Codes and Standards for Managing Degradation of Boilers in Service

2020 ◽  
Author(s):  
Corrado Delle Site ◽  
Emanuele Artenio ◽  
Gennaro Sepede ◽  
Matteo Chini ◽  
Francesco Giacobbe
Keyword(s):  
Service Time ◽  
Power Plants ◽  
Residual Life ◽  
Creep Damage ◽  
Pressure Vessels ◽  
Steam Boilers ◽  
Critical Components ◽  
Set Up ◽  
Effective Use ◽  
Life Consumption

Abstract Degradation of pressure equipment is becoming an important issue due to increasing asset service time in process and power plants across Europe. For this reason it is important to assess life consumption of these assets to avoid catastrophic failures. Therefore it is necessary to refer to national/international normative on this subject. At present time the Italian thermotechnical committee (CTI) has drawn up a comprehensive set of norms which help the user to set up an inspection plan to investigate and assess degradation of pressure vessels and boilers. In the first part of this paper creep damage of Steam Generators is analyzed. For this purpose results of INAIL (Istituto Nazionale per l’ Assicurazione contro gli Infortuni sul Lavoro) database of steam boilers with 100’000 service hours or more is illustrated. Critical components are identified with reference to materials, geometry and operating parameters (pressure, temperature and time). At the end of the design life cycle, components of pressure equipment operated in creep regime must subjected to specific checks to estimate their residual life and the suitability for further use in safety conditions. The procedure allows to define reinspection intervals keeping acceptable the risk associated with the further use of the component related to creep even in evidence of defects in progress. The first check must be performed after 100,000 hours of effective use. Then, residual life evaluations must be repeated according to period of time that are defined as function of the results of all the checks carried out. In the second part of this paper boiler degradation is discussed with reference to NDT results and in-field inspection campaigns which are carried out traditionally after 45 years of service time, to minimize the risk of pressure components failures. In this paper results of different case studies are discussed with reference to degradation mechanisms and applicable standards.

Fitness-for-Service Assessment of a Steam Pipeline Operating in the Creep Range After 230000 Hours of Service

2012 ◽  
Author(s):  
Lorenzo Scano
Keyword(s):  
Residual Life ◽  
Creep Damage ◽  
Paper Mill ◽  
High Energy ◽  
Operating Conditions ◽  
Metal Loss ◽  
Inelastic Analysis ◽  
Critical Components ◽  
Set Up ◽  
Actual Damage

High energy pipes, carrying steam at high pressure and temperature, are very common in the industry. In this paper, a Fitness-For-Service assessment was performed for a pipeline connecting the boiler of a paper mill to the cogeneration turbine and the process headers. A pressure of 6.4 MPa and a temperature of 475 °C were the operating conditions for 230000 hours of continued service, thus arising concern about metal loss due to erosion/corrosion and high temperature creep damage. Original pipeline design information was unknown, hence, an extensive NDE program was carried out to obtain the required data for the FFS analysis. Because of the elevated number of in-service hours, an API 579-1 Level 3 assessment was required and a FE shell model of the line was set up to evaluate plastic strain accumulation due to creep through a time-dependant inelastic analysis. The predicted critical components were then investigated experimentally taking metallographic replicas in situ and the actual damage was finally, qualitatively, compared with that calculated with the API 579-1 procedures, with good agreement. The results of the assessment led to an estimate of 70000 hours of residual life for the pipeline and could drive the planning for future NDE according to a RBI approach.

scholarly journals Hazards assessment and technical actions due to the production of pressured hydrogen within a pilot photovoltaic-electrolyser-fuel cell power system for agricultural equipment

2016 ◽  
Vol 47 (2) ◽  
pp. 88 ◽  
Author(s):  
Simone Pascuzzi ◽  
Ileana Blanco ◽  
Alexandros Sotirios Anifantis ◽  
Giacomo Scarascia-Mugnozza
Keyword(s):  
Fuel Cell ◽  
Power System ◽  
Power Plants ◽  
Heating System ◽  
Pressure Vessels ◽  
Point Of View ◽  
Operational Parameters ◽  
Danger Zone ◽  
Design Values ◽  
Set Up

