Corrosion Based Design Analysis

Corrosion-based design analysis (CBDA)

This approach predicts the performance and assures the reliability of equipment or structure in question. The aim of CBDA is to assure the reliable operation of the  chosen components in the intended application and for the intended life. The main steps involved in CBD analysis amount to the following ten steps:

(i)  The environment in which the material selected can perform reliably. The environment considered is chemical  as well as the thermal conditions and the operating stresses.

(ii) Material is defined to include not only the type of alloy or metal, but also the impurities in grain boundaries, second phases, cold work, etc.

(iii) The 'mode' of corrosion is defined to include the morphology of degradation (corrosion) and its dependence on factors such as potential, pH, temperature, chemical species, alloy composition and stress.

(iv) Superposition involves comparison for the chosen material, various possible modes of degradation and their dependence on the anticipated environmental conditions. If the chosen materials undergo degradation, change in conditions of overlap or change in design or material or modification of environment by the addition of inhibitors is warranted.

(v) Failure is a relative factor and in general means not meeting with the expected requirements. Since the term is relative it is imperative to define the requirements to be met at the design stage.

(vi) Development of a statistical framework of the corrosion modes and the extent of degradation.

(vii) Accelerated testing with the prototype equipment under the expected conditions must be done.

(vii) Based on the foregoing steps the prediction may be made on the performance of thechosen design and material and whether failure can occur.

(ix) The analysis also recommends corrosion monitoring, inspection and feedback of the results.

(x)  Finally, depending upon the data accrued, modification in design, materials selection, operations, monitoring or inspection may be implemented as a result of comparison of operational data with the predictions.

Reference:

Sastri, V. S., Ghali, E., & Elboujdaini, M. (2007). Corrosion Prevention and Protection Practical Solutions. Chichester, West Sussex: John Wiley & Sons Ltd.