Integrity Assessment of Spherical Pressure Components With Local Corrosion and Hot Spots

2006 ◽  
Author(s):  
Pattaramon Tantichattanont ◽  
Seshu Adluri ◽  
Rangaswamy Seshadri
Keyword(s):  
Lower Bound ◽  
Hot Spots ◽  
Structural Integrity ◽  
Hot Spot ◽  
Corrosion Damage ◽  
Pressure Vessels ◽  
Operating Conditions ◽  
Local Corrosion ◽  
Integrity Assessment ◽  
Spherical Pressure

Corrosion damage and hot spots are typical of damages that can occur in ageing pressure vessels and pipelines used in industrial processes. Internal and external corrosion could be the result of corrosive products stored inside or harsh environmental conditions on the outside. Hot spots are caused by damage due to loss of refractory lining on the inside wall of pressure components or due to maldistribution of flow containing catalyst and reactive fluids. The structural integrity of such ageing components needs to be evaluated periodically to establish the continued suitability of the vessels under operating conditions. The present paper develops a method for Level 2 (as categorized by API 579) structural integrity evaluations of spherical pressure vessels containing local corrosion damage or hot spot. The decay lengths for spherical shells subject to local damages have been studied based on stretching and bending effects using elastic shell theories so as to identify the reference volume participating in plastic action. A limit for “local” corroded spot or hot spot is defined by the size of damage that an onset of pure membrane action occurs inside the damaged area. The size of damage indicating the crossover from dominance of stretching effects on the damage behavior to that of bending effects is also presented. The lower bound recommended “remaining strength factors” for spherical pressure vessels containing corrosion or hot spot are formulated by application of Mura’s integral mean of yield criterion and the improved lower bound mα-multiplier. Three alternative recommendations are proposed. The effectiveness of the proposed methods is evaluated and demonstrated through illustrative examples and comparison with inelastic finite element analyses.

Integrity Assessment of Pressure Components With Local Hot Spots

2005 ◽  
Vol 127 (2) ◽  
pp. 137-142 ◽  
Author(s):  
R. Seshadri
Keyword(s):  
Hot Spots ◽  
Structural Integrity ◽  
Refractory Lining ◽  
Assessment Method ◽  
Pressure Vessels ◽  
Industrial Processes ◽  
Integrity Assessment ◽  
Piping Systems ◽  
Further Development ◽  
Level 2

Local hot spots can occur in some pressure vessels and piping systems used in industrial processes. The hot spots could be a result of, for instance, localized loss of refractory lining on the inside of pressure components or due to a maldistribution of process flow within vessels containing catalysts. The consequences of these hot spots on the structural integrity of pressure components are of considerable importance to plant operators. The paper addresses structural integrity issues in the context of codes and standards design framework. Interaction of hot spots, as is the case when multiple hot spots occur, is addressed. An assessment method, suitable for further development of a Level 2 “Fitness-for-Service” methodology, is discussed and applied to a commonly used pressure component configuration.

Fitness-for-Service Evaluation of Thermal Hot Spots and Corrosion Damage in Cylindrical Pressure Components

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
P. Tantichattanont ◽  
S. M. R. Adluri ◽  
R. Seshadri
Keyword(s):  
Hot Spots ◽  
Structural Integrity ◽  
Variational Principles ◽  
Elastic Shell ◽  
Corrosion Damage ◽  
Pressure Vessels ◽  
Alternative Methods ◽  
Linear Interaction ◽  
Reference Volume ◽  
Aspect Ratios

Thermal hot spots and corrosion damage are typical of damages occurring in pressure vessels and piping. Structural integrity of such components needs to be evaluated periodically to determine “fitness-for-service” (FFS) of the components. In the present paper, three alternative methods for level 2 FFS assessments (as described in API 579) are proposed. They are based on variational principles in plasticity, the m-alpha method, the idea of reference volume, and the concept of decay lengths in shells. Decay lengths in the axial and circumferential directions for cylindrical shells are derived based on elastic shell theories. They are used to specify the reference volume participating in plastic action and the extent of what can be called “local” damage. Interaction between longitudinal and circumferential effects is investigated. A linear interaction curve is shown to give good estimation of the “remaining strength factor” for damage of practical aspect ratios. The stretching and bulging effects due to the damage are also studied. The limit defining the threshold to dominance of stretching action is proposed by using an approximate equilibrium calculation based on yield-line analysis. The effectiveness of the proposed assessments is demonstrated through an example and verified by level 3 inelastic finite element analysis.

