LANCASTER COUNTY — The National Transportation Safety Board determined an improperly installed gas connection was the cause of the 2017 explosion that killed one person, injured three others, and destroyed a Millersville home, the agency announced Wednesday on its website.
Central to the investigation was the installation of a tapping tee, the connection between the gas main and the home’s individual gas line, the NTSB said.
Six other homes in the Springdale Lane neighborhood were damaged by the explosion, which occurred on July 2, 2017, according to the NTSB.
The NTSB said its examination of the tee assembly involved in the accident revealed the assembly was incorrectly installed, because a locking sleeve — an important piece of hardware that served as an attachment between the tee and the gas main — was not attached to the main.
“Since the locking sleeve was not attached, additional stress was placed on four nylon bolts which hold the tee assembly in place,” the NTSB said in its determination. “The NTSB determined two of the four nylon bolts fractured when in service in a manner consistent with slow crack growth. The incorrect installation of the tee, combined with the in-service fracture of the two nylon bolts, allowed gas to escape from the tee assembly.”
In June 2018, the NTSB issued four safety recommendations to the Pipeline and Hazardous Materials Safety Administration and Honeywell International Inc. stemming from the Millersville investigation.
The recommendations were intended to prevent the incorrect installation of mechanical tapping tee assemblies in gas distribution systems.
UGI Utilities issued the following statement in response to the NTSB’s determination:
UGI Utilities, Inc. (UGI) is aware of the report published today, on the U.S. National Transportation Safety Board (NTSB) website, regarding an incident that occurred in Millersville, PA on July 2, 2017 involving UGI facilities. UGI has cooperated fully with the NTSB in its investigation of this incident. Previously, UGI carefully reviewed the NTSB Preliminary Incident Report, published in August 2017; as well as the NTSB Safety Recommendation Report on mechanical tapping tee devices, published in June 2018.
During its response to the incident in July of 2017 and throughout the Company’s activities that occurred in the area after the incident, UGI complied with all regulatory requirements regarding the safe and reliable operation of Company facilities.
Since that time, UGI has proactively undertaken efforts to enhance and expand Company-wide safety initiatives. UGI efforts include such activities as: training opportunities for fire department and other first responders, expanding employee safety awareness; development of an enhanced Company safety culture; refined safety policies; increased focus on utilization of Incident Command System (ICS) protocols; and enhanced cooperation with electric utilities operating within the UGI service territory to eliminate potential sources of ignition during response to natural gas incidents.
UGI Utilities remains fully committed to the safe operation of its system, and to the safe and reliable delivery of energy to our customers and to the many communities we serve.