A Study on Degree of Conservatism of Two Safety Assessment Methods for Piping and Vessels With Defects

2019 ◽  
Author(s):  
Meng He ◽  
Haitao Li ◽  
Zhiyuan Han ◽  
Guoshan Xie ◽  
Liang Sun ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Failure Probability ◽  
Safety Assessment ◽  
Evaluation Method ◽  
Assessment Method ◽  
Pressure Vessels ◽  
Assessment Methods ◽  
Operating Pressure ◽  
Safety Factors ◽  
Straight Pipe

Abstract Flaws (defects), such as local thinning due to corrosion, inevitably exist in piping and pressure vessels. These defects can be evaluated using the fitness for service (FFS) method provided in the GB/T 19624 standard. Recently, the GB/T 35013 standard (Fitness-for-service assessment of pressure equipments), which provides another FFS assessment method for local thinning on piping and vessels, has been published. The evaluation method for local thinning in the GB/T 35013 standard is generally similar to that in the API 579-1/ASME FFS-1 (2016), but is totally different from that in the GB/T 19624. In this paper, the differences of the local thinning assessment methods in the GB/T 35013 (or API 579-1/ASME FFS-1 (2016)) and the GB/T 19624 are summarized, and the degree of conservatism comparisons between these standards are presented. The maximum allowable operating pressure (Prmax) that takes into account the effect of defects for straight pipe sections and vessels under different defect sizes and safety factors in these two standards have been calculated and compared. Monte Carlo simulations have been carried out to estimate the failure probability (Pf) and reliability of the straight pipe sections and vessels with different safety factors using the GB/T 19624.

Analysis of the Safety Factors of Municipal Road Undercrossing Existing Bridge Based on Fuzzy Analytic Hierarchy Process Methods

2021 ◽  
pp. 036119812110318
Author(s):  
Yonghong Yang ◽  
Yu Chen ◽  
Zude Tang
Keyword(s):  
Safety Assessment ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Safety Evaluation ◽  
Safety Factors ◽  
Analytic Hierarchy ◽  
Road Engineering ◽  
Existing Bridges ◽  
Hierarchy Process ◽  
Engineering Projects

Increasing traffic volume and insufficient road lanes often require municipal roads to be reconstructed and expanded. Where a road passes under a bridge, the reconstruction and expansion project will inevitably have an impact on the bridge. To evaluate the safety impact of road engineering projects on bridges, this paper evaluates the safety of the roads and ancillary facilities of highway bridges involved in municipal road engineering projects. Based on a comprehensive analysis of the safety factors of municipal roads undercrossing existing bridges, a fuzzy comprehensive analytic hierarchy process (AHP) evaluation method for the influence of road construction on the safety of existing bridges is proposed. First, AHP is used to select 11 evaluation factors. Second, the target layer, criterion layer, and index layer of evaluation factors are established, then a safety evaluation factor system is formed. The three-scale AHP model is used to determine the weight of assessment indexes. Third, through the fuzzy comprehensive AHP evaluation model, the fuzzy hierarchical comprehensive evaluation is carried out for the safety assessment index system. Finally, the fuzzy comprehensive evaluation method is applied to the engineering example of a municipal road undercrossing an existing expressway bridge. The comprehensive safety evaluation of the existing bridge reflects the practicability and feasibility of the method. It is expected that, with further development, the method will improve the decision-making process in bridge safety assessment systems.

An Improved FOSM Method for Calculating the Failure Probability of Welded Pipes with Cracks

2004 ◽  
Vol 261-263 ◽  
pp. 561-566
Author(s):  
Li Xing Huo ◽  
Min Liu ◽  
You Feng Zhang ◽  
Fang Juan Qi
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Failure Probability ◽  
Safety Assessment ◽  
Linear Expansion ◽  
Failure Function ◽  
The Monte Carlo Method

To increase the accuracy of R-F method, it is necessary to solve the problems of the linear expansion of failure function and non-normal variables. In this paper, the improved FOSM method was applied to calculate the failure probability of welded pipes with cracks. The examples show that this method is simple, efficient and accurate for reliability safety assessment of welded pipes with cracks. It can save more time than the Monte Carlo method does, so that the improved FOSM method is recommended for general engineering reliability safety assessment of welded pipes with cracks.

