Natural Gas & NGL Can Be Bombs: Beware of Leaks, Spills, Fires, Explosions

Natural Gas and Natural Gas Liquids are Dangerous Sources of Fires & Explosions

Report prepared by S. Tom Bond, Retired Chemist & Resident Farmer, Lewis County, WV

There are many stories about natural gas explosions. Picking one at random, “Capt. Greg Pixley, a spokesman for the Denver Fire Department, said seven bystanders were treated for minor injuries and released after a portion of a brick rowhouse was leveled in the blast just south of downtown. A man was critically injured, and a woman who was pulled from the debris is in stable condition.” The accompanying picture shows a brick building with one side blown out and the roof in ruins, an unsalvageable wreckage.

The story continues, “Pieces of wood were thrown like sticks, and bricks were spilled on the ground in front of the one-story building, which was searched by a cadaver dog.” Nine people were injured, one critically, by an apparent natural gas explosion.

Is this rare? Hardly! Natural gas provides 29% of our nations energy. More than 177 million Americans use natural gas in their homes. Accidents occur in homes, commercial buildings, in the pipelines that move it and at the point of extraction from the ground.

According to this report, 54% of home fires are started with natural gas and 47% of fires in structures not homes in the United States. 23% of civilian deaths due to home accidents are caused by these fires, and a remarkable 57% of non-home structure accidents caused by gas fires.

Natural gas and propane fires caused 169 civilian deaths per year in the 2007-2011 period, 1029 civilian injuries and caused $644,000,000 property damage per year. There are about 141 gas related structural fires responded to by fire departments each day, on average.

Often the reason these accidents happen is aged equipment. Boston recently had a series of gas fires in three towns or sections of a city that got a lot of attention in the national news. It killed one person and injured dozens. Apparently the reason was a 12 fold increase over the pressure the supply lines should be held to. Natural gas is brought down to 8 ounces per square foot to run out to you appliances to reduce the rate of leakage. (Compare with the pressure in your car tires and how fast they leak with even a tiny hole.) As a result of the series of explosions and fires the local operating utility is going to replace 48 miles of pipeline and the supporting equipment, like pressure reducing devices.

Some times fires are caused by poor maintenance. Quality labor is required. Hiring the cheapest guy who will do the job is not a good policy for the homeowner or for the utility. That is one important value of union labor, trained and supervised at the work far better than can be done by the company.

And sometimes it is simply human stupid mistakes. We rely on design to minimize them.

Bigger transmission lines explode, too. Frequently they are spectacular. One highly publicized example is the Sissionville explosion here in West Virginia. The line was built in 1967 by the NiSource subsidiary Columbia Gas Transmission. You can see a short video of the gas burning after the explosion here. It wiped out several homes, but fortunately there were no deaths. What made it particularly newsworthy was that it closed interstate highway I-77 and ruined an 800 foot section of it.

A 20 foot section of that 20 inch pipe was thrown more than 40 feet according to one account. The failure was blamed on corrosion, since more than 70% of the pipes’s thickness was gone. An in the line inspection (a device can be run through the pipe to look for such faults) would have shown the weakness, but one hadn’t been done since 1988.

How often does this sort of thing happen? “From 2010 to 2016 Gas companies reported 35 explosions and 32 ignitions at their transmission pipelines, according to federal records. These explosions killed 17 people and injured 86. A September 2010 explosion in San Bruno, Calif., killed eight and injured 51 people.” This from an article called “Natural Gas Pipeline and Infrastructure Explosions Nationwide.”

That works out to be nearly 6 explosions and over 5 such ignitions a year. So how much energy does natural gas contain?

More than you would ever dream of, probably. A simple calculation (at the end of the article for the more technically minded), shows that four thousand standard cubic feet of gas has about the same energy content as a ton of TNT! The average U. S. home uses 168 standard cubic feet (SCF) of gas a day or 61,000 a year. That’s equivalent to a ton of TNT every six days. This combustion in the home is well mixed with air to achieve the maximum efficiency, of course.

Explosions are a different matter. If the gas leaks into a tight house and occurs about the time the best mix of gas and air occurs the efficiency would be high. If not well mixed only a portion of the gas would explode but the rest would burn quickly. In explosions in buildings the inefficiently mixed gas would quickly burn and much might not burn at all. The explosion is the thing.

Careful reading of the referenced Sissonville fire article discloses that the amount of gas available in explosions depends on the distance between valves on each side of the break, how quickly those valves are turned off, pressure, and the diameter of the pipe. With gas lines like Sissonville, with the internal pressure of the gas bursting the line, the gas might go some distance before catching fire, and only a small fraction at the front edge would be mixed properly with air. The huge volume following would make a great fire, though. All the gas in the line would be released into the atmosphere, where it would burn, perhaps 20 miles of the high-pressure gas content. The radiant heat could reach far beyond the burn, well beyond the main effects of the explosion.

You see various figures for the impact zone of the new 42 inch pipelines, from 3000 feet to one mile. It’s quite significant. If it is half a mile on each side of the Atlantic Coast Pipeline, 600 square miles is within this zone – people, livestock, wildlife, timber.

There is one more class of gas fires, those that occur on well sites and compressor stations. Colorado has nearly a dozen explosions a year on well sites, according to a study at the Department of Environmental and Occupational Health at the School of Public Health. This study was based on a Colorado Oil and Gas Commission rule that only “fires or explosions that have caused harm” “to a member of the general public which requires medical treatment” or “significant damage to equipment or well site” need to be reported to the Commission. Burned workers are left out. Companies that drill wells have to provide their own fire fighters or train local departments, as we West Virginians say, “ ‘cause it ain’t like fightin’ a house fire.”

Other states that produce oil and gas certainly have the same problem. The long and the short of it is – gas is dangerous. When a company decides to put an installation on, or in many cases, near your property, you are involuntarily enlisted in their project. If you are drafted into the army, there is a finite risk you will be injured or killed, regardless of how careful you are at that work. This sacrifice is justified by the greater interest of all.

If a pipeline, pump station, or well site comes your way, there is a finite risk you will be injured or killed, or your property and family will suffer. Are you and yours soldiers? Is it for the greater interest of all? For whose interest is it, really?

Wouldn’t expediting alternate technologies that are ready to be developed be the rational course? What do you think? What can you do about it?

##########. See the Calculation Below: ########
At this site, (a reference for a college environmental course) you will find the figure one standard cubic foot of natural gas = 1.1 x 10^6 joules of energy. Here you will find a ton of TNT = 4.184 x 10^9 joules of energy.

One ton of TNT times 4.184 x 10^9 joules of energy, divided by 1.1 x 10^6 joules of energy equals approximately 4000 cubic feet of natural gas or 4 Mscf of gas. One thousand standard cubic feet (Mscf) is enough for about 6 days supply, we see above.