Natural Gas Safety
Safe, Sound, and Underground
NGC has just over 1,000 km of natural gas pipelines criss-crossing Trinidad, part of Tobago, and under the sea, off the north coast and south-east coast. Some of these pipelines are as small as 6” or 8”, but some are as large as 30” and 36” in diameter. NGC’s largest pipeline is 56” wide!
Every day, these pipelines carry as much as 3 billion cubic feet (bcf) of natural gas per day, to roughly 150 consumers.
That’s a lot of gas, going to a lot of different places. And, as you know, natural gas is flammable. So how does NGC keep us safe from leaks and accidental damage to their lines?
Safety is everything
NGC is a national company. It was created by and is run by Trinidadians and Tobagonians, people just like you and me. Your safety is more important to us than the gas that we transport and sell, so in everything that we do we always make safety our priority.
There are many ways in which we keep our operations safe. Here are just a few.
We design our pipelines to be safe
Most of our pipelines are made of heavy carbon steel, which is very strong and stands up well to rust. The walls of our pipelines are always slightly thicker than they need to be, so that even if they do rust a little, they are still strong enough to withstand the pressure of gas being pumped through them.
We bury our pipelines deep
Have you ever seen a natural gas pipeline? Not likely, because we bury them deep underground. Most pipelines are buried between 4 and 6 feet deep. Some of our larger ones are buried even deeper.
This way, the pipelines are safe from accidental damage; for example, they cannot be hit by a car if it runs off the road. They are also protected from tampering by people who would like to do them damage, or from interference by curious children.
There are hardly ever any leaks on NGC’s lines, but if there are any, the depth of the ground helps to minimise the amount of gas released into the air.
We mark our pipelines properly
You can always tell where NGC’s pipelines are, because we mark the area where pipelines run (called a pipeline Right of Way or ROW) with yellow marker posts like this one.
In places where we can’t use posts, such as along roadways, we mark the pipeline ROW with yellow stencils or metal plates that lie flat against the ground, like these:
This way, you always know there are pipelines nearby, so you know to be careful. For example, a person digging with a tractor will see the pipeline marker, and know not to dig in that area without permission.
If you do see someone digging near a pipeline marker, please call NGC on our 24-hour hotline, 800-4GAS, or 800-4427. We’ll send someone out right away to tell them where it is safe to dig. And it doesn’t cost a penny!
We check on our pipelines all the time
There are many ways we make sure that our pipelines aren’t leaking. Our pipelines are monitored by a system called SCADA, which electronically checks every inch of the lines for changes in pressure, temperature, etc., or any sign that all is not well with the line.
The SCADA system sends signals to operators who monitor their equipment 24 hours a day. They are trained to respond to any changes in the pipeline network. If there is an emergency, they can respond immediately and make sure that NGC’s technicians fix the problem as soon as they can.
We keep our pipelines from rusting
A few of our smaller pipelines are made from very strong plastic, called High Density Polyethylene or HDPE. Plastic, of course, doesn’t rust, so those don’t pose a problem.
However, most of our pipelines are made from metal. Because they are buried in the ground, they are exposed to moisture and oxygen, which together cause metals to rust. There are many ways to prevent this problem.
- We coat our pipelines with rust-resistant materials, such as fabric dipped in a tar-like substance, or spray them with a powder that forms a strong coating when heated. This keeps moisture away from the pipeline.
- We add a chemical to the natural gas stream that coats the inside of the pipeline to protect it internally from rust.
- We use a system called cathodic protection. Rusting is an electrical phenomenon, and rust happens more frequently when metal is positively charged. So if we send very small negative electrical currents along the outside of the pipeline, we lower the chance of rust because rust is less attracted to it.
- We also place small positively charged pieces of metal a short distance from the line, to attract the rust away from the pipeline. It’s a bit like putting a cupcake in your garden to distract the ants from the birthday cake on your table.
