There are over 300,000 miles of gas transmission pipeline in the US today. The vast majority of these pipelines are medium to large-diameter, ranging from 10 – 48 in., and conveying gas typically at pressures of between 500 – 1400 psig in volumes of billions of ft3/d. As natural gas progressively replaces coal as the preferred fuel for electricity generating plants nationwide, and also becomes a major export commodity in the form of liquefied natural gas (LNG), this national pipeline grid has never been more important. Like any vital technology…