Bazzoni B.,CESCOR Srl |
Lorenzi S.,University of Bergamo |
Marcassoli R.,University of Bergamo |
Pastore T.,University of Bergamo
Corrosion | Year: 2011
Aboveground tanks for the storage of liquid hydrocarbon are often erected with a secondary containment membrane installed below the tank bottom to prevent soil contamination in case of leakage. The design of impressed current cathodic protection in the presence of the plastic membrane is based on distributed anodes installed in the space between the tank bottom and the membrane; among available anodes, the most commonly used are the titanium grid or ribbon activated with noble metal oxides. The configuration of the grid or ribbon anode system confined in the closed space between the bottom and membrane creates specific issues concerning the electrochemical reactions occurring at the anode and cathode, the ohmic drops in the anode system, and the potential and current distribution at the cathode. Results of a number of numeric simulations performed to predict the actual distribution of current and potential are given. Design criteria are discussed. © 2011, NACE International.
Fallahmohammadi E.,Polytechnic of Milan |
Bolzoni F.,Polytechnic of Milan |
Fumagalli G.,Polytechnic of Milan |
Re G.,Polytechnic of Milan |
And 2 more authors.
International Journal of Hydrogen Energy | Year: 2014
This paper describes the process of hydrogen diffusion in API 5L X65 and ASTM A182 F22 steels with three different metallurgical microstructures (quenched and tempered, quenched and annealed) by an electrochemical technique which is a modified Devanathan and Stachurski's cell. The analysis of experimental results compares different measurement methods for hydrogen diffusion coefficients: 1) charge method; 2) partial charge and partial discharge method; 3) discharge method. For the steel, cathodically polarized in acidic medium (pH ≈ 4.2), the less dispersed and more meaningful results are obtained by partial charge and partial discharge method after about one hundred hours of polarization, i.e., when a stationary regime was reached. The discharge method, carried out after one hundred hours of polarization, provides analogous results by extrapolation of the experimental results obtained during the initial phase of hydrogen desorption. The hydrogen diffusion coefficients measured would appear dependent only on the hydrogen migration processes in the crystal lattice regular sites and corresponding values DL increase as follows: quenched < quenched and tempered < annealed. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Dubini S.P.,ENI S.p.A |
Balostro V.,ENI S.p.A |
Francesco P.D.,ENI S.p.A |
Colombo V.,CESCOR Srl
NACE - International Corrosion Conference Series | Year: 2013
This paper describes the improvements of a software program developed for the materials selection of OCTGs and well completion components. The previous version of the program, released in 1998 and presented during 1997 and 2000 NACE Conferences, has been reviewed in terms of technical know-how and information technology to keep up with the modern industry. The most remarkable improvements in the field of technical know-how include the introduction of a number of well completion layouts as well as the management of other types of fluids and well services in addition to reservoir fluids and hydrocarbon production service. Other significant features consist of the development of a pass/fail approach for the selection of CRAs for sour service and the formulation of rules to help the corrosion engineer to select the most suitable test methods and test conditions. Moreover, new materials grades that became available in the last ten years have been added. The improvements in the information technology led also to the development of a new software framework. The new product is a web application, accessible from the company intranet network. It is a shared tool that employees can use, with different levels of authorization, reflecting their own skills and technical competence. Corrosion experts have also the chance to install a "local version" of the software on their laptops and subsequently synchronize all the data with a centralized database. Normal users are allowed limited access to the program functionalities, while users qualified as corrosion experts have the credentials to modify the software basic rules. Administrators can "publish" users' simulations on a centralized public library. In brief, this paper wants to remark how the concept of "expert system", born during the late 80s and developed during the 90s, is not out-of-date in the modern industry, but on the contrary, it is still topical and it has changed its shape in the last 20 years thanks to the improvements on information technology and industry know-how.© 2013 by NACE International.
Bazzoni B.,CESCOR Srl |
Dubini S.P.,ENI S.p.A |
Belloni F.,CESCOR Srl |
Msallem A.,Mellitah Oil and Gas B.V. |
And 2 more authors.
NACE - International Corrosion Conference Series | Year: 2011
Bouri Field is located in the Mediterranean Sea, about 120 km North West of Tripoli - in waters 160-170 m deep. The field includes the following main assets: drilling-production platforms (two); inter-field pipeline; sub-sea wells; FSO. The two platforms are the biggest ones in the Mediterranean Sea. Submerged structures are protected against seawater corrosion by means of aluminum alloy galvanic anodes. The original design life of the cathodic protection system was 35 years; however the Bouri CP System Performance Study has indicated that the expected life span of the CP system can be extended by 15 years. During the past operating life, a number of Underwater Inspection Campaigns have been carried out and a significant amount of data has been collected over a period of more than 20 years. These data, in particular structure potentials and anode consumptions, have been gathered and reviewed. The analysis included: follow up of the structure polarization; assessment of the actual protection current density demand; comparisons with the requirements of the international normative. Furthermore, a statistical analysis has been applied to the whole set of data. The paper illustrates the main evidences from data review, the adopted statistical approach and results of the statistical analysis. © 2011 by NACE International.
Marcassoli P.,CESCOR Srl |
Bonetti A.,CESCOR Srl |
Lazzari L.,Polytechnic of Milan |
Ormellese M.,Polytechnic of Milan
Materials and Corrosion | Year: 2015
This paper deals with the evaluation of the subsea pipeline integrity through the combination of potential profile, electric field gradient, and the modeling of the electric field originated by bracelet galvanic anodes by finite element method (FEM). The potential profile as well as the electric field gradient measured during a survey provide the representation of the cathodic protection (CP) level and the location of anodes and coating defects. Nevertheless, by overlapping the electric field calculated by a dedicated FEM modeling, a more accurate interpretation is achieved in order to estimate the critical coating defect size and to evaluate the effect of the presence of multiple defects. FEM modeling was based on a simplified 2D domain reproducing the main geometrical, physical, and electrochemical parameters, such as sea depth, mud burial depth, seawater and mud resistivity, current density and potential distribution. Boundary conditions were defined by assuming constant potential at galvanic anode, electrical insulation of the coating and by considering Butler-Volmer equation for steel surface at coating defects. Coating defect size, sea depth, mud burial depth were considered in a generalized parametric equation. An example of the application of the model is shown on the basis of results obtained by an inspection campaign. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.