Risk Models for Materials Selection and Corrosion Inhibition for Offshore Oil/Gas Risers and Nuclear Waste Storage Tanks

Building infrastructure for the production, transportation, and storage of hazardous materials is sometimes a risky venture because of environmental variables that conspire against the materials used to construct such infrastructure. Materials are selected early in the development stage, and decisions must be made to sacrifice capital costs for operational costs or vice versa. For example, an upstream producer may weigh the costs of using carbon steel with an inhibitor versus nickel-plated steel to determine the short- and long-term risks of either decision. Whether the enterprise is to build an offshore oil rig or contain and transport hazardous materials, the corrosion rate is a critical parameter in assessing risk. By assessing the corrosion rate and mechanisms of corrosion, prediction of the lifetime and financial performance of the system is possible.  Corrosion is an event that corresponds to a consequence which will have varying degrees of severity, and assigning value to these consequences describes an overall risk picture of the endeavor. Therefore, corrosion rates can be directly correlated to lifetime or financial consequences of materials selection and corrosion inhibition.  This paper examines case studies where laboratory and field data are used as inputs to refine a risk model. The methodology to create the risk picture and assign value to the consequence of corrosion in these systems is explained.