Changes Between API STD 520 Part II 6th Ed and 5th Ed Cataloged

API STD 520, Sizing, Selection, and Installation of Pressure-relieving Devices in Refineries, is a comprehensive set of guidelines on how to properly install relief devices in a refining (or petrochemical) facility.  This paper reviews the differences between the 6th Edition of API RP 521 (Published in late 2014) and the 5^th edition (Published in 2003).  The authors will review changes and highlight several that are deemed critical to relief systems design.  The paper is based on a comprehensive review of the two documents and is a valuable resource for any engineer or process designer who needs to be knowledgeable of the latest relief systems recommendations.