A pilot power system formed by photovoltaic panels, alkaline electrolyser and fuel cell stacks was designed and set up to supply the heating system of an experimental greenhouse. The aim of this paper is to analyse the main safety aspects of this power system connected to the management of the pressured hydrogen, such as the explosion limits of the mixture hydrogen-oxygen, the extension of the danger zone, the protection pressure vessels and the system to make unreactive the plant. The electrolyser unit is the core of this plant and from the safety point of view has been equipped with devices able to highlight the malfunctions before they cause damages. Alarm situations are highlighted and the production process is cut off in safe conditions in the event that the operational parameters have an abnormal deviation from the design values. Also the entire power system has been designed so that any failure to its components does not compromise the workers’ safety even if the risk analysis is in progress because technical operations are being carried out for enhancing the plant functionality, making it more suitable to the designed task of supplying electrically the greenhouse heating system during cold periods. Some experimental data pertinent to the solar radiation and the corresponding hydrogen production rate are also reported. At present it does not exist a well-established safety reference protocol to design the reliability of these types of power plants and then the assumed safety measures even if related to the achieved pilot installation, can represent an original base of reference to set up guidelines for designing the safety of power plants in the future available for agricultural purposes.

On-Line Monitoring System for Main Steam Piping of Power Plants

2009 ◽  
Author(s):  
Ning Wang ◽  
Zhengdong Wang ◽  
Yingqi Chen
Keyword(s):  
Power Plant ◽  
Monitoring System ◽  
Remote Monitoring ◽  
Power Plants ◽  
Residual Life ◽  
Thermal Power ◽  
Creep Damage ◽  
Piping System ◽  
On Line ◽  
Main Steam

An on-line life prediction system is developed for remote monitoring of material aging in a main steam piping system. The stress analysis of piping system is performed by using the finite element method. A sensor network is established in the monitoring system. The creep damage is evaluated from strain gages and a relationship is given based on a database between the damage and residual life. Web technologies are used for remote monitoring to predict the residual life for every part of the piping system. This system is useful for safety assessment procedures in thermal power plant, nuclear power plant and petrochemical industries.

Study of Multiple Holes Influence on Theoretical Stress Concentration Coefficient in Case of Cylindrical Vessels

2014 ◽  
Vol 601 ◽  
pp. 129-132
Author(s):  
Nicolae Faur ◽  
Sergiu Valentin Galatanu ◽  
Mihai Hluscu
Keyword(s):  
Stress Concentration ◽  
Power Plants ◽  
Computational Models ◽  
Pressure Vessels ◽  
Concentration Coefficient ◽  
Concentration Effects ◽  
Steam Boilers ◽  
Multiple Holes ◽  
Theoretical Stress ◽  
Stress Concentration Coefficient

In the construction of pressure vessels, especially for steam boilers used in power plants, cylindrical vessels are commonly used. For this important class of mechanical structures, through holes also frequently cause stress concentration which must be taken into account in the design and estimation of their lifetime. In the scientific literature which addresses stress concentration effects for such structures are studied in cases of which the presence of through holes is singular. This paper studies the effect of stress concentration in case of two or more holes placed at a small distance between them, according to construction requirements. In these cases the simplifying assumption of Saint Venant according to which at sufficient distance from the analyzed area the state of stress is not influenced by how the load is applied cannot be accepted. In this paper we study the stress concentration coefficient with numerical methods using the finite element method and more precisely, ABAQUS software package, version 6.9. Different constructive cases of multiple holes are studied: two and three successive holes with the same diameter and different diameters placed on the generating line with variable distance, for which the ratio between the diameter and the distance between the holes varies. Numerical model validation was done by comparing the results obtained for specific computational models in case of which results are known and presented in the literature [1,2]. Based on the results, variation curves of the theoretical stress concentration coefficient were drawn for all cases listed above.

