COLLECTIONS

Documents published in Scipedia

• COMPARATIVE STRESS ANALYSIS OF ELBOWS IN PIPING SYSTEMS APPLYING THE NORMATIVE SAFETY MARGIN

  A. Giudici, N. Wechselberg, J. Stuardi, G.

  RIDNAIC (2023). Vol. 23, 1

  
  

  Abstract

  Elbows are components in piping systems whose primary function is to achieve a change in flow direction. Their study is relevant, since they present higher stress levels than those observed in straight sections. Early investigations determined that this effect is caused by the ovalization effect and the presence of external moments. The capacity of a cross section to ovalize when external loads are applied results in increased flexibility of the elbows by decreasing the moment of inertia compared to a straight pipe. In this work, stress levels in elbows caused by external moments and internal pressure are studied. As a case study, a series of elbows of various diameters and thicknesses with suitable characteristics for understanding the phenomenon of ovalization and the comparison of different calculation methodologies is proposed. The stresses obtained by applying the ASME B31.1 and ASME B31.3 codes are compared with those obtained by a numerical model of finite elements, through a novel indicator called the Normative Safety Margin. This indicator considers the admissible stresses established by the specifications for the materials of the accessories. Applying B31.1 Code, higher normative safety margins are obtained than those obtained with B31.3. For the entire series under study and all types of applied loads, lower normative safety margins were obtained when the accessories are more flexible.

  Abstract
  Elbows are components in piping systems whose primary function is to achieve a change in flow direction. Their study is relevant, since they present higher stress levels than [...]

  • 11
  •  read

• QUANTITATIVE RISK ANALYSIS OF GAS PIPELINES IN CÓRDOBA, ARGENTINA

  A. Giudici, J. Stuardi, G.

  RIDNAIC (2021). Vol. 21, 22

  
  

  Abstract

  A quantitative risk analysis is presented for a gas pipeline system in the province of Córdoba, Argentina. This is a part of a project on the vulnerability of infrastructure and physical environment associated with the storage and transport of combustible fluids. The developed model considers the identification of threats to the integrity of the pipelines, an estimate of the probabilities of failure of the identified threats, an estimate of the consequences of a failure, the determination and evaluation of the quantitative risk according to acceptance criteria, and the adoption of risk mitigation and control measures. For this study, the main data from the existing backbone network and the recently built gas pipelines in the province of Córdoba are used. This is complemented with a survey of the constructions near the route of the sections under study, as well as the crossings of roads and watercourses, based on available satellite images. The work is focused on establishing the individual and social quantitative risk levels of the gas pipelines with the highest qualitative risk level, already defined by previous work. Finally, and in the necessary cases, the adoption of mitigation measures is considered to adjust the risk levels to the international acceptance criteria.  A quantitative risk analysis is presented for a gas pipeline system in the province of Córdoba, Argentina. This is a part of a project on the vulnerability of infrastructure and physical environment associated with the storage and transport of combustible fluids. The developed model considers the identification of threats to the integrity of the pipelines, an estimate of the probabilities of failure of the identified threats, an estimate of the consequences of a failure, the determination and evaluation of the quantitative risk according to acceptance criteria, and the adoption of risk mitigation and control measures. For this study, the main data from the existing backbone network and the recently built gas pipelines in the province of Córdoba are used. This is complemented with a survey of the constructions near the route of the sections under study, as well as the crossings of roads and watercourses, based on available satellite images. The work is focused on establishing the individual and social quantitative risk levels of the gas pipelines with the highest qualitative risk level, already defined by previous work. Finally, and in the necessary cases, the adoption of mitigation measures is considered to adjust the risk levels to the international acceptance criteria. 

  Abstract
  A quantitative risk analysis is presented for a gas pipeline system in the province of Córdoba, Argentina. This is a part of a project on the vulnerability of infrastructure [...]

