Risk Based Inspection – the API 581 Risk-Based Inspection Resource

Many more comapanies would avail themselves to the benefits of risk based inspections except for a fear of the cost and effort involved in compliance. To overcome this caution on the part of companies and to standardize practices, two noted institutions, ASME and API, have develop tools and software for the RBI method. The ASME research studies present the groundwork necessary to develop risk based inspection guidelines, but do not actually provide such guidelines. The API project builds upon the ASME effort to develop usable tools that companies could benefit from with reasonable cost of effort. API publish those tools in API PUBLICATION 581 Risk-Based Inspection Base Resource Document (RBI BRD).

To optimize and simplify the risk analysis task, API has define three levels of risk analysis in API 581. those three levels of risk analysis are:

1. Qualitative

2. Semi-quantitative

3. Quantitative

API first developed the quantitative risk analysis. After doing some case studies, they analyzed the process and found that the most time consuming step is the release quantity determination in consequence analysis. Simplification of this step led to the development of semi-quantitative risk analysis. The qualitative risk analysis is developed as a preliminary screening tool used before a more rigorous analysis is done. Usually, only items with high risk attributes are further analyzed using quantitative risk analysis while items with lower risk are analyzed using the semi-quantitative method.

API RBI BRD provides guidelines that could serve as heuristics to identify in-service damage mechanism based on operating condition, equipment material, and working fluid properties. It also provides a guideline to establish damage rate for a particular damage mechanism in case that it is not available because no inspection is ever performed on the equipment to look for the damage mechanism. API RBI BRD presents inspection program development in a simple manner with tables to look up for each damage mechanism.

API also publishes API Recommended Practice 581 Risk Based Inspection. This document provides managerial guidelines to successfully implement RBI program in a company.