Application of Hot Hardness Test to the Evaluation of Creep Damage in Cr-Mo-V Turbine Rotor of Fossil Power Plant

2004 ◽  
Author(s):  
Shinsuke Sakai ◽  
Satoshi Izumi ◽  
Takashi Murakami ◽  
Akito Nitta ◽  
Junichi Kusumoto ◽  
...  
Keyword(s):  
Power Plants ◽  
Residual Life ◽  
Creep Damage ◽  
Hardness Test ◽  
Turbine Rotor ◽  
Constitutive Law ◽  
Life Evaluation ◽  
Site Evaluation ◽  
Fossil Power Plant ◽  
Hot Hardness

In residual life evaluation of fossil power plants, improvement of accuracy of creep damage evaluation is extremely important. One of the powerful non-destructive evaluation methods is hardness test. This method is effective because it enables us the on-site evaluation and the results are obtained without laborious work. However, in order to make it more powerful method, improvement of accuracy is inevitable. In this paper, the Vickers hardness test not at ambient but at high temperature is applied to the deteriorated rotor material and the method for the residual life evaluation with high accuracy is newly developed. In the method, creep constitutive law is determined from the results of hot hardness test first. Next, the variation of constitutive law with the creep damage is investigated. Finally, the dependency of exponent of constitutive law on the creep damage is shown and the method to evaluate the creep damage from this dependency will be proposed.

Comparison of a Life Consumption Analysis to Section III, Subsection NH Design Rules for a Main Steam Girth Weld Creep Crack

2003 ◽  
Author(s):  
Marvin J. Cohn
Keyword(s):  
Power Plants ◽  
Creep Damage ◽  
High Energy ◽  
Piping System ◽  
Design Rules ◽  
Class 1 ◽  
American Society ◽  
Girth Welds ◽  
Main Steam ◽  
Life Consumption

Creep damage of high energy piping (HEP) systems in fossil fuel power plants results from operation at creep range temperatures and high stresses over many years. Typically, the operating stresses in an HEP piping system are substantially below the yield stress. They tend to be load controlled and time dependent. In spring 1999, Arizona Public Service Company performed an examination of several girth welds of a main steam piping system at Cholla Power Station, Unit 2. A significant creep-related crack was found in a weld after 158,000 operating hours. The American Society of Mechanical Engineers (ASME) Subsection NH methodology was used to evaluate the load controlled stress design rules for nuclear Class 1 components in elevated temperature service as applied to this piping system. A high energy piping life consumption (HEPLC) analysis was performed prior to the examination to select and rank the most critical welds. After obtaining critical information during the outage, the software was also used to estimate the life exhaustion at the most critical weld. A discussion of results for the two approaches is provided in this paper.

Creep Life Prediction For High Energy Piping Girth Welds Case History: Cholla, Unit 2

2002 ◽  
Author(s):  
Marvin J. Cohn ◽  
Dan Nass
Keyword(s):  
Thermal Expansion ◽  
Yield Stress ◽  
Power Plants ◽  
Thermal Stresses ◽  
Creep Damage ◽  
High Energy ◽  
Time Dependent ◽  
Piping System ◽  
Main Steam ◽  
Life Consumption

Creep damage of high energy piping (HEP) systems in fossil fuel power plants results from operation at creep range temperatures and stresses over many years. Thermal expansion stresses are typically below the yield stress and gradually relax over time. Consequently, the operating stresses in a piping system are typically below the yield stress and become load controlled. Conventional designs of HEP systems use the American Society of Mechanical Engineers B31.1 Power Piping Code. The Code is a general guideline for piping system design. Utilities typically determine examination sites by performing Code piping stress analyses and selecting locations that include the highest sustained longitudinal stress, highest thermal expansion stress, and terminal points. However, the Code does not address weldment properties, redistribution of thermal stresses and time-dependent life consumption due to material creep degradation. As an alternative, a high energy piping life consumption (HEPLC) methodology was used to predict maximum material damage locations. The methodology was used to prioritize expected creep damage locations, considering applicable affects such as weldment properties, field piping displacements, time-dependent operating stresses, and multiaxial piping stresses. This approach was applied to the main steam piping system at Cholla Unit 2. The locations of highest expected creep damage would not have been selected by a conventional site selection approach. Significant creep damage was found at the locations of maximum expected creep damage using the HEPLC methodology.

