From the U.S. Government Accountability Office, www.gao.gov Transcript for: U.S. Energy Gas Pipeline Safety Description: The U.S. energy pipeline network is composed of over 2.7 million miles of pipelines transporting gas and hazardous liquids. What are these pipelines made of and how are they maintained? Related GAO Work: GAO-17-639: Pipeline Safety: Additional Actions Could Improve Federal Use of Data on Pipeline Materials and Corrosion Released: August 2017 [ Background Music ] [ Susan Fleming: ] Pipelines are a relatively safe mode of transporting dangerous materials. However, things can happen. [ Sarah Kaczmarek: ] Welcome to GAO's Watchdog Report, your source for news and information from the U.S. Government Accountability Office. I'm Sarah Kaczmarek. The U.S. Energy Pipeline network is composed of more than 2.7 million miles of pipelines, transporting gas and hazardous liquids. Pipelines are a relatively safe mode of transportation, but incidents caused by material failures and corrosion may result in fatalities and environmental damage. A team led by Susan Fleming, a director in our Physical Infrastructure team, recently looked into gas pipeline materials and corrosion. So I asked her, what are these pipelines typically made of? [ Susan Fleming: ] The vast majority, about 95 percent of pipelines, are constructed of either steel and plastic with some minor use of other materials such as composites and iron. But the extent of steel and plastic in our network really varies. The pipelines that gather natural gas or hazardous liquid materials from production wells and transport these materials to processing facilities. Nearly all of these pipeline systems are made of steel. Transmission pipelines transport gas and natural liquids sometimes over hundreds of miles at very high operating pressures to communities and large volume users such as facilities. Proposed Dakota Access or Keystone pipeline would be an example of a transmission line. And those are also primarily made of steel. Lastly, distribution pipelines which really transmit natural gas to homes and businesses, there's been kind of shift away from steel to plastic and about half of all of those lines are made of plastic currently. [ Sarah Kaczmarek: ] So my house actually backs up to a large gas pipeline and I, and I'm sure many other homeowners worry about leaks. So how do you go about preventing corrosion in these pipelines? [ Susan Fleming: ] Our report focused on the technologies that pipeline operators use to prevent corrosion in pipelines. And along with material and weld failures, they do account for about a third of all significant incidents with pipelines. Operators use primarily two technologies to try to protect steel from corrosion. The first is on the surface of the actual pipeline. Operators apply a coating which is a protective layer of plastic material or other chemical compound and it's applied and bonded across the surface of the pipeline. Second, to supplement these coatings pipeline operators then have to use cathodic protection which applies an electric current in the pipe and it prevents the chemical reaction that causes corrosion. [ Sarah Kaczmarek: ] So, how does the federal government go about overseeing the safety of pipelines that it regulates? [ Susan Fleming: ] PHMSA which is in -- within the U.S. Department of Transportation works hand in hand with state pipeline safety offices to oversee and inspect federally regulated pipelines. As you can imagine, PHMSA basically is responsible for transmission pipelines which cross state boundaries while states are primarily responsible for intrastate pipelines which are those gathering and distribution lines. And PHMSA basically uses a model to try to determine how frequently to inspect particular segments. We basically looked at that approach and we found that PHMSA uses its own professional judgment but didn't really document key decisions and also didn't take that necessary step to determine whether or not it's overall approach is effective and prioritizing the right segments for inspection. [ Background Music ] [ Sarah Kaczmarek: ] Given the challenges of ensuring pipeline safety, I wondered how the government uses its limited inspection resources effectively. I asked Susan to talk about some of the recommendations her team made in this report. [ Susan Fleming: ] Ultimately we recommended that PHMSA take two steps. First, it document those decisions and assumptions in the model that were used to really determine whether or not the right factors and the right weights were assigned. And also to take that step back and to really look at whether or not their overall approach and effect and model is really effective in prioritizing inspections. [ Sarah Kaczmarek: ] So finally, what do you see as the bottom line of this report? [ Susan Fleming: ] You know pipelines -- I think it's important to note that pipelines are a relatively safe mode of transporting dangerous materials. However, things can happen. There are risks imposed just by the fact that they are in your neighborhood. They're in facilities. They're in communities. And I think it's really important that PHMSA really assess the threat that these systems can pose and really take a step back and think about its overall approach and to make sure that it's managing those limited resources effectively and maximizing safety benefits to the public. [ Sarah Kaczmarek: ] Thanks for listening to the Watchdog Report. To hear more podcasts, subscribe to us on iTunes. [ Background Music ] For more from the congressional watchdog, the U.S. Government Accountability Office, visit us at gao.gov.