scholarly journals Use of a Novel Resistive Strain Sensor Approach in an Experimental and Theoretical Study Concerning Large Spherical Storage Tank Structure Behavior During Its Operational Life and Pressure Tests

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 525
Author(s):  
Virgil Florescu ◽  
Stefan Mocanu ◽  
Laurentiu Rece ◽  
Robert Ursache ◽  
Nicolae Goga ◽  
...  
Keyword(s):  
Storage Tank ◽  
Structural Integrity ◽  
Real Life ◽  
Fem Simulation ◽  
Strain Sensor ◽  
Sensor Data ◽  
New Approach ◽  
Integrity Assessment ◽  
Operational Life ◽  
Large Spherical

This paper introduces a new method for the use of tensor-resistive sensors in large spherical storage tank equipment (over 12,000-mm diameters). We did an experiment with 19 petroleum or ammonia product sphere-shaped storage tanks with volumes of 1000 and 1800 cubic meters, respectively. The existing literature only contains experiments based on sensors for tanks with diameters no larger than 600 mm. Based on a number of resistive strain sensor measurements on large spherical pressurized vessels regarding structural integrity assessment, the present paper is focused on the comparison between "real-life" obtained sensor data versus finite element method (FEM) simulation results. The present paper is structured in three parts and examines innovative directions: the use of the classic tensor-resistive sensors in a new approach concerning large structural equipment; an original 3D modeling method with the help of the FEM; and conclusions with possible implications on the regulations, design, or maintenance as a result of the attempt of mutual validation of the new methods previously mentioned.

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.

scholarly journals Strain Monitoring Strategy of Deformed Membrane Cover Using Unmanned Aerial Vehicle-Assisted 3D Photogrammetry

2020 ◽  
Vol 12 (17) ◽  
pp. 2738
Author(s):  
Benjamin Steven Vien ◽  
Leslie Wong ◽  
Thomas Kuen ◽  
Frank Courtney ◽  
Jayantha Kodikara ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Structural Integrity ◽  
Health Assessment ◽  
Treatment Plant ◽  
Real Life ◽  
Aerial Images ◽  
Critical Function ◽  
Integrity Assessment ◽  
Aerial Photogrammetry ◽  
Aerial Vehicle

Large structures and high-value assets require inspection and integrity assessment methodologies that ensure maximum availability and operational capabilities. Large membranes are used as floating covers at the anaerobic wastewater lagoons of Melbourne Water’s Western Treatment Plant (WTP). A critical function of this high-value asset pertains to the harnessing of the biogas gas generated at these lagoons as well as protecting the environment from the release of odours and greenhouse gases. Therefore, a proactive inspection and efficient management strategy are required to ensure these expensive covers’ integrity and continued operation. Not only is identifying the state of stress on the floating cover crucial for its structural integrity assessment, but the development of rapid and non-contact inspections will significantly assist in determining the “real-life” performance of the cover for superior maintenance management. This study investigates a strain determination method for WTP floating cover which integrates unmanned aerial vehicle (UAV)-assisted photogrammetry with finite element analyses to determine the structural integrity of these covers. Collective aerial images were compiled to form 3D digital models of the deformed cover specimens, which were then employed in computational and statistical analyses to assess and predict the strain of the cover. The findings complement the future implementation of UAV-assisted aerial photogrammetry for structural health assessment of the large floating covers.

Structural Integrity Assessment of Weldments at High Temperature: A Proposed New Approach for R5

2008 ◽  
Author(s):  
N. G. Smith ◽  
D. W. Dean ◽  
M. P. O’Donnell
Keyword(s):  
High Temperature ◽  
Fatigue Damage ◽  
Structural Integrity ◽  
Fatigue Crack Initiation ◽  
Current Approach ◽  
Assessment Procedure ◽  
New Approach ◽  
Integrity Assessment ◽  
Creep Fatigue ◽  
Match Effect

