NTSB Interim Report Provides Guidance for Industry To Enhance Safety

News Release October 11, 2018

Washington, D.C. – Safety is the top priority for America’s natural gas utilities. The American Gas Association (AGA) and its members have been using the publicly available information from the incident that took place on September 13, 2018 in Andover, North Andover and Lawrence, Massachusetts to examine their systems and procedures and share best practices for a wide variety of operations activities including upgrading pipelines, over-pressurization protection and the use of pressure sensors. Today’s National Transportation Safety Board (NTSB) interim report on the incident will provide further guidance to enhance safety.

The report states:

“A Columbia Gas-contracted work crew, which included a Columbia Gas inspector, was performing a Columbia Gas-designed and approved pipe-replacement project at a nearby intersection (South Union Street and Salem Street) in South Lawrence. The contracted crew was working on a tie-in project of a new plastic distribution main and the abandonment of a cast-iron distribution main. The distribution main that was abandoned still had the regulator sensing lines that were used to detect pressure in the distribution system and provide input to the regulators to control the system pressure. Once the contractor crews disconnected the distribution main that was going to be abandoned, the section containing the sensing lines began losing pressure.

“A contracted work crew performing a pipe-replacement improperly placed the regulator sensing lines used to detect pressure in the distribution system and provide input to the regulators to control the system pressure. Since the regulators no longer sensed system pressure they fully opened allowing the full flow of high-pressure gas to be released into the distribution system supplying the neighborhood, exceeding the maximum allowable pressure.

“Columbia Gas developed and approved the work package executed on the day of the accident. The work package did not account for the location of the sensing lines or require their relocation to ensure the regulators were sensing actual system pressure. The work was performed in accordance with steps laid out in the work package. In light of this accident, Columbia Gas implemented a safety stand-down for all employees who perform work related to low-pressure natural gas systems for NiSource subsidiaries.”

AGA’s Mutual Assistance Program has been requested by Columbia Gas of Massachusetts for the restoration process. AGA has been coordinating the movement of personnel and resources to the area with the Northeast and Southern Gas Associations to assist in replacing pipelines and appliances, making sure gas systems are up-to-code inside homes and reestablishing gas service.


The American Gas Association, founded in 1918, represents more than 200 local energy companies that deliver clean natural gas throughout the United States. There are more than 73 million residential, commercial and industrial natural gas customers in the U.S., of which 95 percent — more than 69 million customers — receive their gas from AGA members. Today, natural gas meets more than one-fourth of the United States' energy needs.