Composition of Safety and Cyber Security Analysis Techniques and Tools for NPP I&C System Assessment

2020 ◽  
pp. 204-220
Author(s):  
Ievgen Babeshko ◽  
Kostiantyn Leontiiev
Keyword(s):  
Cyber Security ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Security Analysis ◽  
Assessment Method ◽  
Assessment Methods ◽  
Assessment Process ◽  
Safety Level ◽  
Methods And Techniques ◽  
And Control

Safety assessment of nuclear power plant instrumentation and control systems (NPP I&Cs) is a complicated and resource-consuming process that is required to be done so as to ensure the required safety level and comply to normative regulations. A lot of work has been performed in the field of application of different assessment methods and techniques, modifying them, and using their combinations so as to provide a unified approach in comprehensive safety assessment. Performed research has shown that there are still challenges to overcome, including rationale and choice of the safety assessment method, verification of assessment results, choosing and applying techniques that support safety assessment process, especially in the nuclear field. This chapter presents a developed framework that aggregates the most appropriate safety assessment methods typically used for NPP I&Cs.

Research on the Fatigue Assessment Method for Steel Pressure Vessels Containing Surface Defects

2014 ◽  
Vol 628 ◽  
pp. 137-141
Author(s):  
Xian Lei Meng
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Life Prediction ◽  
Safety Assessment ◽  
Surface Defects ◽  
Great Influence ◽  
Assessment Method ◽  
Pressure Vessels ◽  
Test Results ◽  
Fatigue Assessment

Defects have great influence on the safe running of pressure vessels, and the safty assessment for in-service pressure vessels containing defects can realize safe and economical operation of presure vessles.Aiming at the fatigue assement of defect in steel pressure vessels,the fatigue assement method is studied and a primary program can be uesd to calculate fatigue crack propagation and life prediction is programed based on GB19624.The comparison between test and calculated results indicates that the method provided is suitable for fatigue assessment of defects.Combining the test results and cricical conditonds, the presient approach can provide a basis for the fatigue safety assessment and the reasonable overhaul cycle of in-service pressure vessels.

A Comprehensive Analysis Method Based on Fuzzy Hierarchy for the Safety Assessment of Overhead Traveling Crane

2010 ◽  
Vol 20-23 ◽  
pp. 196-201
Author(s):  
Ge Ning Xu ◽  
Fan Jiang
Keyword(s):  
Safety Assessment ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Safety Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Assessment Method ◽  
Assessment Model ◽  
Analytic Hierarchy ◽  
Set Up ◽  
Hierarchy Process

By combined fuzzy comprehensive evaluation with AHP (Analytic Hierarchy Process) together, a safety assessment model for overhead traveling crane is set up in regard to deficiency of safety assessment method for crane at present, which can evaluate safety of overhead traveling crane in-service qualitatively and quantitatively. Through a safety analysis and assessment on general overhead traveling crane, the result of assessment is in accord with the practical situation of overhead traveling crane. It can reflect more fully the safety of the whole crane system and the influence and level of each factor to whole crane system safety, witch an effective synthetic evaluation method is put forward for the safety evaluation of crane.

Pedestrian crosswalks safety assessment in selected countries

2015 ◽  
Vol 287 ◽  
pp. 95-100
Author(s):  
Paweł Lewandowski ◽  
◽  
Krzysztof Fokt ◽  
Keyword(s):  
Safety Assessment ◽  
Pedestrian Safety ◽  
Assessment Method ◽  
Assessment Methods ◽  
Significant Problem ◽  
Urban Agglomerations ◽  
The Subject ◽  
Multiple Levels

This article presents an issue of the assessment of pedestrian crosswalks safety, based on the example of actions undertaken in Norway and Australia. In Oslo, the criteria for safety assessment on pedestrian crossings and the audit results were presented in the TØI Report 1231/2012. In Australia, a draft methodology for pedestrian crosswalks safety assessment, which, according to the authors, needs an improvement at multiple levels, has been developed at Monash University. The examples presented in the article indicate a significant problem with the elaboration of safety assessment methods of unprotected pedestrians and their applications within the framework programs implemented in large urban agglomerations. Despite the difficulties mentioned above, there are undeniably some possibilities regarding the elaboration of an objective pedestrian safety assessment method, which may be the subject to scientific studies.

The Reliability Evaluation Method for Success or Failure Product

2013 ◽  
Vol 710 ◽  
pp. 298-301
Author(s):  
Hai Bo Liu ◽  
Jin Huang Wu ◽  
Yi Dong Wang ◽  
Jun Wei Lei
Keyword(s):  
Evaluation Method ◽  
Reliability Assessment ◽  
Estimation Method ◽  
Reliability Evaluation ◽  
Assessment Method ◽  
Assessment Methods ◽  
Reliability Test ◽  
Confidence Estimation ◽  
Test Assessment

It is illustrated that establishing the reliability assessment method for Success or Failure product is important, and make an analysis and comparison on reliability test assessment methods for the existing four Success or Failure products. Furthermore, a new kind of reliability assessment method and confidence estimation method is proposed in this paper, which is indicated as a rational and applicable method.