Thermal Hot Spot and Corrosion Damage in Conical Pressure Components

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Conical Shell ◽  
Structural Integrity ◽  
Hot Spot ◽  
Active Regions ◽  
Corrosion Damage ◽  
Limit Load ◽  
Decay Length ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Assessment Decisions

Structural integrity of an in-service component containing damage such as corrosion and thermal hot spot has to be evaluated regularly so as to certify the acceptance and safety of continued service of the component. In this paper, limit load solutions of a damaged conical shell, particularly local wall thinning and thermal hot spot, is investigated. The derived solutions are based on identifying the regions in the damaged component that directly participate in the plastic action (kinematically active). The concepts of reference volume and decay length are employed to identify the kinematically active regions in the damaged conical shell. The different solutions proposed in this paper are compared with the elastic-plastic finite element analysis. The results indicate that proposed solutions can be used with acceptable accuracy to make integrity assessment decisions.

Thermal Hot Spot and Corrosion Damage in Conical Pressure Components

2010 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Conical Shell ◽  
Structural Integrity ◽  
Hot Spot ◽  
Active Regions ◽  
Corrosion Damage ◽  
Limit Load ◽  
Decay Length ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Assessment Decisions

Structural integrity of an in-service component containing damage such as corrosion and thermal hot spot has to be evaluated regularly so as to certify the acceptance and safety of continued service of the component. In this paper, limit load solutions of a damaged conical shell, particularly local wall thinning and thermal hot spot, is investigated. The derived solutions are based on identifying the regions in the damaged component that directly participate in the plastic action (kinematically active). The concepts of reference volume and decay length are employed to identify the kinematically active regions in the damaged conical shell. The different solutions proposed in this paper are compared with elastic-plastic finite element analysis. The results indicate that proposed solutions can be used with acceptable accuracy to make integrity assessment decisions.

Integrity Assessment of Pressure Components With Local Hot Spots

2004 ◽  
Author(s):  
R. Seshadri
Keyword(s):  
Hot Spots ◽  
Structural Integrity ◽  
Refractory Lining ◽  
Service Evaluation ◽  
Assessment Method ◽  
Pressure Vessels ◽  
Industrial Processes ◽  
Integrity Assessment ◽  
Piping Systems ◽  
Level 2

Local hot spots can occur in some pressure vessels and piping systems used in industrial processes. The hot spots could be result of, for instance, localized loss of refractory lining on the inside of pressure components or due to a maldistribution of process flow within vessels containing catalysts. The consequences of these hot spots on the structural integrity of pressure components are of considerable importance to plant operators. The paper addresses structural integrity issues in the context of codes and standards design framework. The interaction of hot spots as is the case when multiple hot spots occur is addressed. An assessment method suitable for Level 2 “Fitness-for-Service” evaluation is discussed, and applied to a commonly used pressure component configuration.

Fitness-for-Service Evaluation of Thermal Hot Spots and Corrosion Damage in Cylindrical Pressure Components

2007 ◽  
Author(s):  
P. Tantichattanont ◽  
Seshu M. R. Adluri ◽  
R. Seshadri
Keyword(s):  
Hot Spots ◽  
Structural Integrity ◽  
Variational Principles ◽  
Elastic Shell ◽  
Corrosion Damage ◽  
Pressure Vessels ◽  
Alternative Methods ◽  
Linear Interaction ◽  
Reference Volume ◽  
Aspect Ratios

Thermal hot spots and corrosion damage are typical of damages occurring in pressure vessels and piping. Structural integrity of such components needs to be evaluated periodically to determine “fitness-for-service” of the components. In the present paper, three alternative methods for Level 2 FFS assessments (as defined by API 579) are proposed. They are based on variational principles in plasticity, the limit load multiplier m-alpha method, reference volume and the concept of decay lengths in shells. Decay lengths in the axial and circumferential directions for cylindrical shells are derived based on elastic shell theories. They are used to specify the reference volume participating in plastic action and the limit of what can be called “local” damage. Interaction between longitudinal and circumferential effects is investigated. A linear interaction curve is shown to give good estimations of “remaining strength factor” for damages of practical aspect ratios. The stretching and bulging effects due to the damage are also studied. The limit defining the threshold to dominance of stretching action is proposed by using an approximate equilibrium calculation based on yield-line analysis. The effectiveness of the proposed assessments are demonstrated through an example and verified by Level 3 inelastic finite element analysis.

