HOW TO DESIGN, VERIFY AND VALIDATE EMERGENCY SHUTDOWN SYSTEMS

This paper describes one method to select equipment data and to use engineering tools to design, verify or validate Emergency Shutdown System (ESS) performance. The paper demonstrates ''how to'' in a manner that is easy to follow and understand, thus allowing users to duplicate the approach in a way that reflects their company's operating environment and needs. A hierarchy of equipment data sources is discussed as to desirability, applicability and selection. From quantitative methodologies and representative engineering tools, one is chosen and validated a simple fault tree analysis software tool. The tool is used to illustrate how to evaluate hypothetical designs to develop validated qualitative ''cookbooks'' adhering to a selected set of Primary Integrity Parameters (PIPs). Developing qualitative ''cookbooks'' can speed up the design process for the majority of ESSs. Design verification is applying the tool to the actual equipment and the configuration proposed and can be used if the ''cookbook'' PIPs do not meet the operation's needs. Validation is applying the tool to systems as installed and maintained, using actual documented equipment performance. Installed ESSs performance can be validated to support documented maintenance procedures, such as test frequencies.