The majority of problems associated with the structural integrity of components, particularly those operating at high temperature, are associated with welds. The R5 procedures provide a comprehensive methodology for the assessment of structures operating within the high temperature creep regime. This includes advice on the modifications required to the basic procedure to account for weldments in creep-fatigue crack initiation assessments. The current approach is based on the use of a Fatigue Strength Reduction Factor (FSRF) which has a value according to the particular class of welded joint. The FSRF affects the calculation of creep and fatigue damage. However, the current approach can be excessively conservative for as-welded weldments which are the main type of weldments in plant. This paper outlines the proposed changes to R5, which seek to achieve the following objectives: • to simplify and clarify the current advice for creep-fatigue initiation assessments of weldments, whilst maintaining a conservative assessment procedure; • to have a robust procedure which can be applied to complex components and loading conditions. The new approach separates the FSRF into two components which are as follows: • the geometric strain enhancement due to the weldment geometry (if applicable) and the material mis-match effect between parent material and weld metal, which is called the Weld Strain Enhancement Factor (WSEF), and • the fatigue endurance reduction effect due to the presence of small imperfections (e.g. inclusions, porosity, etc.) in the weldment constituent materials, which is called the Weld Endurance Reduction (WER). The WSEF is used to determine the stress at the start of a dwell or hold period and, because it has a lower value than the FSRF (due to the removal of the WER), results in less conservative calculations of creep damage compared to the current procedure, which uses the full FSRF. For fatigue damage predictions, the modified route is broadly similar to the current route, since the combination of the WER and the WSEF in the modified route corresponds to the FSRF used in the current route. Assessments to demonstrate the improved endurance predictions using the proposed new approach have been performed on several creep-fatigue weldment features tests and examples are provided in this paper.

Asset Integrity Assessment and Management Program for Life Preservation of a Purpose Built FPSO and Associated Subsea System Facilities

2016 ◽  
Author(s):  
Abe Nezamian ◽  
Robert J. Nicolson
Keyword(s):  
Structural Integrity ◽  
Safety Management ◽  
Management Program ◽  
Original Design ◽  
Safety Level ◽  
Maintenance And Repair ◽  
Integrity Assessment ◽  
Operational Life ◽  
Integrity Management ◽  
Maintenance And Inspection

Floating facilities for production, storage and offtake (FPSO) and other offshore production facilities have been used safely and reliably throughout the oil industry for many years. Asset Integrity is increasingly important to optimising safety and operational life and asset performance efficiency. Operators need to comply with Corporate, Regulatory and Certification requirements but recognise that developing and managing an effective and compliant Asset Integrity Management System is both time consuming and costly. Review of operational history of existing large FPSOs around the world indicated low confidence in operational life expectancy and to achieve the design life without possible dry docking or major repair. FPSOs have certain loading characteristics and damage consequences that make them different to other offshore installations and conventional ships, and often more challenging to maintain and operate. Maintenance and inspection campaigns are important inputs in the Asset Integrity Management (AIM) system of FPSOs and other floating offshore facilities. Considering that the unit shall stay on site during the whole life of the field, where disconnection or the removal of the mooring system is not planned, a comprehensive methodology for the asset integrity management, survey, inspection, testing, maintenance and repair of the unit during this period needs to be developed and subject to review based on the results of the scheduled inspections and audits. So as well as class and statutory requirements, inspection and survey, maintenance and repair plans should reflect the required availability, functionality, survivability and durability of the unit, giving due regard to its field life, as part of the safety management of the facility. Risk Based Integrity management methodology has been adopted in several projects and is an important tool to establish a rational inspection campaign for structural components, mainly for those located in areas where access is critical and operational constraints are an important parameter. This paper gives an overview of the challenges and discusses various aspects of ageing related to FPSO facilities, represented risk to the integrity of a facility and the required procedures and reassessment criteria for maintaining the structural integrity. This paper also provides an overall view on the regulatory requirements, documentation and calibrations/validations of the original design values to maintain the safety level by means of a maintenance and inspection programs balancing the ageing mechanisms and improving the reliability of assessment results. A brief summary of an example project of an asset integrity assessment and management program for life preservation of a purpose built FPSO and associated subsea system facilities is presented.

Determination of the Interaction Between Primary and Secondary Stresses Using an Idealised Model

2012 ◽  
Author(s):  
Graeme Horne ◽  
David J. Smith
Keyword(s):  
Residual Stress ◽  
Structural Integrity ◽  
New Approach ◽  
Integrity Assessment ◽  
Primary Stress ◽  
Reference Stress ◽  
Idealised Model ◽  
The Uk

When conducting an assessment of the integrity of a structure the user is directed to classify the stresses as either primary stress or secondary stress. Residual stresses are usually classified as secondary stresses unless they exhibit significant elastic follow-up. In this paper the authors have first summarised current methods and origins of the UK R6 structural integrity assessment methodology for combining primary and secondary stresses. Then, using an idealised model, a new approach has been developed to examine how fixed-displacement secondary stresses interact and redistribute; this model permits a combined reference stress to be determined directly. This combined reference stress is intrinsically linked to the effect of elastic follow-up within the structure and provides a direct measure of how the residual stress relaxes between the extremes of fixed-load and fixed-displacement conditions. The results have been compared with the existing approaches in R6 and it has been demonstrated that the R6 method can be either conservative or non-conservative, depending on the degree of elastic follow-up and residual stress redistribution.

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