Simplified Procedure to Assess Hot Spots in Pressure Vessels

2020 ◽  
Author(s):  
R. Adibi-Asl ◽  
M. Rana ◽  
R. Seshadri ◽  
C. Joshi
Keyword(s):  
Hot Spots ◽  
Structural Integrity ◽  
Refractory Lining ◽  
Hot Spot ◽  
Pressure Vessels ◽  
Piping System ◽  
Lower Yield ◽  
Simplified Procedure ◽  
Creep Regime ◽  
Over Time

Abstract In many instances, pressure vessels and piping system designed for high temperature applications are exposed to localized hot spots. Hot spots usually occur as the refractory lining degrades over time during operation or process changes causing the surface temperature of the localized region to exceed Code allowable metal temperature. These localized overheating can reduce the overall structural integrity of the pressurized components due to lower yield and or ultimate tensile strength of the damaged region. If hot spots are left undetected, they can lead to catastrophic failure of the components. This paper provides a simplified procedure to assess the effect of the hot spots on the pressure strength of the vessel. The procedure presented in this paper is applicable for hot spot temperatures in non-creep regime.

French RPV PTS Assessment: An Overview of EDF Research and Development in Progress on Thermalhydraulic, Materials and Mechanical Aspects

2003 ◽  
Author(s):  
Dominique Moinereau ◽  
Jean-Michel Frund ◽  
Henriette Churier-Bossennec ◽  
Georges Bezdikian ◽  
Alain Martin
Keyword(s):  
Structural Integrity ◽  
Three Dimensional ◽  
Crack Arrest ◽  
Pressure Vessels ◽  
Short Description ◽  
Constraint Effect ◽  
Materials Properties ◽  
Integrity Assessment ◽  
Pressurized Thermal Shock ◽  
Reactor Pressure

A significant extensive Research & Development work is conducted by Electricite´ de France (EDF) related to the structural integrity re-assessment of the French 900 and 1300 MWe reactor pressure vessels in order to increase their lifetime. Within the framework of this programme, numerous developments have been implemented or are in progress related to the methodology to assess flaws during a pressurized thermal shock (PTS) event. The paper contains three aspects: a short description of the specific French approach for RPV PTS assessment, a presentation of recent improvements on thermalhydraulic, materials and mechanical aspects, and finally an overview of the present R&D programme on thermalhydraulic, materials and mechanical aspects. Regarding the last aspect on present R&D programme, several projects in progress will be shortly described. This overview includes the redefinition of some significant thermalhydraulic transients based on some new three-dimensional CFD computations (focused at the present time on small break LOCA transient), the assessment of vessel materials properties, and the improvement of the RPV PTS structural integrity assessment including several themes such as warm pre-stress (WPS), crack arrest, constraint effect ....

Probabilistic Structural Integrity Analysis of Reactor Pressure Vessels During Pressurized Thermal Shock Events

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Koichi Masaki ◽  
Jinya Katsuyama ◽  
Kunio Onizawa
Keyword(s):  
Crack Initiation ◽  
Thermal Shock ◽  
Structural Integrity ◽  
Fracture Probability ◽  
Pressure Vessels ◽  
Sensitivity Analyses ◽  
Conditional Probabilities ◽  
Integrity Assessment ◽  
Pressurized Thermal Shock ◽  
Reactor Pressure

To apply a probabilistic fracture mechanics (PFM) analysis to the structural integrity assessment of a reactor pressure vessel (RPV), a PFM analysis code has been developed at JAEA. Using this PFM analysis code, pascal version 3, the conditional probabilities of crack initiation (CPIs) and fracture for an RPV during pressurized thermal shock (PTS) events have been analyzed. Sensitivity analyses on certain input parameters were performed to clarify their effect on the conditional fracture probability. Comparisons between the conditional probabilities and the temperature margin (ΔTm) based on the current deterministic analysis method were made for various model plant conditions for typical domestic older types of RPVs. From the analyses, a good correlation between ΔTm and the conditional probability of crack initiation was obtained.

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