Natural gas is widely used for heating and cooking and it’s the energy source for much of our electricity. Perhaps less well known, it’s also essential for fertilizers and plastics.
The systems that store and distribute natural gas need gaskets. Here we’ll discuss the materials most often used, but first, a short primer.
Hydrocarbon Origins and Uses
Like coal and oil, natural gas is formed from plant and animal remains. Decomposition produces methane, (CH4), and when trapped underground we call it natural gas. Natural gas is odorless, so a trace of mercaptan, (CH4S) is added to make it detectable.
Reacting natural gas with steam separates the hydrogen and a second reaction, this time with air, results in NH3, or ammonia. Chemists call this the Haber process and it’s the first step in producing fertilizers.
Like methane, plastics are also composed of carbon and hydrogen atoms. The difference is that the atoms are formed into long chains to create polyethylene, polypropylene and similar materials.
Storage and Distribution
When held above 200 bar (3,000 psi) natural gas is known as compressed natural gas (CNG). This makes it sufficiently dense for use as a vehicle fuel. When pipelines aren’t an option, for easier transportation cooling to below -184°F produces liquefied natural gas (LNG).
The Sealing Challenge
The biggest issues are permeability and flammability. Simply put, the very small methane molecules can find their way through some materials, and they burn readily. Fortunately, as it’s lighter than air, escaping natural gas tends to disperse quickly.
Sealing CNG and LNG presents additional challenges. Gasket materials must retain some flexibility at very low temperatures and should have the strength to resist extrusion through joint faces.
Materials for Natural Gas Gaskets
For most low pressure, ambient temperature applications nitrile and neoprene gasket materials are the first choice. In more challenging applications many engineers opt for more expensive Flexitallic spiral wound gaskets. PTFE and graphite are other options.
Every gasket application has some unique challenges. If you need material for natural gas gaskets, ask a product specialist at Hennig Gasket for advice.
