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Description of Driving Event:

A high pressure steam valve ruptured in the basement of the building, releasing steam that damaged walls and floor tiles. The mishap was caused by dynamic loading to the line resulting from severe water hammer. Heavy rainfall preceeding the incident flooded the steam trench. The steam line enclosed with cool water set up a heat exchange process forming excessive condensate that was put into motion by the building demand. Slugs of water generated dynamic loads in the piping. The cast iron steam valve (Chapman gate valve model 59 1/2) then ruptured.