Atlikus projekto analizę, buvo pasirinktas optimalus, ekonomiškiausias ir racionaliausias projekto variantas, padėsiantis užtikrinti mažiausias statybos ir eksploatavimo sąnaudas, taip pat ilgiausią tilto eksploatavimo laiką. Ruošiant suvirinimo procedūrų aprašus atlikti ardomieji ir neardomieji bandymai virintinėms jungtims. Bandymai užtikrina, kad virintinės jungties kokybė atitiks standartų keliamus reikalavimams. Neardomieji tyrimo metodai: apžiūrimoji kontrolė, skvarbiųjų dažalų kontrolė, ultragarso kontrolė. Ardomieji tyrimo metodai: tempimas, lenkimas, smūginis tąsumas, kietumas, mikroskopinis ir makroskopinis tyrimai. Darbą sudaro 6 dalys: įvadas, literatūros šaltinių apžvalga, tilto techninio projekto apžvalga, medžiagų skaičiuotiniai stipriai, išvados, literatūros sąrašas. Darbo apimtis – 74 p. teksto be priedų, 43 iliustr., 12 lent., 4 grafikai, 49 bibliografinių šaltinių. / After completing the project analysis, the most optimal, economical and rational project option was chosen, which will secure the lowest construction and manufacturing costs as well as the longest exploitation time. Making welding procedure specification, destructive and non destructive parts were tested for welding joints. The tests showed that the quality of welded joints will be sufficient for the standard requirement. Non destructive research methods: visual testing, penetrant testing, ultrasonic testing, destructive research methods: tensile test, bend test, impact test, hardness test, microscopic and macroscopic tests. The structure of work : introduction, theory research, overview of the bridges' project, calculated strengths of the materials, conclusions, bibliography. Thesis consist of - 74 pages of text, 43 illustrations, 12 tables, 4 graphs, 49 sources.

M. Tech. (Engineering, Industrial, Dept. Industrial Engineering and Operations management, Faculty of Engineering and Technology) Vaal University of Technology| / This research work focused on welded titanium alloy (grade 5) pipes, to ascertain if the weld joints can withstand the immediate and accumulated effects of fluid flow in (industrial) applications. Modeling of welded pipes was done using Pro/ENGINEER Wildfire 5.0. The cylindrical pipe models were of 206,375mm inner and 219,075mm outer diameter respectively; made of Ti6Al4V material. Three models were made: one of unwelded pipes, another with a seam weldment and the third with a circumferential weld. The welds were modeled as autogenous gas tungsten arc welding and the models included calculated heat affected zones. The pipes were modeled with a flowing fluid under pressure exerted evenly on all sides of the pipe walls (circumference). The boundary conditions were such that the pipe ends were supported as if the pipe were continuous. Stress and strain analysis on the pipe models were performed by the Finite Element Method using Pro/ENGINEER Wildfire 5.0. The results of the Finite Element Analysis (FEA) indicated that stress vary very negligibly along the pipe. A comparison of the FEA modeling results to the analytically determined value of the stress showed very low or zero percentage deviation.

