Pan American Materials Congress: Materials for Oil and Gas Industry: Welding Technology, Corrosion Protection, Non-Destructive Evaluation, and Structural Integrity
Sponsored by: Third Pan American Materials Congress Organizing Committee
Program Organizers: Lorenzo Martinez Gomez, Instituto de Ciencias Fisicas UNAM; Adriana Rocha, Federal University of Rio de Janeiro

Thursday 8:30 AM
March 2, 2017
Room: Marina G
Location: Marriott Marquis Hotel

Session Chair: Lorenzo Gomez, UNAM; Adriana Rocha, UFRJ

8:30 AM  
Effect of Heat Input on the Microstructure and Toughness of Welded API Pipelines: Fernando Guzmán1; Moisés Hinojosa1; Eduardo Frías2; Elisa Schaeffer1; 1UANL, FIME; 2Tubacero
    In the manufacture of welded pipes for oil and gas transportation sometimes a failure known as Weld-Toe Crack occurs close to the fusion line on the Heat Affected Zone side. In order to better understand this failure, we propose a possible mechanism. We speculate that after crack initiation by stress concentration on the Widmanstätten ferrite (WF), propagation occurs either in a brittle manner on the Allotriomorphic ferrite (AlF) or in a ductile manner on the Acicular ferrite (AF). To test this a series of double joints were prepared in simple-wire tandem mode, the heat input was varied so as to modify the microstructure and toughness. We were able to minimize the AlF size and thus reduce the quantity of WF increasing that of AF, which resulted in higher values of toughness in according to the proposed mechanism.

8:50 AM  
The Corrosion Behavior of Newly Developed API X120 Pipeline Steel in H2S and Moderate Temperature Environments: Paul Okonkwo1; R. Shakoor1; A Mohamed2; 1Qatar University; 2Department of Metallurgical and Materials Engineering, Faculty of Petroleum and Mining Engineering
    The corrosion behavior of newly developed API X120 Pipeline steel was studied in 3.5 wt. % NaCl solution bubbled with H2S at temperature range of 20°C to 60°C employing potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). The corrosion products formed on the surface of the base metals were characterized using scanning electron microscopy (SEM). It is noticed that the formation of corrosion product layer takes place at both lower and higher temperatures which is mainly comprised of compounds of iron and sulphide. The electrochemical results confirm that the corrosion rate decreases with increasing temperature until it reaches to a maximum value at 40°C, and then increases with further increase in temperature. This initial decrease in corrosion rate with increasing temperature can be presumably regarded as the effect of formation of protected layer of mackinawite. However, cracking of the formed mackinawite layer beyond 40°C decreases the corrosion rate.

9:10 AM  
Adsorption of Organosulfur Compounds on Doped Boron Nitride Nanostructures: Francisco Villanueva1; Jose Rivera1; Pedro Navarro Santos1; 1Universidad Michoacana de San Nicolas de Hidalgo
    Dibenzothiophene (DBT) and its derivates are the main source of sulfur in oil. Commonly used hydrodesulfurization (HDS) processes eliminate most of those compounds through decomposition reactions. Alkyl derivates of DBT have proven to be hard to eliminate with the traditional processes. Adsorption of DBT and its derivates in boron nitride nanostructure doped with carbon atoms is proposed as an alternative/complementary process to HDS. The adsorption sites are the carbon atoms, which act as an attractive site for the free electron on the sulfur atom of the DBT derivates. The interaction between the DBTs and the nanostructures are studied through Density Function Theory calculations using the generalized gradient approximation GGA implemented in the VASP software. We report the complexation energies, conformations and separation between the sulfur atom and the carbon atoms in the nanostructure, and also studied the band gap change after complexation.

9:30 AM  
Evaluation of Non-Destructive Techniques (Thermography, Ultrasound and Eddy Current) for Detection of Failures in Metallic Substrates with Composite Anticorrosive Coatings: Marcella Grosso1; Priscila de Almeida1; Clara Johanna Pacheco1; Iane Soares1; João Marcos Rebello1; Sergio Soares2; Isabel Cristina Margarit-Mattos1; Gabriela Pereira1; 1UFRJ; 2Petrobras
    The aim of this study is to evaluate the ability of three nondestructive techniques, ultrasound, thermography and eddy current, for the detection of defects that can occur in metallic substrate with anticorrosive coating and compare the results regarding the advantages and disadvantages of each one of these inspection techniques. For this study, samples were made from a metallic substrate on which a composite anticorrosive coating and two types of defects were introduced: localized corrosion (defects of different geometries and depths inserted into the metallic substrate) and adhesion failure between the coating and the substrate. According to the results, the three techniques showed to be able to detect defects simulating localized corrosion on the substrate. However, defects simulating the adhesion failure were only effectively detected by thermography and ultrasound and a high correlation between these two techniques was observed.

9:50 AM Break PM Coffee Break

10:05 AM  
A Study on the Mechanisms Responsible for Dynamic Strain Aging Phenomenon in Inconel 718 Superalloy: Monica Rezende1; Sinara Gabriel1; Leonardo Araújo1; Jean Dille1; Luiz Henrique de Almeida1; 1UFRJ
    It is known that Inconel 718 presents dynamic strain aging (DSA) manifestation, which results in strength increase and ductility decrease. Understanding this phenomenon in Inconel 718 is quite complex, once more than one atomic species is involved and various mechanisms are proposed in literature. In this context, the objective of this study was to investigate the mechanisms responsible for DSA in Inconel 718. Material was subjected to heat treatments to obtain solution annealed and aging conditions. Tensile tests under vacuum were conducted at 200-950°C and strain rate 3.2 x 10-3 to 3.2 x 10-5 s-1. Microstructural analyzes and fractografy were performed on SEM and TEM. The mechanisms responsible for this phenomenon were identified and explained in accordance with initial microstructure and temperature range. The determination of the mechanisms considered competitive phenomena, such as intergranular oxidation (OAIC) and dynamic precipitation, which are also thermally activated and then affect directly DSA manifestation.

10:25 AM  
Structural Integrity of Pipelines: Anibal Di Luch1; Nicolas Oyarzabal2; 1Comision Nacional de Energia Atomica; 2Instituto Tecnologico de Buenos Aires
    This work is part of a comprehensive structural integrity program of pipelines in Argentina, in particular it is applied to a gas pipeline in the North-East region. It is composed mostly of pipes API 5L grade X70 PSL 2, 24 inches nominal diameter and 11.9 mm wall thickness, manufactured by roll bending expand RBE and submerged arc welded SAW inside and outside. For girth welds assessment API Standard 1104 and BS 7910 guidelines are followed. This study is based on engineering critical assessment (ECA) and fitness for service (FFS) and it is required to perform complex tests and calculations like CTOD testing to assess both the weld metal and the heat affected zone. A sensitivity analysis is finally presented showing the effect of imperfection length and height on a failure assessment diagram (FAD).

10:45 AM Panel Discussion