Pipeline Explosions are far from rare.
On February 15, 2017 natural gas leaking from a pipeline exploded in Refugio, Texas – southwest of Houston. It was the second such incident in as many weeks. The previous incident occurred in Paridas, Louisiana – west of New Orleans – Friday February 10. No one was injured in the Texas event. Two workers were reported injured and one missing and presumed dead in Louisiana.
This type of incident is far from rare. Over the past twenty years, pipeline accidents have averaged over 100 per year. With the number of pipelines increasing due to the recent upsurge in domestic natural gas and oil production, and existing pipelines aging, the number of leaks, fires and explosions is likely to increase.
Pipelines in the U.S. carry a wide variety of commodities including natural gas, crude oil, gasoline, and many petrochemicals used in manufacturing.
Of these, natural gas may be the most dangerous for a number of reasons.
Natural gas is invisible and has no odor of its own. Natural gas consists mainly of methane (CH4), but can also contain traces ethane, propane, and other light gases and compounds. When gas arrives to the average consumer, an odorant has been added to give it a distinctive “rotten egg” smell. The odorant is typically added at the local distribution point. Gas in bulk transmission lines generally has no odorant. In the case of a pipeline leak, there may be no obvious sign that a leak is occurring.
Fuel density plays a part in ability of a substance to ignite. Most substances only burn as a gas or vapor. While liquids can evaporate, solids must go through a process known as pyrolysis, where the solid in broken into small vaporous particles when exposed to heat. Methane is already a gas under most circumstances. It will only liquefy under extremely high pressures and/or extremely low temperatures.
When it comes to the ignition of a fuel, size matters. The smaller the fuel molecule to be ignited, the less energy it takes to cause ignition. Methane, with only one carbon atom, is the smallest hydrocarbon molecule. Studies have shown that methane can be ignited with as little as 0.25 milliJoules of energy. (By comparison, the tiny arc of cigarette lighter is about 2-4 milliJoules.)
A leaking natural gas pipeline hits the danger trifecta – hard to detect, ready to burn and requires little energy to ignite.
Regulation for the safety of gas pipelines fall under a number of national standards, including the Code of Federal Regulations (CFR 190 – 199), NFPA 54 – National Fuel Gas Code, and NFPA 58 – Liquified Petroleum Gas Code.
If you have questions about a fire or explosion – gas or otherwise – contact us at Meier Fire Investigation LLC.
Richard Meier, CFEI, CFI, CFII, CVFI