Research on Risk Probability and Economic Safety Assessment Method and Application of Mechanical System

2010 ◽  
Vol 37-38 ◽  
pp. 1072-1075
Author(s):  
Ge Ning Xu ◽  
Xiao Lei Feng
Keyword(s):  
Risk Assessment ◽  
Mechanical System ◽  
Failure Probability ◽  
Safety Assessment ◽  
Human Factor ◽  
Assessment Method ◽  
Economic Losses ◽  
Mechanical Device ◽  
Risk Assessment Method ◽  
Risk Probability

Form human-machine-environment, this paper analyzed the factor of risk assessment, and proposed how to calculate the failure probability of basic event including the human factor and the mechanical device. The accident serious degree was changed into the economic losses by the view of safety economics. Integrating the failure probability and the economic losses to determine the risk assessment items, system rank was evaluated by checking assessment items. After establishing the quantitative risk probability and economic risk assessment method, the example about crane travel mechanism was given to demonstrate the method correct and feasible.

Development of Reliability-Based Criteria for Corrosion Assessment

2018 ◽  
Author(s):  
Riski Adianto ◽  
Maher Nessim ◽  
Dongliang Lu
Keyword(s):  
Failure Probability ◽  
Limit State ◽  
Assessment Criteria ◽  
Ultimate Limit State ◽  
Operating Pressure ◽  
Safety Factors ◽  
Limit States ◽  
Feature Based ◽  
Corrosion Assessment ◽  
Ultimate Limit

Reliability-based corrosion assessment criteria were developed for onshore natural gas and low vapor pressure (LVP) pipelines as part of a joint industry project. The criteria are based on the limit states design (LSD) approach and are designed to achieve consistent safety levels for a broad range of pipeline designs and corrosion conditions. The assessment criteria were developed for two corrosion limit states categories: ultimate limit state, representing large leaks and ruptures; and leakage limit state, representing small leaks. For the ultimate limit state, a safety class system is used to characterize pipelines based on the anticipated severity of failure consequences as determined by pressure, diameter, product, population density and environmental sensitivity. Since the leakage limit state does not result in significant safety or environmental consequences, a single reliability target, applicable for all pipelines at all locations is used. The assessment criteria formulations are characterized by three elements: the equations used to calculate the characteristic demand (i.e. operating pressure) and capacity (i.e. burst pressure resistance at a corrosion feature); the characteristic values of the key input parameters for these formulas (such as diameter, pressure and feature depth); and the safety factors defining the characteristic demand as a ratio of characteristic capacity. The process used to calibrate safety factors and characteristic input parameter values that meet the desired reliability levels is described, and an assessment of the accuracy and consistency of the resulting checks in meeting the reliability targets is included. The assessment criteria include two methods of application: feature-based and section-based. The feature-based method divides the allowable failure probability equally between all features. It is simple to use, but conservative in nature. It is suitable for pipelines with a small number of corrosion features. The section-based method considers the failure probability of the corrosion features in a pipeline section as a group, and ensures that the total group failure probability is below the allowable threshold for the section. This method produces less conservative results than the feature-based method, but it requires more detailed calculations. It is suitable for all pipelines, and is particularly useful for those with a large number of features. The practical implications of the application of these criteria are described in the companion paper IPC2018-78608 Implementation of Reliability-based Criteria for Corrosion Assessment.

Application of Underground Engineering Fire Safety Evaluation Based on the Fuzzy Comprehensive Evaluation Method

2013 ◽  
Vol 765-767 ◽  
pp. 307-310
Author(s):  
Shan Yu Yan ◽  
Jin Ding
Keyword(s):  
Fire Safety ◽  
Safety Assessment ◽  
Evaluation Method ◽  
Safety Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Assessment Method ◽  
Evaluation Index System ◽  
Fuzzy Evaluation ◽  
Fire Control ◽  
Underground Engineering

In this paper, built fire control safety evaluation index system according to the underground engineering characteristics of fire and introduce a method to determine the weighing values for assessment index. Put fuzzy comprehensive assessment method on underground engineering of fire safety assessment, then use fuzzy mathematics theory build a model of engineering of fire safety assessment fuzzy evaluation, and through the underground engineering design of fire safety assessment, to prove its scientific and effective.

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