A utilização de tubos de aços de alta resistência e baixa liga (ARBL) é comumente o mais indicado, segundo a norma American Petroleum Institute (API) 5L, para o transporte de óleo e de gás sob pressão. Em vista da necessidade de adequar as tubulações em campo de acordo com o relevo de cada região, são realizados curvamentos a quente em tubos. Durante este processo, o tubo sofre tratamentos térmicos, modificam sua microestrutura e propriedades mecânicas. Neste sentido, foram realizados, neste trabalho, tratamentos térmicos de têmpera e revenimento, com o objetivo de melhorar as propriedades mecânicas nas juntas soldadas. O material utilizado foi o tubo API 5L X80 com diâmetro de 40 polegadas e 16 mm de espessura. Foi realizada a soldagem circunferencial com passe de raiz pelo processo Metal Active Gas (MAG) com curto circuito controlado, gás de proteção 80% Ar e 20% CO2, passes de enchimento e acabamento pelo processo de soldagem com arame tubular (AT) e gás de proteção 75% Ar 25% CO2. Os consumíveis utilizados no passe de raiz foi arame sólido ER80S-G e nos passes de enchimento e acabamento o arame tubular E101T1GM-H8. Realizaram-se combinações de tratamentos térmicos de têmpera e revenimento com variações nas temperaturas de ambos. Para analisar a influência destes tratamentos térmicos foram realizados ensaios de tração, ensaios de microdureza e ensaios de impacto Charpy às temperaturas de -40 ºC e 0 ºC no metal de solda (MS) e na zona afetada pelo calor (ZAC). Alguns tratamentos térmicos realizados aumentaram a resistência à tração e a tenacidade em relação à condição como soldada, mas o melhor tratamento térmico foi o de tempera a partir de 900ºC seguindo de revenimento a 650 ºC. / The use of high strength low alloy steels tubes is commonly the most appropriate for transporting oil and gas under pressure, according to API 5L. In view of the need to adapt the pipes in the field according to the relief of each region, they are held hot bend in pipelines. During the process, the product undergoes thermal treatments which modify its microstructure and mechanical properties. It has been carried out, in this work, heat treatment of quenching and tempering, with the objective of obtaining the best mechanical properties in the welded joints. The material was API 5L X80 pipe with a 40 inch diameter and 16 mm thick. The circumferential welding pass root was done by GMAW with controlled short circuit transfer, shielding gas 80%Ar and 20% CO2. Filling and finishing passes were welded with FCAW using a shielding gas 75% Ar and 25% CO2. Consumables used in the root pass were ER80S-G and in the filling and finishing passes E101T1GM-H8. There were done four heat treatments of quenching and tempering for 2 hours. The results were analyzed by tensile test, hardness and Charpy V impact tests at temperatures of -40 °C and 0 °C in the weld metal and HAZ. The heat treatments influence statistically on the mechanical properties of welded joints related to as welded condition. The best result was quench heat treatment at 900°C followed by tempering at 650°C.

