NTSB Safety Recommendation Letter P-80-059

Page 1Official PDFWASHINGTQN, D.C. I S S U E D : J u l y 15, 1980 Mr. Howard Dugoff Administrator Research and Special Programs Administration Washington, D.C. 20590 i I SAFETY RECOMMENDATION ( S ) P-80-59 At 11:36 a.m., e.s.t., on October 30, 1979, a natural gas explosion and fire demolished a townhouse at 215 Third Street SE., in Washington, D.C., and damaged nearby buildings and cars. No one was inside the townhouse at the time, but three persons in a stopped car were injured when debris from the explosion shattered a car window. i/ After the accident, an inspection of the gas service line that served the townhouse revealed that it had been struck by excavating equipment. The investigation determined that the I-inch plastic service line inside of a 1 1/4-inch steel line had been pulled out of a transition compression coupling, allowing the natural gas to leak under low pressure and migrate into the townhouse where it was ignited by an unknown source. Shortly after the accident, gas company employees removed the plastic line from the steel casing before exposing the coupling. This prevented Safety Board investigators from determining the distance the plastic pipe had been pulled from t h e coupling and the amount of slack provided in the line to Compensate for contraction and expansion of the plastic pipe. The gas company has established procedures for analyzing accidents and failures that comply with 49 CFR 192.617, "Investigation of failures." Removing evidence prematurely during onsite investigations makes it more difficult for investigators to determine the cause of an accident. In this case, the lines should not have been disturbed until both the Safety Board and gas company personnel had completed the onsite investigation. - 1/ For more detailed information, read "Pipeline Accident Report--Washington Gas Light Company, Natural Gas Explosion, 215 Third Street SE., Washington, D.C., October 30, 1979" (NTSB-PAR-80-4). 2791A#