Risk Based Inspection (RBI)
Risk-Based Inspection (RBI) is an inspection approach that has become more common in the process industries. Inspection codes such as API 510 and API 570 now recognize RBI approaches and have included many of its concepts along with the traditional time-based methods. RBI is a risk assessment and risk management tool that assesses the likelihood and consequence of loss of containment in process equipment. It integrates the traditional codes and standards with the flexibility to focus and optimize the activities on risk reduction by identifying higher-risk assets. RBI is typically used to develop and optimize the inspection plans for pressure vessels, storage tanks, piping, and relief devices, which together are generally called “fixed equipment.”
To assist in developing and implementing RBI programs, the American Petroleum Institute has published API RP 580 (Risk-Based Inspection) and API RP 581 (Risk-Based Inspection Technology) as recommended practices for the implementation of RBI. The RBI methodologies also focus on assets with higher risks through a systematic analysis of damage mechanisms, conditions and the application of the most appropriate inspection techniques.
RBI programs can be much more responsive in updating inspection plans and can substantially reduce inspection and lost production costs while at the same time reducing risk. Because implementing an RBI program often involves extensive cost and time commitments, many facilities use project management procedures to guide the process. Expertise in RBI methodology and implementation will be needed. Whether such expertise is developed in-house or an RBI consultant is used, facilities need to provide work processes, procedures, inspection strategies, training, and software tools. Facility resources from inspection, process, engineering, operations, and maintenance
groups will also need to be tapped to provide input and expertise on the process and its equipment, with the additional involvement of corrosion engineers, equipment engineers, and risk analysts. The features of RBI consist of the following:
- Equipment and Process data: Necessary asset data include design temperatures, design pressures, materials, sizes, details on stress relief, insulation, coatings, etc. Also, the following process information is needed: process stream compositions, fluid properties, operating temperatures, and pressures, flammability, and toxicity.
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- Risk Modeling: To identify the underlying methodology for determining the likelihood and consequences of a release. Facilities typically use computer software to support the methodology, and personnel must understand the methods and assumptions used.
- Inspection Strategies: RBI programs use a set of rules or guidelines for determining appropriate inspection methods, levels of inspection, and maximum intervals. These guidelines provide the methodology for creating inspection plans for each asset based on its risk ranking, equipment type, and deterioration mechanisms.
- Inspection Planning: RBI takes current inspection results, enters data into the risk model, recalculates the risk ranking, and modifies the inspection plan accordingly, based on the inspection strategy and the inspector's expertise. Although many commercially available RBI software packages offer ITPM (inspection, testing, and preventive maintenance) scheduling capabilities, it is advised that this not be done automatically. Instead, the program recommends an inspection plan be reviewed and approved by a designated person with experience in equipment inspection and analysis. Many factors outside of the RBI need to be merged for a proper ITPM plan to be generated, such as turnaround schedules, equipment redundancy, and availability of parts and manpower.?
- Management Systems and Tools: RBI generally uses work processes and computer tools to collect, interpret, integrate, and report the inspection data and plan and schedule inspection tasks. Management of the RBI program also involves reporting on activities, status, exceptions, and trends.