How Can I Learn More about Natural Gas Design?

CRAIG GIFFORD:
Welcome to Ask Swagelok. I'm your host, Craig Gifford, and we're here today with Chuck Hayes, who's Swagelok's Global Technical Lead for clean energy. We're talking about natural gas.

And so Chuck, let's just start the conversation with what are the different types of natural gas and why are there different forms of it?

CHUCK HAYES:
Sure. So natural gas in its basic format is always methane. So that's CH4 – one carbon, four hydrogens make up natural gas. But we deal with it in different ways. We give it different names. You can have it coming to your home through pipelines and used for your furnace, hot water tank, and stove. It's used like that around the world.

But there are also other forms. Other forms can include compressed natural gas, or CNG. We compress it because we want to get more molecules in for transport or use. We increase the pressure to about 3600 PSI, which is approximately 249 bar. One bar is equivalent to one atmosphere, so you're getting about 250 times compression.

Another form is LNG, or liquid natural gas. That's used when we need to move a lot of gas a long distance. We liquefy it and move it as a liquid. You can't compress a liquid, but you get a lot more molecules in – about 600 bar, or 600 atmospheres. If you were to open it up, it would take up the room of 600 kilograms of area that other gases would occupy.

The last one is renewable natural gas, or RNG. It's newer and has different names. In North America it's called RNG; in some places it's called biogas. It comes from waste streams, like animal pens or biodigesters that break down farm waste. Raw biogas still has some impurities like sulfur, siloxanes, and nitrogen/oxygen compounds. We remove these, dry it, pressurize it, and it can be used as gas. If we purify it fully, it becomes essentially natural gas again.

CRAIG GIFFORD:
So Chuck, what are the different types of distribution and refueling infrastructure for natural gas and what are some of the challenges associated with that?

CHUCK HAYES:
Sure. Talking about refueling infrastructure, we're talking about trucks, cars, and possibly ships. CNG and RNG are chemically the same – CH4 in gaseous form and pressurized. We use these to fill trucks, delivery vehicles, buses. Refueling is often done at fueling stations, either roadside truck stops for long-distance travel or at a company's own fleet facility. There, a header line feeds all the trucks in a row, connected via hoses that slowly fill the vehicles overnight. This doesn't work cross-country, so trucks rely on fast-fill stations, which fill a truck in 10–20 minutes.

LNG is liquid and very cold, which can be dangerous. You can get cold burns and need special clamping mechanisms and personal protective equipment, plus extra training. Sometimes operators load it themselves; sometimes trained personnel at the station do it. Ships also use LNG as an alternative fuel, because heavy fuel oil is restricted in ports and littoral waters. LNG is then gasified for use. Large tankers transport CNG or LNG overseas. Key challenges include compression for CNG, safe storage with tanks and containers, and leak-free components. For LNG, the cold temperatures add extra challenges.

CRAIG GIFFORD:
What are the pertinent LNG and CNG standards that designers need to be aware of?

CHUCK HAYES:
That's a great question. It depends on the region. For CNG on vehicles in North America, CSA (Canadian Standards Association) manages safety standards. NGV (Natural Gas Vehicle) standards starting with 3, like NGV 3.1, cover on-vehicle components and how they must be tested. LNG standards follow a similar pattern. In Europe, ECE R110 governs on-vehicle standards with different certifications. We work to harmonize standards across continents.

For stations, NGV standards in the 4A series specify components and assembly requirements. Different countries may adapt international ISO standards with local variations. India, for example, bases standards on ISO but adds its own modifications.

CRAIG GIFFORD:
Tell us what are some key considerations for safety when it comes to CNG and LNG storage?

CHUCK HAYES:
Sure. CNG is designed to be used and burned in a combustion chamber – it’s flammable and potentially explosive, so containment is critical. LNG is stored as a liquid and gasified for use. In both cases, high-quality products and adherence to standards are essential – low leak rates, proper valves, and fittings. Swagelok can help with this. Good design is important as well. LNG adds extra risks because it is extremely cold – cold burns, freezing lungs, and rapid expansion (600:1) can release significant energy. Keeping systems leak-free and safe prevents accidental releases and ensures safety.

CRAIG GIFFORD:
Well, thank you for sharing your knowledge with us, Chuck, and thank you for joining us at Ask Swagelok.