Reserves energy saving under the automated control of powerful ventilators of the steam boilers of power plants

2017 ◽  
Vol 2017 (1) ◽  
pp. 67-73
Author(s):  
G. Kanyuk ◽  
◽  
A. Mezerya ◽  
I. Suk ◽  
I. Babenko ◽  
...  
Keyword(s):  
Energy Saving ◽  
Power Plants ◽  
Automated Control ◽  
Steam Boilers

Atomic Diffusion Induced Damage of Ni-Base Super Alloy at Elevated Temperature

2016 ◽  
Author(s):  
Motoki Takahashi ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Power Plants ◽  
Creep Damage ◽  
Rotor Blades ◽  
Atomic Scale ◽  
Atomic Diffusion ◽  
Kernel Average Misorientation ◽  
Damage Process ◽  
Creep Loading ◽  
Ebsd Method ◽  
Base Superalloy

Ni-base superalloys consisting of binary phases such as cuboidal γ’ (Ni3Al) precipitates orderly dispersed in the γ matrix (Ni-rich matrix) have been generally used for rotor blades in energy power plants. However, fine dispersed γ’ precipitates are coarsened perpendicularly to the applied load direction during high temperature creep loading. As this phenomenon called “Rafting” proceeds, the strengthened micro texture disappears and then, cracks starts to grow rapidly along the boundaries of the layered texture. Thus, it is very important to evaluate the change of the crystallinity of the alloy in detail for explicating the atomic scale damage process. In this study, the change of the micro-texture of the Ni-base superalloy (CM247LC) was observed by using EBSD method. The change in the crystallinity was evaluated using both Kernel Average Misorientation (KAM) and image quality (IQ) values. The KAM value indicates the dislocation density and the IQ value shows the order of atom arrangement in the observed area. As a result, KAM value showed no significant change with increasing the creep damage. On the other hand, the IQ value monotonically shifted to lower values and the average IQ value gradually decreased as the creep loading time increased. Decreasing IQ value without change in KAM value implies that the density of point defects such as vacancies mainly increased under creep loading and ordered Ll2 structure became disordered. Therefore, the creep damage of this alloy is mainly dominated by not the accumulation of dislocations, but the increase in the disorder of atom arrangement in the micro texture caused by the diffusion of component elements.

Verification of Probabilistic Fracture Mechanics Analysis Code for Reactor Pressure Vessel

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Yinsheng Li ◽  
Genshichiro Katsumata ◽  
Koichi Masaki ◽  
Shotaro Hayashi ◽  
Yu Itabashi ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Working Group ◽  
Power Plants ◽  
Structural Integrity ◽  
Pressure Vessels ◽  
Irradiation Embrittlement ◽  
Energy Agency ◽  
Probabilistic Fracture Mechanics ◽  
Integrity Assessments ◽  
Reactor Pressure

Abstract Nowadays, it has been recognized that probabilistic fracture mechanics (PFM) is a promising methodology in structural integrity assessments of aged pressure boundary components of nuclear power plants, because it can rationally represent the influencing parameters in their inherent probabilistic distributions without over conservativeness. A PFM analysis code PFM analysis of structural components in aging light water reactor (PASCAL) has been developed by the Japan Atomic Energy Agency to evaluate the through-wall cracking frequencies of domestic reactor pressure vessels (RPVs) considering neutron irradiation embrittlement and pressurized thermal shock (PTS) transients. In addition, efforts have been made to strengthen the applicability of PASCAL to structural integrity assessments of domestic RPVs against nonductile fracture. A series of activities has been performed to verify the applicability of PASCAL. As a part of the verification activities, a working group was established with seven organizations from industry, universities, and institutes voluntarily participating as members. Through one-year activities, the applicability of PASCAL for structural integrity assessments of domestic RPVs was confirmed with great confidence. This paper presents the details of the verification activities of the working group, including the verification plan, approaches, and results.

Sign in / Sign up

Export Citation Format

Share Document