Identification of Potential Stagnant Areas in an Ethylene Plant

Unexpected over pressurization, reduced rates and/or equipment damage can occur due to polymer build up in stagnant and low flow areas. After an over pressure event occurs frequently the root cause is found to be an unknown low flow, stagnant areas or dead leg that was not recognized prior to the event. For this reason, identifying these stagnant/low flow areas beforehand and event is critical. This paper discusses how one might survey their system, looking for those stagnant areas. This involves a detailed P&ID and field review of the systems to identify the areas of concern. Several examples of what to look for are presented. Once these stagnant areas are identified there are several ways to eliminate them. These common practices will also be discussed.