- We use probes, which are very sensitive instruments shaped like long spikes, to test the pipeline at intervals. The probes are pushed deep into the earth above the line, and the flow of electricity is measured. If the flow changes suddenly, we know that there may be a leak in that section of the pipeline.
- Pipelines out in the sea are even more likely to rust because of the salt water, so we coat these with concrete to keep the rust away. This also makes them heavy, so they stay at the bottom of the sea.
We keep our Right of Way clear
NGC doesn’t allow anyone to build structures, plant trees or crops, or keep animals near the pipeline Right of Way. We also regularly cut the bushes in the area.
It is always kept clear so that if there is an emergency we can quickly get to the site and act on the problem.
In places where the pipeline comes above ground to enter a valve station or monitoring facility, where the flow of gas is controlled or measured, the area is fenced, to keep people out so they don’t hurt themselves or others.
We make our gas smell awful
Most of the natural gas in Trinidad and Tobago has no smell. We call it sweet gas. (In some countries, gas has a sour smell, and it is called sour gas).
But natural gas is colourless as well, so how can people tell of these is a leak?
In heavily built up areas, or in places where there a lot of people, like schools and malls, we add a chemical called mercaptan to the gas. It smells awful, like rotten eggs, but won’t harm you.
This way, if you smell rotten eggs near a pipeline, you know there may be a leak, so you can get to safety quickly.
We teach others how to be safe
NGC teaches people who live, work, or go to school near pipelines how to be safe in case of a pipeline emergency. We regularly hold emergency drills to teach our staff and others what to do if there is a leak, and we go to schools, exhibitions and communities to let everyone know how to be safe and smart near a pipeline.
Here are a few things you need to know:
How pipeline leaks are caused
As you can see, natural gas pipelines are very safe because of how they are built and how they are operated. But leaks can sometimes happen. Most leaks are caused by:
- Digging too close to the pipeline
How to tell if there is a leak
Small, slow leaks can be spotted in 3 ways:
- Grass above the pipeline turns brown in patches
- You can see bubbles in puddles of water above the line
- You smell rotten eggs.
A large and sudden rupture, such as one that might take place with a landslide, will probably make a loud booming noise as the gas escapes very fast. You may see dirt and plants being thrown into the air, and even a jet of fuel spouting upward like a fountain.
Don’t panic! Just follow the rules and you and everyone else will be safe.
How to respond to a natural gas emergency
Here’s what you do if you think there is a natural gas leak:
Shut off sources of ignition
If there is natural gas in the air, a single spark can cause a fire. Don’t use any electrical or electronic item, including a land line or cell phone. Don’t turn light switches on or off. Don’t start a vehicle. If the stove is on, turn it off.
Leave the area on foot
Notify someone, and together you must leave the area. If there is anyone in your home who is too weak or ill to walk, have someone help them leave the house. Move upwind or crosswind of the area, so that the gas does not blow towards you.
Once you are away from the area, call NGC on our 24-hour hotline, 800-4GAS or 800-4427. We will immediately send someone out to investigate and rectify the problem.
Don’t return until you get an all-clear.
Don’t go back to your home unless someone on a clearly marked NGC uniform or a member of the Police or Fire Services tells you it is safe. Obey instructions, and everything will be okay
Some natural gas safety facts
- Natural gas is not toxic, but it replaces air. This means that if you are in a confined space filled with gas, you may suffocate. Leave the area at once.
- Gas fills a confined space from the top down, so as you leave, stoop low where the air is cleaner.
- Natural gas is only flammable within a very small range of concentration. If there is too little gas (less than 5%) or too much (more than 15%) in the air, it will not catch fire.
Let NGC show you how!
Finally, if you live near a natural gas pipeline, ask an adult to organise a natural gas safety lesson for everyone in your community. Or ask your teacher to organise a safety drill or briefing at your school. NGC would be happy to come out to your community or school to show you how it is done. We don’t charge for our visits!
NGC’s 24-Hour Hotline: 800-4427 or 800-4GAS
Remember: Be Safe and Be Smart