A news item in today's New York Daily News reports that a state regulator has found that a crucial valve had malfunctioned prior to last month's massive steam explosion near Grand Central Terminal.
In an affidavit, the engineer who oversees steam services for the New York Public Service Department, Thomas Dvorsky, stated that a steam trap at 41st Street and Lexington Avenue, which should have been draining water from the steam pipe in question, wasn't operating and had a possible debris buildup. The failure of the trap could have led to a condition in the pipe called a water hammer, which can lead to a catastrophic surge in pressure.
While the investigation into the rush-hour explosion, which killed one and injured scores, is ongoing, preliminary tests on the stainless steel trap found it was defective.
"The nondestructive testing was inconclusive; it just showed the trap assembly was not working properly," Dvorsky wrote. He added that the trap should be cut open to look for "sediment or foreign materials in the trap that prevented functioning."
The affidavit was filed in Brooklyn Supreme Court in a lawsuit against Con Edison brought by the family of a driver who was seriously injured by the explosion on 18 July.
[For more on the Midtown Manhattan steam blast, see "New York City Rocked by Steam Pipe Blast" in this space and a backgrounder on urban steam power in this month's online feature "Source of New York Steam Blast Is a Literal Mystery".]