​at 6:57am on April 22, 1974, a massive, low-order explosion demolished the west wall of a 25 story commerical building at 306 East 45th Street in New York City, New York. The structure of the adjacent building was damaged and glass was broken in other buildings in the area. Glass fragments and slivers were blow onto 46th Street, where they lay 1 inch think in places. No persons were killed but more than 70 persons were injured.

​We determined that the probable cause of the accident was the rupture of an overpressured hydropneumatic tank which rocketed upward and tore an overhead gas service line out of its threaded joint; this allowed gas to flow unabated into the building. 

​Contributing to the spreak of the explosive gas air misture throught the building were elevators, which drew the explosive misture up through the elevator shafts before ignition. ​

​​​​​​As a result of this investigation, we made​ the following safety recommendations.

To the Department of Transportation:

• Determine the availability, the practicability, and the state-of-the-art in the manufacture of excess flow valves for use on low-pressure gas distribution systems. Based upon the results of these findings, amend 49 CFR 192 to incorporate the use of these valves in commercial buildings. (P-76-09A​) (Superseded by P-81-38 through P-81-39)
• Amend 49 CFR 192 to define more realistically an operators resposibility  for gas piping inside buildings.(P-76-10)
• Expedite it's review of the studey of "Rapid shutdown of failed pipeline systems and limiting of pressure to prevent pipeline failure due to overpressure" and determine what regulatory action is necessary concerning the use of excess flow valves. (P-76-11​)​