Improved technique for toughness testing of shale rocks

Mode I fracture mechanics tests of mostly calcareous Vaca Muerta shale rocks were performed in a new experimental device. A hydraulic system allows the injection of pressurized fluids inside of cracks to generate applied KI and measure fracture toughness in room pressure and temperature conditions. Multi-notched 1.5″ plugs were tested with different polar and non-polar fluids (waterbased fluids and organic solvents). Some samples were subject to previous saturation in order to activate multiple micro crack initiation via various embrittlement mechanisms. The methodology allows to test a large number of plug samples with low cost and times, and with a comparatively low uncertatinty and scatter of results with respect to other techniques. Results are discussed in terms of the two stress terms at the crack tip: Stress Intensity Factor (KI) and T-stress, and according to the Extended Maximum Tangencial Strain criterion (EMTSN). The variation of toughness in dry and saturated samples are discussed in terms of damage mechanisms, as well as in terms of the stochastic nature of toughness results in these rocks. The convenience of repeating these tests at reservoir pressure and temperature conditions is recognized.Fil: Antinao Fuentealba, Fabián Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería. Instituto Malvinas; ArgentinaFil: Otegui, Luis Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería. Instituto Malvinas; ArgentinaFil: Bianchi, Gustavo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería. Instituto Malvinas; Argentin

Fatigue damage leads to a serious traffic accident

The engineering forensic analysis of a traffic accident involving a truck and a bus is presented. Fractographic, metallographic and mechanical studies and numerical models of load transfer and crack propagation were made. A mechanical failure due to fatigue crack propagation was the immediate cause of the accident. However, a series of other factors contributed to the accident, which are also discussed.Fil: Otegui, Luis Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Technology- based spin outs in materials engineering: The case of GIE S.A

Se presenta la historia de los primeros veinte años de la empresaGIE, especializada en integridad de equipos industriales, en la visión de unode sus fundadores. Se discuten en particular las vicisitudes de losinvestigadores devenidos en emprendedores en los primeros años de formación yconsolidación de la empresa,  lasdificultades más relevantes enfrentadas y las ventajas competitivas quepermitieron el éxito de la empresa.Fil: Otegui, Luis Jose. YPF - Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Failure Analysis: Fundamentals and applications in mechanical components

This book addresses the failures of structural elements, i.e. those components whose primary mission is to withstand mechanical loads. The book is intended as a self-contained source for those with different technical grades, engineers and scientists but also technicians in the field can benefit from its reading.Fil: Otegui, Luis Jose. Universidad Nacional de Mar del Plata; Argentina. YPF - Tecnología; Argentin

Challenges to the integrity of old pipelines buried in stable ground

A succinct description of the particular conditions that have led to failures and damage of buried pipelines in Argentina is given in this article. The particular characteristics of soil, demographic evolution, original construction standards and procedures, and specific damage conditions based in case histories, are taken into account. The purpose of this review is to contribute in orienting the efforts by operators and regulation bodies in order to efficiently increase the reliability of onshore buried pipelines. The author has been involved in many failure analyses involving pipelines in this country, some of the latest being related to explosions involving natural gas pipelines and related equipment. The Argentine high-pressure oil and gas transmission pipeline system includes more than 40,000 km of buried piping. Diameters range from less than 14–36 in. Construction dates of most of these pipes range from around 1960 to around 1980. Particular cases discussed are: • Old pipelines in stable ground • Failures by SCC in buried pipelines • Dealing with low-frequency ERW seam pipe • Unknown materials and historical conditions of operation • Integrity of old repairs • Influence of demographic changes along right of waysFil: Otegui, Luis Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. YPF - Tecnología; Argentin

Failures by SCC in buried pipelines

Until a few years ago there had been no record of stress corrosion cracking (SCC) as a main cause of failures in Argentine pipelines, but as the pipeline system became of a certain age this mechanism started to have an important impact on reliability. This study analyzes three blowouts attributed to high pH SCC in different oil and natural gas transmission pipelines, which occurred by the sudden propagation of longitudinal cracks at the outer surface of the pipes.Fil: Manfredi, C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Otegui, Luis Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Factors influencing transit fatigue of seamless pipes

Full‐scale fatigue tests simulating real pipe stock conditions in ships were carried out in order to reproduce failures of seamless pipes due to fatigue crack growth during shipping. Simple mechanical analyses were then used to assess the factors that influence transit fatigue. As seen in several actual failures, fatigue cracks were found to propagate from both sides of the pipe wall. It is possible to have transit fatigue (TF) when piling up a few pipes for transportation, if there is previous plastic indentation. Susceptibility to TF was found to be independent of the nature of discontinuities in the surfaces of the pipes. Precautions to reduce the probability of TF in sea shipment include preventing plastic indentation of the pipes and storing stiffer pipes in the bottom part of the hold.Fil: Kunert, Hernan Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Otegui, Luis Jose. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Root causes of fire in a solvent pipe at a petrochemical plant

The root causes of a leak followed by a small fire in a 2 in. solvent pipe in a Petrochemical Plant are discussed. The fire occurred during blanket heating to 300 °C to dissolve polymer clogs. Fractographic and metallographic analyses showed that the failure is characterized by intergranular through the thickness propagation of longitudinal cracks initiated at the outer pipe surface. This cracking mode is called r-type cavitation. The leaking solvent self ignited, polymer deposits inside the pipe carbonized, microstructure changed. All these indicate that pipe temperature during blanket heating reached 550 °C, much above the specified 300 °C maximum. At this temperature yield strength of the pipe material got below nominal hoop stress due to normal internal pressure. The failure of the temperature control system in one of the heating blanket sets was the main event that caused the fire. However, other conditions and exceeded barriers are discussed, related with safety procedures and insufficient support of the ongoing investigation by the contractor involved in the incident. As a result, changes in the declogging and safety procedures were introduced. © 2008 Elsevier Ltd. All rights reserved.Fil: Otegui, Luis Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Fazzini, Pablo Gabriel. GIE S.A.; Argentin

Influence of old rectangular repair patches on the burst pressure of a gas pipeline

Seven full scale hydrostatic burst tests were carried out on pipes extracted from an API 5LX52 gas pipeline that contained rectangular and elliptical fillet welded patches and other repairs of different geometries. All breaks took place after widespread yielding. This analysis shows that the patches that generate greater risks are those that: (1) were attached to the pipeline at very low pressure, (2) were placed to repair large defects, (3) are rectangular, long in the direction of the pipe, and narrow, (4) the quality of the weld is doubtful. Based on data reported by In Line Inspection (ILI), of the four conditions mentioned above, only the third can be assessed in order to quantify risks and to schedule replacements.Fil: Fazzini, Pablo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Otegui, Luis Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin