Detecting a Gas Line Leak
(Part Two of a series aimed at neighborhood or workplace teams)
Are you familiar with your local gas lines?
If you have tried finding the location of gas lines in your neighborhood or near your workplace you will have discovered that it takes some time and effort!
Still, using online resources and your local utility you can usually identify the route of:
Transmission lines — long-distance lines, typically more than 10” in diameter (can be as big as 42”), that move large amounts of gas under high pressure (200 – 1,200 psi)
Distribution or main lines –- operate at intermediate pressure (up to 200 psi) and are 2″ to 24″ in diameter
The lines that actually connect to your home are not so easy to track once they disappear underground. These are
Feeder or service lines – pipes less than 2” in diameter carrying odorized gas at low pressures, below 6 psi.
As mentioned in Part One of this series, utility companies are concerned about vandalism and sabotage or even terrorism, so they don’t publicize the location of these lines.
If you have a good relationship with your utility and property manager, you may be able to get some detail; we were actually able to get the construction drawings showing location and sizes of the gas lines for our community.
Action item: create a map of your location, showing the different gas lines as you identify them.
Should we assume that all these lines leak?
The gas distribution system is made up of thousands of miles of pipelines, and they operate safely nearly all of the time. Still, all of the time, the system is under one or another source of stress. The amount of gas that is “lost and unaccounted for” – and probably is mostly the result of leaks — ranges from less than 1 to over 4%.
- Built-in weaknesses from poor connections, bad welds or incorrectly installed equipment
- Corrosion or wear from aging
- Weather-related shifts (winter freeze-thaw cycles)
- Seismic shifts or earthquakes
(If you’ve seen a cracked slab under a home, you know what “seismic shifts” can do. It’s not unusual for shifts to break gas, water and/or cable lines!)
It is the responsibility of the system operators to monitor and maintain the pipelines under their jurisdiction.
In some states legislation has been introduced to require the utilities to report on leaks and on their progress in fixing them. As you can expect, the utilities oppose this legislation, saying that the number of leaks is exaggerated and that fixing more leaks faster would be too expensive. Find out about legislation in your own state!
Can we prevent a gas line leak in any of these pipelines?
But you can do your community a service by finding out what sort of gas line maintenance takes place.
And, you may be able to prevent a disaster by detecting and reporting a leak!
How can we tell if there’s a leak?
1-Use your nose!
The most common indication of a leak is SMELL. An odorizer called Mercaptan is added to feeder lines for the very purpose of making a leak noticeable.
What does Mercaptan smell like? Most people compare it to “rotten eggs.” In any case, it is distinctive and obvious.
You may be able to get “scratch ‘n’ sniff” cards from your local utility that will give you an idea of the smell.
2-Gas sniffer will help in the discovery.
If you don’t have a good nose for smells, or if you sense you might easily get used to a smell, consider investing in a gas sniffer. This is a simple hand-held gadget that can identify a leak — and some can tell you what gas is leaking – using a lighted meter and/or an audio sound (“tic, tic”). As always, the more you pay, the more capabilities you get.
Our local emergency response groups own a couple of different ones. The “pen” model (less than $40) is used by one group to check around their emergency gas generator when they start it up.
The “tube” model (around $150) adjusts from broad to fine sensitivity in order to pinpoint the precise location and type of gas that is leaking. We have used this model with startling success, using it to identify a propane leak from a gas BBQ, among other leaks.
Action item: If you suspect or are plagued with frequent leaks, you may want to add a gas sniffer to your collection of safety equipment. They are easy to operate.
Physical signs of leaks from larger pipelines
You’re not likely to find yourself walking along the route of a larger underground pipeline, but a leak can show up anywhere. Here are some ground-level signs you might notice:
- An unexpected hissing, roaring sound
- Dirt or dust blowing up from the ground
- Water bubbling or spraying
- A spot of dead or brown vegetation when it’s green everywhere else
- Flames coming from the ground
As a reminder, the gas in these larger pipes may have no odorants added.
What should we do when we discover a leak?
When you do identify a leak, you need to act quickly and decisively. Your goal is to avoid a build-up of gas around a leak or a build-up from gas “migrating” to a nearby area (such as a basement) – creating conditions for an explosion.
Your first response should be to get safely away from the area (hundreds of feet away!) and then CALL 911 or the gas line operator to GET THE GAS SHUT OFF.
As you move away, warn other people about the danger, too, and encourage them to move to safety.
Above all, DO NOT CREATE A SPARK by flipping a light switch, lighting a cigarette, starting an engine, turning on a battery-operated light, etc.
Action item: Discuss with your group the ordinary actions that someone might take that could start a gas fire. (In our community, starting up the car to “get away from the danger” is likely to be the most dangerous action possible. The catalytic converters of cars in a traffic jam can reach 1,600 degrees – plenty hot enough to start a fire!)
Is that all we can do?
Calling 911 from a safe distance is the first and most important step. Not creating a spark is the second.
Every member of your family and of your workforce should know and be able to follow this rule.
However, as an emergency response group, there is more you should know and consider when it comes to getting the gas shut off.
We will address some of these options in our next Advisory.
Your Emergency Plan Guide Team
Go any stories about gas line leaks or explosions? Feel free to share . . .! And don’t miss the first article in this series.
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