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.

Structural Integrity Assessment of Steam Generator Tubes Using a New EPRI Statistical Approach

2002 ◽  
Author(s):  
Carlos Alexandre de Jesus Miranda ◽  
Miguel Mattar Neto
Keyword(s):  
Steam Generator ◽  
Wall Thickness ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Tube Wall ◽  
New Approach ◽  
Inconel 600 ◽  
Integrity Assessment ◽  
Tube Wall Thickness ◽  
Uniform Tube

A fundamental step in tube plugging management of a Steam Generator (SG), in a Nuclear Power Plant (NPP), is the tube structural integrity evaluation. The degradation of SG tubes may be considered one of the most serious problems found in PWRs operation, mainly when the tube material is the Inconel 600. The first repair criterion was based on the degradation mode where a uniform tube wall thickness corrosion thinning occurred. Thus, a requirement of a maximum depth of 40% of the tube wall thickness was imposed for any type of tube damage. A new approach considers different defects arising from different degradation modes, which comes from the in-service inspections (NDE) and how to consider the involved uncertainties. It is based on experimental results, using statistics to consider the involved uncertainties, to assess structural limits of PWR SG tubes. In any case, the obtained results, critical defect dimensions, are within the regulatory limits. In this paper this new approach will be discussed and it will be applied to two cases (two defects) using typical data of SG tubes of one Westinghouse NPP. The obtained results are compared with ‘historical’ approaches and some comments are addressed from the results and their comparison.

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.

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.

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.

Integrity Assessment, Repair and Verification of Fitness for Service of a Damaged Offshore Platform Radio Tower

2011 ◽  
Author(s):  
Abe Nezamian ◽  
Robert J. Nicolson
Keyword(s):  
Structural Integrity ◽  
Oil And Gas ◽  
Integrated Approach ◽  
Offshore Structures ◽  
Thickness Measurement ◽  
Initial Assessment ◽  
Structural Members ◽  
Minimum Thickness ◽  
Acceptance Criteria ◽  
Integrity Assessment

The maintenance of structural integrity is a significant consideration in the safety management of offshore installations. This paper presents an integrated approach for fitness-for-service evaluation of a deteriorating offshore radio tower structure. The approach is intended to assist engineers in assessing the overall fitness and survivability of aged offshore structures. A 43 m tall radio tower on an oil and gas platform located offshore Australia was reported with areas of heavy and medium corrosion of structural members. Severe corrosion in one leg of the radio tower had caused an obvious hole (extensive damage) through the leg at approximately 36m above the main deck and raised structural integrity concerns with the tower. The platform had been shut down due to concerns of a possible collapse of the tower. An assessment/repair program was developed to assure the short term integrity of the tower with minimal repair works. The integrity of the critically damaged leg had been temporarily restored using a clamped sleeve repair to allow progress with the inspection / thickness measurement of the corroded areas of the tower. As part of the fitness-for-service assessment, the minimum thickness acceptance criteria for the suspected corroded structural members were developed to enable initial assessment of the measured remaining wall thicknesses of the corroded member. Fitness for service integrity assessment requirements were developed to assess the locations that did not meet the minimum thickness criteria. The integrity requirements were adopted based on the average measured wall thickness, sensitivity structural analyses for reduced wind speeds for shorter life spans, and stability/survival assessment of the tower. An inspection program was carried out for the suspected locations and any additional locations identified during the inspection process. The inspection measurements were assessed against the fitness-for-service criteria. Where the measurements indicated that members did not meet the acceptance criteria temporary repairs were specified. Consequently, the tower fitness-for-service was found sustainable for up to 12 months until a more permanent repair or replacement of the tower could be completed, thus enabling the platform to resume normal operations.

Computed Tomography Wall Thickness Inspection to Support Gas Turbine Blade Life Extension

2021 ◽  
Author(s):  
Scott Hastie ◽  
Anthony Chan ◽  
Kevin Wiens ◽  
Doug Nagy ◽  
Robert Tollett ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Gas Turbine ◽  
Wall Thickness ◽  
Measurement Techniques ◽  
Turbine Blades ◽  
Thickness Measurement ◽  
Life Extension ◽  
Cumulative Number ◽  
Gas Turbine Blades ◽  
Thickness Measurements

Abstract The inclusion of Full Solution Rejuvenation (FSR®) in repairs of flight and aero-derivative gas turbine blades has shifted the primary cause for blade retirement from creep life consumption which is a function of service hours to primarily geometric limitations that are more governed by the cumulative number of repair cycles. For internally cooled components, one of the most significant causes for rejection is the remaining wall thickness of the airfoil. Operating blades with under-sized wall thickness can reduce the load-bearing capability and can increase the stresses that develop under transient thermal conditions found in operation. Typically, ultrasonic wall thickness measurement techniques are used during repair processing for determining remaining wall thickness on components but a number of limitations to obtaining accurate results with this process have been identified. Computed Tomography (CT) wall thickness inspection has addressed these limitations and become an important tool for extending the life of components beyond the typical OEM limits during repair. Entirely from the CT equipment user’s perspective, this paper explores a number of technical findings in the development of a highly accurate CT wall thickness inspection process for flight and aero-derivative gas turbine blades for utilization during repair after one or more service intervals. The importance of the accuracy of these wall thickness measurements is to ensure undersized blades are rejected and blades above the minimum wall thickness are accepted. Reducing uncertainty in the wall thickness measurements allows reconsideration of the acceptance limit and can result in more repairable blades returned for full service intervals. The target accuracy for measurements process was .002”. The findings described include aspects of equipment configuration, process parameters for the initial CT scanning, post-processing and interpretation, results validation specific to the component being measured and process limitations encountered.

Structural Integrity Assessment and Control of Ageing Onshore and Offshore Structures

2017 ◽  
pp. 445-476
Author(s):  
R.M. Chandima Ratnayake ◽  
S.M. Samindi Samarakoon
Keyword(s):  
Structural Integrity ◽  
Offshore Structures ◽  
Life Extension ◽  
Current Status ◽  
Petroleum Production ◽  
Integrity Assessment ◽  
Hazardous Environments ◽  
Highly Sensitive ◽  
International Regulations ◽  
And Control

Structural integrity assessment and control (SIA & C) are vital for existing ageing as well as newly built offshore and onshore structures. The SIA & C becomes highly sensitive to interventions under a potential loss of structural integrity (SI) especially when there are inherent constraints present in carrying out engineering work in hazardous environments such as petroleum production and process facilities (P&PFs). The challenges have been further exacerbated by the constantly ageing onshore and offshore structures whilst it is the necessity of carrying out life extension at the verge of their design service lives. Local and international regulations demand the implementation of appropriate strengthening, modification and repair (SMR) plans when significant changes in the SI have been revealed. This chapter presents potential simulation approaches that are possible to utilize for SIA&C in relation to prioritization as well as evaluation of current status of a SIA&C organization.

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