Case Study of Steam Hammer Event in an Ethylene Plant

A steam explosion incident occurred on a Steam Line in a Gulf Coast Ethylene Production Facility. A detailed review of the third party failure analysis, along with a site visit and field walk down of the equipment determined that the cause of the failure was a condensation induced water hammer. This is a rapid condensation event, sometimes known as a "rapid steam bubble collapse". If conditions exist, a steam pocket becomes totally entrapped in subcooled condensate. When the steam gives up its heat to the adjacent condensate and pipe walls, steam changes from a vapor to a liquid state. As a liquid, the volume formerly occupied by the steam shrinks by a factor of from several hundred to over a thousand times the pressure. A review of one such incident will be discussed with attention on Root Cause and preventative measures.