Deadly Dangers Lurk In Natural Gas Distribution Lines
https://www.forbes.com/sites/rrapier/2018/09/17/deadly-dangers-lurk-in-natural-gas-distribution-lines/#553e7b404890...Last week one person was killed, over 25 were injured, and dozens of homes were damaged or destroyed following a series of natural gas explosions in Massachusetts. The incident remains under investigation, but thus far investigators are focusing on the possibility of overpressurization of a gas main owned by natural gas utility Columbia Gas of Massachusetts.
Columbia Gas of Massachusetts services more than 300,000 customers in three areas in northwestern Massachusetts. Columbia Gas is one of seven regulated natural gas subsidiaries of NiSource, whose combined utility operations serve nearly 4 million customers in seven states. NiSource operates about 60,000 miles of distribution pipelines, and saw its shares drop by nearly 12% following the incident....
...According to the American Gas Association, steel is used in most natural gas transmission systems pipes, while plastic pipe has predominated in gas utility distribution systems over the past 30 years.
Ticking Time Bombs
The problem lies in the older pipelines. During the first half of the 20th century, cast iron was used in many utility systems. Steel replaced cast iron as the material of choice in the 1950s, but that means that there are a lot of older cast iron pipelines still in service.
A 2014 report by USA Today found that there is “at least 85,000 miles of aging cast-iron and bare-steel gas pipes still operating in U.S. communitiesâ€, with many in heavily-populated areas. Most of these aging pipelines can be found in the Northeast. The report also found that these pipelines are involved in a disproportionate share of gas leaks.
The National Transportation Safety Board (NTSB) and the Pipeline and Hazardous Materials Safety Administration have been warning utilities that these aging pipelines need to be replaced, but it isn’t required by law. The cost of replacing these pipelines can exceed more than $1 million a mile, with the costs passed on to consumers.
Columbia Gas has reported that it has 471 miles of cast- and wrought-iron gas distribution lines. This is more than all about 15 of the nation’s 1,000-plus gas utilities. These lines are vulnerable in a couple of ways. As old as they are, they will begin to corrode and crack. They are vulnerable to shifts in the earth that put additional stress on the pipeline.
But they are also vulnerable to overpressure, which is suspected as the cause....
