extension ◽  
Integrity Assessment ◽  
Risk Ranking ◽  
New Findings ◽  
Inspection Techniques

Abstract Assuring integrity of offshore well Conductor is one of the challenges in the aged giant offshore fields operating with 1500+ wells. Such fields should have a robust and efficient integrity management system for inspection and assessment of well conductors through the well life cycle. Offshore well Conductors form the secondary load-bearing element in a well, primary being the surface casing. A practical approach in assessing the structural integrity of the well conductor is proposed in this paper. Wells were classifying into five subgroups; optimized Inspection and Integrity Assessment methods used to establish the structural integrity of conductors; which were evaluated and validated by a 3rd part consultant. The assessment results indicate how over-conservative assumptions in engineering assessment may mislead operators to categorize wells into higher risk. Assessment was performed utilizing various modeling software. Reliability based approach was adopted to accommodate uncertainties in data utilizing appropriate engineering judgement to tackle data gaps. Average thickness measured at discrete elevations was compared with the calculated minimum required thickness (MRT) to assess the structural integrity status of conductors. This approach helped in the decision making and planning for risk mitigation repairs. The results of optimized inspection techniques and structural assessment methodology lead to establishment of clear pattern for critical well conductors and applied to the groups to decide on maintenance strategy. The conductor wall thickness data measured from automated thickness measurement technique is matching with the measured data from manual thickness measurements. The average wall thickness at each elevation, obtained from the raw automated thickness measurement technique data to be used for assessment of the conductor. After building good confidence in the mode of failure the results indicated that manual thickness measurement technique is sufficient to assess the structural integrity of the conductors. The consultant has performed parametric studies to validate the Minimum Required Thickness (MRT) for the most onerous well in the group; by modelling the boundary conditions of conductor span between the guides, the critical water depth, well depth etc. Sensitivity studies were performed considering the environmental loading due to wind, wave, current; vortex induced vibrations, cement height behind the pipes etc. From the new findings the integrity status of the current wells risk ranking will be reviewed and if the average measured thickness is greater than the MRT then a repair program is no more required. The resource utilization was optimized based on the final outcome of the exercise. A procedure based optimized inspection techniques and structural integrity assessments to the group the well conductors resulted in the revision of risk ranking of wells, efficient maintenance planning and achieve high-cost optimization for its life extension. The outcome of the consultancy study will also substantiate our current method of conductor assessment and decision for repair based on risk-based approach. Based on the learnings this paper will be focusing on utilizing optimal inspection and assessment approach.

Engineering Criticality Assessments of Floating Offshore Platforms Based on Time Domain Structural Response Analysis

2021 ◽  
Author(s):  
Jeffrey O’Donnell ◽  
Johyun Kyoung ◽  
Sagar Samaria ◽  
Anil Sablok
Keyword(s):  
Fracture Mechanics ◽  
Time Domain ◽  
Structural Integrity ◽  
Structural Response ◽  
Life Extension ◽  
Response Analysis ◽  
Offshore Platforms ◽  
Industry Standards ◽  
Offshore Industry ◽  
Integrity Assessments

Abstract This paper presents a time-domain S-N fatigue analysis and an approach to reliable and robust engineering criticality assessments to supplement or provide an alternative to S-N fatigue assessments of offshore platform structures based on time domain structural response analysis. It also provides recommendations for industry standards to improve guidance for structural integrity assessments of offshore platforms using fracture mechanics. Demand continues to grow in the offshore industry to attain value from captured operational data for a number of purposes, including the reduction of uncertainties in structural integrity assessments during design and over the operational lifetime of floating offshore platforms. Recent advances in time domain structural analysis technology demonstrate substantially more accurate assessments of non-linear platform loadings and responses with enhanced computational efficiency. The current S-N approach for fatigue design and integrity assessments calculates a fatigue damage factor that does not address how loading occurs over time (ABS, DNVGL-RP-C203). For the present study, engineering criticality assessments (ECAs) based on fracture mechanics theory (BS 7910) are applied utilizing time-domain loading information theory. The ECA returns the smallest initial flaws that can grow to a critical size during a design lifetime, which can serve as an indicator of acceptability during design, a technical basis for in-service inspection intervals and facilitates asset integrity and life extension assessments. Critical initial flaws are calculated using the Paris Law (BS 7910) and cumulative fatigue crack growth in two ways: with and without an integrated and consistent check for fracture instability. The results are compared with those from S-N fatigue analyses and recommendations are provided.

Time-Variant Ultimate Reliability Analysis of Jacket Platforms Considering a New Probabilistic Corrosion Model for the Persian Gulf

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Hossein Gholami ◽  
Behrouz Asgarian ◽  
Saeed Asil Gharebaghi
Keyword(s):  
Reliability Analysis ◽  
Probabilistic Model ◽  
Persian Gulf ◽  
Structural Integrity ◽  
Actual Condition ◽  
Offshore Platforms ◽  
Gulf Region ◽  
Corrosion Loss ◽  
Reliability Method ◽  
The Persian Gulf

Corrosion is identified as one of the most important deterioration factors for structural integrity of offshore platforms. For reliability analysis of these platforms, a probabilistic model for prediction of long-term corrosion loss as a function of time is essential. The purpose of this study is to propose a novel model for steel corrosion of jacket platforms in the Persian Gulf region. Field measurements for members in seawater are collected and statistically analyzed to identify the probability function for corrosion loss at different times. A new probabilistic model with time-dependent parameters is suggested, based on the statistical analysis results. Application of above-mentioned model in the reliability analysis of jacket platforms is investigated by introducing a new reliability analysis framework. This framework is a general solution for probabilistic analysis of jacket platforms with several stochastic variables which can be used for the platforms with different configuration and loads. In this framework, direct analysis is performed in each stage of first-order reliability method (FORM) instead of using the response surface method which is a common approach to obtaining the required response. This framework is applied to three jackets and the annual probability of failure (Pf) over the platforms service life is computed. Comparison of results revealed that among the years beyond the platform design life, the amount of annual Pf is increased in parabolic function. Also, studying the results is illustrated that in the case of ignoring the corrosion loss as a stochastic variable, Pf is estimated 7% lower than values obtained in actual condition.

Using Vibration Measurements to Assess Structural Integrity

2009 ◽  
Author(s):  
Jared L. Black
Keyword(s):  
Structural Damage ◽  
Structural Integrity ◽  
Low Cost ◽  
Low Frequency ◽  
Vibration Monitoring ◽  
Life Extension ◽  
Structural Vibration ◽  
Natural Period ◽  
Production Area ◽  
Fit For Purpose

Structural vibration monitoring can aid in assessing offshore platform structural integrity. The method utilizes topside acceleration measurements to detect the platform’s natural periods of vibration; the periods depend only on platform weights (mass) and resistance (stiffness). If the platform’s natural period increases over time, in the absence of a change in mass, it can indicate a loss of structural integrity. The vibration survey utilizes a portable monitoring system, which includes sensitive low frequency accelerometers. The above water monitoring provides information on the below water structural integrity; the method is very low cost when compared to diver or ROV surveys. Examples of structural monitoring surveys are presented, including the following: verification that a platform remained fit for purpose despite having its foundation disturbed by a shallow gas release, two cases of using surveys to confirm jacket stiffness recovery following repairs of structural damage caused by Gulf of Mexico hurricanes and evaluation of a minimal platform after a heavy compressor was installed. The development of a natural period database is reviewed. The database, covering 95 platforms in Asian waters, was developed to reduce inspection costs and aid in life extension reviews, as well as providing quick integrity assessments should a tropical cyclone cross the production area.

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