Posts Tagged ‘explosion’


Detecting a Gas Line Leak

Wednesday, January 25th, 2017
Share

(Part Two of a series aimed at neighborhood or workplace teams)

Are you familiar with your local gas lines?

Could this be leaking? What is it, anyway?

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?

Yes!

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%.

Stresses include:

  • 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?

No.

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.

 

General Tools PNG2000A Natural Gas Detector Pen

 

 

 

UEi Test Instruments CD100A Combustible Gas Leak Detector

 

 

 

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.

Virginia
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.

 

 

Are you sitting on top of a leaking gas line?

Thursday, January 19th, 2017
Share

(Part One of a series aimed at neighborhood or workplace teams)

An often-overlooked threat

Pipeline brochures

Toss as junk mail???

The word “disaster” usually makes people think about natural disasters like tornado, flood, or earthquake.  You’ve probably already talked in your group about how to prepare for these specific events.

Unless we’re reminded by notices from our local utility — Image at left shows a couple of brochures I’ve received recently — we may never even think about the gas lines that run under or near our homes or places of business.

But . . .

A gas line break can be deadly.

When a leak erupts in an explosion or fire, it’s dramatic and dangerous. Surely you remember these three big ones:

  • In 2010 an explosion in an underground gas main followed by a massive fire destroyed over 50 homes and killed 8 people in a mostly residential neighborhood in San Bruno, California. Alleged Cause: stressed system with inadequate maintenance.
  • In March 2015, two people were killed and four injured when a gas explosion in a Brooklyn, New York restaurant reduced the building to rubble and damaged neighboring businesses. Cause: leak from illegal pipe siphoning gas from restaurant to apartments above.
  • In October of 2015, the Aliso Canyon gas leak was discovered north of Los Angeles. The leak was from a well within an underground storage facility – the second-largest gas storage facility of its kind in the United States. Over 97,000 tons of methane escaped in the 5 months before the well was capped; no one was killed but hundreds of people were displaced complaining of headaches, nausea and nosebleeds. Lawsuits continue. Cause: failure of equipment at 60-year-old facility.

Have you or your group asked:

Where are the lines around you?

Finding out where the gas lines run in your neighborhood will take some effort.

In the years that we’ve been studying our own community we have run up against resistance from a number of sources. As can be expected, cities and gas line operators are concerned about sabotage and/or terrorist activities so they protect the details of their systems.

However, a good emergency response group wants to understand its community’s risks, and so perseveres . . .!

Three places to start your research.

1-The National Pipeline Mapping System (NPMS) is an online map provided by the Department of Transportation. As a member of the public you can search by your State and COUNTY to get an idea of where gas transmission and hazardous gas pipelines are located.

I say “get an idea” because the public viewer is good only to +/- 500 ft.  (If you are actually going to dig, then you need to contact your local pipeline operator – or call 811 – to find out exactly where the pipes are.)

Here’s the link to the map (“Public Map Viewer”):  https://www.npms.phmsa.dot.gov/Default.aspx

2-Your local gas company

Here in California we have two of the largest public utilities in the country, and our local utility provides a map showing transmission and distribution lines. Once again, the authors of the map stress that the maps are accurate only to +/- 500 ft. Still, we can easily identify the “hazardous liquid” line running along the railroad tracks very near our home.

My research on other utility companies shows that there is no consistency. Many of the websites simply refer readers to the National Pipeline Mapping System.

3-Your local pipeline operator

The pipeline operator is not necessarily the same as the utility.

Keep your eye open for pipeline signs. They are not required, nor are they necessarily placed in the same way every time. What they seem to have in common is the gold color.

The round warning sign will tell you who the pipeline operator is. (You’ll see a round sign on the brochure in the image above, too.) Write down the name and emergency phone number. You may be able to get further information about that particular pipeline and what it carries from the operator.

Kinder/Morgan is the largest pipeline operator in the country, transporting nearly 40% of all piped natural gas, refined petroleum products, crude oil, carbon dioxide (CO2) and more. I found this map at their website. It shows their biggest pipes.

Kinder/Morgan PipelinesThe point of all this is that with some digging (bad joke!) you can discover a lot about where pipelines are located in your community.

How we got information about our own community.

This Advisory is meant to give you an idea of where to start. Different members of our neighborhood emergency response group took on different tasks in researching our gas pipelines.

  • I tracked down online maps like the ones shown in this Advisory.
  • One member hiked along the railroad tracks and photographed a construction project showing the size and exact location of gas lines.
  • One member went to city hall to get the original construction drawings for our community. These drawings showed not only the location but also the size of the various pipes in the network, plus shut-off valves.
  • As a group we queried the management of our community regarding make-up and maintenance of our local system.
  • Our group invited the fire department, the police department and our local utility to special meetings on gas safety. (You will not be surprised to learn that they don’t always agree on where the lines are, what information to share or how to respond in an emergency!)

OK, so we know where the pipelines are and what they are carrying.

Now, how to prevent an explosion or fire?

Gas is leaking from all these systems all the time! Most of the time the gas that escapes isn’t even noticed (except by the atmosphere, of course, since methane – the main component of natural gas – is 30 times more potent as a heat trapping gas than CO2.)

But any time there’s a leak, there’s a potential for explosion or fire.

In our next Advisory we’ll share what we have learned about recognizing a leak when you see, hear or smell one, and what to do when you find one.

Stay tuned for Part Two.

Virginia Nicols
Your Emergency Plan Guide Team

 

 

Gas Line Leak!

Sunday, January 20th, 2013
Share

High pressure lines are closely monitored by a number of agencies.  Your local utility or city will be the most familiar with the state of high pressure lines in your area, and with the monitoring guidelines and records.

Gas fire in street.

Gas fire erupting through LA street after Northridge earthquake. (photo by M. Rymer)

No matter how carefully lines are monitored, however, leaks and breaks can happen.  Most often, they happen when construction equipment accidentally punctures a line.  They can result from a natural event like a storm, earthquake, tornado, or ice storm.  Sometimes an over-loaded, aged infrastructure is to blame.

Leaks could happen at any time.

How do your local gas lines stack up?

An online search using the National Pipeline Mapping system is a good place to start. Dig deep on that site to find the names of the various operators of the different lines in your area. Contact them to get more details about the age and condition of their lines, their monitoring and safety policies and plans, etc.

If you think you have an emergency…

If you see or hear any of these near a pipeline right-of-way, it could signal a leak:

  • A hissing, roaring sound
  • Dirt or dust blowing
  • Water bubbling or spraying
  • Dead or brown vegetation
  • Flames coming from the ground
  • “Rotten egg” smell

(Typically the “rotten egg” smell is added only to smaller distribution lines. It won’t appear in major transmission lines.)

What’s the right response to a potential gas leak?

Get out! But do it intelligently.

  • Turn off any machinery or motors.
  • Don’t turn on or use any electrical equipment that could create a spark. This includes turning lights on or off, making a cell phone call, closing a garage door, or using a battery-operated radio!
  • Do not allow any open flames, including matches, cigarette lighters, welding equipment, etc.
  • Evacuate the immediate area. If exiting a building, leave the doors open.
  • Keep bystanders away.
  • Do not try to find the source of the leak.
  • Do not operate any valves or other shut-offs.
  • Do not attempt any repairs.
  • Do not attempt to put out any fires.
  • From a safe distance, call 911.

Emergency Preparedness Training

Action Item: Train your Emergency Response Team to recognize this hazard and to respond accordingly. Our “Neighborhood Plan” provides more detailed suggestions for effective training, including experts to invite to an organizational meeting.