ASSET, a corrosion prediction system

ChemApp is a significant component of ASSET, an information system that predicts corrosion of commercial alloys in complex industrial environments.

The United States Department of Energy – Office of Industrial Technologies has recently agreed to fund a project which will extend ASSET’s capabilities. The joint industry project, which will begin in January 2003 and last two years, brings together many industrial companies, several research institutions and testing facilities, and experts in the fields of corrosion, thermochemistry, and software development. Additional companies and organizations are welcome to join the project.

ASSET is a PC-based tool to help engineers assess the probable corrosion of commercial alloys used in process equipment containing complex, hot corrosive gases. Many aspects of equipment and process design and operation, alloy selection, plant maintenance, and process economics are influenced by the expected lifetimes of equipment in these environments.

ASSET has many user-friendly features and has been in practical use for about a decade. Over that period it has had many enhancements. During the last year its thermochemical modeling capability has been significantly improved by incorporating ChemApp and by including a new thermochemical database including the system of Fe-Cr-Ni-Co-C-O over the temperature range of 250 – 1,2000C. Sulfur-containing species will be added in March 2003.

Functionally the software consists of three main modules:

  • a database of corrosion measurements under well-defined conditions. The database now contains 5,900 corrosion measurement records with a total exposure time of 8.3 million hours, for 88 commercial alloys.
  • a capability to develop correlations between corrosion and exposure conditions, using the measurements in the database to predict corrosion. Corrosion for different alloys can be compared and calculated over a range of temperature, time, or gas compositions.
  • a Gibbs free energy minimization approach is used to determine the equilibrium gas composition and the stable corrosion products that might form on the surface of the metal. The corrosion products determine the dominant corrosion mechanism (for example, oxidation, sulfidation, or sulfidation/oxidation) and thus the correlation equation that should be used to predict corrosion. The software runs ChemApp in the background; the user sees only the customized ASSET interface.

Some 70 companies are participating in an ongoing three-year joint industry program and have access to the ASSET technology.

The core team of the new project will be the same as that of the current project: Shell Global Solutions, which manages the project and performs corrosion testing; Oak Ridge National Laboratories, which also performs corrosion testing; The Center for Research in Computational Thermochemistry of the École Polytechnique de Montréal, which develops the thermochemical database; and Humberside Solutions Ltd., which creates, enhances, and supports the software.

ASSET can currently predict corrosion product formation and corrosion for wide ranges of conditions for four corrosion mechanisms: oxidation, sulfidation, carburization, and sulfidation/oxidation. Corrosion product stability assessments for nitridation are also possible. The new project will extend these capabilities to include metal dusting, cyclic oxidation, and Cl2/HCl corrosion. (Details are now being finalized.)

Numerous technical papers have been published about ASSET. For more information about ASSET and the new joint industry program, please contact the project manager, Dr. R. C. John, Shell Global Solutions (U.S.),