  • 32
  •  read

• BEHAVIOUR OF A CRACKED GAS PIPELINE

  J. Massa, A. Giudici

  Revista Internacional de Desastres Naturales, Accidentes e Infraestructura Civil (2009). Rev. Int. de Desastres Naturales, Accidentes e Infraestructura Civil. Vol. 9(1-2)

  
  

  Abstract

  When designing systems for the transportation and distribution of gas, safety is one of the main issues to be considered. In order to minimize potential hazards, this subject is treated in international regulations. Manufacturing characteristics of gas pipes and their typical defects are described in the first part of this work. Safety concerns related to the presence of real and potential crack type defects in gas pipes are presented. An actual gas pipeline, which has been feeding natural gas to the city of Córdoba (Argentina) for more than forty years, is considered as a study case. In order to determine the properties of this gas pipeline, mechanical tests from material samples were carried out. The stress state associated with “plane” type defects is determined using a model that is based on the material toughness of the pipe, which is appropriate for studying the behavior of cracks. This model allows computing, depending on the dimensions of the pipe, the transition pressure which separates possible defects into two categories: defects which cause failure by breakage of the pipe and defects which only cause gas leaks. The pipe failure pressure for passing and non-passing defects can also be determined using this model. The system safety conditions are defined considering the size of the defects and the work pressure. The range of lengths of possible defects, the size of the defects that are critical, and the size of the defects which are tolerable for a fixed safety coefficient, are determined. Finally, the problem of determining in a quick way, the reduced pressure acceptable for the safe operation until repairs, of a system under the presence of a crack of “non-tolerable size”, is addressed.  

  Abstract
  When designing systems for the transportation and distribution of gas, safety is one of the main issues to be considered. In order to minimize potential hazards, this subject is [...]

  • 1
  •  read

• DAMAGE BY CORROSION IN PIPELINES

  J. Massa, A. Giudici

  Revista Internacional de Desastres Naturales, Accidentes e Infraestructura Civil (2010). Rev. Int. de Desastres Naturales, Accidentes e Infraestructura Civil. Vol. 10(2)

  
  

  Abstract

  When designing systems for the transportation and distribution of gas, safety is one of the main issues to be considered.  In order to minimize potential hazards, this subject is treated in international regulations. Safety concerns related to the presence of real and potential corrosion type defects in gas pipes are presented. An actual gas pipeline, which has been feeding natural gas to the city of Córdoba (Argentina) for more than forty years, is considered as a study case. In order to determine the properties of this gas pipeline, mechanical tests from material samples were carried out. The stress state associated with “volumetric” type defects is determined using a model that is based on the flux stress of the material of the pipe, which is appropriate for studying the behavior of corroded pipelines. This model allows computing, depending on the dimensions of the pipe and the length of the defect, the transition pressure which separates possible defects into two categories: those which cause failure by breakage of the pipe and those which only cause gas leaks. The pipe failure pressure for passing and non-passing defects can also be determined using this model. The system safety conditions are defined considering the size of the defects and the work pressure. The range of lengths of possible defects, the size of the defects that are critical, and the size of the defects which are tolerable for a fixed safety coefficient, are determined. Finally, the problem of determining in a quick way, the reduced pressure acceptable for the safe operation until repairs, of a system under the presence of flaws of “non-tolerable size”, is addressed.

  Abstract
  When designing systems for the transportation and distribution of gas, safety is one of the main issues to be considered.  In order to minimize potential hazards, this [...]

  • 1
  •  read

• Characterization of gas pipelines in the province of Córdoba, Argentina

  A. Giudici, J. Stuardi, C. Estrada

  RIDNAIC (2017). Vol. 17, (2), 4

  
  

  Abstract

  To study the vulnerability of the natural gas pipeline infrastructure in a region of Argentina, the characterization of gas pipelines from the province of Córdoba is carried out in this work. For this purpose, parameters and value intervals that delimit the vulnerability assessment are defined. The following risk issues associated with pipelines are taken into account: a) third-party damage, b) external corrosion, and c) operation conditions that differ from those defined in the pipeline design.The first part of this work presents a survey of main data from the existing gas pipeline network of the province of Córdoba and also of new pipelines that are to be constructed by the government of Córdoba during the triennium 2017-2019. The second part deals with the qualitative risk assessment of the pipeline network under analysis, using the survey data. The proposed qualitative risk assessment determines the probability and the consequences of events that likely occur in the network. The qualitative methodology uses indexes to compare the relative risk of different sections of the network and consequently, pipeline sections that require vulnerability assessments can be determined.

  Abstract
  To study the vulnerability of the natural gas pipeline infrastructure in a region of Argentina, the characterization of gas pipelines from the province of Córdoba is [...]

  • 38
  •  read