Este trabalho trata sobre o estudo numérico das forças motrizes (J e CTOD) em corpos-de-prova SE(T), usualmente extraídos da junta soldada do componente estrutural defeituoso, especificamente dutos submarinas (risers) com trincas circunferências alocadas no metal de solda. Durante o processo de instalação (reeling method) o duto é submetido a grandes carregamentos cíclicos (principalmente momentos de flexão) os quais introduzem fortes deformações plásticas (~2 e ~3%) afetando diretamente a integridade estrutural e a operação segura do sistema dutoviário. Procedimentos correntes aplicados na determinação da tenacidade à fratura de materiais, frequentemente, baseiam-se no coeficiente adimensional de proporcionalidade plástica (o fator n) e tem se mostrado válido em espécimes homogêneos. Para configurações com dissimilaridade mecânica, a aplicação direta deste método fica comprometida pelo grau de complexidade que existe entre a relação acoplada das forças motrizes (J e CTOD) e carregamento remoto com a dissimilaridade mecânica introduzida pelo processo de soldagem. O objetivo da presente tese é desenvolver um procedimento numérico de estimação de parâmetros de mecânica da fratura aplicáveis em configurações não padronizadas SE(T) para condições de dissimilaridade mecânica (weld strength mismatch). Uma extensiva análise de elementos finitos é desenvolvida na obtenção dos fatores n aplicáveis para espécimes SE(T) com várias profundidades de trincas (a/W) e níveis de dissimilaridade mecânica (My) para dois tipo de carregamento: garra (clamped end) e pino (pin loading). Três diferentes, mas correlatos métodos são aplicados para a obtenção acurada dos fatores n em condição de dissimilaridade mecânica, a saber, são: trabalho plástico, separação de cargas e carga limite. Os efeitos tridimensionais são analisados de forma sistemática para diferentes valores de espessura (B/W) e comprimentos do espécime (H/W) com a finalidade de avaliar a robustez das soluções obtidas das análises em estado plano de deformação. Finalmente, os resultados obtidos fornecem suporte para uso de espécimes SE(T) em procedimentos de avaliação de defeitos em dutos soldados submetidos a carregamento de flexão. / This work focuses on the numerical study of crack driving forces (J and CTOD) on single edge notch in tension (SE(T)) specimens usually extracted from defective structural components, specifically, circumferentially welded cracked pipes. The most efficient procedure to deploy submarine pipes (risers) on the sea floor is the reeling method. This procedure introduces a huge amount of cyclic loading to the girth welded pipe during the installation causing permanent plastic deformation (around ~2 to ~3%), which can affect the structural integrity and safe operation of the pipeline system. Current material fracture toughness procedures rely upon accuracy of proportionality plastic coefficient (also known n factor), which has to be effective for homogeneous condition. For mismatched configurations, where the strength of the weld metal is higher than the strength of base metal (also referred as overmatching), the direct applicability of such procedures remains a key aspect for defect assessment procedures and fitness for service codes, due to the complexity of the univocal relationship between crack driving forces and remote loading and the weld strength mismatch effect. The goal of the present thesis is to develop an estimation procedure of fracture mechanics parameters (J and CTOD) for SE(T) specimens in heterogeneous conditions. Extensive finite element analyses were conducted in order to obtain n factors for mismatched SE(T) specimens with varying crack lengths (a/W), different levels of overmatch (My) and two loading schemes (clamped and pin loading). Three different but related methods are applied to compute the n factor for welded mismatch configurations, namely the plastic work, load separation and limit load method. Also, the 3D effects are systematically analyzed for different thickness (B/W) and different specimen lengths (H/W) in order to prove the robustness of the proposed solutions derived from FE analyses in plane strain conditions. Finally, the results provide strong support for the use of constraint designed SE(T) specimens in fracture assessments of circumferential surface cracks in girth welded pipes subjected to bending moment.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Bibliography: leaves 141-142. / by David Adams Garlow. / M.S.

Abstract not available

The strength of thin-walled cylindrical shell structures is highly dependent on the nature and magnitude of imperfections. Most importantly, circumferential imperfections have been reported to have an especially detrimental effect on the buckling resistance of these shells under axial load. Due to the manufacturing techniques commonly used during the erection of steel silos and tanks, specific types of imperfections are introduced into these structures, among them circumferential weld-induced imperfections between strakes of steel plates. The main objective of this thesis was to investigate the exact nature of these circumferential welds and their influence on the buckling resistance of silos and tanks under axial load. The results of a survey of imperfections in existing silos at a location in Port Kembla / Australia (Ding 1992) were used to develop and calibrate a shape function which accurately describes the geometric features of circumferential weld imperfections. It was found that after filtering out the effects of overall imperfections, three parameters governed the shape of the surveyed imperfections: the depth; the wave length; and the roundness. A study on several factors influencing the buckling of silos and tanks was carried out using the finite element method. The interaction between neighbouring circumferential weld imperfections was investigated and it was found that the influence on the buckling behaviour depended on the strake height in relation to the linear meridional bending half wave length and the depth of the imperfection. The strengthening effect of weld-induced residual stress fields for a range of different geometries was also studied, and diagrams were derived giving the influence of the newly developed shape function on the buckling behaviour. A post-buckling analysis was undertaken and a model for the post-buckling behaviour of cylindrical thin-walled shells with circumferential weld imperfections was developed. The methods used for the analysis of thin-walled cylinders were applied in a study on the buckling behaviour of welded box-sections. It was found that weld-induced residual stress fields governed the buckling behaviour of these columns / Doctor of Philosophy (PhD)

"1st February 2002" / Includes bibliographical references (leaves 265-273) / xi, 273 leaves : ill. (some col.), plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Concerns the specialized requirements of welding procedures used on operational gas pipelines. / Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 2004?

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 182-188). Also available on the Internet.

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2009. / Includes bibliographical references.